Practice Reactant in Chemistry

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

Quick Recap

A starting substance that is consumed and chemically transformed during a chemical reaction, appearing on the left side of a chemical equation before the reaction arrow.

What you start with — the ingredients that get used up to make something new.

Example 1

easy
Define the term 'reactant' in a chemical reaction. In the reaction 2\text{H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}, identify all reactants.

Example 2

medium
In the reaction \text{CaCO}_3 + 2\text{HCl} \rightarrow \text{CaCl}_2 + \text{H}_2\text{O} + \text{CO}_2, identify the reactants and determine the mole ratio in which they react.

Example 3

medium
In the combustion of propane, \text{C}_3\text{H}_8 + 5\text{O}_2 \rightarrow 3\text{CO}_2 + 4\text{H}_2\text{O}, how many moles of \text{O}_2 are needed to react completely with 2 moles of \text{C}_3\text{H}_8?

Example 4

hard
A student mixes 5.0 g of sodium (\text{Na}) with excess water. The reaction is: 2\text{Na} + 2\text{H}_2\text{O} \rightarrow 2\text{NaOH} + \text{H}_2. Calculate the mass of the reactant sodium consumed and the moles of \text{H}_2 produced. (Na = 23.0\,\text{g/mol})
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