Butane, C4H10, is stored as a liquid in a small camping stove canister at 1 atm and −0.5∘C, its normal boiling point. When the valve is opened, 25.0 g of liquid butane is released and immediately vaporizes completely at constant pressure and temperature.
The molar enthalpy of vaporization of butane at 1 atm is 22.4kJ mol−1.
(a) Calculate the quantity of heat (in kJ, include sign) exchanged between the butane and the surroundings as the 25.0 g sample vaporizes.
(b) State whether the surroundings experience a temperature increase or decrease, and explain your answer in terms of energy flow.
(c) Describe the changes in intermolecular forces experienced by butane molecules during this process and connect these changes to the calculated enthalpy value.