Unit 1 Section B - Looking at Water and Its Contaminants

Review Name______

Physical Properties

1. Name two physical properties would allow you to distinguish between liquid water and rubbing alcohol.

Density

2. A graduated cylinder has a mass of 125 g. When a sample of an unknown liquid is placed in the cylinder, its new mass is 155 g. The volume of the liquid is

25 mL. What is the density of the liquid?

3. If the liquid in question 2 is insoluble in water, will it sink or float in the water?

How do you know?

4. A block has measurements of 6 cm, 17 cm, and 5.2 cm. The density of the block is 1.85 g/cm3. What is the mass of the block?

Classification of Matter

5. What does the symbol (aq) following the formula for a compound mean? Would this substance be an element, a compound, a homogeneous mixture or a heterogeneous mixture?

6. Classify the following substances as pure substances or mixtures.

_____ a. Cl2 _____ e. oil and water

_____ b. potassium _____ f. air

_____ c. KCl(aq) _____ g. sedimentary rock

_____ d. KNO3 _____ h. a solution

7. Classify the following substances as an element, compound, homogeneous mixture or heterogeneous mixture.

_____ a. Cl2 _____ e. oil and water

_____ b. potassium _____ f. air

_____ c. KCl(aq) _____ g. sedimentary rock

_____ d. KNO3 _____ h. a solution

8. Fill in the following data chart.

Substance / Did it settle out? / Did it show Tyndall effect? / Is it a solution, colloid or suspension?
Milk / No / Yes
CuSO4(aq)
Gold in water from stream / Yes / No
Amoxicillan / Yes / Yes
Polluted air / Yes / Yes
Jello / No / Yes

9. Carbon tetrachloride, CCl4 is a liquid that can be used in dry cleaning. When

5.0 g of bromine is added to 75 g of clear colorless CCl4, the mixture has a reddish brown color. Over time, no settling out is observed. When the mixture is filtered, no residue is observed on the filter paper. When a light beam is directed at the mixture, its path through the mixture is not visible. Is the mixture a solution, colloid or suspension? Explain your answer.

10. Show the formula for seven elements that exist in nature as diatomic molecules.

Symbols, Formulas and Equations

11. Write a chemical equation that represents the following word equation:

Two atoms of potassium and one molecule of copper(II) chloride form two molecules of potassium chloride and one atom of copper.

14. Use the following reaction to answer the questions below

2 NaI + Cl2 → 2 NaCl + I2

a. Write a sentence describing this reaction in terms of molecules.

(hint: use your common ions sheet to help name molecules)

b. Did any elements react, or were they all compounds? Explain your answer.

c. Were any elements produced, or were they all products? How do you know?

d. Complete an atom inventory for the equation.

Reactants Products

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13. Give the symbol for each element present in each molecule of Al2(SO4)3 and tell how many of atoms of each element are present.

Electrical Charges, Protons, Electrons, Atoms and Ions

14. Classify the following as anions, cations, or electrically neutral atoms.

_____ a. Rb+1 _____ c. Se–2

_____ b. CrO4–2 _____ d. Sn

15. Give the symbol and electrical charge for each of the following ions or atoms.

_____ a. gold ____ protons 76 electrons

_____ b. ______2 protons 2 electrons

_____ c. fluorine 9 protons 10 electrons

16. For each of the atoms or ions, identify the number of protons and electrons.

a. P–3 _____ protons _____ electrons

b. Zn _____ protons _____ electrons

c. Ba+2 _____ protons _____ electrons

17. Give the symbol and charge for each of the following ions:

_____ a. calcium atom that lost 2 electrons

_____ b. nitrogen atom that gained 3 electrons

18. Were electrons gained or lost in order to form Be+2?

19. Complete the following table.

Cation / Anion / Formula / Name
Mg 2+ / O2–
Al3+ / Cl–
Mg2+ / PO4–3
NH4+ / CO32–
Iron(III) sulfite
CdCl2
Cu(NO3)2
Aluminum hydroxide

20. As an environmental chemist, you are testing for the presence of chloride ion in samples of stream water. You perform the appropriate test on a sample for Stream A and observe a white precipitate. The same test performed on a sample from Stream B yields no change.

a. What can you conclude about the presence of chloride ion in Stream A?

b. Can you make a definite conclusion about the presence of the chloride ion in

Stream B? Why or why not?