Chemistry Chapter 3 A mole of the substance water, H2O, refers to

General Chemistry, 11e (Petrucci)

Chapter 3 Chemical Compounds

1) A molecule is a group of bonded atoms that exist as an entity.

2) The structural formula is the simplest formula.

3) For an ionic compound, the term formula mass is more appropriate than the term molecular mass.

4) Combustion analysis is one way to determine the simplest formula of some compounds.

5) Oxidation state is related to the number of protons involved in bonding.

6) Organic chemistry refers to compounds of oxygen, and hydrogen.

7) Chemical nomenclature is a systematic way of assigning names to chemical compounds.

8) Only metals in binary compounds use prefixes such as di–, tri–, tetra-, etc.

9) Polyatomic ions end in –ate or –ite.

10) Hydrocarbons contain only carbon and hydrogen.

11) Choose the INCORRECT statement.

A) A molecule is a group of bonded atoms that exist as an entity.

B) Ionic compounds result from combinations of metals and nonmetals.

C) An anion is a positive ion.

D) The empirical formula is the simplest formula of the ratio of atoms.

E) The molecular formula is the listing of the atoms in an actual molecule.

12) Choose the INCORRECT statement.

A) A structural formula shows which atoms are bonded together and by what type of bond.

B) Formula mass is the mass of a formula unit.

C) Molecular mass is the mass of a molecular compound.

D) The molecular mass of hydrogen is 1.008 u.

E) The molecular formula is the same as, or a multiple of, the empirical formula.

13) A 200.0 g sample of pure MgCl2 contains:

A) 95.211 formula units MgCl2

B) 2.101 formula units MgCl2

C) 1.265 × 1024 formula units MgCl2

D) 1.204 × 1026 formula units MgCl2

E) 5.734 × 1025 formula units MgCl2

14) A mole of the substance water, H2O, refers to:

A) 12.0000 g H2O

B) one H2O molecule

C) 6.02 × 1023 g H2O

D) 6.02 × 1023 H2O molecules

E) 6.02 × 1023 atoms of H and O

15) A 10.0 g sample of bismuth tribromide, BiBr3, contains:

A) 5.37 × 1022 total number of ions

B) 0.322 mol BiBr3

C) 3.14 × 1022 formula units BiBr3

D) 1.34 × 1022 bromide ions

E) 4.020 × 1022 total number of ions

16) The number of atoms in 10.0 g of CaCO3 (100.0 g/mol) is:

A) 18.1 × 1022 atoms

B) 30.1 × 1022 atoms

C) 6.02 × 1022 atoms

D) 12.1 × 1023 atoms

E) 12.1 × 1022 atoms

17) Aspartame, C14H18N2O5, a low-calorie sweetener, is about 200 times sweeter than sugar. How many

molecules of aspartame are there in a one-gram packet of sweetener containing 36 mg aspartame?

A) 2.0 × 1018 molecules of aspartame

B) 4.0 × 1020 molecules of aspartame

C) 7.2 × 1025 molecules of aspartame

D) 1.4 × 1022 molecules of aspartame

E) 7.4 × 1019 molecules of aspartame

18) How many hydrogen atoms are present in 2.84 moles of water?

A) 3.42 × 1024 H atoms

B) 1.71 × 1024 H atoms

C) 4.24 × 1023 H atoms

D) 9.44 × 1024 H atoms

E) 3.42 × 1023 H atoms

19) Which of the following contains the greatest number of atoms?

A) 1 mole of S8 molecules

B) 2 moles of P4 molecules

C) 4 moles of chlorine molecules

D) 8 moles of H atoms

E) 3 moles of ozone, O3

20) Which of the following could be an empirical formula?

A) C9H8O4 (aspirin)

B) C6H8O6 (vitamin C)

C) C8H10N4O2 (caffeine)

D) C10H14N2 (nicotine)

21) The explosive, trinitrotoluene, TNT, C6H3N3O6, has the same proportion of:

A) N to H atoms as does NH3

B) H to O atoms as does H2O

C) N to O atoms as does NO2

D) C to H atoms as does C6H6

E) C to O atoms as does CO2

22) White phosphorus, P4, spontaneously bursts into flame in oxygen. If 6.500 g of white phosphorus

reacts with oxygen to form 11.54 g of a phosphorus oxide, what is the empirical formula of this oxide?

