GENERAL CHEMISTRY 115 SPRING 2010 SECTION NO.______

FIRST EXAM NAME ______

1 inch = 2.54 cm; 1 mile = 1.609 km; 1L = 1.056 qt.

Multiple choice = 4 points each

Circle the best answer

?? 1. Express 18.56 square feet in square centimeters.

a) 27237 cm2 c) 5.256 x 105 cm2 e) 8.597 x 103 cm2 g) 1.724 x 104 cm2

b) 5.986 x 104 cm2 d) 3.655 x 104 cm2 f) 5.66 x 102 cm2 h) 5.735 x 104 cm2

?? 2. Perform the indicated mathematical operations and round off the answer to the proper number of significant figures:

(0.825 – 0.215)/ (2.346 - 2.323)(6.35) =

a) 4.17665 c) 4.177 e) 4.18

b) 4.176652 d) 4 f) 4.1

3. Below is a list of common prefixes used in the SI and metric systems. Fill in the appropriate blanks.

Mega 10+6

a) kilo- k _____

b) ______10-9

c) milli- m _____

d) deci- d _____

4. (8 pts) Fill the blanks in the following table.

Cation

/

Anion

/

Formula

/

Name

Ca(NO2)2
Calcium nitride
Al3+ / S2-

??

?? ?? 5. Which of the following numbers has 4 significant figures?

a) 0.0065 c) 0.15837 e) 0.0563 g) 5.90 i) 0.048

b) 1.63980 d) 0.670909 f) 8.6090 h) 0.063010 j) 0.06798

6. The mileage rating of an automobile that is 12.0 kilometers per liter could also be expressed as

______miles per gallon.

a) 28.3 c) 23.5 e) 32.6 g) 25.3 i) 73.1

b) 31.6 d) 71.6 f) 32.0 h) 29.8 j) 33.8

7. The mass of 1.74 moles of K2CO3 is:

a) 111 g c) 236 g e) 226 g g) 35.2 g i) 216 g

b) 138 g d) 1.25 g f) 79.3 g h) 247 g j) 240 g

?? 8. Calculate the mass of one thousand oxygen atoms.

a) 6.022 x 10-23 g c) 1.600 x 10-23g e) 2.00 x 10-17 g g) 7.985 x 1023 g i) 2.00 x 10-23 g

b) 16.00 g d) 2.658 x 10-20 g f) 1.600 x 106 g h) 4.810 x 10-23 g j) 4.810 x 10-22 g

9. An aluminum ore contains 33% aluminum oxide, Al2O3, plus other material that does not contain aluminum. How many kg of aluminum can be extracted from 2500 kg of this ore?

a) 220 kg c) 437 kg e) 776 kg g) 1000 kg i) 56 kg

b) 699 kg d) 1 kg f) 580 kg h) 154 kg j) 780 kg

10. How many atoms of carbon are there in 432 g of C6H12O6 ?

a) 2.6 x 1022 c) 4.1x 1025 e) 4.7 x 1024 g) 1.4 x 1024 i) 2.3 x 1023

b) 6.3 x 1023 d) 1.5 x 1024 f) 2.5 x 1023 h) 3.0 x 1024 j) 8.7 x 1024

?? 11. Circle the element that has a mass very close to one-sixth that of barium -138.

a) Na c) Ar e) Kr g) Cs i) Rb

b) Sr d) Cr f) O h) Ge j) Ca

12. A compound is known to contain only carbon, hydrogen, and oxygen and has a molecular weight

of 88. If the complete combustion of a 0.185-g sample of this compound produces 0.370 g of CO2 and 0.151 g of H2O, what is the molecular formula of this compound?

a) C3H3O c) C2H4O e) CH12O4 g) C6H6O2

b) C4H8O2 d) C5H7O5 f) C3H4O3 h) C5H6O5

?? 13. An ore of copper is 85.0% pure copper (I) sulfide, Cu2S, and 15.0% impurities in which no other

copper compounds are present. What mass of this copper ore is required to extract 75.5 g of copper.

a) 81.4 g c) 94.5 g e) 78.0 g g) 85.0 g i) 88.5 g

b) 63.8 g d) 18.0 g f) 9.05 g h) 67.5 g j) 111 g

?? 14. Methanol, CH4O, burns in oxygen to form CO2 and H2O according to the following equation. How

many moles of methanol will react with 9 moles of oxygen?

CH4O + O2 à CO2 + H2O

a) 1 c) 6 e) 7 g) 5 i) 11

b) 4 d) 8 f) 10 h) 9 j) 12

?? ???? 15. A compound contains hydrogen, bromine, and oxygen. Analysis shows that it contains by mass 0.88% hydrogen and 70.80% bromine. What is the simplest formula for this compound?

a) HBrO c) HBrO2 e) H2BrO3 g) HBrO3

b) HBr6O2 d) H2BrO4 f) H2BrO2 h) H2BrO

16. If 12.0 g of sugar is dissolved in 400 g of methanol, what is the percent by mass of sugar in the

resulting solution?

a) 3.00% c) 7.67% e) 7.76% g) 0.080% i) 2.91%

b) 0.767% d) 0.16% f) 0.56% h) 2.14% j) 1.80%

17. Ethanol, C2H6O, burns in oxygen to form CO2 and H2O according to the following equation. How

many moles of CO2 will be produced if 4 moles of ethanol is allowed to react with 9 moles of

oxygen?

