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Solving Chemical Equations for Excess Reactant

1. Formaldehyde HCHO, once used as a preservative in biology laboratories, is prepared commercially by the reaction:

2 CH3OH + O2 = 2 HCHO + 2 H2O

The percent yield is 84.9% in a manufacturing plant. How much formaldyhyde can be expected from processing 397kg CH3OH?

2. A solution containing 1.63g of barium chloride is added to a solution containing 2.40 grams of sodium chromate. Find the number of grams of barium chromate that can precipitate. Also determine which reactant was in excess, as well as the number of grams over the amount required by the limiting reactant.

3. Calculate the mass of CaCO3 that will precipitate from the addition of excess sodium carbonate to a solution containing .523 grams of calcium chloride.

Solution Preview

1) CH3OH : HCHO ratio is 1:1

HCHO -> 30g/mol
CH3OH -> 32g/mol

397e3 / 32 = 1.24e4 mol CH3OH
1.24e4 * 84.9% = 1.05e4 mol HCHO
1.05e4 * 30 = 316kg ...

Solution Summary

The solution gives the formulas for each question succinctly.