Question

2SO3(g)⟶2S(s)+3O2(g)ΔH=+790kJ. How many kilojoules are required when 2.1 moles of SO3 reacts?

Answer 1

Answer: 829.5 kilo Joule heat will be required when 2.1 moles of sulfur trioxide reacts.

Solution:

Given reaction:

$2SO_3(g)\rightarrow 2S(s)+3O_2(g),\Delta H=+790 kJ$

On dividing the chemical equation by 2 we get :

$SO_3(g)\rightarrow S(s)+\frac{3}{2}3O_2(g),\frac{\Delta H}{2}=395 kJ$

If 1 mole of sulfur trioxide requires 395 kJ then 2.1 moles will require:

$=2.1\times 395 kJ= 829.5kJ$

829.5 kiloJoule heat will be required when 2.1 moles of sulfur trioxide reacts.

Answer 2

Given:

Enthalpy change (ΔH) for SO3 decomposition = +790 kJ

Moles of SO3 = 2.1 moles

To determine:

Energy required when 2.1 moles of SO3 reacts

Explanation:

The decomposition reaction is -

2SO3(g) → 2S(s) + 3O2 (g)

Energy required when 2 moles of SO3 reacts is 790 kJ

Thus, for 2.1 moles of SO3 the energy requirement would be

= 2.1 moles SO3 * 790 kJ/2 moles SO3 = 829.5 kJ

Ans: 830 kJ are required when 2.1 moles of SO3 reacts.