Enthalpy of formation

Question

Using standard heats of formation, calculate the standard enthalpy change for the following reaction.

2Fe(s) + 3Cl₂(g)2FeCl₃(s)

Answer 1

To solve this problem, you'll use the equation ΔH_rxn = ∑nΔH_{f, products} - ∑nΔH_{f, reactants}

1. the "n" values are the coefficients in the balanced equation
2. your textbook should have a table of ΔH_f's - use that to find the value for FeCl₃
3. recall that ΔH_f's of elements are always 0 kJ/mol

So, you'll:

1. multiply the product's ΔH_f by it's coefficient
2. multiply the reactants' ΔH_f's by their coefficients and add those results
3. subtract!

Let me know if this helps/if you need further clarification!