How much energy is required to heat 87.1 g acetone (molar mass = 58.08 g/mol) from a solid at -154.0°C to a liquid at -42.0°C?

No. of moles of acetone used, n = (87.1 g) / (58.08 g/mol) = 1.50 mol

Refer to: https://en.wikipedia.org/wiki/Acetone
Melting point of acetone = -94.7°C


Refer to: https://en.wikipedia.org/wiki/Acetone_(data_page)
Heat capacity of solid acetone, c(solid) = 96 J / (mol K) = 96 J / (mol °C)
Heat capacity of liquid acetone, c(liquid) = 125.5 J / (mol K) = 125.5 J / (mol °C)
standard enthalpy change of fusion, ΔH(fusion) = 5.7 kJ/mol = 5700 J/mol

Energy required to change 1.50 mol solid acetone from -154.0°C to -94.7°C
= n × c(solid) × ΔT(solid)
= (1.50 mol) × [96 J / (mol °C)] × [(-94.7°C) - (-154.0°C)]
= 8539 J

Energy required to melt 1.50 mol solid acetone into liquid
= n × ΔH(fusion)
= (1.50 mol) × (5700 J/mol)
= 8550 J

Energy required to change 1.50 mol liquid acetone from -94.7°C to -42.0°C
= n × c(liquid) × ΔT(liquid)
= (1.50 mol) × [125.5 J / (mol °C)] × [(-42.0°C) - (-94.7°C)]
= 9921 J

Total energy required to change acetone from a solid at 154.0°C to a liquid at 42.0°C
= (8539 + 8550 + 9921) J
= 27010 J
= 27.0 kJ (to 3 sig. fig.)