1.217-g sample of commercial KOH, contaminated by Noel with K2CO3, was dissolved in water and the resulting solution was diluted to 500.00 mL. A 50.0 mL aliquot of the solution was treated with 40.0 mL of 0.05304 M HCl and boiled to remove CO2. The excess acid consumed 4.74 mL of 0.04983 M NaOH using phenolphthalein indicator. An excess of neutral BaCl2 was added to another 50.00 mL aliquot to precipitate the carbonate as BaCO3. The solution was then titrated with 28.56 mL of the acid to a phenolphthalein endpoint. The important reactions are: KOH + HCl H2O + KCl K2CO3 + 2 HCl CO2 + H2O + 2 KCl
A 1.217-g sample of commercial KOH, contaminated by Noel with K2CO3, was dissolved in water and the resulting solution was diluted to 500.00 mL. A 50.0 mL aliquot of the solution was treated with 40.0 mL of 0.05304 M HCl and boiled to remove CO2. The excess acid consumed 4.74 mL of 0.04983 M NaOH using phenolphthalein indicator. An excess of neutral BaCl2 was added to another 50.00 mL aliquot to precipitate the carbonate as BaCO3. The solution was then titrated with 28.56 mL of the acid to a phenolphthalein endpoint.
The important reactions are:
KOH + HCl H2O + KCl
K2CO3 + 2 HCl CO2 + H2O + 2 KCl
Calculate the following items in (a) – (f).
a) Calculate the combined amount (mmol) of KOH and K2CO3 in the first aliquot.
b) Calculate the amount (mmol) of KOH.
c) Calculate the amount (mmol) K2CO3.
d) Calculate the percentage KOH (MW = 56.11 g/mol).
e) Calculate the percentage K2CO3 (MW = 138.21 g/mol).
f) Calculate the percentage H2O
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