UNIT REVIEW

UNIT REVIEW

Part 1 (Pages 68–69) 1. D 2. C 3. C 4. B 5. 3, 2, 4 6. 6, 6, 8 7. C 8. A 9. 1, 2 10. 2, 3 11. 1, 2, 2, 1 12. 2, 1, 1, 1 13. 1, 5, 3, 4 14. 2, 3, 3, 1 15. 2, 2, 1, 1 16. D 17. A 18. 80.1 19. 1.13 20. 1.19 21. 1.07

Solutions 18.

CH OH3

2.50 mol

m 32.05 g

1 mol

u 80.1 g

19.

4 2 4

(NH ) SO

150 g

n 1 mol

132.17 g

u = 1.13 mol

20.

KMnO4

7.50 m mol

m 158.04 g

1 mol

u = 1185 mg = 1.19 g

21. n

285 g 1 mol

267.21 g

u = 1.07 mol

Part 2 (Pages 69–71)

22. (a) Groups are the vertical columns of elements on our periodic table. There are 18 groups in

the periodic table. Some groups contain elements that all have similar empirical and

theoretical characteristics. For example, empirically, group 18 elements are called noble

gases because they are essentially non-reactive. Groups of main-group elements also have

similar atomic structures. For example, from a theoretical perspective, Group 1 elements

(alkali metals) all contain one valence electron in their outermost energy level.

(b) Periods are the horizontal rows of elements on our periodic table. There are seven periods on this periodic table. Periods of elements do not have chemical characteristics in

common, but their empirical properties gradually change from metal to nonmetal as you travel across the periodic table from left to right. Theoretically, there is an increase in protons and neutrons in the nucleus, and an increase of electrons in the same energy level or shell.

(c) The staircase line on our periodic table divides the elements into metals (left of the line) and nonmetals (right of the line). The semi-metals are distributed along the staircase line.

23. Table 1: Atoms and Ions

Symbol Name # protons # electrons Net charge S

sulfide ion 16 18 2

Br

bromide ion 35 36 1

Ca

calcium ion 20 18 2+

V vanadium atom 23 23 0

Fe

iron(III) ion 26 23 3+

Ar argon atom 18 18 0

24. Table 2: Radioisotopes [Note: The answers are in bold type.]

Name Use # protons # electrons # neutrons

cobalt-60 cancer treatment 27 27 33 iodine-131 hyperthyroid treatment 53 53 78

phosphorus-32 reduces white cell count 15 15 17 strontium-85 bone scanning 38 38 47

25. (a) complete combustion

2 C

H

(l) + 13 O

(g) o 8 CO

(g) + 10 H

O(g) (b) single replacement

Cu(s) + 2 AgNO

(aq) o 2 Ag(s) + Cu(NO

)

(aq) (c) double replacement

Cd(NO

)

(aq) + Na

CO

(aq) o 2 NaNO

(aq) + CdCO

(s) (d) simple decomposition

2 KOH(l) o 2 K(l) + O

(g) + H

(g) (e) formation

4 Al(s) + 3 O

(g) o 2 Al

O

(s)

26. (a) CH

OH(l) + 2 O

(g) o CO

(g) + 2 H

O(g)

One mole of liquid methanol reacts with two moles of oxygen gas to produce one mole of carbon dioxide gas and two moles of water vapour.

(b) 2 Na

PO

(aq) + 3 CaCl

(aq) o 6 NaCl(aq) + Ca

(PO

)

(s)

Two moles of aqueous sodium phosphate reacts with three moles of aqueous calcium chloride to produce six moles of aqueous sodium chloride and one mole of solid calcium phosphate.

27. (a) 2 Mg(s) + O

(g) o 2 MgO(s) (b) 2 NaCl(l) o 2 Na(l) + Cl

(g)

(c) Al

(SO

)

(aq) + 6 NaOH(aq) o 2 Al(OH)

(s) + 3 Na

SO

(aq) (d) 2 Al(s) + 6 HCl(aq) o 3 H

(s) + 2 AlCl

(aq)

(e) C

H

(s) + 38 O

(g) o 25 CO

(g) + 26 H

O(g) 28. Prediction

According to the double replacement reaction generalization, the products of the reaction are:

CuCl

(aq) + 2 NaOH(aq) o Cu(OH)

(s) + 2 NaCl(aq)

Design

The two solutions are mixed and the following diagnostic tests are performed.

(a) If the chemical mixture is observed and a precipitate forms, then this is consistent with the prediction that a copper(II) hydroxide precipitate forms.

(b) If the colour of the solution is observed and the solution changes from blue to colourless, then this is consistent with copper(II) ions being precipitated out of the solution.

