Practice Combustion in Chemistry

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

Quick Recap

A rapid exothermic chemical reaction in which a fuel reacts with oxygen gas, releasing large amounts of energy as heat and light.

Burning. When something burns, it's reacting with oxygen and releasing energy as heat and light.

Showing a random 20 of 50 problems.

Example 1

easy
Is O2 always a reactant in combustion?

Example 2

hard
A hydrocarbon produces 4 mol of CO2 and 5 mol of H2O per mol burned. Find its formula.

Example 3

medium
Balance: C3H7OH+O2→CO2+H2O (1-propanol).

Example 4

medium
Balance: C5H12+O2→CO2+H2O (pentane).

Example 5

easy
Balance: C+O2→CO2.

Example 6

hard
Ethanol (C2H5OH) is used as a fuel additive. Write the balanced equation for its complete combustion. If only limited oxygen is available, what products form instead (incomplete combustion)?

Example 7

medium
How many moles of O2 are needed to completely burn 3 mol of propane (C3H8)?

Example 8

medium
How many mol O2 are needed to burn 2 mol CH4 completely?

Example 9

easy
Complete combustion of C2H6 gives which products?

Example 10

easy
Is 2Mg+O2→2MgO a combustion reaction?

Example 11

easy
Balance the combustion of butane: C4H10+O2→CO2+H2O.

Example 12

hard
Burning 0.10 mol of ethanol (C2H5OH) completely gives what mass of CO2 (M = 44 g/mol)?

Example 13

challenge
1.00 mol of an unknown hydrocarbon CxHy requires 6.5 mol O2 for complete combustion. If it forms 4 mol CO2, find x and y.

Example 14

medium
Balance: CH4+O2→CO2+H2O.

Example 15

challenge
Complete combustion of 8.0 g CH4 (M=16) gives what mass of H2O (M=18)?

Example 16

medium
True or false: combustion always involves a flame.

Example 17

easy
What two products form in complete combustion of a hydrocarbon?

Example 18

medium
Balance: C2H4+O2→CO2+H2O (ethene).

Example 19

medium
What gas detector should every home have to warn against incomplete combustion?

Example 20

medium
Why is incomplete combustion of CH4 dangerous?