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

DOC BROWN'S HOMEPAGE and WELCOME ALPHABETICAL SITE INDEX for chemistry KS3 SCIENCE QUIZZES and WORKSHEETS (~US grades 6-8) KS4 Science GCSE/IGCSE CHEMISTRY NOTES (~US grades 8-10) KS4 Science GCSE/IGCSE CHEMISTRY QUIZZES and WORKSHEETS (~US grades 8-10) KS4 Science GCSE/IGCSE CHEMISTRY SYLLABUS HELP LINKS (~US grades 8-10) ADVANCED LEVEL CHEMISTRY NOTES (~US grades 11-12) ADVANCED LEVEL CHEMISTRY QUIZZES and WORKSHEETS (~US grades 11-12) ADVANCED LEVEL CHEMISTRY SYLLABUS HELP LINKS (~US grades 11-12)  
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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!

(c) doc b

 

Answers to Questions 3 and 4

(c) doc b

 

Answers to Questions 5 to 7

(c) doc b

 

Answers to Question 8

(c) doc b

 

Answers to Question 9

Q9   Calculating the enthalpy of formation of propane from bond energy data and ∆Hsub(carbon)

Don't forget to change the positive signs for bond enthalpies of dissociation into negative values of bond formation.

3C(s) + 4H2(g) (c) doc b C3H8(g)

ΔHØsub(C(s)) + 4 x ΔHØbond diss(H2(g))

= (3 x 715) + (4 x 436)

= 2145 +  1744 = +3889 kJ

(c) doc b (c) doc b

2 x ΔHØbond form(C-C(g)) + 8 x ΔHØbond form(C-H(g))

(2 x -348) + (8 x -412) =

= -696 - 3296 = -3992 kJ

3C(g) + 8H(g)
∆Hform(C3H8) = +3889 + (-3992) =  -103 kJ mol-1 (data book value -104 kJ mol-1)

(c) doc b

 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!

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Revision notes for GCE Advanced Subsidiary Level AS Advanced Level A2 IB Revise AQA GCE Chemistry OCR GCE Chemistry Edexcel GCE Chemistry Salters Chemistry CIE Chemistry revising courses for pre-university students (equal to US grade 11 and grade 12 and Honours/honors level courses)

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