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Problem 59
Suppose that 0.95 g of water condenses on a 75.0-g block of iron that is initially at 22 °C. If the heat released during condensation goes only to warming the iron block, what is the final temperature (in °C) of the iron block? (Assume a constant enthalpy of vaporization for water of 44.0 kJ/mol.)
Problem 61
This table displays the vapor pressure of ammonia at several different temperatures. Use the data to determine the heat of vaporization and normal boiling point of ammonia.
Temperature (K) Pressure (torr)
200 65.3
210 134.3
220 255.7
230 456.0
235 597.0
- This table displays the vapor pressure of nitrogen at several different temperatures. Use the data to determine the heat of vaporization and the normal boiling point of nitrogen. Temperature (K) Pressure (torr) 65 130.5 70 289.5 75 570.8 80 1028 85 1718
Problem 62
Problem 63
Ethanol has a heat of vaporization of 38.56 kJ/mol and a normal boiling point of 78.4 °C. What is the vapor pressure of ethanol at 15 °C?
Problem 64
Benzene has a heat of vaporization of 30.72 kJ/mol and a normal boiling point of 80.1 °C. At what temperature does benzene boil when the external pressure is 445 torr?
Problem 65
Carbon disulfide has a vapor pressure of 363 torr at 25 °C and a normal boiling point of 46.3 °C. Find ΔHvap for carbon disulfide.
Problem 67
How much energy is released when 65.8 g of water freezes?
Problem 69
An 8.5-g ice cube is placed into 255 g of water. Calculate the temperature change in the water upon the complete melting of the ice. Assume that all of the energy required to melt the ice comes from the water.
Problem 70
How much ice (in grams) would have to melt to lower the temperature of 352 mL of water from 25 °C to 5 °C? (Assume the density of water is 1.0 g/mL.)
- How much heat (in kJ) is required to warm 10.0 g of ice, initially at -10.0 °C, to steam at 110.0 °C? The heat capacity of ice is 2.09 J/g°C, and that of steam is 2.01 J/g°C.
Problem 71
- How much heat (in kJ) is evolved in converting 1.00 mol of steam at 145 °C to ice at -50 °C? The heat capacity of steam is 2.01 J/g°C, and that of ice is 2.09 J/g°C.
Problem 72
Problem 73
Consider the phase diagram shown here. Identify the states present at points a through g.
- Consider the phase diagram for iodine shown here. a. What is the normal boiling point for iodine? b. What is the melting point for iodine at 1 atm? c. What state is present at room temperature and normal atmospheric pressure? d. What state is present at 186 °C and 1.0 atm?
Problem 74
Problem 75
Nitrogen has a normal boiling point of 77.3 K and a melting point (at 1 atm) of 63.1 K. Its critical temperature is 126.2 K and its critical pressure is 2.55×104 torr. It has a triple point at 63.1 K and 94.0 torr. Sketch the phase diagram for nitrogen. Does nitrogen have a stable liquid state at 1 atm?
Problem 77b
The phase diagram for sulfur is shown here. The rhombic and monoclinic states are two solid states with different structures. b. Which of the two solid states of sulfur is more dense?
Problem 80
Water is a good solvent for many substances. What is the molecular basis for this property, and why is it significant?
- Explain the role of water in moderating Earth's climate.
Problem 81
- How is the density of solid water compared to that of liquid water atypical among substances, and why is this significant?
Problem 82
Problem 83
Explain the observed trend in the melting points of the hydrogen halides.
HI -50.8 °C
HBr -88.5 °C
HCl -114.8 °C
HF -83.1 °C
Problem 84
Explain the observed trend in the boiling points of these compounds.
H2Te -2 °C
H2Se -41.5 °C
H2S -60.7 °C
H2O 100 °C
Problem 86
The vapor pressure of CCl3F at 300 K is 856 torr. If 11.5 g of CCl3F is enclosed in a 1.0-L container, will any liquid be present? If so, what mass of liquid?
- Four ice cubes at exactly 0 °C with a total mass of 53.5 g are combined with 115 g of water at 75 °C in an insulated container. If no heat is lost to the surroundings, what is the final temperature of the mixture?
Problem 89
Problem 90
A sample of steam with a mass of 0.552 g and at a temperature of 100 °C condenses into an insulated container holding 4.25 g of water at 5.0 °C. Assuming that no heat is lost to the surroundings, what is the final temperature of the mixture?
- Draw a heating curve (such as the one in Figure 11.36) for 1 mole of methanol beginning at 170 K and ending at 350 K. Assume that the values given here are constant over the relevant temperature ranges. Melting point: 176 K, Boiling point: 338 K, ΔH_fus: 2.2 kJ/mol, ΔH_vap: 35.2 kJ/mol, C_s,solid: 105 J/mol·K, C_s,liquid: 81.3 J/mol·K, C_s,gas: 48 J/mol·K.
Problem 91
- Draw a heating curve (such as the one in Figure 11.36) for 1 mol of benzene beginning at 0 °C and ending at 100 °C. Assume that the values given here are constant over the relevant temperature ranges: Melting point 5.4 °C, Boiling point 80.1 °C, ΔHfus 9.9 kJ/mol, ΔHvap 30.7 kJ/mol, Cs,solid 118 J/mol⋅K, Cs,liquid 135 J/mol⋅K, Cs,gas 104 J/mol⋅K.
Problem 92
Problem 93
Air conditioners not only cool air, but dry it as well. A room in a home measures 6.0 m × 10.0 m × 2.2 m. If the outdoor temperature is 30 °C and the partial pressure of water in the air is 85% of the vapor pressure of water at this temperature, what mass of water must be removed from the air each time the volume of air in the room is cycled through the air conditioner? (Assume that all of the water must be removed from the air.) The vapor pressure for water at 30 °C is 31.8 torr.
Problem 94
A sealed flask contains 0.55 g of water at 28 °C. The vapor pressure of water at this temperature is 28.35 mmHg. What is the minimum volume of the flask in order that no liquid water be present in the flask?
- Based on the phase diagram of CO2 shown in Figure 11.39(b), describe the state changes that occur when the temperature of CO2 is increased from 190 K to 350 K at a constant pressure of (b) 5.1 atm, (c) 10 atm, and (d) 100 atm.
Problem 95
Problem 95a
Based on the phase diagram of CO2 shown in Figure 11.39(b), describe the state changes that occur when the temperature of CO2 is increased from 190 K to 350 K at a constant pressure of (a) 1 atm
- Consider a planet where the atmospheric pressure at sea level is 2500 mmHg. Does water behave in a way that can sustain life on the planet?
Problem 96