Summary An analysis of a mixture of Na2CO3 and NaOH using two indicators and a standard HCl solution

Fifth lab

An analysis of a mixture of Na2CO3 and NaOH using two indicators and a standard HCl
solution

Theory:
1- When a known volume of the mixture is titrated with HCl in presence of
ph. ph., the acid reacts with all the sodium hydroxide and with only half
Of the carbonate.
V1 = all hydroxide + 1/2 the carbonate
2- When a known volume of the mixture is titrated with HCl in presence of M.O., the acid reacts
with all the hydroxide and all the carbonate.
V2 = all hydroxide + all carbonate
Volume of HCl = 1/2 carbonate = V2 – V1 = V ml
Volume of HCl = all carbonate = 2V ml
Volume of HCl = NaOH = V2 - 2V ml
.


Procedure 2:
1- Transfer with a pipette 10 ml of the mixture to a conical flask, and add one or two drops of ph.
ph.
2- Add the acid from the burette till the solution becomes colorless.
 The volume of acid in the case is V1 and is equivalent to all the hydroxide and half the
carbonate.
3- Then add two drops of methyl orange to the same conical flask and continue titration to the
faint red color or the orange color.
 The volume of acid in the case is V2 and is equivalent to the second half of carbonate.
3- Repeat the experiment three times and tabulate your results.
4- Calculate the strength of the sodium hydroxide and the sodium carbonate in the mixture.

, Calculations2:
 In the case of Na2CO3:
N1 x 2V2 = N (Na2CO3) x 10
Strength Na2CO3 = N (Na2CO3) x 53 g/L
 In the case of NaOH:
N1 x (V1 - V2) = N (NaOH) x 10
Strength NaOH =N (NaOH) x 40 g/L