Question

Calculate δhrxn for the following reaction:

CH₄(g) + 4Cl₂(g) → CCl₄(g) + 4HCl(g)
given these reactions and their δh values:
C(s) + H₂(g) → 2H₂(g) δh = -74.6 kJ
2Cl₂(g) → Cl₄(g) δh = -95.7 kJ
δh = -184.6 kJ
Express the enthalpy in kilojoules to one decimal place.

Answer 1

The ΔHrxn for the given reaction is -281.0 kJ.

Step-by-step explanation:

To calculate ΔHrxn for the reaction CH4(g) + 4Cl2(g) → CCl4(g) + 4HCl(g), we can use Hess's Law and the given reactions. First, we need to balance the equation to match the given reactions. The balanced equation is:

CH4(g) + 4Cl2(g) → CCl4(g) + 4HCl(g)

Now, we can use the given reactions with their ΔH values to find ΔHrxn.

We have:

• C(s) + H2(g) → 2H2(g) ΔH = -74.6 kJ
• 2Cl2(g) → Cl4(g) ΔH = -95.7 kJ
• 2HCl(g) ΔH = -184.6 kJ

Using these reactions, we can calculate ΔHrxn as follows:

ΔHrxn = 4(ΔHHCl) + ΔHCCl4 - 4(ΔHCl2) - ΔHCH4

= 4(-184.6 kJ) + 0 kJ - 4(-95.7 kJ) - (-74.6 kJ)

= -738.4 kJ + 382.8 kJ + 74.6 kJ

= -281.0 kJ