# You are given the following two equations. How do you calculate DeltaH for this reaction: Sn(s) + 2Cl_2(g) -> SnCl_4 (l)?

## $S n \left(s\right) + C {l}_{2} \left(g\right) \to S n C {l}_{2} \left(s\right)$ $\Delta H = - 325 k J$ $S n C {l}_{2} \left(s\right) + C {l}_{2} \left(g\right) \to S n C {l}_{4} \left(l\right)$ $\Delta H = - 186 k J$

Jul 16, 2016

You can do it like this:

#### Explanation:

We can apply Hess' Law. This states that the overall enthalpy change for a reaction is independent of the route taken.

It helps to use an energy level diagram:

From this you can see that the route in red is equal in energy to the route in blue:

$\therefore$sf(DeltaH=-325-186=-511color(white)(c)kJ