Calcium dihydrogen phosphate, Ca(H2PO4)2, and sodium hydrogen carbonate, NaHCO3,
ID: 942396 • Letter: C
Question
Calcium dihydrogen phosphate, Ca(H2PO4)2, and sodium hydrogen carbonate, NaHCO3, are ingredients of baking powder that react with each other to produce CO2, which causes dough or batter to rise:
Ca(H2PO4)2 (s) + NaHCO3 (s) ------------ CO2(g) + H2O(g) + CaHPO4(s) + Na2HPO4(s) (unbalanced)
If the baking powder contains 31.0% NaHCO3 and 35.0% Ca(H2PO4)2 by mass:
a.) How many moles of CO2 are produced from 1.41 g of baking powder?
b.) If 1 mol of CO2 occupies 37.0 L at 350 degrees F, what volume of CO2 is produced from 1.41 g of baking powder?
Explanation / Answer
Ca(HPO) + 2NaHCO 2CO + 2HO + CaHPO + NaHPO.
a. Each molecule of NaHCO yields one molecule of CO, so however many moles there are of NaHCO shows how many moles of CO are produced.
The mass of NaHCO in 1.41 g of baking powder is 0.4371 g (since the mass percentage is 31%).
The molar mass of NaHCO is 84 g/mol. Divide this into 0.4371 g to get the number of moles of CO released: 0.00520 mol.
b. Since CO has a volume ratio of 37 L/mol (at the given temperature), multiply this by 0.00520 mol to find the volume here: 0.192 L.