Answer:
∆Hrxn = -390.3 kJ.
Explanation:
Okay, let us first write out the additional equations given below;
C(s) + 2 H2(g) -----> CH4(g); ΔH= −74.6kJ ------------------------------------(1).
C(s) + 2 Cl2(g) -----------------> CCl4(g); ΔH=−95.7kJ -----------------------------(2).
H2(g) + Cl2(g) -----------> 2HCl(g); ΔH=−184.6kJ ----------------------------(3).
Step one: reverse equation (1).
This gives us equation (4) which is;
CH4 -----------------------------> C + 2H2 ; ∆H = + 74.6 kJ --------------------------(4).
Step two: multiply equation (3) by 2 to get equation (5) which is;
2 H2(g) + 2 Cl2(g) -----------> 4 HCl(g); ΔH=− 369.2 kJ. -------------------------(5).
Step three: addition of equation (4), (2) and (5) gives us our desired equation;
CH4(g) + 4 Cl2(g) -------> CCl4(g) + 4 HCl(g).
Step four:
Addition of all the ∆H gives us our answer;
(+74.6)kJ + (-95.7)kJ + (− 369.2)kJ.
Therefore, ∆Hrxn = -390.3 kJ.
