DAT General Chemistry: Stoichiometry 3

Question 1

What volume does 1.0 mol of an ideal gas occupy at STP?

Accepted Answer

22.4 L

Answer

At STP one mole of any ideal gas occupies 22.4 L.

Question 2

If a reaction has a theoretical yield of 50 g and an actual yield of 40 g, what is the percent yield?

Accepted Answer

80%

Answer

Percent yield is actual/theoretical × 100 = 40/50 × 100 = 80%.

Question 3

How many moles of CO2 are produced from 1.5 mol of CaCO3 in CaCO3 → CaO + CO2?

Accepted Answer

1.5 mol

Answer

The 1:1 ratio means 1.5 mol CaCO3 yields 1.5 mol CO2.

Question 4

What is the molar mass of glucose, C6H12O6 (C=12, H=1, O=16)?

Accepted Answer

180 g/mol

Answer

6(12) + 12(1) + 6(16) = 72 + 12 + 96 = 180 g/mol.

Question 5

How many oxygen atoms are present in one formula unit of Al2(SO4)3?

Accepted Answer

12

Answer

Three sulfate groups each with 4 oxygens give 3 × 4 = 12 oxygen atoms.

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