Method for quickly calibrating concentration of potassium dichromate standard titration solution

Abstract

The invention provides a method for quickly calibrating the concentration of potassium dichromate standard titration solution. The method is characterized by comprising the following steps: preparing standard solution with the concentration equal to that of potassium dichromate standard solution to be calibrated by using standard potassium dichromate and calculating the concentration C1; removing ferrous ion solution, titrating by using standard solution prepared by a standard reagent of the standard potassium dichromate and recording the consumed volume V1; removing ferrous ion solution with the same quantity, titrating by using the potassium dichromate standard solution to be calibrated and recording the volume V2 consumed by the standard solution; and calculating the concentration C2 of the potassium dichromate standard solution to be calibrated by a formula. According to the method, the concentration of the ferrous ion standard solution is not calculated; the concentration of the potassium dichromate standard titration solution is calculated without the concentration of the ferrous ion standard solution; and a blank test is not required. Calibration is performed synchronously; an indicator, blank and the like in the original calibration, and the undetermined superimposed and amplification effect during calculation are reduced; and calibration is accurate, simple and easy to master and calculation is simple and convenient.

Description

technical field

[0001] The invention relates to a method for calibrating the concentration of potassium dichromate standard titration solution. Background technique

[0002] Potassium dichromate standard titration solution is a commonly used standard titration solution in chemical analysis titration. It is often used in the titration of oxidation-reduction reactions, and its standard value must be accurately known in the calculation of the results. Its preparation method has two methods according to GB / T601-2002, one is to directly prepare with the standard potassium dichromate standard reagent, and the calculated concentration does not need to be calibrated, which is feasible for the small amount of potassium dichromate standard titration solution. But the consumption of potassium dichromate standard titration solution is very large in the daily production analysis of many laboratories, and the cost that all spends with standard potassium dichromate benchmark reagent prepar...

Examples

example 1

[0021] Example 1: Calibrate the concentration of potassium dichromate standard titration solution with a calculated concentration of about 0.025mol / mL

[0022] (1) Weigh 1.2258g of potassium dichromate (reagent, dried at 120°C±5°C to constant weight), dissolve it in water, transfer it into a 1000mL volumetric flask, dilute with water to the mark, mix well, and titrate the potassium dichromate standard The concentration of the solution is c(1 / 6K 2 Cr 2 o 7 )=0.02500mol / L.

[0023] (2) Weigh 10g ammonium ferrous sulfate [(NH 4 ) 2 Fe(SO 4 ) 2 ·6H 2 O, formula weight 392.13], dissolved in 1000mL sulfuric acid (5+95), and mixed.

[0024] (3) Take four portions of 25.00mL ferrous ammonium sulfate titration solution, add 15mL sulfuric acid-phosphoric acid mixed acid (15+15+70), dilute to 100mL with water, add 4~5 drops of sodium diphenylamine sulfonate indicator solution ( 2g / L), two parts are the potassium dichromate standard titration solution that concentration is 0.0250...

example 2

[0025] Example 2: Calibrate the concentration of potassium dichromate standard titration solution with a calculated concentration of about 0.05mol / mL

[0026] (1) Weigh 12.258g of potassium dichromate (reagent, dried at 120°C±5°C to constant weight), dissolve it in water, transfer it into a 5000mL volumetric flask, dilute with water to the mark, mix well, and titrate the potassium dichromate standard The concentration of the solution is c(1 / 6K 2 Cr 2 o 7 )=0.05000mol / L.

[0027] (2) Weigh 100g ammonium ferrous sulfate [(NH 4 ) 2 Fe(SO 4 ) 2 ·6H 2 O, formula weight 392.13], dissolved in 5000mL sulfuric acid (5+95), and mixed.

[0028] (3) Take four portions of 20.00mL ferrous ammonium sulfate titration solution, add 15mL of sulfuric acid-phosphoric acid mixed acid (15+15+70), dilute to 100mL with water, add 4 to 5 drops of sodium diphenylamine sulfonate indicator solution ( 2g / L), two parts are the potassium dichromate standard titration solution that concentration is ...

example 3

[0029] Example 3: Calibrate the concentration of potassium dichromate standard titration solution whose calculated concentration is about 0.1mol / mL

[0030] (1) Weigh 2.4516g of potassium dichromate (reagent, dried at 120°C±5°C to constant weight), dissolve it in water, transfer it into a 500mL volumetric flask, dilute with water to the mark, mix well, and titrate the potassium dichromate standard The concentration of the solution is c(1 / 6K 2 Cr 2 o 7 )=0.1000mol / L.

