Question

What volume of hydrogen gas is produced when 97.4 g of sodium reacts completely according to the following reaction at 25 °C and 1 atm?

sodium (s) + water(l)sodium hydroxide (aq) + hydrogen(g)

? liters hydrogen gas

Answer 1

The given reaction is

Na(s) + H2O(l) ------> NaOH(aq) + H2(g)

The reaction is not balanced

Balanced reaction is

2Na(s) + 2H2O(l) ------> 2NaOH(aq) + H2(g)

From the balanced reaction,

2 moles of sodium reacts to give 1 mole of hydrogen gas

Atomic weight of Na = 23 g/mol

Since 97.4 g of sodium reacts therefore moles of Na = 97.4/23 mol = 4.23 moles

From the stoichiometry of the reaction 4.23 moles of Na reacts to give 4.23/2 = 2 11 moles of hydrogen

At STP 1mole of hydrogen gas has 22.4 litre volume

2.11 moles of hydrogen gas has 2.11x22.4 litre = 47 42 litres of hydrogen gas

Hence answer is 47.42 litres