A) P2O3

B) PO3

C) P2O6

D) P4O6

23) Combustion analysis of a 22.0 mg sample of the painkiller morphine produced 13.2 mg of water.

What is the percentage by mass of hydrogen in morphine?

A) 6.71%

B) 3.36%

C) 13.4%

D) 60.0%

24) In the following group, the compound with the greatest percentage of oxygen by mass is:

A) ClO2

B) Na2CO3

C) P4O6

D) SO2

E) As2O3

25) Nitroglycerin, C3H5N3O3:

A) has equal amounts of C and N by mass

B) has less than 50% O by mass

C) has the same proportion of N to H atoms as does NH3

D) has the same mass percent of C and N

E) has higher mass percent of H than O

26) Crystals from evaporation of urine analyze to 22.6% phosphorus. Which compound is probably

present?

A) NaNH4HPO4

B) (NH4)3PO4

C) Na3PO4

D) H3PO4

E) Ca3(PO4)2

27) In which compound does iodine have an oxidation state of +3?

A) HIO3

B) IF5

C) Ca(IO2)2

D) HI

E) I2

28) In which compound does carbon have an oxidation state of zero?

A) C2H2

B) CH2O

C) CH3OH

D) Na2CO3

E) CO2

29) Choose the INCORRECT oxidation state.

A) Cl is +5 in HClO3

B) C is +4 in CS2

C) S is +6 in H2SO3

D) C is -2 in CH3OH

E) Br is +3 in BrF3

30) Choose the INCORRECT oxidation state.

A) C is 0 in H2CO

B) S is +4 in H2SO3

C) C is +2 in HCOOH

D) Fe is +2 in Fe2O3

E) Mn is +7 in KMnO4

31) The name of which compound ends in -ite?

A) HIO3

B) Na2SO3

C) H2SO3

D) Na2CO3

E) CaH2

32) Choose the INCORRECT name formula combination.

A) Fe2O3 iron(III) oxide

B) H2SO3 sulfurous acid

C) NH4ClO3 ammonium chlorate

D) CaH2 calcium hydride

E) SiO2 silicon oxide

33) Choose the INCORRECT name formula combination.

A) CaH2 calcium hydroxide

B) SiO2 silicon dioxide

C) HClO hypochlorous acid

D) Cu3(PO4)2 copper(II) phosphate

E) AlCl3 aluminum chloride

34) Choose the INCORRECT name formula combination.

A) HNO2 nitrous acid

B) Fe2(SO4)3 iron(III) sulfite

C) LiCN lithium cyanide

D) Na2CO3 sodium carbonate

E) Ba(OH)2 barium hydroxide

35) Choose the INCORRECT name/formula combination.

A) NaClO sodium hypochlorite

B) NaClO4 sodium chlorate

C) NaClO2 sodium chlorite

D) Sr(IO3)2 strontium iodate

E) SCl4 sulfur tetrachloride

36) Choose the INCORRECT name formula combination.

A) Fe2(SO4)3 iron(III) sulfate

B) HBrO3 bromic acid

C) PCl5 phosphorus chloride

D) SCl4 sulfur tetrachloride

E) Sr(IO3)2 strontium iodate

37) Hydrates are:

A) moisture sensitive hygroscopic inorganic salts

B) compounds in which each formula unit has one or more water molecules associated with it

C) readily soluble in water and release energy

D) organic compounds that contain oxygen together with usual carbon and hydrogen

E) concentrated solutions of salts in water

38) Which of the following functional groups gives acidic properties to organic molecules?

A) -C(O)CH3

B) –COOCH3

C) –COOH

D) -C(O)H

E) –CH2OH

39) Which of the following is(are) isomer(s) of organic compound with formula C5H12O?

A) 4

B) 1 and 2

C) 1 and 3

D) 6

E) 5 and 4

40) Which of the following are isomers?

A) CH3CH(CH2CH3)CH2CH2CH3 and CH3CH(CH3)CH2CH2CH3

B) CH3CH(OH)CH2CH2CH3 and CH3CH(CH3)CH2CH2CH3

C) CH3CH(OH)CH2CH2CH3 and CH3CH(OH)CH2CH(CH3)CH3

D) CH3CH(OH)CH2CH2CH3 and CH3CH(CH3)CH2CH2OH

E) CH3CH(CH3)CH2CH(CH3)CH3 and CH3CH2CH2CH2CH3

41) Which of the following is the correct definition of an isomer?

