6.E: Exercise

CHEM U109 Chemistry of Living Things · LibreTexts

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    From LibreTexts, under CC BY-NC-SA 4.0, as the source states it; its equations are written in TeX, which the PDF shows typeset. This page at LibreTexts.

    Additional Exercises

    1. If the average male has a body mass of 70 kg, of which 60% is water, how many moles of water are in an average male?

    2. How many moles of each element are present in 2.67 mol of each compound?

      a)  HCl;  b)  H2SO4;  c)  Al(NO3)3;  d)  Ga2(SO4)3

    3. What is the mass of one hydrogen atom in grams? What is the mass of one oxygen atom in grams? Do these masses have a 1:16 ratio, as expected?

    4. If 6.63 × 10−6 mol of a compound has a mass of 2.151 mg, what is the molar mass of the compound?

    5. Hemoglobin (molar mass is approximately 64,000 g/mol) is the major component of red blood cells that transports oxygen and carbon dioxide in the body. How many moles are in 0.034 g of hemoglobin?

    6. How many individual hemoglobin molecules are present in 0.034 grams of hemoglobin?

    7. Plants cannot use nitrogen in air, N2, but can use it in other forms like ammonia, NH3. If 7.0 grams of nitrogen, N2, completely reacts with hydrogen, H2, (A) How many moles of H2 are required? and (B) How many grams of ammonia, NH3, can be formed? (Hint: You will need a balanced chemical equation.)

    Answers

    1. 2,330 mol (Or since the original numbers each only have one significant figure, 2x103 mol)
    2. a)  2.67 mol of H and 2.67 mol of Cl;  b)  5.34 mol of H, 2.67 mol of S, and 10.68 mol of O;  c)  2.67 mol of Al, 8.01 mol of N, and 24.03 mol of O;  d)  5.34 mol of Ga, 8.01 mol of S, and 32.04 mol of O
    3. H = 1.66 × 10−24 g and O = 2.66 × 10−23 g; yes, they are in a 1:16 ratio.
    4. 324 g/mol
    5. 5.3x10-7 moles of hemoglobin
    6. 3.2x1018 molecules of hemoglobin
    7. (A) 0.75 mol H2; (B) 8.5 g NH3
     

    6.E: Exercise is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts.