Table of contents

3. Chemical Reactions

Balancing Chemical Equations

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Multiple Choice

Consider the balanced equation for the combustion of heptane: C7H16(g) + 11 O2(g) → 7 CO2(g) + 8 H2O(g). How many moles of O2 are required to react completely with 4.8 moles of C7H16?

48.0 moles

44.0 moles

52.8 moles

33.6 moles

Verified step by step guidance

Identify the balanced chemical equation for the combustion of heptane:

C_{7} H_{16} (g) + 11 O_{2} (g) \to 7 {CO}_{2} (g) + 8 H_{2} O (g)

Determine the mole ratio between heptane (

C_{7} H_{16}

) and oxygen (

O_{2}

) from the balanced equation. The ratio is 1 mole of

C_{7} H_{16}

to 11 moles of

O_{2}

Use the mole ratio to set up a proportion to find the moles of

O_{2}

needed for 4.8 moles of

C_{7} H_{16}

\frac{11}{1}

\frac{x}{4.8}

Solve the proportion for

x

, which represents the moles of

O_{2}

required. Multiply both sides of the equation by 4.8 to isolate

x

x = 11 × 4.8

Calculate the product to find the number of moles of

O_{2}

required for the complete combustion of 4.8 moles of heptane.

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