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Homework 52

  • Page ID
    28966
  • 9.39, 10.53

    Question 9:39:Determine if the following compounds resulting aqueous solutions conduct an electrical current? (All are water soluble.)

    A)NaCl

    B)AgNO3

    C)C12H22O11

    D)C2H5OH

    Solution:

    Strategy:

    1) Break down the compounds into aqueous solutions.

    2) Determine if the compound dissociates into ions or molecules.

    3) If it breaks down into ions, therefore conducts an electrical current.

    A) 1. NaCl(s)→Na+ (aq) + Cl-(aq)

    2. Na+ and Cl- are both ions.

    3. NaCl therefore conducts an electrical charge.

    B) 1. AgNO3(s)→Ag+(aq) + NO3-(aq)

    2. Ag+ and NO3- are both ions

    3. AgNO3 conducts an electrical charge.

    C) 1. C12H22O11 (s)→ C12H22O11 (aq)

    2. C12H22O11 does not dissociate to produce ions.

    3. It does not produce an electrical charge.

    D) 1. C2H5OH(s)→C2H5OH (aq)

    2. C2H5OH does not dissociate to produce ions.

    3. It does not produce an electrical charge.


    Question 10:53: Consider the equation for the combustion of methane (CH4), a natural gas.

    CH4(g) + 2O2(g)→ CO2(g) + 2H2O Delta Hrxn = -807.3kJ

    If a bottle contains 200mL of methane, how much heat is released by its complete combustion? The density of methane is 0.716 g/mL.

    Solution:

    Strategy:

    1. Set up a conversion factor from the given volume of 200mL and density of 0.716 g/mL to detemine the mass of methane.

    2. Set up a conversion factor to determine moles of methane from the mass.

    3. Set up a conversion factor to determine the kJ of heat released from the ratio of moles of methane to Delta Hrxn.

    A) 200mL CH4 X 0.716 g/ML CH4 1 mol CH4 X 807.3kJ CH4

    1 mL CH4 16.04g CH4 1 mol CH4 = 7207.3 kJ

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