WorksheetsMidterm 2 preparation
Total questions: 25
Worksheet time: 2hrs 5mins
Which of the following will always increase the internal energy of a system?
The system gains energy and performs work.
The system gains energy and work is performed on it.
The system loses energy and performs work.
The system loses energy and work is performed on it.
None of the changes A–D will always increase the internal energy of a system.
The dissolution of cesium hydroxide in water is exothermic (ΔHsoln = –71.55 kJ/mol). Calculate the change in temperature of a solution produced by dissolving 0.150 kg CsOH (150 g/mol) in 1.00 kg water. Assume the heat capacity of the solution is 4.18 J/(g·°C).
+44.9°C
+114°C
+17.1°C
+14.9°C
+114°C
The standard enthalpy of combustion of liquid hexane (C6H14) is –4163 kJ/mol. What is the standard enthalpy of formation of C6H14, given that the standard enthalpies of formation of CO2(g) and H2O(l) are –394 and –286 kJ/mol, respectively?
+203 kJ/mol
+362 kJ/mol
–3483 kJ/mol
–203 kJ/mol
–362 kJ/mol
Which of the following bar charts shows the correct energy changes that occur in a beaker full of ice (system) as it warms up on a lab bench (surroundings)?
[Bar chart a]
[Bar chart b]
[Bar chart c]
[Bar chart d]
none of these
Which statement below regarding heating curves is FALSE?
A heating curve tracks the temperature of a system as it is heated at a constant rate.
Different substances will have different heating curves.
A heating curve will reflect the amount of material present.
When a substance undergoes a phase change, there is no energy change because the temperature is constant.
If a cooling curve were to be made, the amounts of energy would be equal to those in a heating curve but opposite in sign.
What is the change in internal energy (ΔE) of the system when it loses 76.0 J of heat while the surroundings perform 29.0 J of work?
-76.0 J
+105.0 J
-105.0 J
+47.0 J
-47.0 J
The following diagrams illustrate the flow of energy (q) and work (w) in different processes. In which ones does the internal energy of the system DEFINITELY increase? Assume the magnitudes of q and w are equal.
[Diagram a]
[Diagram b]
[Diagram c]
[Diagram d]
none of these
Which of the following statements about energy, systems, and surroundings is NOT true?
The system can be a chemical reaction that occurs in a sample of matter.
The surroundings experience the same energy change as the system in order to keep the total energy in the universe constant.
The system is the part of the universe that is the focus of thermochemical study.
The surroundings can provide thermal energy to the system.
The system can do work on the surroundings.
The capacity to do work is a definition of
heat.
thermochemistry.
work.
energy.
force.
Create the Born–Haber cycle and calculate the lattice energy of lithium oxide (Li2O) from the following data:
–2586 kJ/mol
–2972 kJ/mol
–3081 kJ/mol
–2205 kJ/mol
–2831 kJ/mol
In an experiment, 30.0 g of metal is heated to 98.0°C and then quickly transferred to 50.0 g of water in a calorimeter at 27.0°C. The heat capacity of the calorimeter with the water is 211 J/°C. The final temperature comes to 32.5°C. What is the approximate specific heat capacity of the metal?[Cp(water)=4.18J/(g ℃)]
0.140 J/(g·°C)
83.0 J/(g·°C)
0.540 J/(g·°C)
0.591 J/(g·°C)
29.5 J/(g·°C)
What is the osmotic pressure of a 0.0540 M aqueous sodium sulfate (Na2SO4, 142.04 g/mol) solution at 25.0°C?
1.32 atm
2.64 atm
3.96 atm
1.34 atm
33.7 atm
A physiological saline solution is 0.92% NaCl by mass. What is the osmotic pressure of such a solution at a body temperature of 37°C? Assume the density of the solution is 1.0 g/mL.
8.0 atm
3.9 atm
2.3 atm
4.3 atm
4.1 atm
Calculate the minimum pressure that must be applied to achieve reverse osmosis of 0.320 M KBr at 25.0°C.
1.31 atm
133 atm
1590 atm
7.82 atm
15.7 atm
Which solution will have the lowest osmotic pressure when measured against pure water?
0.10 M sodium chloride
0.10 M sodium sulfate
0.10 M sodium sulfide
0.10 M sodium phosphate
0.10 M sodium carbonate
Which of the following pairs of liquids probably exhibits positive deviations from Raoult’s law when mixed?
CH3OH and H2O
C4H8 and C4H6
CH3Br and H2O
CH3CH2OH and CH3COOH
C7H8 and C6H5H
A solution is prepared by mixing 75 g of methanol (CH3OH, 32.04 g/mol) with 25 g of ethanol (CH3CH2OH, 46.07 g/mol). What is the mole fraction of ethanol in the vapor phase at 20°C?
0.10
0.12
0.19
0.32
0.54
A solution is prepared by mixing 75 g of methanol (CH3OH, 32.04 g/mol) with 25 g of ethanol (CH3CH2OH, 46.07 g/mol). Use the following data to determine the vapor pressure of this solution at 20°C.
69 torr
57 torr
80 torr
73 torr
83 torr
A solution of 5.00 g of sodium chloride in 1.00 kg of water has a freezing point of –0.299°C. What is the actual van 't Hoff factor for this salt at this concentration? (Kf(water) = 1.86°C/m)
1.88
1.98
1.93
1.83
1.94
Lanterns and stoves that use n-pentane as a fuel are often difficult to light on a cold day because the fuel has a low vapor pressure at low temperatures. Determine the vapor pressure of n-pentane on a night when the temperature is 0.0°C. The enthalpy of vaporization of n-pentane is 27.6 kJ/mol, and its boiling point is 36.0°C.
228 torr
367 torr
185 torr
479 torr
209 torr
The Henry’s law constant for oxygen dissolving in blood is 3.74 × 10^–2 mol/L · atm at body temperature, 37°C. Calculate the molar concentration of oxygen in blood for an alpine climber where the atmospheric pressure is 0.45 atm. The mole fraction of oxygen in air is 0.209.
7.8 × 10^–3 M
3.5 × 10^–3 M
2.3 × 10^–2 M
1.3 × 10^–2 M
0.11 M
The normal temperature range of the liquid phase of pure water is 0°C to 100°C. Which of the following solutions will have the largest temperature range for the liquid state?
1 M aqueous ethanol solution
1 M aqueous potassium bromide solution
1 M aqueous acetic acid solution
1 M aqueous magnesium bromide solution
1 M aqueous magnesium sulfate
You have learned that adding table salt, NaCl (58.44 g/mol, 2.16 g/cm3), to water (Kb = 0.52°C/m) increases the temperature at which it boils. You decide to try cooking pasta faster at a higher temperature in boiling salty water. What increase in the boiling point do you expect if you add 1 tablespoon (1 tbsp = 14.8 cm^3) of salt to one 8 oz cup of water (237 mL)?
1.0°C
2.4°C
28°C
1.5°C
3.7°C
Which of the following statements regarding the phase diagram of water and an aqueous solution is NOT correct? Temperature is on the x-axis; pressure is on the y-axis.
The boiling point of the solution is higher than that of the solvent by an amount indicated by the difference in temperature between points E and F.
Point D corresponds to the triple point of the solvent.
The solution boils at the temperature corresponding to point F.
The normal freezing point of the solvent corresponds to point A.
The freezing point of the solvent is higher than that of the solution.
Indicate which aqueous solution has the slowest evaporation rate.
0.1 M NH4Cl
0.2 M K2SO4
0.2 M NaOH
0.1 M BaCl2
0.2 M C6H12O6
