Enthalpy Calculations Answers

* Advanced Level chemistry ENTHALPY Calculation Revision Questions at Doc Brown's Chemistry *

HELP NOTES for the extra ΔH Q's for Advanced Level Chemistry

Enthalpy Calculation Revision Question Answers

Associated LINKS

Thermodynamics Part 1: Thermochemistry - Calorimetry experiments - Enthalpies of reaction,formation, combustion and bond dissociation are explained with exempler calculations * EMAIL

Original set of ∆H enthalpy of combustion/formation calculation questions to go with these answers

GCSE notes on Energy Changes - exothermic/endothermic reaction changes

Answers to Questions 1 and 2

I DO MY BEST TO CHECK MY CALCULATIONS, as you yourself should do, BUT I AM HUMAN! AND IF YOU THINK THERE IS A 'TYPO' or CALCULATION ERROR PLEASE EMAIL ME ASAP TO SORT IT OUT!

Answers to Questions 3 and 4

Answers to Questions 5 to 7

Answers to Question 8

Answers to Question 9

Q9 Calculating the enthalpy of formation of propane from bond energy data and ∆H_sub(carbon) Don't forget to change the positive signs for bond enthalpies of dissociation into negative values of bond formation.
3C_(s) + 4H_2(g) C₃H_8(g)
ΔH^Ø_sub_{(C_(s))} + 4 x ΔH^Ø_bond_{diss(H_2(g))} = (3 x 715) + (4 x 436) = 2145 + 1744 = +3889 kJ			2 x ΔH^Ø_{bond form}_{(_C-C(g))} + 8 x ΔH^Ø_{bond form}_{(_C-H(g))} (2 x -348) + (8 x -412) = = -696 - 3296 = -3992 kJ
3C_(g) + 8H_(g)
∆H_{form(C₃H₈)} = +3889 + (-3992) = -103 kJ mol^-1 (data book value -104 kJ mol^-1)

I DO MY BEST TO CHECK MY CALCULATIONS, as you yourself should do, BUT I AM HUMAN! AND IF YOU THINK THERE IS A 'TYPO' or CALCULATION ERROR PLEASE EMAIL ME ASAP TO SORT IT OUT!