Chloroform, CHCl3, is formed from methane and chlorine in the following reaction.
CH4(g) + 3 Cl2(g) → 3 HCl(g) + CHCl3(g)
Calculate ΔrH°, the enthalpy change for this reaction, using the enthalpies of formation of CO2(g), H2O(ℓ), CHCI3(g) (ΔfH° = –103.1 kJ/mol), and the enthalpy changes for the following reactions:
CH4(g) + 2 O2(g) → 2 H2O(ℓ) + CO2(g)
ΔrH° = –890.4 kJ/mol-rxn
2 HCl(g) → H2(g) + Cl2(g)
ΔrH° = +184.6 kJ/mol-rans
Interpretation:
The enthalpy change for the reaction of has to be calculated.
Concept Introduction:
The standard enthalpy change of combustion of a compound is the enthalpy change which occurs when one gram of the compound is burned completely in oxygen under standard conditions, and with everything in its standard state.
Answer to Problem 89GQ
The enthalpy change for the reaction is
Explanation of Solution
Given,
Reverse the 2nd equation and multiply by 3.
Inorder to consume the
In order to consume the
To produce
Using Hess law:
So, the change in enthalpy of the reaction is
The enthalpy change for the reaction was calculated
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Chapter 5 Solutions
Chemistry & Chemical Reactivity
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