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Chemistry 20

Chemistry 20 · Worksheets

Cumulative review

Ten questions of mixed difficulty, covering Acids and bases, Bonding, Gases, Solutions. Print it, or work through it on screen — the answer key starts on its own page.

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Cumulative review

Chemistry 20 · maddyhelps.com

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Circle the best answer for each question. Show your work in the space provided.

  1. Water dissolves many ionic compounds because water molecules are

    1. a) polar, so they surround and pull apart the ions
    2. b) very small
    3. c) acidic
    4. d) non-polar

  2. The mass of NaCl needed to make 500.0 mL of 0.200 mol/L solution is about

    1. a) 5.8 g
    2. b) 2.9 g
    3. c) 0.10 g
    4. d) 11.7 g

  3. A balloon holds 6.0 L at 300 K. Heated to 600 K at constant pressure, it holds

    1. a) 12.0 L
    2. b) 3.0 L
    3. c) 6.0 L
    4. d) 24.0 L

  4. At the same temperature, the gas whose molecules have the greatest average speed is

    1. a) Cl₂
    2. b) CO₂
    3. c) O₂
    4. d) H₂

  5. The Lewis structure of CO₂ contains

    1. a) two carbon–oxygen triple bonds
    2. b) two carbon–oxygen single bonds, in a bent arrangement
    3. c) one double and one single bond
    4. d) two carbon–oxygen double bonds, in a linear arrangement

  6. The pH of 0.010 mol/L NaOH is

    1. a) 10
    2. b) 12
    3. c) 2
    4. d) 1.0 × 10⁻¹²

  7. Diluting 50.0 mL of 2.00 mol/L solution to 200.0 mL gives a concentration of

    1. a) 8.00 mol/L
    2. b) 0.500 mol/L
    3. c) 1.00 mol/L
    4. d) 0.125 mol/L

  8. Molar concentration is measured in

    1. a) g/L
    2. b) L/mol
    3. c) mol/L
    4. d) mol

  9. A covalent bond forms when two atoms

    1. a) are both metals
    2. b) exchange protons
    3. c) share a pair of electrons
    4. d) transfer a pair of electrons

  10. A compound formed between a metal and a non-metal is usually

    1. a) ionic, and held together by the attraction between oppositely charged ions
    2. b) molecular, and held together by metallic bonding
    3. c) molecular, and held together by the attraction between ions
    4. d) ionic, and held together by shared pairs of electrons

Answer key · Cumulative review

Chemistry 20 · maddyhelps.com

  1. a) polar, so they surround and pull apart the ions — The partly negative oxygen end is attracted to positive ions and the partly positive hydrogen ends to negative ions. Enough of these attractions will pull an ion out of the lattice — which is why like dissolves like.
  2. a) 5.8 g — First n = cV = (0.200)(0.5000) = 0.100 mol. Then m = nM = (0.100)(58.44) = 5.8 g. Volume has to be in litres before it is multiplied by a concentration in mol/L.
  3. a) 12.0 L — Charles's law: V₁/T₁ = V₂/T₂, so doubling the absolute temperature doubles the volume. This only works in kelvins — doubling 27 °C to 54 °C would not double the volume at all.
  4. d) H₂ — Same temperature means the same average kinetic energy, ½mv². The lightest molecules must therefore be moving fastest to carry the same energy, and hydrogen is by far the lightest here.
  5. d) two carbon–oxygen double bonds, in a linear arrangement — Carbon has four valence electrons and each oxygen needs two more, so carbon forms a double bond to each oxygen. With two bonding groups and no lone pairs on carbon, VSEPR puts them as far apart as possible: 180° apart, linear.
  6. b) 12 — Sodium hydroxide is a strong base, so [OH⁻] = 0.010 mol/L and pOH = 2. Then pH = 14 − 2 = 12. Taking the logarithm of the concentration and stopping there gives 2, which is the pOH, not the pH.
  7. b) 0.500 mol/L — Dilution does not change the amount of solute, so c₁V₁ = c₂V₂ and c₂ = (2.00)(50.0)/200.0 = 0.500 mol/L. Quadrupling the volume divides the concentration by four.
  8. c) mol/L — Molar concentration is amount of solute per litre of solution, so mol/L. Grams per litre is a concentration too, but it is not molar concentration and cannot be used directly in stoichiometry.
  9. c) share a pair of electrons — Two non-metals both want to gain electrons, so neither can take them outright. Sharing lets both count the pair towards a full outer shell.
  10. a) ionic, and held together by the attraction between oppositely charged ions — Metals lose electrons easily and non-metals gain them, so electrons transfer rather than being shared. The result is positive and negative ions pulling on each other. Sharing is what non-metals do with other non-metals.