Calcium hydride purity detection method

Abstract

The invention relates to a calcium hydride purity detection method, which comprises the following steps: weighing calcium hydride particles with a predetermined mass, and carrying out hydrolysis reaction to obtain a first mixed solution containing calcium hydroxide and a substance amount for releasing gas; diluting the first mixed solution to a constant volume, adding deionized water to the constant volume in a volumetric flask, and keeping the constant volume diluted second mixed solution for later use; adding the light pink solution into the second mixed solution to obtain a third mixed solution, adding a hydrochloric acid standard solution into an acid burette for titration until the third mixed solution becomes colorless from amaranth, namely a titration end point, and recording the volume of the consumed standard hydrochloric acid titration solution, obtaining the amount of substance of hydroxyl ions based on the volume of the consumed hydrochloric acid standard solution; the amount of substance of calcium hydroxide in the solution is obtained on the basis of the difference between the amount of substance of hydroxyl ions, and the purity of calcium hydride is obtained by simultaneous calculation on the basis of the amount of substance of calcium hydroxide, the predetermined amount of calcium hydride particles and the amount of substance of hydrogen and gas release.

Description

Technical Field

[0001] The present invention relates to the technical field of calcium hydride detection, and particularly to a method for detecting the purity of calcium hydride generated by the direct hydrogenation reaction of metallic calcium. Background Art

[0002] At present, the methods for detecting the purity of calcium hydride at home and abroad are the method combining hydrogen evolution by hydrolysis and acid-base titration or other large-scale detection equipment, such as inductively coupled plasma mass spectrometry analysis, X-ray fluorescence spectrometry analysis, etc. In the method combining hydrogen evolution method and acid-base titration, after adding phenolphthalein solution to the solution after hydrogen evolution, the hydrochloric acid standard titration solution is directly used for titration until the solution changes from colorless to purplish red as the judgment end point. Although this method takes into account the influence of metallic calcium, it ignores that calcium hydroxide generated after hydrogen evolution by hydrolysis of calcium hydride and metallic calcium is a slightly soluble substance, which results in that hydroxide ions do not exist in ionic state in the solution after hydrogen evolution by hydrolysis, so that the titration result of hydrochloric acid is lower than the true value, causing a large detection error. Inductively coupled plasma mass spectrometry analysis and X-ray fluorescence spectrometry analysis can only give the content of elements correspondingly, and it is difficult to detect light elements such as hydrogen. Therefore, calcium hydride and metallic calcium cannot be distinguished either, the detection accuracy is low, and the corresponding detection conditions and detection environment requirements are high. The equipment itself is of high value, and the detection requires equipment operation training for the detection personnel, with high operation difficulty and poor universality.

[0003] The above information disclosed in the background art part is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0004] The present invention provides a method for detecting the purity of calcium hydride, which can reduce the detection error of the purity of calcium hydride.

[0005] A method for detecting the purity of calcium hydride includes:

[0006] Weigh a predetermined mass of calcium hydride particles and carry out a hydrolysis reaction to obtain a first mixed solution containing calcium hydroxide and the amount of substance of the released gas;

[0007] Dilute and make the volume constant for the first mixed solution, and take an appropriate amount of the second mixed solution after dilution and volume constant for standby;

[0008] Prepare a sucrose solution with a certain concentration, take an appropriate amount of the prepared sucrose solution in a small beaker, add 1 drop of phenolphthalein indicator solution, shake well, then add sodium hydroxide standard titration solution until the solution changes from colorless to light pink, and add the light pink solution to the second mixed solution to obtain a third mixed solution;

[0009] Add a hydrochloric acid standard solution to an acid burette for titration until the third mixed solution changes from purple-red to colorless, record the volume of the standard hydrochloric acid titration solution consumed, and obtain the amount of the substance of hydroxide ion based on the volume of the hydrochloric acid standard solution consumed;

[0010] Conduct a blank experiment to obtain the amount of hydroxide ion substance in the blank experiment;

[0011] The amount of calcium hydroxide in the solution is obtained based on the difference in the amount of hydroxide ions, and the purity of calcium hydride is obtained by joint calculation based on the amount of calcium hydroxide, the predetermined mass of the calcium hydride particles, and the amount of hydrogen released and released gas.

[0012] In the method for detecting the purity of calcium hydride, before the hydrolysis reaction, a hydrogen release device is built, a conical flask is connected to a constant pressure separatory funnel for adding deionized water, a gas measuring tube is connected to the conical flask via a valve for opening and closing, a level bottle is connected to the gas measuring tube from the bottom, and the gas measuring tube is provided with a thermometer for measuring temperature.

[0013] In the method for detecting the purity of calcium hydride, a predetermined amount of calcium hydride particles is weighed and placed in a conical flask, deionized water is added to a constant pressure separatory funnel, the valve above the gas burette is opened, the position of the level bottle is adjusted so that the liquid level in the gas burette is consistent with the level bottle and the liquid level is at the "0" scale line, the valve is closed at this time, the valve of the constant pressure separatory funnel is opened, deionized water is added to the conical flask, the calcium hydride sample is hydrolyzed and hydrogenated, after the hydrogen release is completed, it is allowed to stand and cool until the gas temperature in the gas burette is consistent with the indoor temperature, the level bottle is moved so that the liquid level of the level bottle is consistent with the liquid level in the gas burette, and the atmospheric pressure and the indoor temperature values ​​are recorded at the same time to obtain the amount of the substance generating the gas, and at the same time, a first mixed solution containing calcium hydroxide is obtained.

