thermo11_20_solutions

# thermo11_20_solutions - 1680 kJ 85 A 0.250 chunk of sodium...

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1. Predict the contribution to the heat capacity C v,m made by molecular motions for each of the following atoms and molecules: (a) HCN; (b) C 2 H 6 ; (c) Ar; (d) HBr. 2. From the following enthalpies of reaction, find ΔH rxn for 2HCl(g) + F 2 (g) 2HF( l ) + Cl 2 (g). 4 HCl(g) + O 2 (g) 2 H 2 O( l ) + 2 Cl 2 (g) ΔH= -202.4 kJ/mol rxn 1/2 H 2 (g) + 1/2 F 2 (g) HF( l ) ΔH= -600.0 kJ/mol rxn H 2 (g) + 1/2 O 2 (g) H 2 O( l ) ΔH= -285.8 kJ/mol rxn 3. Use the bond energies to estimate the enthalpy of reaction for each of the following gas phase reactions. (see table 13.6, 13.7 on p. 608) (a) H 2 C=CH 2 + Br 2 BrH 2 C─CH 2 Br, (b) H 2 O 2 H 2 O + 1/2 O 2 .
4. Given that SiO 2 (s) + 3C(graphite) SiC(s) + 2CO(g) with ΔH rxn = 624.6 kJ/mol rxn; ΔH 0 f for SiO 2 (s) and CO(g) are -910.9 kJ/mol and -110.5 kJ/mol, respectively. Calculate ΔH 0 f for SiC. Heating Curves (phase changes) From Ch. 16 in Text NOTE: C s,ice = 2.08 J/(g*C); C s,water = 4.184 J/(g*C), H fus,water = 6.01 kJ/mol, H vap, water = 40.7 kJ/mol. 83. How much energy does it take to convert 0.500 kg of ice at -20 C to steam at 250 C?
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Unformatted text preview: 1680 kJ 85. A 0.250 chunk of sodium metal is cautiously dropped into a mixture of 50.0 g of water and 50.0 g of ice (in equilibrium). The reaction is: 2 Na(s) + 2 H 2 O(l) 2 NaOH(aq) + H 2 (g) DH = -368kJ Will the ice melt? Assuming that the sodium hydroxide mixture has the same specific heat as water, calculate the final temperature. The reaction doesn’t release enough heat to melt all the ice. The temp of water will remain at 0 C. 87. An ice cube train contains enough water at 22.0 C to make 18 ice cubes, each of which has a mass of 30.0 g. The tray is placed in a freezer that uses CF 2 Cl 2 as a refrigerant. The heat of vaporization of CF 2 Cl 2 is 158 J/g. What mass of CF 2 Cl 2 must be vaporized in the refrigeration cycle to convert all of the water at 22 C to ice at -5 C? 1490 g...
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thermo11_20_solutions - 1680 kJ 85 A 0.250 chunk of sodium...

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