mid2_f03 - Please use the following constants and...

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Please use the following constants and conversions in the problems below as needed h = 6.626 × 10 -34 J-s R H = 1.10 × 10 7 m c = 3.00 × 10 8 m/s Avogadro&s Number = 6.022 × 10 23 1. [7 points] Which of the following statements regarding enthalpy is false ? (a) Enthalpy is a state function (b) Enthalpy is an extensive property (c) To determine the enthalpy of a reaction it is necessary to know the mechanism by which the reaction proceeds. (d) The enthalpy of a reaction is equal to the heat produced/absorbed by the reaction when it occurs at constant pressure (e) The enthalpy change for a reaction depends upon the state (solid, liquid, gaseous or aqueous) of the products and reactants 2. [7 points] Which of the following equations represents the standard enthalpy of formation of ammonium chloride? (a) N 2 (g) + H 2 (g) + Cl 2 (g) NH 4 Cl(s) (b) N 2 (g) + 4H 2 (g) + Cl 2 (g) 2NH 4 Cl(s) (c) N(g) + 2H 2 (g) + Cl(g) NH 4 Cl(s) (d) ‰N 2 (g) + 2H 2 (g) + ‰Cl 2 (g) NH 4 Cl(s) (e) N (g) + 4H(g) + Cl(g) NH 4 Cl(s) 3. [7 points] Which of the following processes are endothermic? (a) Freezing water (liquid solid) (b) Boiling water (liquid gas) (c) The combustion of methane [CH 4 (g) + 2O 2 (g) CO 2 (g) + 2H 2 O(g)] (d) Electrolysis of water [2H 2 O(l) 2H 2 (g) + O 2 (g)] (e) Both (b) and (d) are endothermic. 4. [7 points] There are two forms of elemental phosphorous, white phosphorous, which has a standard enthalpy of formation, H f ° = 0 kJ/mol, and red phosphorous, which has a standard enthalpy of formation, H f ° = -17.5 kJ/mol. Given this information which of the following statements is true? (a) White phosphorous is more stable than red phosphorous (b) Red phosphorous is more stable than white phosphorous (c) Conversion of red phosphorous to white phosphorous will generate heat (d) Both (a) and (c) are true statements. (e) Both (b) and (c) are true statements.
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5. [7 points] If 11.40 g of methanol (CH 3 OH, MW = 32.0 g/mol) is reacted with 12.1 g of oxygen (O 2 , MW = 32.0 g/mol) according to the following thermochemical equation: 2CH 3 OH (l) + 3O 2 (g) 2CO 2 (g) + 4H 2 O(l) H = -1448 kJ What quantity of heat is released (assuming the pressure is held constant)?
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This note was uploaded on 07/17/2008 for the course CHEM 121 taught by Professor Wyzlouzil during the Fall '07 term at Ohio State.

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mid2_f03 - Please use the following constants and...

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