[0014] In the calcium hydride purity detection method, 20 ml of deionized water is added to a constant pressure separatory funnel, and after the hydrogen release is completed, the funnel is left to stand for more than 30 minutes.

[0015] In the calcium hydride purity detection method, the calcium hydride to be detected is pressed into tablets and crushed to obtain calcium hydride particles.

[0016] In the calcium hydride purity detection method, the amount of hydroxide ion substance in the titration solution is calculated according to the concentration and volume of the hydrochloric acid standard titration solution; and the amount of hydroxide ion substance in the blank experiment is calculated at the same time.

[0017] In the method for detecting the purity of calcium hydride, the amount of hydroxide ions in the titration solution is calculated by the following formula:

[0018] n OH - =c HCl vHCl ,

[0019] in:

[0020] n OH - : The amount of hydroxide ion in the titration solution, unit (mol);

[0021] C HCl : The concentration of the hydrochloric acid standard solution used for titration, unit (mol / L);

[0022] v HCl : The volume of hydrochloric acid standard solution consumed in titration, unit (L);

[0023] The amount of hydroxide ion in the blank experiment was calculated by the following formula:

[0024] n 空白 =c 空白HCl V 空白HCl ,

[0025] in:

[0026] n 空白 : The amount of hydroxide ion in the solution in the blank experiment, unit (mol);

[0027] c 空白HCl : The concentration of the standard hydrochloric acid titration solution in the blank experiment, unit (mol / L);

[0028] V 空白HCl : The volume of hydrochloric acid standard solution consumed in the blank experiment, unit (L);

[0029] After obtaining the amount of substance of hydroxide ions in the titration experiment and the blank experiment, the amount of substance of calcium hydroxide in the first solution is obtained according to the following formula:

[0030] n Ca(OH)2 =0.5*(n oH - -n 空白 );

[0031] Comprehensive hydrogen release and acid-base titration chemical reaction formula, simultaneous equation:

[0032] The chemical equation for the release of hydrogen from calcium hydride is:

[0033] CaH 2 +2H 2 O=Ca(OH) 2 ↓+2H 2 ↑………………Chemical reaction formula

[0034]

[0035] The chemical equation for the release of hydrogen from metallic calcium is

[0036] Ca + 2H 2 O=Ca(OH) 2 ↓+H 2 ↑………………Chemical reaction formula

[0037]

[0038] The following equations are obtained:

[0039]

[0040] It can be deduced that the purity of calcium hydride in the sample is:

[0041]

[0042] The parameters are explained as follows:

[0043] ω CaH2 : The mass fraction of calcium hydride in the test sample;

[0044] P: The difference between the atmospheric pressure recorded after the hydrogen release reaction ends and the saturated vapor pressure of water at the temperature at that time, unit (Pa);

[0045] V: The volume of gas in the gas tube after the hydrogen release reaction is completed, unit (ml);

[0046] R: gas constant;

[0047] T: the indoor temperature value recorded after the hydrogen release reaction is completed, unit (℃);

[0048] n Ca(OH)2 : The calculated amount of calcium hydroxide in the first solution, unit (mol);

[0049] m: The mass of the calcium hydride sample weighed during hydrolysis, unit (g).

[0050] In the calcium hydride purity detection method, the gas constant is 8.314 J / (mol·K).

[0051] In the calcium hydride purity detection method, in step S6, the second mixed solution is placed on a magnetic stirrer for stirring and shaking to obtain a third mixed solution.

[0052] In the method for detecting the purity of calcium hydride, calcium hydride particles are weighed with a 1 / 10,000 balance and placed in a conical flask under an argon or nitrogen atmosphere.

[0053] Compared with the prior art, the present invention has the following advantages: The present invention avoids the detection differences caused by ignoring the slightly soluble characteristics of calcium hydroxide in the combined detection process of the existing hydrolysis hydrogen evolution method and acid-base titration method, and greatly improves the detection accuracy; at the same time, this method greatly reduces the operation requirements and detection costs. In the detection process disclosed herein, the data to be read, the concentration and volume of the standard solution used are all objective readings, and the sucrose solution selected in the present disclosure can well dissolve calcium hydroxide slightly soluble in water, so that hydroxide ions exist in the solution in the form of ions to the greatest extent, making the acid-base titration result more accurate. For the above reasons, the result of the detection method disclosed herein has high accuracy and good stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] By reading the following detailed description of the preferred specific embodiments, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The accompanying drawings of the specification are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Obviously, the following-described drawings are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts. Moreover, throughout the drawings, the same reference numerals are used to represent the same components.

[0055] In the drawings:

[0056] Figure 1 is a schematic diagram of the hydrogen evolution device in the hydrogen evolution stage required for a preferred embodiment of the present invention;

[0057] Figure 2 is a schematic diagram of the process flow of a method of a preferred embodiment of the present invention.

[0058] The following further explains the present invention in conjunction with the drawings and embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0059] The specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the specific embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present invention can be more thoroughly understood and the scope of the present invention can be completely conveyed to those skilled in the art.

[0060] It should be noted that in the description and claims, certain terms are used to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. The description and claims of this specification do not distinguish components by the difference in nouns, but by the difference in the functions of the components. As mentioned throughout the description and claims, the term "comprising" or "including" is an open-ended term and should be interpreted as "including but not limited to". The following description of the specification is the preferred embodiment for implementing the present invention, but the description is for the purpose of the general principles of the specification and is not intended to limit the scope of the present invention. The protection scope of the present invention shall be subject to that defined by the appended claims.

