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    Gas Laws, Stoichiometry and Enthalpy

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    Question 1
    A sample of a gas occupies 1.40 x 103 mL at 25oC and 760 mmHg. What volume will it occupy at the same temperature and 380 mmHg?

    2,800 mL
    2,100 mL
    1,400 mL
    1,050 mL
    700 mL

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    Question 2
    The gas pressure in an aerosol can is 1.8 atm at 25oC. If the gas is an ideal gas, what pressure would develop in the can if it were heated to 475oC?

    0.095 atm
    0.717 atm
    3.26 atm
    4.52 atm
    34.2 atm

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    Question 3
    A small bubble rises from the bottom of a lake, where the temperature and pressure are 4oC and 3.0 atm, to the water's surface, where the temperature is 25oC and pressure is 0.95 atm. Calculate the final volume of the bubble if its initial volume was 2.1 mL.

    0.72 mL
    6.2 mL
    7.1 mL
    22.4 mL
    41.4 mL

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    Question 4
    A sample of N2 gas occupies 2.40 L at 20oC. If the gas is in a container that can contract or expand at constant pressure, at what temperature will the N2 occupy 4.80 L?

    10oC
    40oC
    146oC
    313oC
    685oC

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    Question 5
    A gas evolved during the fermentation of sugar was collected at 22.5oC and 702 mmHg. After purification its volume was found to be 25.0 L. How many moles of gas were collected?

    0.95 mol
    1.05 mol
    12.5 mol
    22.4 mol
    724 mol

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    Question 6
    Which of the following gases will have the greatest density at the same specified temperature and pressure?

    H2
    CClF3
    CO2
    C2H6
    CF4

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    Question 7
    A 0.271 g sample of an unknown vapor occupies 294 mL at 140oC and 847 mmHg. The empirical formula of the compound is CH2. What is the molecular formula of the compound?

    CH2
    C2H4
    C3H6
    C4H8
    C6H12

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    Question 8
    What volume of oxygen gas at 320 K and 680 torr will react with 2.50 L of NO gas at the same temperature and pressure?

    2NO(g) + O2(g) 2NO2(g)

    1.25 L
    2.50 L
    3.00 L
    1.00 L
    5.00 L

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    Question 9
    What mass of KClO3 must be decomposed to produce 126 L of oxygen gas at 133oC and 0.880 atm?

    2KClO3(s) 2KCl(s) + 3O2(g)

    24.6 g
    70.8 g
    272 g
    408 g
    612 g

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    Question 10
    Which gas has molecules with the greatest average molecular speed at 25oC?

    CH4
    Kr
    N2
    CO2
    Ar

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    Question 11
    An endothermic reaction causes the surroundings to ________.

    warm up
    become acidic
    condense
    decrease in temperature
    release CO2

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    Question 12
    How many degrees of temperature rise will occur when a 25.0 g block of aluminum absorbs 10 kJ of heat? The specific heat of Al is 0.900 J/g · oC.

    0.44oC
    22.5oC
    225oC
    360oC
    444oC

    --------------------------------------------------------------------------------

    Question 13
    The specific heat of gold is 0.129 J/g · oC. What is the molar heat capacity of gold?

    0.039 J/mol · oC
    0.129 J/mol · oC
    25.4 J/mol · oC
    39.0 kJ/mol · oC
    197.0 J/mol · oC

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    Question 14
    Which of the following processes is endothermic?

    O2(g) + 2H2(g) 2H2O(g)
    H2O(g) H2O(l)
    3O2(g) + 2CH3OH(g) 2CO2(g) + 2H2O(g)
    H2O(s) H2O(l)

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    Question 15
    When 0.56 g of Na(s) reacts with excess F2(g) to form NaF(s), 13.8 kJ of heat is evolved at standard-state conditions. What is the standard enthalpy of formation (ΔH) of NaF(s)?

    +24.8 kJ/mol
    +570 kJ/mol
    -24.8 kJ/mol
    -7.8 kJ/mol
    -570 kJ/mol

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    Question 16
    Find the standard enthalpy of formation of ethylene, C2H4(g), given the following data:

    C2H4(g) + 3O2(g) 2CO2(g) + 2H2O(l)
    ΔH = -1411 kJ

    C(s) + O2(g) CO2(g)
    ΔH = -393.5 kJ

    H2(g) + ½O2(g) H2O(l)
    ΔH = -285.8 kJ

    52 kJ
    87 kJ
    731 kJ
    1.41 x 103 kJ
    2.77 x 103 kJ

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    Question 17
    Given:

    H2(g) + ½O2(g) H2O(l), ΔH = -286 kJ

    What is the enthalpy change for the following reaction?

    2H2O(l) 2H2(g) + O2(g), ΔHorxn = ?

    ΔHo = -286 kJ
    ΔHo = +286 kJ
    ΔHo = -572 kJ
    ΔHo = +572 kJ
    ΔHo = -143 kJ

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    Question 18
    For the reaction:

    C(graphite) + O2(g) CO2(g), ΔH = -393 kJ

    How many grams of C(graphite) must be burned to release 275 kJ of heat?

    22.3 g
    0.70 g
    12.0 g
    17.1 g
    8.40 g

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    Question 19
    According to the first law of thermodynamics:

    Energy is neither lost nor gained in any energy transformations.
    Perpetual motion is possible.
    Energy is conserved in quality but not in quantity.
    Energy is being created as time passes. We have more energy in the universe now than when time began.

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    Question 20
    10.1 g CaO is dropped into a styrofoam coffee cup containing 157 g H2O at 18.0oC. If the following reaction occurs, then what temperature will the water reach, assuming that the cup is a perfect insulator and that the cup absorbs only a negligible amount of heat?

    CaO(s) + H2O(l) Ca(OH)2(s), ΔHorxn = -64.8 kJ/mol

    18.02oC
    35.8oC
    311oC
    42.2oC
    117oC

    © BrainMass Inc. brainmass.com June 3, 2020, 10:33 pm ad1c9bdddf
    https://brainmass.com/chemistry/gas-stoichiometry/237090

    Solution Summary

    This solution explains how to answer 20 problems dealing with stoichiometry, gas laws, and enthalpy.

    $2.19

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