Part A Give the H value for the combustion of ethanol as shown in the reaction C

Question

Part A

Give the H value for the combustion of ethanol as shown in the reaction C2H5OH(g)+3O2(g)2CO2(g)+3H2O(g)+1278 kJ.

Express your answer using four significant figures. If the value is positive, do not include the + sign in your answer.

_____ kJ

Part B

Give the H value for the formation of binary compounds as shown in the reaction Ba(s)+Cl2(g)BaCl2(s)+855kJ.

Express your answer using three significant figures. If the value is positive, do not include the + sign in your answer.

____kJ

Part C

Give the H value for the decomposition of phosphorus pentachloride as shown in the reaction PCl5(g)+67 kJPCl3(g)+Cl2(g).

Express your answer using three significant figures. If the value is positive, do not include the + sign in your answer.

____kJ

Explanation / Answer

a)

since energy is being released, this implies that

HRxn = exothermic, so

HRxn = -1278 kJ

b)

once again, this is exothermic

HRXN = -855 kJ

c)

this is endothermic, therefore, HRXN must be positive

choose:

HRXN = 67.0 kJ

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