CH 11 HW#3

If this energy were used to vaporize water at 100.0 ∘C, how much water (in liters) could be vaporized? (Assume the density of water is 1.00 g/mL.)

.421L

The vapor pressure of CCl3F at 300K is 856 torr. If 12.5 g of CCl3F is enclosed in a 1.1 L container, calculate the number of moles of CCl3F in the gas phase. Given your answer to Part A, will any liquid be present? If so, what mass of liquid will be present?

0.0503 mol yes 5.6g

Which of the temperatures below is most likely to be the boiling point of water at 880 torr?

105°C

How much energy is released when 42.5 g of water freezes? Express your answer using three significant figures.

14.2 kJ

Determine the amount of heat (in kJ) required to vaporize 1.25 kg of water at its boiling point. For water, ΔHvap = 40.7 kJ/mol (at 100 ∘C). Express your answer to three significant figures and include the appropriate units.

2820kJ

How long would it take for 1.50 mol of water at 100.0 ∘C to be converted completely into steam if heat were added at a constant rate of 24.0 J/s ?

42.2min or 2.54*10³ s

Four ice cubes at exactly 0 ∘C with a total mass of 54.0 g are combined with 160 g of water at 85 ∘C in an insulated container. (ΔH∘fus=6.02 kJ/mol, cwatercwater=4.18J/g⋅∘C) If no heat is lost to the surroundings, what is the final temperature of the mixture?

43°C

Calculate the amount of heat required to completely sublime 62.0 g of solid dry ice (CO2) at its sublimation temperature. The heat of sublimation for carbon dioxide is 32.3 kJ/mol. Express your answer in kilojoules.

45.5kJ

How much heat is released upon converting one mole of steam (18.0 g) from 100.0 ∘C to water at 25.0 ∘C?

46.3 kJ of heat is released 30.0kJ

Suppose that 0.48 g of water at 25∘C condenses on the surface of a 55-g block of aluminum that is initially at 25∘C. If the heat released during condensation goes only toward heating the metal, what is the final temperature (in degrees Celsius) of the metal block? (The specific heat capacity of aluminum, Cs,Al, is 0.903 J/(g⋅∘C).) Express your answer in degrees Celsius to two significant figures.

49⁰C

Calculate the amount of heat (in kilojoules) required to vaporize 2.58 kg of water at its boiling point. Express your answer in kilojoules to three significant figures.

5830kJ or 5.83*10³kJ

How much heat is evolved in converting 1.00 mol of steam at 140.0 ∘C to ice at -45.0 ∘C? The heat capacity of steam is 2.01 J/(g⋅∘C) and of ice is 2.09 J/(g⋅∘C). Express your answer in units of kilojoules Assume the system is at atmospheric pressure

58kJ

Liquid butane (C4H10) and liquid propane (C3H8) are often stored in cylinders, to be used as fuels. The normal boiling point of butane is −0.5 ∘C and its ΔHvap is 23.1 kJ/mol. The corresponding values for propane are −42.1 ∘C and 15.4 kJ/mol, respectively What volume will 175 g of butane occupy at 745 torr and 35 ∘C?

77.6 L

Which molecules have dipole-dipole forces? CHCl3 H2O SiCl4

CHCl3 H2O

Which has the higher boiling point, NH3 or PH3? Why?

NH3 has the higher boiling point because it exhibits hydrogen bonding.

Classify each property as associated with a liquid that has strong or weak intermolecular forces. high viscosity high boiling point low surface tension high vapor pressure high surface tension low boiling point low viscosity low vapor pressure

Strong intermolecular forces: high boiling point high surface tension high viscosity low vapor pressure Weak intermolecular forces: low boiling point low surface tension low viscosity high vapor pressure

A chunk of dry ice, solid CO2, "disappears" after sitting at room temperature for a while. There is no puddle of liquid. What happened?

The solid CO2 sublimed

What happens to the temperature of a mixture of ice and liquid water as heat is applied at a constant rate?

The temperature of the mixture does not change at all until all the ice has melted, at which point it increases at a constant rate.

How is vapor pressure related to temperature? What happens to the vapor pressure of a substance when the temperature is increased? Decreased? The vapor pressure of a liquid increases with increasing temperature. The relationship between vapor pressure and temperature is linear. As the temperature is decreased, the vapor pressure decreases. The vapor pressure of a liquid decreases with increasing temperature.

The vapor pressure of a liquid increases with increasing temperature. As the temperature is decreased, the vapor pressure decreases.

How is the volatility of a substance related to the intermolecular forces present within the substance?

The weaker the intermolecular forces, the more likely it is that molecules are to evaporate at a given temperature, making the liquid more volatile.

A tank containing liquid butane and one containing liquid propane are sitting adjacent to one another. Each tank is equipped with a regulator with a pressure gauge. Classify these statements as true or false. The pressure reading for the butane tank is higher than that for the propane tank If the tanks are placed outside and the sun warms each tank to 46 C, the pressure readings will be higher than they were initially The pressure readings will change when more liquid is added to the tanks If an equal number of moles of gas is allowed to escape rapidly from each tank, the temperature of the butane tank will be lower than that of the propane tank

True:If an equal number of moles of gas is allowed to escape rapidly from each tank, the temperature of the butane tank will be lower than that of the propane tank True:If the tanks are placed outside and the sun warms each tank to 46 C, the pressure readings will be higher than they were initially False:The pressure reading for the butane tank is higher than that for the propane tank False:The pressure readings will change when more liquid is added to the tanks

Classify the following phase changes as exothermic processes or endothermic processes. melting deposition condensing vaporizing freezing subliming

exothermic process: deposition condensing freezing endothermic process: melting vaporizing subliming

Rank from highest to lowest boiling point. To rank items as equivalent, overlap them. methane octane 2,2,4-trimethylpentane hexadecane paraffin

paraffin hexadecane octane 2,2,4-trimethylpentane methane

Arrange the liquids pentane, pentanol , and pentanal in order of decreasing viscosity, surface tension, and boiling point. Rank from highest to lowest viscosity, surface tension, and boiling point. To rank items as equivalent, overlap them.

pentanol pentanal pentane

When a small ice cube at -10∘C is put into a cup of water at room temperature, which of the following plays a greater role in cooling the liquid water: the warming of the ice from -10∘C to 0∘C , or the melting of the ice?

the melting of the ice

Which property of a liquid increases with increasing temperature?

vapor pressure

A substance has a heat of vaporization of ΔHvap and heat of fusion of ΔHfus. Express the heat of sublimation in terms of ΔHvap and ΔHfus. Express your answer in terms of H1 (H1=ΔHvap) and H2 (H2=ΔHfus).

∆Hsub=H₁+H₂