130 12) 110 00 AH, x 2 kl/mol 9) 80- AH 0.24 kJ/mol 70 40 30 Heal Added Use the

Question

130 12) 110 00 AH, x 2 kl/mol 9) 80- AH 0.24 kJ/mol 70 40 30 Heal Added Use the diagram above to answer the next three questions about methane, CH4. 10. How much energy is required to melt 64 g of methane at 90 K? a. 0.24 kJ b. 3.8 kJ c. 33 kJ d. 60. 11. Which of the following best explains why more energy is required for the process occurring at 110 K than for the process occurring at 90 K? a. Intermolecular attractions are completely overcome during vaporization b. Intermolecular attractions in the solid phase are weaker than in the liquid phase Electron clouds of methane molecules are less polarizable at lower temperatures d. vaporization involves a larger increase in temperature 12. The enthalpy of vaporization of water is 40.7 ku/mol. hich of the following best explains why the enthalpy of vaporization of methane is less than that of water? a. Methane does not exhibit hydrogen bonding but water does b. Methane has weaker dispersion forces c. Methane has a smaller molar mass d, Methane has a much lower density

Explanation / Answer

Question 10.

m = 65 g of metane at T = 90 K

so..

from the graph, the heat of fusion is

Hfus = 0.94 kJ/mol

note that we need

mol = mass/MW = 64/16 = 4 mol

Total Q = n*Hfux = 4*0.94 = 3.76 kJ = 3.8 kJ

best answer is B

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