Chemcom Unit 2 Exam . . . Water: Exploring Solutions

 

True/False (Choose the best answer.)

  1. In the Western United States, water is ued primarily for irrigation for agriculture.


  2. Most of the world's fresh water is found in rivers.


  3. One way to tell if a sample is a solution is to shine light through the sample.


  4. An ion is an atom or molecule that has a positive or negative charge.


  5. Hydrogen gas, H2, is a compound composed of molecules.


  6. In a liquid, the atoms or molecules touch one another, but are free to change positions.


  7. A saturated solution can dissolve more solute.


  8. Household ammonia has a pH = 11, so it is a basic substance.


  9. Polar substances tend to dissolve in non-polar solvents.


  10. Water vapor dissolved in the atmosphere can dissolve gases produced by humans.

  11. In drinking water treatment, flocculation serves to kill disease causing organisms.

  12. Chlorine can react with organic matter in water to produce trihalomethanes (THMs)

  13. Water softeners replace cations like sodium and potassium with cations like calcium and magnesium.

Multiple Choice (Choose the best answer.)

  1. When you pour yourself a morning cup of coffee, the water used to grow the coffee beans is an example of an _____ use of water and the water you used to make the coffee is an example of a _____ use of water.

    direct . . . direct

    indirect . . . indirect

    direct . . . indirect

    indirect . . . direct

  2. In the Foul Water lab which step removed the coffee grounds in the water sample?

    Solubility Separation

    Sand Filtration

    Charcoal Adosorption

    Distillation

  3. In the Foul Water lab, which step removed the salt present in the water?

    Solubility Separation

    Sand Filtration

    Charcoal Adosorption

    Distillation

  4. In the Western United States, little water (13 %) is used to produce steam to generate electricity, while in the Eastern U.S. 79% of water is used to produce steam to generate electricity. Why do you suppose this is true?

    The Eastern U.S. has a much higher population.

    The Eastern U.S. has more industry.

    Hydroelectric power is mostly used in the West.

    All these are true.

  5. A water-efficient shower head uses 9 L of water per minute. A regular shower head uses 19 L of water per minute. Assuming a typical shower lasts 10 minutes, how much water is saved using a water-efficient shower head?

    90 L

    100 L

    190 L

    None of these are correct.

  6. A conventional toilet uses 19 L per flush. A "Water Saver" toilet uses 13 L per flush. A "Low Flow" Toilet uses 6 L per flush.

    I) How much water is saved per flush by using a "Low Flow" toilet compared to using a "Water Saver" toilet?

    II) How much water is saved per flush by using a "Low Flow" toilet compared to using a conventional toilet?

    I) 7 L . . . II) 6 L

    I) 7L . . . II) 13 L

    I) 13 L. . . II) 6 L

    I) 13 L. . . II) 13 L

  7. Some people do not wish to purchase "Low Flow" toilets because they complain about sometimes having to flush the toilet twice to dispose of waste. Why is this not a persuasive arguement? (Use information in problem 5 if you need to.)

    Even if it takes two flushes, a "Low Flow" toilet still saves water compared to a conventional toilet.

    Two flushes are not necessary every time the toilet is used.

    Both A and B support the use of "Low Flow" toiliets.

    Neither A nor B support the use of "Low Flow" toiliets.

  8. Rank the following places water is found from least to greatest abundance.

    Ocean Water < Atmospheric Moisture < Ground Water < Glaciers/Ice Caps

    Ground Water < Atmospheric Moisture < Ocean Water < Glaciers/Ice Caps

    Ground Water < Atmospheric Moisture < Glaciers/Ice Caps < Ocean Water

    Atmospheric Moisture < Ground Water < Glaciers/Ice Caps < Ocean Water

  9. Rank the following types of water in terms least to greatest purity.

    Ocean Water < Atmospheric Moisture< Ground Water < Rivers and Lakes

    Ocean Water < Rivers and Lakes < Ground Water < Atmospheric Moisture

    Ground Water < Atmospheric Moisture < Rivers and Lakes< Ocean Water

    Atmospheric Moisture < Ground Water < Rivers and Lakes < Ocean Water

  10. Which of the following water sources is not generally used to obtain water for cities?

    Ground Water

    Rivers

    Glaciers/Ice Caps

    Lakes

  11. Unlike many substances, solid water (ice) floats in liquid water. Compare the densities of ice and liquid water.

    You need to know the mass and volumes of ice and liquid water to be able to compare their densities.

    Ice and liquid water have similar densities.

    Ice is less dense than liquid water.

    Ice is more dense than liquid water.

  12. Milk is a substance that does not have particles that eventually settle out of the liquid. Yet, light scatters when it is shown through a test tube of milk. Milk is best described as a _____.

    heterogeneous mixture

    homogeneous mixture

    colloidal suspension

    suspension

  13. Solutions are homogenous mixtures that are created when a solute and solvent form a homogeneous mixture. In a solution of salt and water, water is the _____ and salt is the _____.

    solute . . . solvent

    solution . . . . solvent

    solute . . . solution

    solvent . . . solute

    The diagrams below refer to Cl 2, Ne, CO 2 , and CH 4. Use the diagrams for questions 14 - 17.

