HIRANUMA APPLICATION DATA

Data No.

Automatic Titrator

J5Apr. 5,
2019

Fractional determination ofhydrochloric acid and sulfuric acid

Inorganic acids &Mixed acids
1. Abstract

The mixed solution of hydrochloric acid and sulfuric acid works as strong acid, and also has the strongoxidizability and solvency. It is used as the surface treatment solution for metals, glass products, andsemiconductors. Hydrochloric acid and sulfuric acid are strong acids, therefore the fractional determination byneutralization titration is difficult.
The total acids of hydrochloric acid and sulfuric acid in the mixed solution are determined first by
neutralization titration in this report. Nitric acid is added to the sample solution continuously to adjust the pH.
Finally, the concentration of hydrochloric acid is determined by precipitation titration, the concentration of
sulfuric acid is calculated by subtracting the concentration of hydrochloric from the total acids concentration.
The example of fractional determination for hydrochloric acid and sulfuric acid with additional burets areintroduced in this report.
Preparation of 100-fold diluted sample solution

Dilution of sample

Collection of 100-fold diluted sample solution (10 mL)
Glass electrode, Silver-reference combination electrode (use as reference electrode.)

Neutralization titration for total acids (converted into hydrochloric acid)
Formula (1) + Formula (2)Buret I
(Sodium hydroxide standard solution)

Dispense 2 mL of 1 mol/L Nitric acidpH adjustment(Automatic dispensing by peristaltic pump type dispenser)

Silver-reference combination electrode
Buret II (Silver nitrate standard solution)

Precipitation titration for hydrochloric acid
Formula (3)Total acids concentration－Hydrochloric acid concentration

Calculation of sulfuric acid= Sulfuric acid concentration
H2SO4＋2NaOH→

Na2SO4＋H2 O・・・(1)

HCl＋

NaOH

→

NaCl＋

H2 O・・・(2)HCl＋

AgNO3→AgCl＋

HNO3・・・(3)2. Configuration of instruments and reagents(1) Configuration of instruments
Main unit:

Hiranuma Automatic Titrator COM series

Options:

One buret, Peristaltic pump type dispenser

Electrodes:

Glass electrodeGE-101B for total acids measurement

Connect to IE-1.
Silver -reference electrode

AGR-811Z for hydrochloric acid measurement(Double junction type) Connect to IE-2 and RE-2.

(2) Reagents
Titrant:

0.1 mol/L Sodium hydroxide standard solution for total acids measurement
0.1 mol/L Silver nitrate for hydrochloric acid measurement

Additive solution:

2 mL of 1 mol/L Nitric acid solution for pH adjustment

3. Measurement procedure(1) Dispense 1 mL of sample into 30 mL DI water in a volumetric flask with volumetric pipette. Cool it toroom temperature and dilute to 100 mL with DI water.
(2) Dispense 10 mL of diluted sample solution into a 100 mL beaker with volumetric pipette.
(3) Add 40 mL of DI water.
(4) Immerse electrodes and start titration with 0.1 mol/L sodium hydroxide standard solution.
(5) After the procedure (4), 2 mL of 1 mol/L nitric acid is automatically dispensed by optional dispenser.
(6) Titrate with 0.1 mol/L silver nitrate standard solution with optional buret.

4. Measurement conditions and results
Examples of titration conditions(1) Titration for total acids with sodium hydroxide standard solution (converted into hydrochloric acid)
Cndt No.
MethodBuret No.
Amp No.
D. UnitS-Timer
C.P. mLT Timer
D.P. mLEnd Sens
Over mL
Max.Vol.

1Auto
11pH
50001000
020sec
mLsec
mL
mL
mL

ConstantNo.
SizeBlank
Molarity
FactorKL
Unit
FormulaDecimal Places
Auto In Pram.

K: Equivalent of NaOH to HCl

110.000
00.100
1.004
1.000
0.010
mol/L

mL
mL
mol/L

Mode No.
Pre Int
Del K
Del Sens
Int Time
Int Sens
Brt Speed
Pulse

2009023240

Mode No.
Pre Int
Del K
Del Sens
Int Time
Int Sens
Brt Speed
Pulse

602033240sec
mV
sec
mV

(D-B)*K*F*M/(S*L)
3Non

L: Dilution ratio(2) Dispense 1 mol/L nitric acidCndt No.
MethodBuret No.
S-Timer
Disp Vol.

2Disp
302secmL(3) Titration for hydrochloric acid with silver nitrate standard solutionCndt No.
MethodBuret No.
Amp No.
D. Unit
S-Timer
C.P. mLT Timer
D.P. mLEnd Sens
Over mL
Max.Vol.

3Auto
22mV
5000300
0.2
20sec
mL
sec
mL
mL
mL

ConstantNo.
SizeBlank
Molarity
FactorKL
Unit
FormulaDecimal Places
Auto In Pram.

310.000
0.0000
0.100
1.005
1.000
0.010
mol/L

mL
mL
mol/L

(D-B)*K*F*M/(S*L)
4NonsecmVsec
mV(4) Calculation for sulfuric acid concentration
Cndt No.
Method4Calc

ConstantNo.
SizeBlank
Molarity
FactorKL
Unit
Formula4
10.000
0.000
0.100
1.000
1.000
0.01
mol/L

mL
mL
mol/L

(CA-CB)/24
Non

Decimal Places
Auto In Pram.

Measurement results
Number ofSize

Dilution

NaOH Titrant

Measurement

(mL)

ratio

Volume (mL)

12101/100

3
Statistic
calculation

Total acids (mol/L)(converted intohydrochloric acid)

AgNO3 Titrant

Hydrochloric acidSulfuric acid

Volume (mL)

Conc. (mol/L)

Conc. (mol/L)

6.777

6.80410.683

0.68643.05896.776

6.80310.680

0.68343.05996.779

6.8061

0.682

0.68543.0603Avg.

6.804 mol/L

0.685 mol/L

3.060 mol/L

SD

0.002 mol/L

0.002 mol/L

0.001 mol/L

RSD

0.022 %

0.223 %

0.02 %

Measurement of total acids

Measurement of hydrochloric acid

Examples of titration curves

5. Note(1) Fractional determination of hydrochloric acid and sulfuric acid
The concentration of hydrochloric acid is measured by the determination of chloride ion in this method.
This method cannot be applied to the sample containing chloride ion from other than hydrochloric acid.
(2) Control of titrant
The carbon dioxide gas absorber (soda lime) on reagent bottle has to be regularly exchanged because
sodium hydroxide used for total acids determination readily absorbs carbon dioxide gas in the air.
Keywords: Fractional determination of hydrochloric acid and sulfuric acid, Neutralization titration,
Precipitation titration*Some measurement would not be possible depending on optional configuration of system.