[0061] For the convenience of understanding the embodiments of the present invention, the following will further explain with specific examples in conjunction with the drawings, and each drawing does not constitute a limitation on the embodiments of the present invention.

[0062] As Figures 1 to 2 shown, the calcium hydride purity detection method includes the following steps:

[0063] Weigh a predetermined amount of calcium hydride particles and perform a hydrolysis reaction to obtain a first mixed solution containing calcium hydroxide and the amount of substance of the released gas;

[0064] Dilute and make up the volume of the first mixed solution, add deionized water to make up the volume in a volumetric flask, and take a certain amount of the second mixed solution after dilution and volumetric fixation for standby under a shaken state;

[0065] Prepare a sucrose solution with a certain concentration, take an appropriate amount of the sucrose solution in a small beaker, add 1 drop of phenolphthalein indicator solution, shake well, then add a sodium hydroxide standard titration solution dropwise until the solution changes from colorless to light pink, add the light pink solution to the second mixed solution to obtain a third mixed solution, and add 2 - 3 drops of phenolphthalein indicator to the third mixed solution. At this time, the third mixed solution is in a magenta state;

[0066] Add a hydrochloric acid standard solution to an acid burette for titration until the third mixed solution changes from magenta to colorless, which is the titration end point. Record the volume of the standard hydrochloric acid titration solution consumed, and obtain the amount of substance of hydroxide ions based on the volume of the consumed hydrochloric acid standard solution;

[0067] Conduct a blank experiment. Titrate the same volume of deionized water after adding the same amount of sucrose solution with a hydrochloric acid standard titration solution until the solution changes from magenta to colorless at the end point. Record the volume of the hydrochloric acid standard titration solution consumed during the blank experiment, and obtain the amount of substance of hydroxide ions in the blank experiment;

[0068] Based on the difference in the amount of substance of hydroxide ions, the amount of substance of calcium hydroxide in the solution is obtained. Based on the amount of substance of calcium hydroxide, the predetermined amount of calcium hydride particles, and the amount of substance of the released hydrogen gas, the purity of calcium hydride is calculated by simultaneous calculation.

[0069] In a preferred embodiment of the method for detecting the purity of calcium hydride, before the hydrolysis reaction, a hydrogen release device is set up. A constant-pressure separating funnel for adding deionized water is connected to the triangular flask. The gas measuring tube is connected to the triangular flask via a valve for opening and closing. The leveling bottle is connected to the gas measuring tube from the bottom. The gas measuring tube is provided with a thermometer for measuring temperature.

[0070] In a preferred embodiment of the method for detecting the purity of calcium hydride, a predetermined amount of calcium hydride particles is weighed and placed in a triangular flask. Deionized water is added to the constant-pressure separating funnel. The valve above the gas measuring tube is opened, and the position of the leveling bottle is adjusted so that the liquid level in the gas measuring tube is the same as that in the leveling bottle and the liquid level is at the "0" scale line. At this time, the valve is closed, and the valve of the constant-pressure separating funnel is opened to add deionized water to the triangular flask to cause the calcium hydride sample to hydrolyze and release hydrogen. After the hydrogen release ends, it is left to stand and cool until the temperature of the gas in the gas measuring tube is the same as the indoor temperature. The leveling bottle is moved so that the liquid level in the leveling bottle is the same as the liquid level in the gas measuring tube. At the same time, the atmospheric pressure and the indoor temperature value are recorded to obtain the amount of substance of the generated gas, and a first mixed solution containing calcium hydroxide is obtained simultaneously.

[0071] In a preferred embodiment of the method for detecting the purity of calcium hydride, 20 ml of deionized water is added to the constant-pressure separating funnel. After the hydrogen release ends, it is left to stand for more than 30 minutes.

[0072] In a preferred embodiment of the method for detecting the purity of calcium hydride, the calcium hydride to be measured is pressed into tablets and crushed to obtain calcium hydride particles.

[0073] In a preferred embodiment of the method for detecting the purity of calcium hydride, the amount of substance of hydroxide ions in the titration solution is calculated according to the concentration and volume of the hydrochloric acid standard titration solution; at the same time, the amount of substance of hydroxide ions in the blank experiment is calculated.

[0074] In a preferred embodiment of the method for detecting the purity of calcium hydride, the amount of substance of hydroxide ions in the titration solution is calculated by the following formula:

[0075] n OH - =c HCl v HCl ,

[0076] Where:

[0077] n OH - : The amount of substance of hydroxide ions in the titration solution, unit (mol);

[0078] c HCl : The concentration of the hydrochloric acid standard solution used for titration, unit (mol / L);

[0079] v HCl : The volume of hydrochloric acid standard solution consumed in titration, unit (L);

[0080] The amount of hydroxide ion in the blank experiment was calculated by the following formula:

[0081] n 空白 =c 空白HCl V 空白HCl ,

[0082] in:

[0083] n 空白 : The amount of hydroxide ion in the solution in the blank experiment, unit (mol);

[0084] c 空白HCl : The concentration of the standard hydrochloric acid titration solution in the blank experiment, unit (mol / L);

[0085] V 空白HCl : The volume of hydrochloric acid standard solution consumed in the blank experiment, unit (L);

