Chem. Final

25 July 2022
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question
Which statement describes how a basic coffee cup calorimeter works?
answer
It uses the mass and specific heat of water along with a thermometer to measure the gain or loss of energy when a substance is added.
question
Which statement defines calorimetry?
answer
the measurement of energy that is given off or absorbed in a physical or chemical process
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Which statement defines the heat capacity of a sample?
answer
the quantity of heat that is required to raise the sample's temperature by 1°C (or Kelvin)
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A 1.20-g sample of propane (C3H8) is burned in a bomb calorimeter. The temperature of the calorimeter rises from 20.0°C to 30.0°C. The calorimeter has a mass of 2.000 kg and a specific heat of 2.95 J/(g • °C). If the molar mass of propane is 44.0 g/mol, what is the molar heat of combustion of propane?
answer
2,160 kJ/mol
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When complete combustion of a 0.260-mol sample of a compound occurs in a bomb calorimeter, the temperature of the calorimeter increases from 20.0°C to 52.0°C. The mass of the calorimeter is 1.50 kg, and its specific heat is 3.410 J/(gi°C). What amount of heat would be produced by burning 1 mol of the compound?
answer
630 kJ
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A sample of octane (C8H18) that has a mass of 0.750 g is burned in a bomb calorimeter. As a result, the temperature of the calorimeter increases from 21.0°C to 41.0°C. The specific heat of the calorimeter is 1.50 J/(g • °C), and its mass is 1.00 kg. How much heat is released during the combustion of this sample?
answer
30.0 kJ
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A sample of an unknown substance has a mass of 0.465 kg. If 3,000.0 J of heat is required to heat the substance from 50.0°C to 100.0°C, what is the specific heat of the substance?
answer
0.129 J/(gi°C)
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Which statement defines calorimeter?
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a device that measures the heat that is gained or lost in a chemical change
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Which diagram is a bomb calorimeter?
answer
b.
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A copper rod that has a mass of 200.0 g has an initial temperature of 20.0°C and is heated to 40.0°C. If 1,540 J of heat are needed to heat the rod, what is the specific heat of copper?
answer
0.385 J/(gi°C)
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Which units express heat capacity?
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J/°C, J/K, cal/°C, cal/K
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Which statement defines specific heat capacity for a given sample?
answer
the quantity of heat that is required to raise 1 g of the sample by 1°C (Kelvin) at a constant pressure
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Complete combustion of a 0.600-g sample of a compound in a bomb calorimeter releases 24.0 kJ of heat. The bomb calorimeter has a mass of 1.30 kg and a specific heat of 3.41 J/(gi°C). If the initial temperature of the calorimeter is 25.5°C, what is its final temperature?
answer
30.9°C
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During an endothermic phase change, what happens to the potential energy and the kinetic energy?
answer
Potential energy increases, and kinetic energy stays the same.
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Which phase change is most likely taking place in this graph?
answer
a solid to a liquid
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The molar heat of fusion for water is 6.01 kJ/mol. How much energy must be added to a 75.0-g block of ice at 0°C to change it to 75.0 g of liquid water at 0°C?
answer
25.04 kJ
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Which substance releases 4.58 kJ of energy when 6.37 mol freeze?
answer
nitrogen
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The molar heat of fusion of lead (Pb) is 1.140 kcal/mol. How much heat must be added to 97.0 g of solid lead at its melting point in order for it to completely melt?
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0.534 kcal
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Which explanation correctly describes the phase change in the graph?
answer
This is an exothermic reaction that involves freezing.
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The heat of vaporization for water is 40.7 kJ/mol. How much heat is released when 755.5 g of water vapor at 100°C condenses to liquid water at 100°C?
answer
-1,708.27 kJ
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The heat of vaporization of methanol (CH3OH) is 1076 J/g. How much energy is absorbed by 2.35 mol of methanol when it vaporizes at its boiling point?
answer
81.02 kJ
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These data apply to the specific heat and molar enthalpy of H2O: Cp,ice = 2.09 J/g•°C Cp,water = 4.18 J/g•°C Cp,vapor = 1.84 J/g•°C mc018-1.jpgHfus = 6.01 kJ/mol mc018-2.jpgHvap = 40.7 kJ/mol If a 50.0 g sample of ice at -11.5°C is heated to water vapor at 110°C, how much heat is required for this process?
answer
152.9 kJ
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The information below shows properties of aluminum (Al). mc023-1.jpgHfus = 10.07 kJ/mol mc023-2.jpgHvap = 225 kJ/mol Which quantity of heat is required to melt a 342.9-g sample of Al?
answer
127.98 kJ
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An engineer wants to determine an efficient method for condensing large amounts of steam into liquid water. Which constant should she use?
answer
b. -Hvap
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What does the symbol (-mc004-1.jpgHfus) indicate in a phase change?
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A solid is being formed.
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NaCl has a mc020-1.jpgHfus = 30.2 kJ/mol. What is the mass of a sample of NaCl that needs 732.6 kJ of heat to melt completely?
