Question

1. The standard enthalpy of formation of phenol is -165.0 kJ/mol. Calculate its standard enthalpy of combustion. [Express your answer in units of kilojoules per mole, kJ/mol]

C6H5OH + 7O2 --> 6 CO2 + 3H2O

ΔHc = 6ΔHf(CO2) + 3ΔHf(H2O) - ΔHf(C6H5OH) - 7ΔHf(O2)

2. Calculate the work done on a closed system consisting of 50.0 grams of argon, assumed ideal, when it expands isothermally and reversibly from a volume of 5.00 L to a volume of 10.00 L at a temperature of 298 K. [Express your answer in units of kiloJoules, kJ]

w = -nRT ln(V2/V1)

3. The heat capacity of a substance is often reported in the form C_p,m = a + bT + c/T². Use this expression to make a more accurate estimate of the change in molar enthalpy of carbon dioxide when it is heated from 15°C to 37°C, given a = 44.22 J K⁻¹ mol⁻¹, b = 8.79 × 10⁻³ J K⁻² mol⁻¹, and c = −8.62 × 105 J K mol⁻¹. Give your answer in the units of J/mol.

dH = C_pdT.

Answer 1