2. In the following experiment, a coffee-cup calorimeter containing 100 mL of H2OH2O is used. The initial temperature of the calorimeter is 23.0 ∘C∘C. If 6.00 gg of CaCl2CaCl2 is added to the calorimeter, what will be the final temperature of the solution in the calorimeter? The heat of solution ΔHsoln of CaCl2CaCl2 is −82.8 kJ/mol−82.8 kJ/mol. Assume that the specific heat of the solution formed in the calorimeter is the same as that for pure water: Cs=4.184Cs=4.184 J/g⋅∘CJ/g⋅∘C.

3.Calculate the standard enthalpy change for the reaction

2A+B⇌2C+2D

Use the following data:
Substance ΔH∘f
(kJ/mol)
A -229
B -379
C 219
D -489

4. Pentane (C5H12)(C5H12) is a component of gasoline that burns according to the following balanced equation:
C5H12(l)+8O2(g)→5CO2(g)+6H2O(g)

Calculate ΔH∘rxn for this reaction using standard enthalpies of formation. (The standard enthalpy of formation of liquid pentane is -146.8 kJ/mol.)

Express the enthalpy in kilojoules to four significant figures.