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    Exercises

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    hnt47wsypk

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    © All Rights Reserved
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    Exercises

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    hnt47wsypk
    7 views2 pages

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    7 views2 pages

    Exercises

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    hnt47wsypk

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    © All Rights Reserved
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    Exercises

    1. How many Zn atoms are present in a piece of brass alloy weighing 54.26 g? (Brass alloy
    is a zinc–copper alloy containing 66% Cu by mass.)
    204
    2. How many Pb atoms are present in a piece of lead weighing 215 mg? The percent
    isotopic abundance of 204Pb is 1.4%.
    3. A 3.124 g sample of the alcohol C4H9OH is burned in an excess of oxygen. What masses
    of CO2 and H2O should be obtained?
    4. 0.4039 g sample of this carbon–hydrogen–oxygen compound yields 1.1518 g CO2 and
    0.2694 g H2O in combustion analysis. Its molecular mass is 108.1 u. Determine it’s a)
    mass percent composition; b) empirical formula, c) molecular formula.
    5. a) Write formulas for the compounds: tricarbon disulfide, hydrobromic acid, aluminum
    sulfate.
    b) Name these compounds: ZnS, Cu(OH)2, K2CrO4, Fe2(SO4)3, N2O5, CS2.
    6. Ag2CO3 ⟶ Ag (s) + CO2 (g) + O2 (g)

    How many grams of Ag2CO3 are decomposed to yield 75.1 g Ag in this reaction?

    7. When Fe2O3 is heated with an excess of carbon, metallic iron and carbon monoxide gas
    are produced. From a sample of ore weighing 938 kg, 523 kg of pure iron is obtained.
    What is the mass percent Fe2O3 in the ore sample? (Assume that none of the impurities
    contain Fe.)
    8. How much ethanol, (d=0.789 g/mL), in liters, must be dissolved in water to produce
    200.0 L of 1.65 M ethanol? How much glucose, C6H12O6, in grams, must be dissolved
    in water to produce 75.0 mL of 0.350 M C6H12O6?
    9. 2Ag NO3 (aq) + Na2S (s) ⟶ Ag2S (s) + 2 NaNO3 (aq)

    a) How many grams of Na2S(s) are required to react completely with 27.8 mL of
    0.163 M AgNO3? b) How many grams of Ag2S(s) are obtained from the reaction in part
    (a)?

    10. Ammonia can be generated by heating together the solids NH4Cl and Ca(OH)2. CaCl2
    and H2O are also formed. If a mixture containing 33.0 g each of NH4Cl and Ca(OH)2 is
    heated, how many grams of NH3 will form? Which reactant remains in excess, and in
    what mass? Reaction: Ca(OH)2 (s) + 2 NH4Cl (s) ⟶ CaCl2 (aq) + 2 H2O (l) + 2 NH3 (g)
    11. Balance these equations for redox reactions occurring in acidic solution.

    a) MnO4- + I- ⟶ Mn2+ + I2 (s)

    b) BrO3- + N2H4 ⟶ Br- + N2 (g)

    12. What volume of 0.0962 M NaOH is required to exactly neutralize 10.00 mL of 0.128
    M HCl?
    13. An iron ore sample weighing 0.9132 g is dissolved in HCl(aq), and the iron is obtained
    as Fe2+(aq). This solution is then titrated with 28.72 mL of 0.05051 M K2Cr2O7. What is
    the mass percent Fe in the ore sample?
    6Fe2+ + 14H+ + Cr2O72- ⟶ 6Fe3+ + 2Cr3+ + 7H2O
    14. A 74.8 g sample of copper at 143.2°C is added to an insulated vessel containing 165 mL
    of glycerol, C3H8O3(l) (d=1.26 g/mL), at 24.8°C. The final temperature is 31.1°C. The
    specific heat capacity of copper is 0.385 J g−1 °C−1. What is the heat capacity of glycerol
    in J mol−1 °C−1.
    15. Acetylene (C2H2) torches are used in welding. How much heat (in kJ) evolves when 5.0
    L of C2H2 (d=1.0967 kg/m3) is mixed with a stoichiometric amount of oxygen gas?
    (The combustion reaction ∆rH= -1299.5 kJ/mol)
    16. Use Hess’s law to determine ΔrH° for the reaction:
    C3H4(g) + 2H2(g) ⟶ C3H8(g) , given that

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