1. On a relative basis, which of these statements is/are false: 1. The stronger the intermolecular forces in a substance are, the larger is its molar heat capacity as a liquid. 2. The weaker the intermolecular forces in a substance are, the lower is its boiling point. 3. The stronger the Antermolecular forces in a substance are, the greater is its vapor pressure at a particular temperature. A. 1, 2, and 3 B. 1 only or 2 only or 3 only C. 1 and 3 D. 2 and 3 E. 1 and 2 A

Benzene, C6H6, is an organic liquid that freezes at 5.5 C (Figure 11.1) to form beautiful, feather-like crystals. How much energy is evolved as heat when 15.5 g of benzene freezes at 5.5 C? (The enthalpy of fusion of benzene is 9.95 kJ/mol.) If the 15.5-g sample is remelted, again at 5.5 C, what quantity of energy is required to convert it to a liquid?

9.46 The heat of fusion of pure silicon is 43.4 kJ/mol. How much energy would be needed to melt a 5.24-g sample of silicon at its melting point of 1693 K?

Define the joule in terms of SI base units.

The enthalpy change when 1 mol methane (CH4) is burned is 890 kJ. It takes 44.0 kJ to vaporize 1 mol water. What mass of methane must be burned to provide the heat needed to vaporize 1.00 g water?

The enthalpy of vaporization of water is larger than its enthalpy of fusion. Explain why.

When steam condenses to liquid water, 2.26 kJ of heat is released per gram. The heat from 168 g of steam is used to heat a room containing 6.44 104 g of air (20 ft 12 ft 8 ft). The specific heat of air at normal pressure is 1.015 J/(gC). What is the change in air temperature, assuming the heat from the steam is all absorbed by air?

9.29 In which case is heat added to the system: (a) E=43J , w=40J ; or (b) E=31J , w=34J ?

A student is asked to calculate the amount of heat involved in changing 10.0 g of liquid bromine at room temperature (22.5C) to vapor at 59.0C.To do this, one must use Tables 8.1 and 8.2 for information on the specific heat, boiling point, and heat of vaporization of bromine. In addition, the following step-wise process must be followed. (a) Calculate H for: Br2(l,22.5C)Br2(l,59.0C) (b) Calculate H for: Br2(l,59.0C)Br2(g,59.0C) (c) Using Hess's law, calculate H for: Br2(l,22.5C)Br2(g,59.0C)

Which evolves more heat—freezing 100.0 g of benzene or 100.0 g of bromine?