CHEM111F16_DQ_week7entropykey.docx - CHEM111 W7 Entropy Fall 2015 1 Coal is converted into a cleaner more transportable fuels by burning it with oxygen

# CHEM111F16_DQ_week7entropykey.docx - CHEM111 W7 Entropy...

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CHEM111 W7 Entropy Fall 2015 1) Coal is converted into a cleaner, more transportable fuels by burning it with oxygen to produce carbon monoxide. The carbon monoxide then is reacted with hydrogen using a catalyst to produce methane and water. Is the reaction between CO and H 2 exothermic or endothermic, and what is the change in enthalpy for it? The enthalpies of formation of the reactants and products are given below. Molecule o f ΔH CO -110 H 2 0 CH 4 -75 H 2 O -242 CO + 3 H 2 CH 4 + H 2 O H rxn = (-75+-242)-(-110+0) = -207 kJ/mol exothermic reaction 2) Methane gas is used as a fuel source for mechanical devices. Hydrogen gas reacts with graphite to produce this fuel source. Use the following thermochemical equations to determine the o rxn ΔH the reaction to produce methane gas. C (s, graphite) + O 2(g) CO 2(g) H o = -393.5 kJ/mol CH 4(g) + 2O 2(g) CO 2(g) + 2H 2 O (l) H o = -890.3 kJ/mol H 2(g) + 1 2 O 2(g) → H 2 O (l) H o = -285.8 kJ/mol C (s, graphite) + O 2(g) CO 2(g) H o = -393.5 kJ/mol CO 2(g) + 2H 2 O (l) CH 4(g) + 2O 2(g) -1* H o = 890.3 kJ/mol 2H 2(g) + O 2(g) → 2H 2 O (l) 2* H o = -571.6 kJ/mol _________________________________________________ C (s, graphite) + 2 H 2(g) → CH 4(g) o rxn ΔH = -74.8 kJ/mol of reaction 3) Determine the o ΔH rxn for C(diamond) → C(graphite) based on enthalpy change of the following reactions: (1) C(diamond) + O 2 (g) CO 2 (g) H 395.4 kJ /mol   (2) 2CO 2 (g) 2CO(g) + O 2 (g) H 566.0 kJ /mol (3) C (graphite) + O 2 (g) CO 2 (g) H 393.5 kJ /mol   (4) 2CO(g) C(graphite) + CO 2 (g) H 172.5 kJ /mol  
CHEM111 W7 Entropy Fall 2015 4) Use bond enthalpy values to calculate the enthalpy of reaction.

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• Spring '08
• Kenney