A) Isomers are molecules that have the same empirical formula but different arrangements of atoms in

space.

B) Isomers are molecules that have the same molecular formula but different arrangements of atoms in

space.

C) Isomers are molecules that have the same arrangements of atoms in space but different empirical and

molecular formulas.

D) Isomers are molecules that have the same molecular formula but contain different isotopes.

E) Isomers are molecules with the same empirical formula but have different isotopes.

42) Which of the following can be one of the isomers of a compound with molecular formula C4H10?

A) 2-methylpropane (methylpropane)

B) 2-methylbutane

C) 3-methylpentane

D) 3-methylbutane

E) 2-methylpentane

43) Which of the following substances contains the greatest number of atoms?

A) 5 mol H2O

B) 6 mol CS2

C) 3 mol NaNO3

D) 2 mol NH4OH

E) 6 mol NaH

44) The formula mass of arachidic acid, a fatty acid found in peanut oil, is ________.

A) 176.000 u

B) 312.538 u

C) 92.079 u

D) 306.126 u

E) 352.000 u

45) How many hydrogen atoms are there in 12.4 g of Al2(HPO4)3?

A) 6.55 × 1022 H atoms

B) 1.09 × 1022 H atoms

C) 6.07 × 1022 H atoms

D) 1.32 × 1023 H atoms

E) 4.39 × 1022 H atoms

46) The molecular formula for caffeine is C8H10O2N4. How many moles of C atoms are present in a 2.0 g

sample of caffeine?

A) 0.32 mole

B) 0.27 mole

C) 0.041 mole

D) 0.082 mole

E) 0.010 mole

47) The material Styrofoam is made by blowing a gas into the polymer polystyrene made from styrene.

Styrene has the percent composition of C 92.26% and H 7.74% and molecules weigh 2.44

grams. What is the molecular formula for styrene?

A) CH

B) C2H2

C) C8H8

D) C4H4

E) C6H6

48) An unknown organic compound contains carbon, hydrogen, and bromine only. The mass percentages

of C and H are 12.77% C and 1.60% H. Bromine from 1.87 g of this compound has been completely

converted into 3.70 g of AgBr. The molar mass of unknown organic compound is 188 u. Determine the

molecular formula of the unknown.

A) CH3Br

B) C2H3Br2

C) C2H2Br2

D) C2H2Br4

E) C4H6Br4

49) Nitrogen forms at least three stable oxides: N2O, NO, and NO2. How many grams of nitrogen reacts

with 32 grams of oxygen to form NO?

A) 16 grams

B) 28 grams

C) 14 grams

D) 32 grams

E) 8 grams

50) How many grams of K are found in 1.00 × 102 g of K2Cr2O7?

A) 18.3 g

B) 36.5 g

C) 53.2 g

D) 13.3 g

E) 26.6 g

51) How many grams of Cr are found in 1.00 × 102 g of K2Cr2O7?

A) 35.4 g

B) 24.3 g

C) 12.2 g

D) 48.6 g

E) 33.8 g

52) How many grams of O are found in 1.00 × 102 g of K2Cr2O7?

A) 14.9 g

B) 38.1 g

C) 5.44 g

D) 11.3 g

E) 78.8 g

53) A 2.000 g sample of water contains 11.19% H by mass and 88.81% O by mass. What percent of H by

mass will be found in a 6.00 g sample of water?

A) 33.33%

B) 88.81%

C) 5.60%

D) 33.57%

E) 11.19%

54) A 2.000 g sample of water contains 11.19% H by mass and 88.81% O by mass. What mass of H will be

found in a 27.000 g sample of water?

A) 3.021 g

B) 1.511 g

C) 2.413 g

D) 1.206 g

E) 23.98 g

55) Fumaric acid, C4H4O4, can be extracted from plants and can be used as a substitute for citrus acid in

fruit drinks. The percent composition by mass of fumaric acid is ________.

A) C 33.33% H 33.33% O 33.33%

B) C 39.80% H 6.68% O 53.52%

C) C 40.00% H 6.67% O 53.33%

D) C 41.39% H 3.47% O 55.14%

E) C 0.25% H 0.25% O 0.50%

56) Determine the mass percent H in NH4Cl.