[0031] (2) Weigh 20g ammonium ferrous sulfate [(NH 4 ) 2 Fe(SO 4 ) 2 ·6H 2 O, formula weight 392.13], dissolved in 500mL sulfuric acid (5+95), and mixed.

[0032] (3) Take four portions of 25.00mL ferrous ammonium sulfate titration solution, add 15mL sulfuric acid-phosphoric acid mixed acid (15+15+70), dilute to 100mL with water, add 4-5 drops of sodium diphenylamine sulfonate indicator solution ( 2g / L), two parts are the potassium dichromate standard titration solution of 0.1000mol / L with standard potassi...

technical field

[0001] The invention relates to a method for calibrating the concentration of potassium dichromate standard titration solution. Background technique

[0002] Potassium dichromate standard titration solution is a commonly used standard titration solution in chemical analysis titration. It is often used in the titration of oxidation-reduction reactions, and its standard value must be accurately known in the calculation of the results. Its preparation method has two methods according to GB / T601-2002, one is to directly prepare with the standard potassium dichromate standard reagent, and the calculated concentration does not need to be calibrated, which is feasible for the small amount of potassium dichromate standard titration solution. But the consumption of potassium dichromate standard titration solution is very large in the daily production analysis of many laboratories, and the cost that all spends with standard potassium dichromate benchmark reagent prepar...

Examples

example 1

[0021] Example 1: Calibrate the concentration of potassium dichromate standard titration solution with a calculated concentration of about 0.025mol / mL

[0022] (1) Weigh 1.2258g of potassium dichromate (reagent, dried at 120°C±5°C to constant weight), dissolve it in water, transfer it into a 1000mL volumetric flask, dilute with water to the mark, mix well, and titrate the potassium dichromate standard The concentration of the solution is c(1 / 6K 2 Cr 2 o 7 )=0.02500mol / L.

[0023] (2) Weigh 10g ammonium ferrous sulfate [(NH 4 ) 2 Fe(SO 4 ) 2 ·6H 2 O, formula weight 392.13], dissolved in 1000mL sulfuric acid (5+95), and mixed.

[0024] (3) Take four portions of 25.00mL ferrous ammonium sulfate titration solution, add 15mL sulfuric acid-phosphoric acid mixed acid (15+15+70), dilute to 100mL with water, add 4~5 drops of sodium diphenylamine sulfonate indicator solution ( 2g / L), two parts are the potassium dichromate standard titration solution that concentration is 0.0250...

example 2

[0025] Example 2: Calibrate the concentration of potassium dichromate standard titration solution with a calculated concentration of about 0.05mol / mL

[0026] (1) Weigh 12.258g of potassium dichromate (reagent, dried at 120°C±5°C to constant weight), dissolve it in water, transfer it into a 5000mL volumetric flask, dilute with water to the mark, mix well, and titrate the potassium dichromate standard The concentration of the solution is c(1 / 6K 2 Cr 2 o 7 )=0.05000mol / L.

[0027] (2) Weigh 100g ammonium ferrous sulfate [(NH 4 ) 2 Fe(SO 4 ) 2 ·6H 2 O, formula weight 392.13], dissolved in 5000mL sulfuric acid (5+95), and mixed.

[0028] (3) Take four portions of 20.00mL ferrous ammonium sulfate titration solution, add 15mL of sulfuric acid-phosphoric acid mixed acid (15+15+70), dilute to 100mL with water, add 4 to 5 drops of sodium diphenylamine sulfonate indicator solution ( 2g / L), two parts are the potassium dichromate standard titration solution that concentration is ...

example 3

[0029] Example 3: Calibrate the concentration of potassium dichromate standard titration solution whose calculated concentration is about 0.1mol / mL

[0030] (1) Weigh 2.4516g of potassium dichromate (reagent, dried at 120°C±5°C to constant weight), dissolve it in water, transfer it into a 500mL volumetric flask, dilute with water to the mark, mix well, and titrate the potassium dichromate standard The concentration of the solution is c(1 / 6K 2 Cr 2 o 7 )=0.1000mol / L.

[0031] (2) Weigh 20g ammonium ferrous sulfate [(NH 4 ) 2 Fe(SO 4 ) 2 ·6H 2 O, formula weight 392.13], dissolved in 500mL sulfuric acid (5+95), and mixed.

[0032] (3) Take four portions of 25.00mL ferrous ammonium sulfate titration solution, add 15mL sulfuric acid-phosphoric acid mixed acid (15+15+70), dilute to 100mL with water, add 4-5 drops of sodium diphenylamine sulfonate indicator solution ( 2g / L), two parts are the potassium dichromate standard titration solution of 0.1000mol / L with standard potassi...