lecture17 - Chapter 5 Enthalpies, Fuel and Hesss Law...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Chapter 5 Enthalpies, Fuel and Hess’s Law a) -605 b) -890 c) 605 d) 890 Calculate enthalpy of reaction in kJ/mol for CH 4 (g) + 2O 2 (g) CO 2 (g) + 2H 2 O(l) (-393.5) +2(-285.8) –(- 74.8) – 2(0) kJ/mol = -890.3 kJ/mol
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Fuel and food values Until now, we have compared enthalpies on a per-mole basis For consumer products, we usually make decisions based on masses or volumes We can do simple unit conversions in order to calculate energy produced or consumed in terms of mass or volume Use molar mass to get grams, and then use density if you need volume Fuel value: energy per gram Which produces more heat of combustion per gram , CH 4 or C 3 H 8 ? 1) Calculate heat of combustion per mole 2) Convert to units of grams 3) Compare results CH 4 + 2O 2 CO 2 + 2H 2 O
Background image of page 2
3 Which produces more heat of combustion per gram , CH 4 or C 3 H 8 ? CH 4(g) + 2O 2 (g) CO 2 (g) + 2H 2 O(g) H = -393.5 +2(-241.8) – (-74.8) -2(0) = -802.3kJ/mol -802.3kJ/mol (1mol/16.04g) = 50.08 kJ/g C 3 H 8 (g) + 5O 2 (g) 3CO 2 (g) + 4H 2 O(g) H = 3(-393.5)+4(-241.8) –(-103.8) -5(0) = -2043.9kJ/mol -2043.9kJ/mol (1mol/44.1g) = 46.35 kJ/g Fuel Values * Based on the formation of H
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 11/18/2011 for the course CHE 131 taught by Professor Kerber during the Spring '08 term at SUNY Stony Brook.

Page1 / 8

lecture17 - Chapter 5 Enthalpies, Fuel and Hesss Law...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online