consider the following intermediate chemical equations.\nch₄(g)→c(s)+2h₂(g) δh₁ = 74.8 kj\nccl₄(g)→c(s)+2cl₂(…

consider the following intermediate chemical equations.\nch₄(g)→c(s)+2h₂(g) δh₁ = 74.8 kj\nccl₄(g)→c(s)+2cl₂(g) δh₂ = 95.7 kj\nh₂(g)+cl₂(g)→2hcl(g) δh₃ = -92.3 kj\nwhat is the enthalpy of the overall chemical reaction ch₄(g)+4cl₂(g)→ccl₄(g)+4hcl(g)?\n-205.7 kj\n-113.4 kj\n-14.3 kj\n78.0 kj
Answer
Explanation:
Step1: Identify the target reaction and given reactions
The target reaction is $CH_4(g)+4Cl_2(g)\rightarrow CCl_4(g) + 4HCl(g)$. The given reactions are: Reaction 1: $CH_4(g)\rightarrow C(s)+2H_2(g)\quad\Delta H_1 = 74.8\ kJ$ Reaction 2: $CCl_4(g)\rightarrow C(s)+2Cl_2(g)\quad\Delta H_2=95.7\ kJ$ Reaction 3: $H_2(g)+Cl_2(g)\rightarrow 2HCl(g)\quad\Delta H_3=- 92.3\ kJ$
Step2: Manipulate the given reactions
Reverse Reaction 2 to get $C(s)+2Cl_2(g)\rightarrow CCl_4(g)\quad\Delta H_{2 - reversed}=- 95.7\ kJ$. Multiply Reaction 3 by 2: $2H_2(g)+2Cl_2(g)\rightarrow 4HCl(g)\quad\Delta H_{3 - multiplied}=2\times(-92.3\ kJ)=-184.6\ kJ$
Step3: Add the manipulated reactions
Add Reaction 1, the reversed - Reaction 2 and the multiplied - Reaction 3: $(CH_4(g)\rightarrow C(s)+2H_2(g))+(C(s)+2Cl_2(g)\rightarrow CCl_4(g))+(2H_2(g)+2Cl_2(g)\rightarrow 4HCl(g))$ The $C(s)$ and $2H_2(g)$ terms cancel out on the left - hand and right - hand sides. The overall $\Delta H=\Delta H_1+\Delta H_{2 - reversed}+\Delta H_{3 - multiplied}$ $\Delta H = 74.8\ kJ-95.7\ kJ - 184.6\ kJ=-205.5\approx - 205.7\ kJ$
Answer:
$-205.7\ kJ$