  14. Which of the diagrams above show elements?

    Cl2 and Ne

    Cl2 only

    Ne only

    All of the above are elements.

  15. Which of the above diagrams show compounds?

    Cl2 only

    CO2 only

    CO2 and CH4 only

    Cl2, CO2, and CH4 only

  16. Which of the above digrams show molecules?

    Cl2 only

    CO2 only

    CO2 and CH4 only

    Cl2, CO2, and CH4 only

  17. Which of the above diagrams are composed of atoms?

    Ne only

    Cl2

    Ne and Cl2 only

    All are composed of atoms

  18. Fluorine, F, has nine protons and nine electrons. The fluoride ion, F -1 , has how many protons and electrons?

    9 protons and 10 electrons

    10 protons and 10 electrons

    10 protons and 9 electrons

    9 protons and 8 electrons

  19. The sodium ion is represented by the symbol, Na +1. The oxide ion is represented by the symbol, O 2-. The formula for soidum oxide is _____.

    NaO

    Na 2 O

    Na O 2

    Na 2 O 2

  20. Use Figure 18 on page 33 of your text to name MgI 2.

    Magnesium Diiodide

    Manganese Iodide

    Magnesium Iodine

    Magnesium Iodide

    Use the diagram below to answer questions 21 - 25.

  21. Which substance has the highest solubility at 60 o C?

    Substance A

    Substance B

    Substance C

    Substances A and B have similar solubilities.

  22. If you dissolved 20 g of substance A in 100g of water at 80 o C, the solution would be _____.

    Saturated

    Unsaturated

    Super Saturated

    Heterogeneous

  23. What is the solubility of Substance B at 20 o C?

    32 g / 100g Water

    30 g / 100g Water

    27 g / 100g Water

    13 g / 100g Water

  24. How much of substance B would dissolve in 50 g of water at 30 o C?

    About 15 g of B would dissolve in 50 g of water at 30 o C.

    About 30 g of B would dissolve in 50 g of water at 30 o C.

    About 10 g of B would dissolve in 50 g of water at 30 o C.

    About 5 g of B would dissolve in 50 g of water at 30 o C.

  25. Which substance in the graph is probably a gas?

    Substance A

    Substance B

    Substance C

    It is impossible to tell.

  26. % concentration is the mass of solute divided by the mass of total solution. If 50 g of salt is dissolved in 100 g of water the % concentration is _____.

    200 %

    150%

    50%

    33 %

  27. Which diagram above shows how water interacts with NaCl to dissolve NaCl?

    Diagram A

    Diagram B

    Diagram C

    Diagram D

  28. Which of the following are heavy metals that can poison living organisms?

    I. K--Potassium

    II. Lead--Pb

    III. Mercury--Hg

    IV. Ca--Calcium

    I and II only

    I and III only

    II and III only

    III and IV only

  29. Soft drinks have a pH of about 3. Sea water has a pH of about 8. Milk has a pH of about 6.5 Arrange these substances from least to most acidic.

    Sea Water < Milk < Soft Drinks

    Milk < Sea Water < Soft Drinks

    Soft Drinks < Milk < Sea Water

    Soft Drinks < Sea Water < Milk

  30. Substance I has a pH = 3 and substance II has a pH = 5. Which of the statements is true?

    Substance II is 100 x more acidic than substance I..

    Substance II is 2 X more acidic than substance II.

    Substance I is 2X more acidic than substance II.

    Substance I is 100 X more acid than substance II.

  31. Water is a polar solvent. Iodine (I2) is not very soluble in water while sugar (C6H12O6) is very soluble in water. What is true about iodine and sugar?

    I2 is polar and C6H12O6 is polar.

    I2 is non-polar and C6H12O6 is non-polar.

    I2 is polar and C6H12O6 is non-polar.

    I2 is non-polar and C6H12O6 is polar.

  32. When water is purified by the hydrologic cycle, the water that collects in underground aquifers can contain _____.

    atmospheric gases

    minerals from rocks and gravel

    disease causing bacteria

    organic matter

  33. Drinking water is often treated in the following order by most municipal water treatment plants:

    screening, sand filtration, flocculation, and aeration

    screening, flocculation, sand filtration, and aeration

    aeration, sand filtration, flocculation, and screening

    sand filtration, screening, flocculation, aeration

  34. Ways to reduce trihalomethanes (THMs) in drinking water include:

    Pass water through activated charcoal to remove organic matter before adding chlorine.

    Do not pre-chlorinate the water.

    Use ozone or ultraviolet light to kill disease causing bacteria.

    All of the above are ways to reduce THMs.

  35. Hard water can cause many problems. Which of the following is NOT a problem associated with hard water?

    poor tasting water

    the production of soap scum

    health hazards

    the clogging of water pipes

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