Limiting Reactant Questions

  1. Heating zinc sulfide in the presence of oxygen yields the following:

2 ZnS + 3 O2  2 ZnO + 2 SO2

If 0.72 mol of ZnS is heated in the presence of 3.04 mol O2, which reactant will be used up first?

Mole ratio

Chose one of the given pieces of information, set up the conversion and cross multiply.

Based on your answer, determine which one will run out first?

  1. Use the following equation for the oxidation of aluminum in the equations below: 4 Al + 3 O2  2 Al2O3
  1. Which reactant is the limiting if 0.32 mol of Al and 0.26 mol of oxygen gas are available?

Mole ratio

Chose one of the given pieces of information, set up the conversion and cross multiply.

Based on your answer, determine which reactant will run out first

  1. How many moles of aluminum oxide are formed from the reaction of 6.38 x 10-3 mol of oxygen gas and 9.15 x 10-3 mol of aluminum?

Mole ratio between aluminum oxide and oxygen gas

Set up the conversion and cross multiply.

Mole ratio between aluminum oxide and aluminum.

Set up the conversion and cross multiply.

  1. If 3.17 g of aluminum and 2.55 g of oxygen gas are available, which reactant is limiting?

Moles of aluminum

Moles of oxygen gas

Mole ratio between aluminum and oxygen gas

Set up conversion with one of the pieces if information

Based on the result, do you have enough of the other element or not enough?

  1. In the production of copper from ore containing copper (II) sulfide, the ore is first roasted to change it to the oxide according to the following equation: 2 CuS + 3 O2  2 CuO + 2 SO2
  2. If 100.0 g of CuS and 56 g of O2 are available, which reactant is limiting?

Moles of CuS

Moles of O2

Mole ratio between CuS and O2

Set up conversion with one of the pieces of information

Based on the result, do you have enough of the other element or not enough?

  1. What mass of CuO can be formed from the reaction of 18.7 g of CuS and 12.0 g of O2?

Moles of CuS

Moles of O2

Mole ratio between CuS and O2

Set up conversion with one of the pieces of information

Based on the result, do you have enough of the other element or not enough?

Use the reactant that will run out first, the limiting reactant, to find the mole ratio with CuO

Once you find the moles of CuO, determine the grams.

  1. A reaction such as the one shown here is often used to demonstrate a single replacement reaction.

3 CuSO4 + 2 Fe  3 Cu + Fe2(SO4)3

  1. If you place 0.092 mol of iron filings in solution containing 0.158 mol of CuSO4, what is the limiting reactant? How many moles of Cu will be formed?

Mole ratio

Set up conversion with one piece of information

Based on the result, which element will run out first?

Using the limiting reactant, find the mole ratio between it and

Cu

Set up the conversion and cross multiply

  1. In the reaction BaCO3 + 2 HNO3  Ba(NO3)2 + CO2 + H2O, what mass of Ba(NO3)2 can be formed by combining 55 g BaCO3 and 26 g HNO3?