2al (s) + 3cl2 (g) →2alcl3 (s) δh∘ = - 1408.4 kj. how much heat (in kilojoules) is released on reaction of 4.70 g of al?

- 122.58 kJ

Solution:

According to following equation,

2 Al + 3 Cl ₂ → 2 AlCl ₃ δH ° = - 1408.4 kJ

When,

54 g (2 mole) Al on reaction releases = 1408.4 kJ heat

So,

4.70 g of Al will release = X kJ of Heat

Solving for X,

X = (4.70 g * 1408.4 kJ) : 54 g

X = - 122.58 kJ