[0086] After obtaining the amount of substance of hydroxide ions in the titration experiment and the blank experiment, the amount of substance of calcium hydroxide in the first solution is obtained according to the following formula:

[0087] n Ca(OH)2 =0.5*(n OH - -n 空白 );

[0088] Comprehensive hydrogen release and acid-base titration chemical reaction formula, simultaneous equation:

[0089] The chemical equation for the release of hydrogen from calcium hydride is:

[0090] CaH 2 +2H 2 O=Ca(OH) 2 ↓+2H 2 ↑………………Chemical reaction formula

[0091]

[0092] The chemical equation for the release of hydrogen from metallic calcium is

[0093] Ca + 2H 2 O=Ca(OH) 2 ↓+H 2 ↑………………Chemical reaction formula

[0094]

[0095] Simultaneous equations yield the following equations:

[0096]

[0097] From this, the purity of calcium hydride in the sample is deduced as:

[0098]

[0099] The parameter explanations are as follows:

[0100] ω CaH2 : mass fraction of calcium hydride in the test sample;

[0101] P: the difference between the value of the atmospheric pressure recorded after the hydrogen release reaction and the saturated vapor pressure of water at the time temperature, unit (Pa);

[0102] V: the volume of the gas in the gas burette recorded after the hydrogen release reaction, unit (ml);

[0103] R: gas constant;

[0104] T: the indoor temperature value recorded after the hydrogen release reaction, unit (°C);

[0105] n Ca(OH)2 : the amount of substance of calcium hydroxide in the first solution calculated, unit (mol);

[0106] m: the mass of the calcium hydride sample weighed during hydrolysis, unit (g).

[0107] In the described method for detecting the purity of calcium hydride, the gas constant is 8.314 J / (mol·K).

[0108] In a preferred embodiment of the described method for detecting the purity of calcium hydride, in step S6, the second mixed solution is placed on a magnetic stirrer and stirred and shaken to obtain a third mixed solution.

[0109] In a preferred embodiment of the described method for detecting the purity of calcium hydride, under an argon or nitrogen atmosphere, calcium hydride particles are weighed with a ten-thousandth balance and placed in a triangular flask.

[0110] In one embodiment, a method for detecting the purity of calcium hydride includes the following steps:

[0111] 1. Under an argon or nitrogen atmosphere, weigh 0.2141 g of calcium hydride particles with a ten-thousandth balance and place them in a triangular flask.

[0112] In this step, by pressing the calcium hydride powder into tablets and then crushing it into particles, the phenomenon of powder flying and sticking to the wall in the process of putting the calcium hydride powder into the conical flask can be avoided, thereby minimizing the detection error caused by the sample powder in the bottle mouth part due to the inability to hydrolyze;

[0113] 2. Add a certain amount of deionized water (for example, 20 ml, which can meet the hydrolysis requirements) to the constant pressure separatory funnel, adjust the hydrogen release device to allow the deionized water to hydrolyze the calcium hydride sample. After the reaction is completed, let it stand for more than 30 minutes (30 minutes is a reference value here, and the actual test can be carried out according to the change of ambient temperature. Take a suitable time) until the temperature in the gas collecting pipe is consistent with the indoor temperature, move the level bottle so that the liquid level of the level bottle is flush with the liquid level in the gas collecting pipe, and read the corresponding atmospheric pressure, indoor temperature, and gas volume readings. At the same time, obtain the first mixed solution containing calcium hydroxide;

[0114] 3. After the hydrolysis reaction is completed, add deionized water to the first mixed solution containing calcium hydroxide to a 100 ml volumetric flask, and take 5 ml of the second mixed solution diluted to the same volume while shaking for later use;

[0115] 4. Prepare 300 g / L sucrose solution, take 50 ml in a small beaker, add 1 drop of phenolphthalein indicator solution, shake well, add sodium hydroxide standard titration solution until the solution changes from colorless to light pink, add the light pink solution to 5 ml of the second mixed solution taken in step 3, the specific data described here are also exemplary, and can be adjusted according to actual conditions, place on a magnetic stirrer for stirring and shaking to obtain a third mixed solution;

[0116] In this step, the calcium hydroxide aqueous solution is added to the sucrose solution and stirred sufficiently to completely dissolve the calcium hydroxide in the sucrose solution, so that the hydroxide is completely present in the solution in the form of ions.

[0117] 5. Add 2 to 3 drops of phenolphthalein indicator to the third mixed solution. At this time, the solution is purple-red;

[0118] 6. Add 0.1026 mol / L hydrochloric acid standard titration solution to a 5 ml micro-acid burette, and add 0.1026 mol / L hydrochloric acid standard titration solution dropwise to the third mixed solution containing calcium hydroxide, sucrose solution and phenolphthalein indicator solution. The concentration and dosage of the hydrochloric acid standard titration solution described here are also exemplary and can be adjusted according to actual conditions. Titrate until the solution changes from purple-red to colorless, which is the titration endpoint, and record the volume of the standard hydrochloric acid titration solution consumed;

[0119] In this step, a standard hydrochloric acid titration solution is added to the third mixture, so that the calcium hydroxide in the solution reacts with the hydrochloric acid to undergo a neutralization reaction. The specific reaction is shown in the following formula:

[0120] OH - +H + →H 2 O

[0121] 7. Take 5 ml of deionized water, place it in a duckbill flask, add the same 50 ml of light pink sucrose solution as in step 4. Add a standard hydrochloric acid titrant solution with a concentration of 0.1026 mol / l to a 5 ml micro burette (the concentration and dosage of the hydrochloric acid standard solution described here are also exemplary and can be adjusted according to the actual situation), titrate it, record the volume of the standard hydrochloric acid titrant solution consumed at the end point when the solution changes from purplish red to colorless, which is the consumption in the blank experiment;

[0122] After completing the above experiment, the amount of substance of hydroxide ions in the titrant solution can be calculated based on the concentration and volume of the standard hydrochloric acid titrant solution; at the same time, calculate the amount of substance of hydroxide ions in the blank experiment. Specifically,

[0123] The amount of substance of hydroxide ions in the titrant solution is calculated by the following formula:

[0124] n OH - =c HCl v HCl

[0125] Where:

[0126] n OH - : The amount of substance of hydroxide ions in the titrant solution, unit (mol);

[0127] c HCl : The concentration of the standard hydrochloric acid titrant solution used in the titration, unit (mol / L);

[0128] v HCl : The consumed volume of the standard hydrochloric acid titrant solution used in the titration, unit (L);

[0129] The amount of substance of hydroxide ions in the blank experiment is calculated by the following formula:

[0130] n 空白 =c 空白HCl V 空白HCl ,

[0131] Where:

[0132] n 空白 : The amount of substance of hydroxide ions in the solution in the blank experiment, unit (mol);

[0133] c 空白HCl: The concentration of the standard hydrochloric acid titration solution in the blank experiment, unit (mol / L);

[0134] V 空白HCl : The volume of hydrochloric acid standard solution consumed in the blank experiment, unit (L);

[0135] After obtaining the amount of substance of hydroxide ions in the titration experiment and the blank experiment, the amount of substance of calcium hydroxide in the first solution can be obtained according to the following formula:

[0136] n Ca(OH)2 =0.5*(n OH - -n 空白 );

[0137] Comprehensive hydrogen release and acid-base titration chemical reaction formula, simultaneous equation:

[0138] CaH 2 +2H 2 O=Ca(OH) 2 ↓+2H 2 ↑………………Chemical reaction formula

[0139]

[0140] The chemical equation for the release of hydrogen from metallic calcium is

[0141] Ca + 2H 2 O=Ca(OH) 2 ↓+H 2 ↑………………Chemical reaction formula

[0142]

[0143] The following equations are obtained:

[0144]

[0145] It can be deduced that the purity of calcium hydride in the sample is:

[0146]

[0147] The parameters shown in the above formula are explained as follows:

[0148] ω CaH2 : Detect the mass fraction (purity) of calcium hydride in the sample;

[0149] P: The difference between the atmospheric pressure recorded after the hydrogen release reaction ends and the saturated vapor pressure of water at the temperature at that time, unit (Pa);

[0150] V: The volume of gas in the gas tube after the hydrogen release reaction is completed, unit (ml);

[0151] R: The gas constant, 8.314 J / (mol·K);

[0152] T: The indoor temperature value recorded after the hydrogen release reaction, unit (°C);

[0153] n Ca(OH)2 : The amount of substance of calcium hydroxide in the first solution calculated, unit (mol);

[0154] m: The mass of the calcium hydride sample weighed during the hydrolysis experiment, unit (g).

[0155] According to the above formula, the purity of calcium hydride in the 0.2141 g calcium hydride granule sample is 98.813%.

[0156] In another embodiment, the present disclosure proposes a method for detecting the purity of calcium hydride. Different from the above embodiment, the calcium hydride granules weighed in this embodiment are 0.1119 g. Based on the above formula, the calculated purity of calcium hydride is 98.381%. The purity difference from the above embodiment is 0.432%. The detection result is relatively stable and has small fluctuations.

[0157] In another embodiment, the present disclosure proposes a method for detecting the purity of calcium hydride. Different from the above embodiment, the detection object in this embodiment is calcium hydride powder. After tabletting and crushing the powder, 0.2109 g of the granular sample is weighed. Based on the above formula, the calculated purity of calcium hydride is 98.433%.

[0158] In another embodiment, the present disclosure proposes a method for detecting the purity of calcium hydride. Different from the above embodiment, the calcium hydride powder weighed in this embodiment is 0.1301 g. After the same tabletting and crushing treatments as in the above embodiment, the detection is carried out. Based on the above formula, the calculated purity of calcium hydride is 98.279%. The purity difference from the above embodiment is 0.154%. The detection result is relatively stable and has small fluctuations.

[0159] Above, the present disclosure detected and calculated the purity of calcium hydride samples by weighing calcium hydride granules and calcium hydride powder of different masses. According to the final detection results, it can be concluded that for samples of different masses (when the mass increases or decreases), the detection method given in this article will not affect the result stability.

[0160] Next, the present disclosure performs purity detection on calcium hydride powder of the same mass simply by using the same hydrolysis hydrogen release method and the method of acid-base neutralization titration after dissolving with sucrose solution without tabletting treatment for comparison with the embodiments described in the present disclosure.

[0161] In one embodiment, calcium hydride powder of different masses was weighed. Further, a hydrogen hydrolysis device was used. Water was added to the gas burette. By adjusting the position of the leveling bottle, the excess gas in the burette was removed first. Then, the height of the leveling bottle was adjusted again so that the liquid level in the gas burette was at the "0" scale line. At this time, the whole device was turned on to prepare for hydrolysis. 20 ml of deionized water was added to the separatory funnel, the upper cover was plugged, and it was slowly added to the Erlenmeyer flask. The Erlenmeyer flask was slowly shaken to promote complete reaction. After the reaction was complete, it was left to stand for 30 min. Wait for the gas in the gas burette to cool to room temperature (judged by no further volume contraction). Move the leveling bottle so that the liquid level of the leveling bottle is parallel to the liquid level of the gas burette, and record the volume of the gas in the gas burette. At the same time, record the atmospheric pressure and the temperature.

