4. A company uses sodium carbonate, soda ash, as a base in manufacturing its pro

Question

4. A company uses sodium carbonate, soda ash, as a base in manufacturing its products, and must continuously analyze its materials. If a sample of soda ash weighs 1.2224 grams and requires 17.11 ml of 0.1288 M hydrochloric acid to titrate the base, calculate the % sodium carbonate in the original soda ash sample. Make sure that you write the correct equation and balance it. (15 points) If your job also included obtaining the sample from a 50 lb bag of soda ash from the vendor, describe in detail how you might sample the bag to obtain a representative sample. Is there a problem with the value of this soda ash? Would you recommend purchasing it?

Explanation / Answer

Balanced equaiton is,

Na2CO3 (aq.) + 2 HCl (aq.) -------------> 2 NaCl (aq.) + H2O (l) + CO2 (g)

Moles of HCl required = Molarity * volume / 1000 = 0.1228 * 17.11 / 1000 = 0.002101 mol

from the balanced equation,

2 mol HCl consumes 1 mol Na2CO3

then,

0.002101 mol of HCl consumes 1 * 0.002101 / 2 = 0.001050 mol of Na2CO3

Now,

Mass of N2CO3 = moles * molar mass = 0.001050 * 106 = 0.1114 g.

% by mass of Na2CO3 in soda ash = Mass of Na2CO3 * 100 / Mass of soda ash = 0.1114 * 100 / 1.2224 = 9.110 %

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