Question

Given the information below, calculate ΔH_rxn for: C₂H₄(g) + 6F₂(g) => 2CF₄ + 4HF(g) H₂(g) + F₂(g) => 2HF(g) ΔH° = -537 kJ, C(s) + 2F₂(g) => CF₄(g) ΔH° = -680 kJ, 2C(s) + 2H₂(g) => C2H4(g) ΔH° = 52.3 kJ

a) -1165 kJ
b) -1269 kJ
c) -2382 kJ
d) -2486 kJ
e) -1642 kJ

Answer 1

To calculate ΔH_rxn for the given reaction, we can use Hess's Law and combine the enthalpy changes of multiple reactions. By reversing and doubling the necessary reactions, we can ultimately determine the ΔH_rxn for the desired reaction.

Step-by-step explanation:

To calculate ΔH_rxn for the given reaction, we can use Hess's Law. We need to find a combination of reactions that will cancel out all the reactants and products except for the ones in the desired reaction.

Let's break down the given reactions and their enthalpy changes:

1) H₂(g) + F₂(g) => 2HF(g) (ΔH° = -537 kJ)

2) C(s) + 2F₂(g) => CF₄(g) (ΔH° = -680 kJ)

3) 2C(s) + 2H₂(g) => C₂H₄(g) (ΔH° = 52.3 kJ)

We can start by reversing equation 2 and doubling equation 3:

-2(C(s) + 2F₂(g) => CF₄(g)) => -2(-680 kJ) => 1360 kJ

4(C(s) + 2H₂(g) => C₂H₄(g)) => 4(52.3 kJ) => 209.2 kJ

Now, we can add all the equations together:

C₂H₄(g) + 6F₂(g) => 2CF₄ + 4HF(g)

1360 kJ + 209.2 kJ - 537 kJ = 1032.2 kJ

Therefore, the value of ΔH_rxn for the given reaction is approximately 1032.2 kJ.