Questions: A sample of sodium reacts completely with 0.142 kg of chlorine, forming 234 g of sodium chloride. What mass of sodium reacted? Express your answer to three significant figures and include the appropriate units.

Solution Steps

The balanced chemical equation for the reaction between sodium (Na) and chlorine (Cl\(_2\)) to form sodium chloride (NaCl) is: \[ 2 \text{Na} + \text{Cl}_2 \rightarrow 2 \text{NaCl} \]

Calculate the molar masses of the reactants and products:

• Molar mass of Na: \( 22.99 \, \text{g/mol} \)
• Molar mass of Cl\(_2\): \( 2 \times 35.45 \, \text{g/mol} = 70.90 \, \text{g/mol} \)
• Molar mass of NaCl: \( 22.99 + 35.45 = 58.44 \, \text{g/mol} \)

Convert the given mass of chlorine to moles: \[ \text{Mass of Cl}_2 = 0.142 \, \text{kg} = 142 \, \text{g} \] \[ \text{Moles of Cl}_2 = \frac{142 \, \text{g}}{70.90 \, \text{g/mol}} = 2.0028 \, \text{mol} \]

From the balanced equation, 1 mole of Cl\(_2\) reacts with 2 moles of Na: \[ \text{Moles of Na} = 2 \times \text{Moles of Cl}_2 = 2 \times 2.0028 \, \text{mol} = 4.0056 \, \text{mol} \]

\[ \text{Mass of Na} = \text{Moles of Na} \times \text{Molar mass of Na} \] \[ \text{Mass of Na} = 4.0056 \, \text{mol} \times 22.99 \, \text{g/mol} = 92.06 \, \text{g} \]

Final Answer