C2H6O + O2 à CO2 + H2O

a) 11 c) 9 e) 7 g) 13 i) 6

b) 14 d) 5 f) 8 h) 10 j) 4

18. Sulfur will react with oxygen to produce sullfur trioxide, S + O2 à SO3. If 16 g of sulfur is allowed to react with 10g of oxygen, which reactant is in excess and by how much?

a) O2, 2 g c) S, 7 g e) S, 13 g g) O2, 10 g i) S, 2 g

b) O2, 3 g d) S, 13 g f) O2, 10 g h) S, 14 g j) neither is in excess

19. In an acid-base titration, calculate the volume of 0.25 M sodium hydroxide, NaOH, needed to

completely neutralize 32.5 mL of 0.35 M sulfuric acid, H2SO, a diprotic acid.

a) 32.5 mL c) 29.1 mL e) 45.5 mL g) 98.3 mL i) 91.0 mL

b) 60.5 mL d) 58.2 mL f) 36.5 mL h) 30.5 mL j) 121.0 mL

20. What is the molarity of 300 mL of solution containing 7.28 grams of CaBr2?

a) 3.77 x 10-2 M c) 4.77 x 10-3 M e) 1.18 x 10-3 M g) 6.23 x 10-2 M i) 3.45 x 10-2 M

b) 6.77 x 10-2 M d) 3.33 x 10-2 M f) 2.73 x 10-2 M h) 5.62 x 10-2 M j) 1.21 x 10-1 M

21. In each of the following reactions circle the reactant Bronsted base:

HPO42- + H2CO3 = H2PO42- + HCO3-

HCO3- + H2O = H2CO3 + OH-

Circle the insoluable salts below. Circling a wrong answer will cancel the credit for a right answer.

CaCO3 BaS K2S Ca(NO3)2 CaSO4 (NH4)3PO4

22. Determine the oxidation number of the underlined element in:

CaSO4 ______

Li2S ______

NaClO2 ______

H2MnO3 ______

?? ?? 23. What volume of 2.00 molar hydrochloric acid HCl, is required to react with 15.0 grams of calcium carbonate, CaCO3?

CaCO3 + 2HCl à CaCl2 + CO2 + H2O

a) 104 mL c) 83.3 mL e) 167 mL g) 33.0 mL

b) 150 mL d) 75.0 mL f) 67.0 mL h) 208 mL

24. In the following redox reactions circle the reactant which is the reducing agent:

CH4O + O2 à CO2 + H2O

Cl2 + 2NaBr à NaCl + Br2

4Fe + 3O2 à 2Fe2O3

5NaClO3(aq) + 3H2O(l) + 3I2 (s) à 6HIO3 (aq) + 5NaCl(aq)

??

1.  Calculate the mass of silver sulfate, Ag2SO4, that precipitates when 30.0 mL of 0.250 M K2SO4 is added to 40.0 mL of 0.350 M AgCl.

a) 9.45 g c) 8.14 g e) 8.50 g g) 7.80 g i) 8.85 g

b) 6.38 g d) 2.18 g f) 9.05 g h) 6.75 g j) 1.80 g

?? 24. What is the reducing agent in the following reaction?

6KOH(aq) + 3Cl2 (g) à KClO3(aq) + 5KCl(aq) + 3H2O(l)

a) KOH

b) Cl2

c) KClO3

d) KCl

e) H2O

?? 25. In the following reaction NaClO3 is ______.

5NaClO3(aq) + 3H2O(l) + 3I2 (s) à 6HIO3 (aq) + 5NaCl(aq)

a) the oxidizing agent and is oxidized

b) the oxidizing agent and is reduced

c) the reducing agent and is oxidized

d) the reducing agent and is reduced

e) neither an oxidizing agent nor a reducing agent

?? 7. A 10.0 kg piece of metal at 50.0oC is placed in 1000. g of water at 10.0 oC in an insulated container. The metal and water come to the same temperature at 30.6 oC. What is the specific heat of metal? The specific heat of water is 4.18 J/g oC.

a) 0.0686 J/g oC f) 0.215 J/g oC

b) 0.444 J/g oC g) 0.0836 J/g oC

c) 0.721 J/g oC h) 0.564 J/g oC

d) 0.124 J/g oC i) 0.638 J/g oC

e) 0.0216 J/g oC j) 0.369 J/g oC

What is the maximum amount of Na(PO4)2 that can be prepared from 9.8 g of Ca(OH)2 and 9.8 g

of H3PO4?

3Ca(OH)2 + 2 H3PO4 à Ca3(PO4)2 + 6H2O

a) 6.8 g c) 20.6 g

b) 8.6 g c) 17.2 g

c) 10.3 g c) 11.0 g

d) 13.7 g c) 20.3 g

e) 15.5 g c) 21.8 g

The specific gravity of commercial nitric acid solution is 1.42 g/cc and it is 70.0% HNO3 by mass. Calculate its molarity.

a) 18.0 M a) 22.5 M

b) 15.8 M a) 10.0 M

c) 12.8 M a) 7.0 M

d) 99.4 M a) 12.0 M

e) 26.2 M a) 14.2 M