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Chemistry Textbook

Self-Assessments

 

A piece of unknown substance weighs 44.7 g and requires 2.11 kJ to increase its temperature from 23.2 °C to 89.6 °C. What is the specific heat of the substance?

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How much heat, in calories, must be added to a 75.0 g granite block with a specific heat of 0.790 J/g-K to increase its temperature from 25 °C to 80oC?

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An aluminum kettle weighs 1.05 kg. If the kettle loses 6540 J of heat to reach 42.1oC, what is the kettle’s initial temperature? The specific heat of Aluminum is 0.89 J/g-K.

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The specific heat of copper is 0.385 J/g o What is it’s molar heat capacity?

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Calculate the heat capacity, in joules per degree, of 2.00 pound of aluminum metal. The specific heat of Aluminum is 0.89 J/g oC.

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At a constant temperature, an ideal gas expands from 5.0 liters to 7.0 liters by a constant external pressure of 4.0 atm. Calculate the work involved in the process.
1 L atm = 101.33 J

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What is the change in internal energy of a combustion engine that absorbs 100 J of heat while 130 J of work is done by the engine?

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A system releases 260 J of heat and at the same time 450 J of work is done on the system by the surroundings. What is the change in internal energy of the system?

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A system undergoes an increase in internal energy of 90 J and at the same time performs 55 J of work. Which of the following is true about the heat transferred during the process?

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A gas enclosed in a metal container with a piston absorbs 1050 J of heat and 250 J of work is done by the gas while it expands at constant pressure. What is the change in internal energy and change in enthalpy of the gas during the process?

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Consider the reaction,
2Fe2O3(s) + 3C(s) → 4Fe(s) + 3CO2(g)  ΔH = 468.87 kJ.

How much heat is released at constant pressure when 35.0 g of iron is formed in the reaction?

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Consider the reaction,
2Al(s) + Fe2O3(s) → 2Fe(s) + Al2O3(s) ΔH = -851.5 kJ.

If 18.2 g of powdered aluminum is allowed to react with excess Fe2O3, how much heat is produced at constant pressure?

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Consider the reaction,
2H2(g) + O2(g) → 2H2O(g) ΔH = -484 kJ.

If 282 kJ of heat is released in the reaction at constant pressure, how many grams of water are formed during the process?

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For reaction, 2H2(g) + O2(g) → 2H2O(g), ΔH = -484 kJ.

What is the enthalpy change associated with the following reaction?
6H2(g) + 3O2(g) → 6H2O(g)

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Certain parts of the world, such as southern California and Saudi Arabia, are short of freshwater for drinking. One possible solution to the problem is to tow icebergs from Antarctica and then melt them as needed. The enthalpy change for melting ice at 0oC and constant pressure, referred to as molar enthalpy of fusion, is 6.01 kJ/mol:
H2O(s)→H2O(l)    ΔH = 6.01 kJ

How much energy would be required to melt a moderately large iceberg with a mass of 1.00 million metric tons (1.00 × 106 metric tons)? (A metric ton is 1000 kg.)

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A 70.0-g piece of metal at 80.0 °C is placed in 100.0 mL of water at 22.0 °C contained in a coffee-cup calorimeter. The final temperature of water was found to be 24.6 °C. What is the specific heat of the metal? (Assume that no heat is transferred to the surroundings.)

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A 151.0 g of coolant having a specific heat of 3.18 J/goC is mixed with 100.0 g of water with an initial temperature of 18.2 °C. If the final temperature of the water is 34.0 °C, what was the initial temperature of the coolant? (Assume that no heat is transferred to the surroundings.)

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If a 30.0 g piece of copper pipe at 80.0 °C is placed in 100.0 g of water at 27.0 °C, what is the final temperature? Assume that no heat is transferred to the surroundings.
Specific heat of copper is 0.385 J/go

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A coffee-cup calorimeter contains 50.0 mL of distilled water at 22.7 °C. Solid ammonium bromide (6.14 g) is added, and the solution is stirred, giving a final temperature of 18.2°C. Find the enthalpy of dissolution (ΔH) for NH4Brin kilojoules per mole.

(Density of water is 1.00 g/mL.
Assume that there is no transfer of heat to the container or the surroundings, and that the specific heat of the solution is same as the specific heat of water.)

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A 5.03 g sample of solid potassium hydroxide is dissolved in 100.0 mL of distilled water at 23.0 °C in a coffee-cup calorimeter. What is the final temperature of the solution?
The enthalpy of dissolution (ΔH)for KOH is -44.51 kJ/mol.
(Density of water is 1.00 g/mL.
Assume that there is no transfer of heat to the container or the surroundings, and that the specific heat of the solution is same as the specific heat of water.)

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Which of the following is Hess’s law?

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Which of the following reactions represent the reaction for standard enthalpy of formation of bromomethane gas (CH3Br)?

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Using the table of standard enthalpies of formation, calculate the standard enthalpy (ΔHoreaction) of the following reaction:
4NH3(g)+5O2(g)→6H2O(g)+4NO(g)

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The combustion of glucose (C6H12O6), the reaction that provides energy for your brain, is shown below:
C6H12O6(s) + 9O2(g) → 6H2O(l) + 6CO2(g)
Calculate the enthalpy of combustion (ΔHoreaction) of glucose.

Standard enthalpy of formation (ΔHof) values of some substances are provided below.
C6H12O6(s):      -1273 kJ/mol
H2O(g):            -241.8 kJ/mol
H2O(l):             -285.8 kJ/mol
CO2(g):             -393.5 kJ/mol
O(g):                5 kJ/mol

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Ammonium sulfate, (NH4)2SO4, is used as a fire retardant and wood preservative; it is prepared industrially by the highly exothermic reaction of gaseous ammonia with sulfuric acid:
        2NH3(g)+H2SO4(aq)→(NH4)2SO4(s)      ΔHo = -178.9  kJ
Calculate the standard enthalpy of formation of ammonium sulfate (in kilojoules per mole).

Standard enthalpy of formation (ΔHof) values of ammonia and sulfuric acid are provided below.
NH3(g):         -45.90 kJ/mol
H2SO4(aq):    -909.3 kJ/mol

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