Consider the reaction, C2H4(g) + H2(g) → C2H6(g), where ΔH = –137 kJ. How many kilojoules are released when 3.5 mol of C2H4 reacts?
The enthalpy change for the reaction is -137 kJ/mol C2H4. This means that 137 kJ of energy is released for every 1 mol of C2H4 that reacts.
Therefore, for 3.5 mol of C2H4 that reacts, the total energy released can be calculated as:
3.5 mol C2H4 x 137 kJ/mol = 478.5 kJ
Therefore, 478.5 kJ of energy are released when 3.5 mol of C2H4 reacts.