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Multiple Choice
How much energy (kJ) is required to convert a 76.4 g acetone (MM = 58.08 g/mol) as a liquid at -30°C to a solid at -115.0°C?
A
-11.406 kJ
B
-39.820 kJ
C
-22.811 kJ
D
-82.592 kJ
Verified step by step guidance
1
Calculate the energy required to cool the liquid acetone from -30°C to its melting point at -95°C using the formula: q = m * C * ΔT, where m is the mass, C is the specific heat of the liquid, and ΔT is the change in temperature.
Convert the mass of acetone from grams to moles using its molar mass: moles = mass / molar mass.
Calculate the energy required for the phase change from liquid to solid at the melting point using the formula: q = n * ΔH_fusion, where n is the number of moles and ΔH_fusion is the enthalpy of fusion.
Calculate the energy required to cool the solid acetone from its melting point at -95°C to -115°C using the formula: q = m * C * ΔT, where C is the specific heat of the solid.
Sum the energies calculated in the previous steps to find the total energy required for the entire process.