Calculating Reactants in Chemical Reaction

How can we calculate grams of reactants in a chemical reaction?

In a reaction between sodium and chlorine gas, a student obtained 39.7 g of sodium chloride from 15.6 g of sodium. How many grams of chlorine gas reacted?

a. 24.09 grams

b. 34.62 grams

c. 45.78 grams

d. 51.25 grams


24.09 grams of chlorine gas reacted.


A chemical equation for the reaction between sodium and chlorine is given as:

2Na(s) + Cl₂(g) → 2NaCl(s)

To calculate the grams of chlorine gas reacted, we need to follow these steps:

1. Determine the moles of sodium chloride formed:

Moles of NaCl = 39.7 g / 58.5 g/mol = 0.6786 mol

2. Use stoichiometry to find moles of chlorine gas:

According to the balanced equation, 2 moles of NaCl are formed from 1 mole of chlorine gas.

Therefore, 0.6786 moles of NaCl correspond to 0.3393 moles of chlorine gas.

3. Calculate the mass of chlorine gas:

Mass of 0.3393 moles of chlorine gas = 0.3393 mol × 71 g/mol = 24.09 g

Therefore, 24.09 grams of chlorine gas reacted in the given reaction.

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