Urgent! (Chemistry) Silver is one of the best conductors of electricity and used in the electrical wiring for high-end stereo equipment...?

Posted on 2016-04-06 18:44:00 in Chemistry by STELLEN

These are some Chem hw questions I couldn't figure out. Please show your work, thank you! 

1.) Silver is one of the best conductors of electricity and used in the electrical wiring for high-end stereo equipment. Determine the mass of the silver if the wire absorbs 3.45 x 103 J of energy at 23.0° C and is heated to 69.0° C after carrying a current for two hours. [The specific heat of silver is 0.230 J/g C] 

2.) What is the standard heat of reaction (∆H^0) for the combustion of ethane, C2H6(g), to form carbon dioxide gas and water? 
2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(l) 
Standard heats of formation (∆Hf⁰): C2H6 = –84.68 kJ 
O2(g) = 0.00 kJ CO2(g) = –393.5 kJ H2O(l) = –285.5 kJ 

3.) What is the enthalpy of reaction for the decomposition of calcium carbonate? Is this endothermic or exothermic? 
CaCO3(s) → CaO(s) + CO2(g) 

4.) 31.7 g CO2 is cooled from a gas at 358 K to a liquid at 213 K. The boiling point of CO2 is 216 K. List the sequential steps and equations needed to determine the heat flow of this change. Is this an exothermic or endothermic change? 

5.) Tin and Chlorine synthesize Stannous Chloride according to a two step mechanism: 
Sn (s) + Cl2 (g) ⇌ SnCl2 (s) + 83.6 kcal 
SnCl2 (s) + Cl2 (g) ⇌ SnCl4 (l) + 46.7 kcal 
Determine the overall heat of reaction and write the final equation for the reaction. 

6.) Water freezes completely at 0.00° C, giving off 12.0 kcal of heat. What is the mass of the water? (heat of fusion (∆Hf) = 80.0 cal/g)

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