(c) If the solution is tested (pre and post) with neutral litmus paper, and the litmus paper turns from dark blue in the initial solution but stays a neutral colour in the final solution, then this is consistent with hydroxide ions being removed from (precipitated out of) the solution.

(d) If flame tests are conducted (pre and post) on the solution and the flame is yellow in both cases, then this is consistent with the presence of sodium ions in solution.

29. (a) 2 C

H

(g) + 5 O

(g) o 4 CO

(g) + 2 H

O(g) technological

(b) MgCl

(l) o Mg(s) + Cl

(g) scientific

(c) 2 Fe(s) + 3 CuSO

(aq) o Fe

(SO

)

(aq) + 3 Cu(s) economic

(d) 2 ZnS(s) + 3 O

(g) o 2 ZnO(s) + 2 SO

(g) political

(e) 2 Pb(C

H

)

(l) + 27 O

(g) o 2 PbO(s) + 16 CO

(g) + 20 H

O(g) ecological

30. (a) technological (b) scientific (c) economic (d) political (e) economic

31. (a) A double blind control study is conducted. A random sample of 100 people (half in an experimental group and half in a control group) is asked to use the special pillows provided to them. Fifty of the pillows have real magnets and fifty have fake magnets.

Participants are asked to record, each morning for 3 months, the degree of restful sleep (on a scale of 1 to 10). Neither the subject nor the experimenter who provided the pillow knows whether the pillow has real or fake magnets. The results of the study are analyzed by using a decoder that identifies whether the subjects are in the experimental group or in the control group. [Note: All experiments to date show no significant difference between the experimental groups and the control groups.]

(b) An experiment is set up on terrain similar to the surface of the moon. A single light source similar to that of the Sun is employed to create shadows of objects similar to those in the moon photos and videos. The shadows are observed. [Note: Tests like this one have supported the validity of the moon photos and videos. The anecdotal hypothesis that shadows from a single light source projected over an uneven terrain are parallel is

falsified (not supported by the evidence).

(c) A numbered list of the names of simple objects is prepared by a researcher. A person who is unknown to the psychicthe “artist”selects at random a number on the researcher’s list. Working out of sight of the psychic, the artist draws the object. The psychic and one (or more) other persons attempt to draw the object that the artist has drawn. The psychic’s drawing will be analyzed for similarity to the artist’s drawing, as will the other person’s.

The degree of similarity of the secondary drawings to the artist’s drawing will be

analyzed.

(d) A selection of people suffering from this disease is divided randomly into two groups.

One group receives the alternative medical care; the other receives standard medical treatment. An independent medical researcher, who does not know which treatment each person is getting, monitors the progress of the disease in each patient. At least two other independent researchers analyze the data to decide whether the patients receiving the alternative treatment fared significantly better than those receiving the standard treatment.

(e) Thirty volunteers are randomly divided into two groups and given an unlabelled bottle of shampoo. Half of the bottles contain the advertised shampoo; the other half contain a generic brand. Only one of the researchers knows who is getting which shampoo. The volunteers are asked to rate the “body” of their hair at the beginning of the research period, use the provided shampoo every day for two weeks, then rate their hair again at the end of that period. Another researcher then compiles the data, which are analyzed by the first researcher to establish whether the test group reported a significantly greater improvement in their hair than did the control group.

(f) Four identical socks, pairs of pants, and soccer jerseys are rubbed in grass to give them all similar stains. The garments are then divided into four mesh bags, labelled A, B, C, and D. The four bags are assigned to four different treatments: one gets the new

detergent; two get the two leading detergents; and one gets no detergent at all. Apart from the detergent used, the four bags of garments are washed and dried in identical ways:

same washing machine; same setting; same drier time. After washing and drying, another researcher rates the garments for cleanliness. Only then will the results be matched up with the type of detergent used.

32. Prediction

(a) Cl

(aq) + 2 KI(aq) o 2 KCl(aq) + I

(s) single replacement

diagnostic test: If the mixture is observed and the mixture turns yellow-brown, then iodine is likely produced. If a chlorinated hydrocarbon is added to the mixture and a purple colour appears, then iodine is likely produced.

(b) MgCl

(aq) + 2 NaOH(aq) o Mg(OH)

(s) + 2 NaCl(aq) double replacement

diagnostic test: If the mixture is observed and a white precipitate forms, then magnesium hydroxide is likely produced.

(c) Al(NO

)

(aq) + Na

PO

(aq) o AlPO

(s) + 3 NaNO

(aq) double replacement

diagnostic test: If the mixture is observed and a white precipitate forms, then aluminium phosphate is likely produced.

