CHEM 1E03 TUTORIAL #3 _____________________________________________________________________ Page 1 of 1 1. Use enthalpies of formation (found in Appendix D of your textbook) to calculate the standard enthalpy change for the following reaction at 298K: 2 C 2 H 6 (g) + 7 O 2 (g) → 4 CO 2 (g) + 6 H 2 O(l) 2. Coal and natural gas are both fuels used for home heating. Assuming that coal is pure graphite and that natural gas is pure methane, and that graphite and methane have the same cost per gram, decide which of these two fuels is the more economical for heating a home. (Assume that gaseous water is produced when methane burns, and that both combustion reactions are complete.) Use ∆ H f ° values from Appendix D of your textbook. 3. Calculate the enthalpy change, in kJ, at 25 o C for 2HBr(g) → H 2 (g) + Br 2 (g) given that ∆ H f ° of HBr(g) is –36.23 kJ mol –1 and the enthalpy of vaporization of bromine is 30.96 kJ mol –1 . 4. Tungsten carbide is a very hard substance, used to make cutting tools and rock drills. Using
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