Spray deodorants contain low boiling point compounds. One compound added to deodorants is butane (C₄H₁₀) which boils at -1.0°C. When liquid butane is sprayed on the skin at room temperature, the skin feels cold. If the heat lost by the skin is gained by butane, determine the enthalpies that must be used in order to calculate the final temperature of the skin.

Identify if the following processes are endothermic or exothermic and determine the phase transition: Liquid nitrogen is poured onto food to freeze it, and then quickly evaporates.

Calculate the mass (in grams) of ethanol that can be cooled from 45.0°C to 30.0°C by the evaporation of 150 g of ethanol. [Useful date: ΔH_vap ethanol = 0.826 kJ/g; specific heat of ethanol = 2.46 J/g•K]

Calculate the final temperature of water when 5.00 g ice melts in 150 g of water initially at 8.00°C. All of heat required to melt ice comes from water.

Calculate the heat required in kJ for in the process of vaporizing 36.0 g of ethanol at 25°C to the vapor phase at 78°C. Write your answer using 2 significant figures

Date for ethanol: 

T_f = -114°C

T_b = 78°C

ΔH_fus = 5.02 kJ/mol

ΔH_vap = 38.56 kJ/mol

C_EtOH(s) = 0.97 J/g-K

C_EtOH(l)  = 2.3 J/g-K

C_EtOH(g)  = 2.03 J/g-K

Calculate the energy involved in kJ in the conversion of 503 g of steam at 373 K to ice at 254 K

C_H2O(s) = 2.06 J/g.°C

C_H2O(l)  = 4.18 J/g.°C

C_H2O(g)  = 2.03 J/g.°C

ΔH_vap = 40.6 kJ/mol

ΔH_fus = 6.02 kJ/mol