[0162] The hydrogen-released solution was added to the prepared sucrose solution and stirred until dissolved. After complete dissolution, 3 drops of phenolphthalein indicator solution were added to the solution, and it was titrated with a standard hydrochloric acid titration solution until the solution changed from purple to colorless, which was the end point. Record the volume of the standard hydrochloric acid titration solution consumed. At the same time, a blank test was carried out, and the volume of the standard hydrochloric acid titration solution consumed in the blank test was recorded, and calculations were carried out in combination with the hydrogen release results.

[0163] Calculation result: The purity of the 0.2001 g calcium hydride powder sample was: 97.476%;

[0164] The purity of the 0.0995 g calcium hydride powder sample was: 96.731%;

[0165] The difference between the two results was: 0.745%. The result stability was poor. And in this embodiment, the same calcium hydride sample as above was used. Through the test results, it was found that when weighing the calcium hydride powder without tablet pressing treatment, due to electrostatic action, the calcium hydride powder was adsorbed on the mouth and upper wall of the Erlenmeyer flask, resulting in some samples being unable to release hydrogen effectively. The test result was about 1.5% smaller than the method given in this disclosure, and the accuracy of the test result was relatively low.

[0166] In another embodiment, a detection method combining the hydrolysis hydrogen evolution method and the acid-base titration method is used. However, different from the content of the present disclosure, before acid-base neutralization titration, a sucrose solution is not used to fully dissolve calcium hydroxide for detection. Weigh different masses of calcium hydride particles. Further, use a hydrolysis hydrogen evolution device. Add water to the gas burette. By adjusting the position of the leveling bottle, first remove the excess gas in the burette. Then, adjust the height of the leveling bottle again so that the liquid level in the gas burette is at the "0" scale line. At this time, turn on the entire device and prepare for hydrolysis. Add 20 ml of deionized water to the separatory funnel, plug the upper cover, and slowly add it to the Erlenmeyer flask. Slowly shake the Erlenmeyer flask to promote complete reaction. After the reaction is complete, let it stand for 30 min and wait for the gas in the gas burette to cool to room temperature (judged by no further volume contraction). Move the leveling bottle so that the liquid level of the leveling bottle is parallel to the liquid level of the gas burette, and record the volume of the gas in the gas burette. At the same time, record the atmospheric pressure and temperature.

[0167] Add the prepared sucrose solution to the solution after hydrogen evolution and stir to dissolve. After complete dissolution, add 3 drops of phenolphthalein indicator solution to the solution and titrate with a standard hydrochloric acid titrant until the solution changes from purple to colorless, which is the end point. Record the volume of the standard hydrochloric acid titrant consumed. At the same time, conduct a blank test and record the volume of the standard hydrochloric acid titrant consumed in the blank test, and calculate in combination with the hydrogen evolution results.

[0168] Calculation result: The purity of the 0.2319 g calcium hydride particle sample is: 99.819%;

[0169] The purity of the 0.1237 g calcium hydride particle sample is: 97.418%;

[0170] The difference between the two results: 2.401%, and the stability of the same result is poor.

[0171] By detecting and calculating the purity of calcium hydride particle samples with different masses, it can be obtained that for samples with different masses (when the mass increases), without using a sucrose solution to fully stir and dissolve calcium hydroxide for detection, the detection results have large differences, and the detection results have larger errors compared with the detection method given in the present disclosure.

[0172] Next, the present disclosure conducts a purity detection on calcium hydride powder with the same mass simply using an inductively coupled plasma mass spectrometer for comparison with the embodiments described in the present disclosure.

[0173] In one embodiment, weigh different masses of calcium hydride powder. Further, use a standard hydrochloric acid solution to perform hydrolysis and acidification treatment to obtain a solution, and then take a sample for sample detection according to the operation method of ICP-MS (inductively coupled plasma mass spectrometer).

[0174] Test result: The purity of 0.2132 g of calcium hydride powder sample is: 99.672%;

[0175] The purity of 0.0989 g of calcium hydride powder sample is: 99.414%;

[0176] The difference between the two results is: 0.258%. The result stability is good. However, since the inductively coupled plasma mass spectrometer is used for detection and it is impossible to distinguish calcium hydride from unreacted metallic calcium in the sample, the detection result is about 1.2% larger than that of the method given in this disclosure, and the detected value is on the high side.

[0177] In another embodiment, calcium hydride particles of different masses are weighed. Further, hydrolysis and acidification solution treatment are carried out with a hydrochloric acid standard solution to obtain a solution, and then a sample is taken for sample detection according to the operation method of an ICP-MS (inductively coupled plasma mass spectrometer) instrument.

[0178] Calculation result: The purity of 0.2133 g of calcium hydride powder sample is: 99.691%;

[0179] The purity of 0.1271 g of calcium hydride powder sample is: 99.385%;

[0180] The difference between the two results is: 0.306%. Similarly, the result stability is good, and the detected value is on the high side.

