Hi could anyone help me solve this question?
A 1.00g sample of a mixture of sodium carbonate and sodium
hydrogen carbonate was titrated with 0.200 mol/dm3 hydrochloric
acid using phenolphthalein as indicator. If 17.50 cm3 of HCL were
required, what is the percentage by mass of sodium hydrogen
carbonate in the mixture?
Answer: 62.9 %
This is my solution but I was stuck somewhere and my answer is
wrong:
Mol of HCL: (0.2x 17.50)/1000 = 0.0035 mol
Na2CO3 + 2HCL ---> 2 NaCl + H2O + CO2
2 mol of HCL ---> 1 mol of Na2CO3
NaHCO3 + HCL ---> NaCl + CO2 + H2O
1 mol of HCL ---> 1 mol of NaHCO3
total mol of HCL required: 3 mol
0.0035 / 3 = 0.00116666...
0.00116666....x Mr of NaHCO3 = 0.00116666....x (23 + 1 + 12 + 3
x16)
= 0.098g
0.098/1 x 100% = 9.8
% ???