Sodium reacts with water to give hydrogen gas and sodium hydroxide solution - HSC - SSCE Chemistry - Question 14 - 2013 - Paper 1

The reaction of sodium with water is given by:

$2 \text{Na} + 2 \text{H}_2\text{O} \rightarrow 2 \text{NaOH} + \text{H}_2$

From this reaction, 2 moles of sodium produce 1 mole of hydrogen gas. Thus, 1 mole of sodium will produce:

$\frac{1.00}{2} = 0.50 \, \text{mol of } H_2$

To calculate the volume of hydrogen gas produced, we can use the ideal gas law:

$PV = nRT$

Rearranging gives:

$V = \frac{nRT}{P}$

Where:

• $R = 8.31 \, \text{J/(mol K)}$
• Convert pressure $P$ from kPa to Pa: $100 \, \text{kPa} = 100,000 \, \text{Pa}$
• Convert temperature to Kelvin: $25°C = 298 \, K$

Inserting the values: $V = \frac{0.50 \, \text{mol} \times 8.31 \, \text{J/(mol K)} \times 298 \, K}{100,000 \, ext{Pa}}$

Calculating: $V \approx 0.01240 \, m^3$

Converting cubic meters to liters (1 m³ = 1000 L): $V \approx 12.40 \, L$