Spring Final Review

Chemical equations must be balanced to satisfy:

• law of definite proportions

• law of multiple proportions

• law of conservation of mass

• principle of Avogadro

In every balanced chemical equation, each side of the equation has the same number of:

• atoms

• molecules

• moles

• coefficients

Write a balanced equation to represent the decomposition of lead (IV) oxide.

• PbO₂ → Pb + 2O

• PbO₂ → Pb + O₂

• Pb₂O → 2Pb + O

• PbO → Pb + O₂

The equation 2C₃H₇OH + 9O₂ → 6CO₂ + 8H₂O

• decomposition

• combustion

• single-replacement

• double-replacement

To predict whether or not a single-replacement reaction takes place, we need to consult a chart which shows the ________.

• activity series of metals

• common polyatomic ions

• ionic charges of representative elements

• formulas of metal ions with charges greater than 1

What is the molar mass of chromic sulfate Cr₂(SO₄)₃?

• 148.1 g

• 200.0 g

• 344.2 g

• 392.2 g

What is the number of moles in 500 L of He gas at STP?

• 0.05 mol

• 0.2 mol

• 22 mol

• 92 mol

Which statement is true if 12 mol CO and 12 mol Fe₂O₃ are allowed to react?

3CO_(g) + Fe₂O_3(s) → 2Fe_(s) + 3CO_2(g)

• The limiting reagent is CO and 8.0 mol Fe will be formed.

• The limiting reagent is Fe₂O₃ and 36 mol CO₂ will be formed.

• The limiting reagent is Fe and 18 mol CO₂ will be formed.

• The limiting reagent is Fe₂O₃ and 24 mol Fe will be formed.

• The limiting reagent is CO and 3.0 mol of CO₂ will be formed.

Metallic copper is formed when aluminum reacts with copper (II) sulfate. How many grams of metallic copper can be obtained when 54.0 g of Al reacts with 319 g of CuSO₄?

2Al + 3CuSO₄ → Al₂(SO₄)₃ + 3Cu

• 21.2 g

• 127 g

• 162 g

• 381 g

Lead nitrate can be decomposed by heating. What is the percent yield of the decomposition reaction of 9.9 g Pb(NO₃)₂ is heated to give 5.5 actual grams of PbO?

2Pb(NO₃)_2(s) → 2PbO_(s) + 4NO_2(g) + O_2(g)

• 18%

• 82%

• 67%

• 56%