(d) 2 Mg(s) + 2 HCl(aq) o MgCl

(aq) + H

(g) single replacement

diagnostic test: If a gas is generated, collected, and tested with a flame, then hydrogen gas is likely produced.

(e) 3 NaOH(aq) + CrCl

(aq) o Cr(OH)

(s) + 3 NaCl(aq) double replacement

diagnostic test: If the mixture is observed and a precipitate forms, then chromium(III) hydroxide is likely produced. If the colour of the mixture is observed and changes from green to colourless, then the chromium(III) ions likely reacted and the sodium chloride solution is likely produced.

(f) 2 Li(s) + 2 H

O(l) o 2 LiOH(aq) + H

(g)

single replacement

diagnostic tests: If a gas is generated, collected, and tested with a flame, and the gas explodes when ignited, then hydrogen gas is likely produced. If the solution is tested (pre and post) with litmus paper and the litmus paper in the post-test turns blue, then lithium hydroxide is likely produced. If pre- and post-flame tests are conducted on the liquid phase, and the post-test produces a red flame, then lithium ions are likely produced.

(g) Co(s) + 2 AgNO

(aq) o Co(NO

)

(aq) + 2 Ag(s) single replacement

diagnostic test: If the mixture is observed and the final solution is pink, then aqueous cobalt(II) ions are likely produced. If the mixture is observed and silvery needles form on the cobalt metal, then silver is likely produced.

(h) HNO

(aq) + NH

CH

COO(aq) o CH

COOH(aq) + NH

NO

(aq) double replacement

diagnostic test: If the mixture is observed and remains colourless, then the reaction as predicted likely occurs. If the mixture is tested for an odour change, and the odour of vinegar is detected, then acetic acid is likely produced.

Analysis

On the basis of the evidence gathered in this investigation,

(a) there was a reaction as predicted, as indicated by the change in appearance of the solutions when mixed. The yellow-brown colour was likely iodine.

Cl

(aq) + 2 KI(aq) o 2 KCl(aq) + I

(s)

(b) there was a reaction as predicted—a precipitate was formed. The precipitate is likely to be magnesium hydroxide.

MgCl

(aq) + 2 NaOH(aq) o Mg(OH)

(s) + 2 NaCl(aq)

(c) there was a reaction as predicted—a precipitate was formed. The precipitate is consistent with its being aluminium phosphate.

Al(NO

)

(aq) + Na

PO

(aq) o AlPO

(s) + 3 NaNO

(aq) (d) the gas bubbles observed were likely hydrogen, as predicted.

2 Mg(s) + 2 HCl(aq) o MgCl

(aq) + H

(g)

(e) the dark precipitate is almost certainly chromium hydroxide. The clear solution is consistent with soluble sodium chloride.

3 NaOH(aq) + CrCl

(aq) o Cr(OH)

(s) + 3 NaCl(aq)

(f) the diagnostic test for hydrogen indicated that that gas was produced. The fact that red litmus turned blue indicates a basic solution, most likely LiOH(aq).

2 Li(s) + 2 H

O(l) o 2 LiOH(aq) + H

(g)

(g) the silvery needles are likely small pieces of solid silver. The pink solution likely contains cobalt ions.

Co(s) + 2 AgNO

(aq) o Co(NO

)

(aq) + 2 Ag(s)

(f) acetic acid (vinegar) is produced, as is evident from the odour. All the products are highly soluble, consistent with the prediction.

HNO

(aq) + NH

CH

COO(aq) o CH

COOH(aq) + NH

NO

(aq) Evaluation

Part 2

By comparing the answers to the Problem obtained from the Prediction and the Analysis, the Prediction can be judged as follows:

(a) The evidence from the diagnostic tests supports the prediction, so the prediction is verified.

(b) The prediction indicated that a precipitate would form, so the prediction is supported.

(c) The prediction indicated that a precipitate would form, so the prediction is supported.

(d) The appearance of the gas bubbles and the diagnostic test on the gas bubbles supports the prediction, so the prediction is verified.

(e) The observed precipitate is consistent with the predicted reaction taking place, so the prediction is verified.

(f) The prediction is supported by the apparent production of hydrogen gas and a basic solution.

(g) The observed appearance of a silvery solid and a pink solution were predicted, so the prediction is supported.

(h) The evidence of an odour change supports the prediction.

Part 3

Since all of the predictions are judged to be verified, the single- and double-replacement reaction generalizations used to make these predictions are judged to be acceptable. Although more evidence should be collected to increase certainty in this judgement, this investigation lends support to the validity of these reaction generalizations.

The Purpose of this investigation was met. The single and double replacement

reaction generalizations were tested. In this investigation, the generalizations passed the tests

conducted. These generalizations can continue to be used with confidence, until evidence is

gathered to the contrary.