A) 1.9%

B) 14%

C) 7.5%

D) 3.6%

E) 67%

57) A sample contains 43.7% phosphorus and 56.3% oxygen. The molar mass is 284 g/mol. What is the

molecular formula of the compound?

A) P2O5

B) PO3

C) P4O10

D) P4O5

E) P5O8

58) The simplest formula of a substance is found to be CH2O, and its approximate molar mass is found

by experiment to be 93 grams/mole. What is the exact molar mass of this substance in grams/mole?

A) 30.0

B) 87.0

C) 90.1

D) 93.0

E) 93.1

59) What is the percentage by weight of phosphorus in calcium phosphate, Ca3(PO4)2?

A) 20%

B) 10%

C) 36%

D) 29%

E) 40%

60) Complete combustion of a 0.500 g sample of a pure hydrocarbon yielded 0.973 g CO2 and 0.319 g

H2O. The empirical formula of this hydrocarbon is ________.

A) C3H5

B) C2H3

C) C4H6

D) C5H8

E) C6H9

61) Maprotiline, a tetracyclic drug prescribed for the treatment of depression, has the following mass

composition: .

The empirical formula of maprotiline is ________.

A) C7H8N3

B) C20H23N

C) C87H8N5

D) C3H3N

E) C14H14N

62) A strip of electrolytically purified copper weighing 3.178 grams is strongly heated in a stream of

oxygen until it is all converted to a black oxide. The resultant black powder weighs 3.978 g. What is the

formula of the oxide?

A) CuO2

B) Cu2O3

C) CuO3

D) Cu2O

E) CuO

63) The magnesium in a sample of mineral water weighing 110.520 g is first converted to MgNH4PO4

and then to Mg2P2O7. The mass of Mg2P2O7 obtained is 0.0216 g. Express the quantity of magnesium in

the mineral water in parts per million (that is in g Mg per 106 g H2O).

A) 1.95 × 103 ppm

B) 8.95 ppm

C) 234 ppm

D) 42.7 ppm

E) 21.4 ppm

64) 2.404 g of a compound were burned in oxygen and found to produce only 3.520 g CO2(g), 2.564 g

SO2(g) and 1.440 g H2O(l). Determine the empirical formula of the compound.

A) CSH

B) C2SH4

C) C4SH2

D) C2S2H4

E) C2SH2

65) The molecular formula for a sugar molecule is C12H22O11. What is the percent of carbon in the

molecule?

A) 2.37%

B) 67.88%

C) 42.12%

D) 8.34%

E) 26.67%

66) The complete combustion of 0.285 g of a pure hydrocarbon yielded 0.878 g CO2 and 0.405 g H2O.

What is the mass % C in this hydrocarbon?

A) 27.3%

B) 24.0%

C) 84.1%

D) 32.4%

E) 72.7%

67) Elemental analysis of 50.0000 g of a compound showed that it contained 12.7520 g C, 3.2105 g H, and

the rest was S. The empirical formula of this compound is ________.

A) CHS

B) CH2S

C) CH3S

D) C2H2S

E) C2H3S2

68) A 4.05 g sample of a compound containing only C, H, and O was burned completely. The only

combustion products were 10.942 g CO2 and 4.476 g H2O. What is the empirical formula of the

compound?

A) C7H14O

B) C7H7O

C) C7H14O7

D) CH2O

E) C6H12O

69) Naphthalene, commonly found in mothballs, is 93.75% carbon and 6.25% hydrogen by mass. If

naphthalene’s molecular formula is twice its empirical formula, what would its molecular mass be?

A) 64 u

B) 96 u

C) 128 u

D) 192 u

E) 160 u

70) An organic compound contains C, H, and O. The percentages of H and C are 6.73% H, and 39.99% C

by mass. The molecular mass is 60.06 u. What is the molecular formula of the compound?

A) CH2O

B) C3H6O3

C) C2H3O2

D) C2H4O2

E) C4H8O4

71) From the following percent by mass compositions, determine the empirical formula of the compound.

A) LiPO2

B) Li3PO4

C) LiPO3

D) Li3PO3

E) LiPO4

72) A compound is found to have the following percent composition by mass: 38.7% K, 13.8% N, 47.5% O.

What is the empirical formula of the compound?

A) KNO3

B) KNO2

C) K2NO2

D) K2NO3

E) K2N2O3