Question

Use the following information to determine the enthalpy for the reaction shown below.

 CO₂(g) + 2SO₂(g) --> CS₂(l) + 3O₂(g)     ΔH^o = ?

C(graphite) + O₂(g) --> CO₂(g)            ΔH^o = −393.5 kJ

S(s) + O₂(g) --> SO₂(g)                        ΔH^o = −296.8 kJ

C(graphite) + 2S(s) --> CS₂(l)             ΔH^o = 87.9 kJ

Answer 1

The equation which e have to form is:

$CO_2+2SO_2\Rightarrow CS_2+3O_2:\Delta H_f$

Equation 1:

$C+O_2 \Rightarrow CO_2:\Delta H_1=-393.5kJ$

Equation 2:

$S+O_2 \Rightarrow SO_2 :\Delta H_2=-296.8kJ$

Equation 3:

$C+2S \Rightarrow CS_2: \Delta H_3=87.9kJ$

Now to form the main equation we have to

$\Rightarrow$ $Equation1+2(Equation 2)-Equation 3$

$\Delta H_f=\Delta H_1+2\Delta H_2-\Delta H_3$

$\Delta H_f=-393.5+2(-296.8)-87.9=-1075kJ$