[0181] It can be obtained by detecting and calculating the purity of calcium hydride powder and particle samples of different masses that for samples of different masses (when the mass increases), when the inductively coupled plasma mass spectrometer is used alone for detection, the difference in detection results is small, but compared with the detection method given in this disclosure, the detection result is on the high side, and it is impossible to distinguish calcium hydride from unreacted metallic calcium.

[0182] In one embodiment, the method includes: tableting and crushing the calcium hydride powder to be tested to obtain calcium hydride particles; weighing a certain amount of calcium hydride particles for hydrolysis and hydrogenation, recording the volume of released gas and the corresponding gas temperature and atmospheric pressure, and hydrolyzing to obtain a mixed solution; preparing a sucrose solution, and adding 1 drop of phenolphthalein solution to the sucrose solution before detection, and adding a sodium hydroxide standard titration solution dropwise to make the sucrose solution appear light pink; adding the light pink sucrose solution to the mixed solution and stirring until completely dissolved; adding a phenolphthalein indicator to the mixed solution after stirring and dissolving, titrating with a hydrochloric acid standard solution, and recording the consumed volume of the hydrochloric acid standard solution; obtaining the molar mass of hydroxide ions in the solution based on the consumed volume of the hydrochloric acid standard solution; performing a blank experiment, and recording the consumed volume of the hydrochloric acid standard solution during the blank experiment, and obtaining the molar mass of hydroxide ions in the blank experiment; based on the volume of gas released by hydrolysis and hydrogenation and the volume of the hydrochloric acid standard solution consumed in the titration, the chemical equation of the two-step reaction is combined to calculate the mass of the incompletely reacted metallic calcium and the synthesized calcium hydride in the sample, and further calculate the purity of the calcium hydride.

[0183] In one embodiment, a method for detecting the purity of calcium hydride comprises the following steps:

[0184] Step 100, build a hydrogen release device, the conical flask is connected to a constant pressure separatory funnel for adding deionized water, a gas burette is connected to the conical flask via a valve for opening and closing, a level bottle is connected to the gas burette from the bottom, and the gas burette is provided with a thermometer for measuring temperature,

[0185] Step 200, weigh a first predetermined amount of calcium hydride particles and place them in a conical flask, add deionized water to a constant pressure separatory funnel, open the valve above the gas burette, adjust the position of the level bottle so that the liquid level in the gas burette is consistent with the level bottle and the liquid level is at the "0" scale line, then close the valve, open the valve of the constant pressure separatory funnel, add deionized water to the conical flask, hydrolyze and hydrogenate the calcium hydride sample, and after the hydrogen release is completed, cool it to the gas temperature in the gas burette consistent with the room temperature, move the level bottle so that the liquid level of the level bottle is consistent with the liquid level in the gas burette, and record the atmospheric pressure and the room temperature values ​​to obtain the amount of the substance generating the gas, and at the same time obtain a first mixed solution containing calcium hydroxide;

[0186] Step S300: dilute the first mixed solution to a fixed volume by adding deionized water to a 100 ml volumetric flask, and take 5 ml of the second mixed solution after the fixed volume dilution under shaking for later use;

[0187] Step S400: Prepare a 300 g / L sucrose solution. Take 50 ml and place it in a small beaker. Add 1 drop of phenolphthalein indicator solution. After shaking well, add sodium hydroxide standard titration solution drop by drop until the solution changes from colorless to light pink. Add this light pink solution to 5 ml of the second mixed solution, and place it on a magnetic stirrer to stir and shake well to obtain a third mixed solution;

[0188] Step S500: Add 2 - 3 drops of phenolphthalein indicator to the third mixed solution. At this time, the third mixed solution is in a purple - red state;

[0189] Step S600: Add hydrochloric acid standard solution to an acid burette for titration until the solution changes from purple - red to colorless, which is the titration end point. Record the volume of the standard hydrochloric acid titration solution consumed;

[0190] Step S700: Obtain the amount of substance of hydroxide ions based on the volume of hydrochloric acid standard solution consumed;

[0191] Step S800: Conduct a blank experiment. Titrate the same volume of deionized water after adding the same amount of sucrose solution, record the volume of hydrochloric acid standard titration solution consumed during the blank experiment, and obtain the amount of substance of hydroxide ions in the blank experiment;

[0192] Step S900: Obtain the amount of substance of calcium hydroxide in the solution based on the difference in the amount of substance of hydroxide ions;

[0193] Step S1000: Based on the amount of substance of calcium hydroxide, the mass of calcium hydride particles, and the amount of substance of hydrogen - releasing gas, perform a combined calculation to obtain the purity of calcium hydride in the sample.

[0194] Although the embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above - mentioned specific embodiments and application fields. The above - mentioned specific embodiments are merely illustrative and guiding, rather than restrictive. Those of ordinary skill in the art can also make many forms under the inspiration of this specification and without departing from the scope protected by the claims of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A method for detecting the purity of calcium hydride, suitable for detecting the calcium hydride product obtained by direct hydrogenation reaction of metallic calcium, characterized in that: The steps include: Weighing a predetermined mass of calcium hydride particles and subjecting them to a hydrolysis reaction to obtain a first mixed solution containing calcium hydroxide and an amount of a substance that releases gas; The first mixed solution is diluted to a fixed volume, and an appropriate amount of the second mixed solution after dilution to a fixed volume is taken for use; Prepare a sucrose solution of a certain concentration, take an appropriate amount of the prepared sucrose solution into a small beaker, add 1 drop of phenolphthalein indicator solution, shake well, and then add a standard sodium hydroxide titration solution until the solution changes from colorless to light pink, and add the light pink solution to the second mixed solution to obtain a third mixed solution; Add a hydrochloric acid standard solution to an acid burette for titration until the third mixed solution changes from purple-red to colorless, record the volume of the standard hydrochloric acid titration solution consumed, and obtain the amount of the substance of hydroxide ion based on the volume of the hydrochloric acid standard solution consumed; Conduct a blank experiment to obtain the amount of hydroxide ion substance in the blank experiment; The amount of calcium hydroxide in the solution is obtained based on the difference in the amount of hydroxide ions, and the purity of calcium hydride is obtained by joint calculation based on the amount of calcium hydroxide, the predetermined mass of the calcium hydride particles, and the amount of hydrogen released and released gas.

