Question

When 1 mole of hydrogen gas (H2) reacts with excess oxygen to form water at a constant pressure, 241.8 KJ of energy is released as heat. Calculate ΔH for a process in which 21.9 g sample of hydrogen gas (H2) reacts with excess oxygen at constant pressure.

Answer 1

The value of ΔH when 21.9 grams of hydrogen gas reacts with an excess of oxygen gas is 2,647.71 kilo Joules.

Step-by-step explanation:

`H_2+(1)/(2)O_2\rightarrow H_2O,\Delta H=-241.8 kJ`

Mass of hydrogen gas = 21.9 g

Moles of hydrogen gas =
`(21.9 g)/(2 g/mol)=10.95 mol`

When 1 mole of hydrogen gas reacts with an excess oxygen gas it gives 241.8 kJ of heat.

Then 10.95 moles hydrogen gas will give :

`241.8 kJ* 10.95 =2,647.71 kJ`

The value of ΔH when 21.9 grams of hydrogen gas reacts with an excess of oxygen gas is 2,647.71 kilo Joules.