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82.7 g
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Consider Ca(OH)2 mc025-1.jpg mc025-2.jpg + 2mc025-3.jpg and the following information. mc025-4.jpgHlat = -2,506 kJ/mol mc025-5.jpgHhydr of mc025-6.jpg= -1,591 kJ/mol mc025-7.jpgHsol = -151 kJ/mol What is the mc025-8.jpgHhydr of mc025-9.jpg?
answer
-533 kJ/mol
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Consider KF mc022-1.jpg mc022-2.jpg and the following information. mc022-3.jpgHlat = -784 kJ/mol mc022-4.jpgHhydr of mc022-5.jpg = -336 kJ/mol mc022-6.jpgHsol = 17 kJ/mol What is the DHhydr of mc022-7.jpg?
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-431 kJ/mol
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mc009-1.jpg Which answer accurately describes the diagram?
answer
The temperature decreases, and the process is endothermic.
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What is the mc012-1.jpgHsol for LiF mc012-2.jpg mc012-3.jpg + mc012-4.jpg? The lattice energy is -1,036 kJ/mol, the enthalpy of hydration for mc012-5.jpg is -499 kJ/mol, and the enthalpy of hydration for mc012-6.jpg is -431 kJ/mol.
answer
106 kJ/mol
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Which statement defines the enthalpy of hydration?
answer
the change in enthalpy when 1 mol of a gaseous ion becomes fully hydrated
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Consider NaI mc021-1.jpg mc021-2.jpg and the following information. mc021-3.jpgHlat = -704 kJ/mol mc021-4.jpgHhydr of mc021-5.jpg= -410.0 kJ/mol mc021-6.jpgHhydr of mc021-7.jpg= -247 kJ/mol What is the mc021-8.jpgHsol of this compound?
answer
47 kJ/mol
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Which formula can be used to calculate the enthalpy of solution?
answer
c
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Which energy changes in the enthalpy of solution are endothermic, and which are exothermic?
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a
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Which statement accurately describes the diagram?
answer
a. The temperature increases after dissolution, and the process is exothermic.
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The mc017-1.jpgHsol for CaCl2 is 41 kJ/mol, and the lattice energy is mc017-2.jpg2,258 kJ/mol. If the hydration enthalpy for chloride ions is -313 kJ/mol, what is the hydration enthalpy for calcium ions?
answer
b -1,591 kJ/mol
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What is the mc016-1.jpgHsol for MgF2 mc016-2.jpg Mg2+ + 2mc016-3.jpg? The lattice energy is -2,957 kJ/mol, the enthalpy of hydration for Mg2+ is -1,903 kJ/mol, and the enthalpy of hydration for mc016-4.jpg is -431 kJ/mol.
answer
b. 192 kJ/mol
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What is the mc010-1.jpgHsol for mc010-2.jpg? The lattice energy is -788 kJ/mol, the enthalpy of hydration for mc010-3.jpg is -410 kJ/mol, and the enthalpy of hydration for mc010-4.jpg is -313 kJ/mol.
answer
65 kJ/mol
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Consider RbOH mc020-1.jpg mc020-2.jpg and the following information. mc020-3.jpgHlat = -765.01 kJ/mol mc020-4.jpgHhydr of mc020-5.jpg = -315.2 kJ/mol mc020-6.jpgHhydr of mc020-7.jpg = -532.7 kJ/mol What is the mc020-8.jpgHsol rounded to the correct number of significant figures?
answer
-82.9 kJ/mol
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Consider the following intermediate chemical equations. mc015-1.jpg What is the enthalpy of the overall chemical equation NO(g) + O(g) mc015-2.jpg NOmc015-3.jpg(g)?
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-304.1 kJ
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What is enthalpy?
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the total heat content of the system
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Consider the following intermediate chemical equations. mc007-1.jpg When you form the final chemical equation, what should you do with CO?
answer
Cancel out CO because it appears as a reactant in one intermediate reaction and a product in the other intermediate reaction.
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Consider these intermediate chemical equations: mc005-1.jpg What is an overall chemical equation that has only HCN and CH4 as products, and NHmc005-2.jpg and C as reactants?
answer
d. mc005-6.jpg
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What is the overall enthalpy change DHrxn for the system?
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300 kJ
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According to the enthalpy diagram below, which of the following statements is true?
answer
Arrow C indicates that the third intermediate reaction is exothermic.
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What is the overall chemical equation for smog after the above intermediate reactions are combined?
answer
d. mc003-6.jpg
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Which of the following statements is true?
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a. The overall chemical reaction is exothermic.
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Which overall chemical equation is obtained by combining these intermediate equations?
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a. ch4(g) +20..
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What is the enthalpy of the overall chemical reaction mc014-2.jpg?
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-1,300 kJ
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What is the overall enthalpy change DHrxn for the system?
answer
300 kJ
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What is the correct enthalpy diagram using the Hess law for this system?
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a. When you combine the intermediate chemical equations, which substance do you cancel out?
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What is the enthalpy of the overall chemical equation NO(g) + O(g) mc015-2.jpg NOmc015-3.jpg(g)?
answer
-304.1 kJ
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According to the enthalpy diagram below, which of the following statements is true?
answer
Arrow C indicates that the third intermediate reaction is exothermic.
question
According to the Hess law, which of the following depicts the enthalpy diagram summarizing the above intermediate reactions and their overall chemical reaction?
answer
d