Unit 8 Stoichiometry Review

According to the following balanced chemical equation, which molar ratio is consistent with the chemical equation based on the stoichiometric coefficients?

3 KOH + FeCl₃ → Fe(OH)₃ + 3 KCl

• 1 mol KOH : 1 mol Fe(OH)₃

• 1 mol KOH : 1 mol KCl

• 3 mol FeCl₃ : 1 mol KCl

• 1 mol FeCl3 : 3 mol Fe(OH)₃

Answer explanation

If the coefficients are EQUAL (for exmample 1:1, 2:2, 3:3) then they are also 1:1

When silver nitrate (AgNO₃) reacts with hydrochloric acid (HCl), silver chloride (AgCl) precipitates out of solution. What is the stoichiometric coefficient of HCl in the balanced chemical equation?

AgNO₃ + HCl → AgCl + HNO₃

• 1

• 2

• 3

• 4

A mixture of CO(g) and O₂(g) is placed in a rigid, sealed container as shown in the particle diagram above. The CO(g) reacts with the O₂(g) according to the following reaction. 2CO(g) + O₂(g) → 2CO₂(g). Which of the following diagrams correctly illustrates the reaction mixture after the reaction goes to completion?

• Diagram A

• Diagram B

• Diagram C

• Diagram D

Balance the chemical equation below using coefficients. The stoichiometric coefficient for oxygen gas is...

___ NH₃(l) + ___ O₂(g) → ___ NO₂(g) + ___ H₂O(l)

HINT: (Start by trying to balance hydrogen first. You may need to double some coefficients...)

• 1

• 4

• 6

• 7

What mass of dissolved HCl is needed to completely react with 1 mole of solid Mg?

Mg(s) + 2 HCl(aq) → MgCl₂(aq) + H₂(g)

(Hint: Use the stoichiometry map. What units do they give us, what are they asking us for, and what path do we take?)

• 72.92 g

• 18.3 g

• 24.3 g

• 48.6 g

When 10.0 grams of magnesium react with excess hydrochloric acid, investigators expected to collect 39.2 g of magnesium chloride. Instead, the investigators only collected 30.0 grams of magnesium chloride. What is the percent yield of this experiment?

• 25.5%

• 33.0%

• 76.5%

• 131%

If the reaction produces 0.400 L of 1.5 M MgCl2, which setup shown will correctly calculate how many grams of HCl reacted with excess solid magnesium? (Type A, B, C, or D)

In the equation 2KClO₃ → 2KCl + 3 O₂, how many moles of KCl are produced when 5.0 moles of KClO3 decomposes completely?

• 1.5 mol KCl

• 2.0 mol KCl

• 3.0 mol KCl

• 5 mol KCl

When the limiting reactant in a chemical reaction is completely used up...

• the reaction slows down.

• the reaction stops.

• the excess reactants begin combining.

• the reaction speeds up.

For the reaction equation C₃H₈(g) + 5 O₂(g) → 3 CO₂(g) + 4 H₂O(g), how many moles of H₂O are produced from 2 moles of C₃H₈?

• 2 moles

• 3 moles

• 6 moles

• 8 moles