1 markCup | Specific heat capacity of spoon (J / g oC) | Mass of spoon (g) | Initial temperature of spoon (oC) |
|---|---|---|---|
A | 0.90 | 7.0 | 20 |
B | 0.39 | 20.0 | 20 |
C | 0.84 | 15.0 | 20 |
D | 0.24 | 25.0 | 20 |
Four identical 300 mL cups of fresh brewed coffee, originally at 91 °C, were stirred with different spoons, as listed in the table above.
In which cup will the temperature of the coffee be highest at thermal equilibrium?
(Assume that the heat lost to the surroundings is negligible.)
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Which of the following phase changes would result in the greatest increase in the potential energy of the system?
Condensation of steam.
Melting of ice.
Sublimation of dry ice (solid CO2).
Vaporization of water.
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During a phase change, which of the following statements is true regarding the kinetic and potential energies of the particles?
Both kinetic and potential energies increase.
Kinetic energy remains constant while potential energy increases.
Kinetic energy increases while potential energy remains constant.
Both kinetic and potential energies remain constant.
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Which of the following phase changes involves the largest increase in the potential energy of the system?
Melting 10 g of ice.
Evaporating 10 g of water.
Sublimating 10 g of dry ice.
Freezing 10 g of water.
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Which of the following statements best explains why water takes longer to heat up than most metals when the same amount of heat energy is applied?
Water is a liquid, and metals are solids.
Water has a higher specific heat capacity than most metals.
Water molecules form hydrogen bonds that absorb heat energy.
Water has a higher density than most metals.
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Which of the following is the minimum amount of data needed to determine the molar enthalpy of solution of KNO3 (s) in pure H2O (l)?
(Assume that the KNO3 (aq) has the same specific heat capacity as pure water and that the initial temperatures of the KNO3 (s) and the water are the same.)
Mass of KNO3 (s), initial temperature of the water, and final temperature of the solution
Mass of H2O, initial temperature of the water, and final temperature of the solution
Mass of KNO3 (s), mass of H2O, initial temperature of the water, and final temperature of the solution
Mass of KNO3 (s), mass of H2O, initial temperature of the water, final temperature of the solution, and atmospheric pressure
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A fuel undergoes complete combustion in a calorimetry experiment. A 2.50 g sample of the fuel is burned, releasing energy that heats 500.0 g of water. Only 30% of the energy released is absorbed by the water, increasing its temperature from 25.0°C to 68.0°C.
Given that the specific heat capacity of water is 4.18 J g–1 K–1, what is the total energy released per gram of fuel burned?
35 948 J
119 827 J
299 567 J
880 587 J
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A 0.50 kg sample of iron is heated, increasing its temperature by 12.7 K. The specific heat capacity of iron is 0.45 J g−1 K−1.
What is the enthalpy change in kJ mol−1 for heating the iron sample?
0.32 kJmol−1
0.57 kJ mol−1
1.02 kJ mol−1
2.26 kJ mol−1
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A student conducts a calorimetry experiment to determine the enthalpy of combustion of cyclohexane. During the experiment, 16.44 kJ of energy is transferred to 150.0 g of water in a calorimeter. The initial temperature of the water is 22.5 °C.
What is the final temperature of the water?
(The specific heat capacity of water is 4.18 J g−1 K−1)
32.8 oC
42.2 oC
45.0 oC
48.7 oC
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A student burns 0.600 g of ethanol in a spirit burner under a calorimeter containing 200.0 g of water. The temperature of the water rises by 25.0 °C.
Given cwater = 4.18 J g−1 K−1, what is the enthalpy of combustion of ethanol in kJ mol−1?
-1200 kJ mol-1
-1400 kJ mol-1
-1600 kJ mol-1
-1800 kJ mol-1
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A 100 g block of copper at 85 °C is placed into 200 g of water at 25 °C. The final temperature of the system is 28 °C.
Assuming no heat is lost to the surroundings, what is the specific heat capacity of copper?
(The specific heat capacity of water is 4.18 J g−1 K−1)
0.34 J g−1 K−1
0.44 J g−1 K−1
0.50 J g−1 K−1
0.60 J g−1 K−1
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A calorimeter is used to measure the enthalpy of dissolution of KCl. A 10.0 g sample of KCl is dissolved in 200.0 g of water, causing the temperature to decrease from 25.0 °C to 20.4 °C.
Assuming no heat loss and cwater = 4.18 J g−1 K−1, what is the enthalpy change per mole of KCl?
+19.1 kJ mol-1
-19.1 kJ mol-1
+28.7 kJ mol-1
-28.7 kJ mol-1
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A reaction carried out in a coffee-cup calorimeter produces a temperature change from 20.0 °C to 27.5 °C in 150.0 g of solution. The calorimeter has a mass of 200.0 g and a specific heat capacity of 0.75 J g−1 K−1.
Assuming that the solution has the density and specific heat capacity of water, what is the enthalpy change if the reaction involves 0.0500 mol of reactant?
-108.2 kJ mol-1
-116.6 kJ mol-1
-124.4 kJ mol-1
-132.7 kJ mol-1
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