2. A method for detecting the purity of calcium hydride according to claim 1, characterized in that, Preferably, before the hydrolysis reaction, a hydrogen release device is built, the conical flask is connected to a constant pressure separatory funnel for adding deionized water, a gas burette is connected to the conical flask via a valve for opening and closing, a level bottle is connected to the gas burette from the bottom, and the gas burette is provided with a thermometer for measuring temperature.

3. A method for detecting the purity of calcium hydride according to claim 2, characterized in that, Weigh a predetermined amount of calcium hydride particles and place them in a conical flask, add deionized water to a constant pressure separatory funnel, open the valve above the gas tube, adjust the position of the level bottle so that the liquid level in the gas tube is consistent with the level bottle and the liquid level is at the "0" scale line, then close the valve, open the valve of the constant pressure separatory funnel, add deionized water into the conical flask, hydrolyze and hydrogenate the calcium hydride sample, and after the hydrogen release is completed, let it stand and cool until the gas temperature in the gas tube is consistent with the room temperature, move the level bottle so that the liquid level of the level bottle is consistent with the liquid level in the gas tube, and record the atmospheric pressure and room temperature values ​​to obtain the amount of the substance generating the gas, and at the same time obtain a first mixed solution containing calcium hydroxide.

4. A method for detecting the purity of calcium hydride according to claim 2, characterized in that, Add 20 ml of deionized water to the constant pressure separatory funnel and let it stand for more than 30 minutes after the hydrogen release is completed.

5. A method for detecting the purity of calcium hydride according to claim 1, characterized in that: The calcium hydride tablet to be tested is crushed to obtain calcium hydride particles.

6. A method for detecting the purity of calcium hydride according to claim 1, characterized in that: The amount of hydroxide ion in the titration solution is calculated based on the concentration and volume of the hydrochloric acid standard titration solution; at the same time, the amount of hydroxide ion in the blank experiment is calculated.

7. A method for detecting the purity of calcium hydride according to claim 1, characterized in that: The amount of hydroxide ion in the titration solution is calculated by the following formula: n oH - =c HCl v HCl , in: n OH - : The amount of hydroxide ion in the titration solution, unit (mol); C HC1 : The concentration of the hydrochloric acid standard solution used for titration, unit (mol / L); V HCl : The volume of hydrochloric acid standard solution consumed in titration, unit (L); The amount of hydroxide ion in the blank experiment was calculated by the following formula: n 空白 =c 空白HCl V 空白HCl , in: n 空白 : The amount of hydroxide ion in the solution in the blank experiment, unit (mol); c 空白HCl : The concentration of the standard hydrochloric acid titration solution in the blank experiment, unit (mol / L); V 空白HCl : The volume of hydrochloric acid standard solution consumed in the blank experiment, unit (L); After obtaining the amount of substance of hydroxide ions in the titration experiment and the blank experiment, the amount of substance of calcium hydroxide in the first solution is obtained according to the following formula: n Ca(oH)2 =0.5*(n OH - -n 空白 ); Comprehensive hydrogen release and acid-base titration chemical reaction formula, simultaneous equation: The chemical equation for the release of hydrogen from calcium hydride is: The chemical reaction formula is: CaH2+2H2O=Ca(OH)2↓+2H2↑ Calculation of the amount of substance: The chemical equation for the release of hydrogen from metallic calcium is The chemical reaction formula is: Ca+2H2O=Ca(OH)2↓+H2↑ The amount of substance is calculated as: The following equations are obtained: It can be deduced that the purity of calcium hydride in the sample is: Among them, ω CaH2 : Detect the mass fraction of calcium hydride in the sample; P: The difference between the atmospheric pressure recorded after the hydrogen release reaction ends and the saturated vapor pressure of water at the temperature at that time, unit (Pa); V: The volume of gas in the gas tube after the hydrogen release reaction is completed, unit (m1); R: gas constant; T: the indoor temperature value recorded after the hydrogen release reaction is completed, unit (℃); n Ca(OH)2 : The calculated amount of calcium hydroxide in the first solution, unit (mol); m: The mass of the calcium hydride sample weighed during hydrolysis, unit (g).

8. A method for detecting the purity of calcium hydride according to claim 7, characterized in that: The gas constant is 8.314 J / (mol·K).

9. A method for detecting the purity of calcium hydride according to claim 1, characterized in that: The second mixed solution is placed on a magnetic stirrer and stirred and shaken to obtain a third mixed solution.

10. A method for detecting the purity of calcium hydride according to claim 1, characterized in that: Under argon or nitrogen atmosphere, weigh the calcium hydride particles using a 1 / 10,000 balance and place them in a conical flask.

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