Practice Exam 4 – examines Chapters 19 through 21 and also Chapters 7 and 9

1)  If 60.2 grams of Hg combines completely with 24.0 grams of Br to form a compound, what is the percent composition of Hg in the compound? 1)  ________

A) 251% B)  71.5% C)  60.1% D)  39.9% E)  28.5%

2)  If the density of a gas is 0.902 g/L at STP, that gas is _____. 2)  ________

A) SO3 B)  He C)  Ne D)  H2 E)  F2

3)  Which of the following compounds has the highest oxygen content, by weight? 3)  ________

A) BaO B)  H2O C)  Na2O D)  CO2 E)  NO

4)  What is the percent by mass of carbon in acetone, C3H6O? 4)  ________

A) 20.7% B)  1.61% C)  62.1% D)  30.0%

5)  What is the percent composition of chromium in BaCrO4? 5)  ________

A) 25.2% B)  20.5% C)  9.47% D)  4.87% E)  54.2%

6)  All of the following are empirical formulas EXCEPT _____. 6)  ________

A) Sn3(PO4)4 B)  N2O4 C)  Na2SO4 D)  C6H5Cl

7)  Given the following densities of five different gases, all measured at STP, which density indicates the gas with the greatest gram formula mass? 7)  ________

A) 3.5 g/L B)  1.1 g/L C)  2.7 g/L D)  4.9 g/L E)  5.6 g/L

8)  How many moles of tungsten atoms are there in 4.8 x 1025 atoms of tungsten? 8)  ________

A) 8.0 x 10 to power of (2) moles

B) 1.3 x 10 to power of (-1) moles

C) 1.3 x 10 to power of (-2) moles

D) 8.0 x 10 to power of (1) moles

E) 8.0 moles

9)  Avogadro's number is _____. 9)  ________

A) 6.02 x 10 to power of (23)

B) a dozen

C) a mole

D) dependent on what is measured

E) the weight of a carbon atom

10)  To determine the formula of a new substance, one of the first steps is to find the _____. 10)  _______

A) volume at STP

B) gram formula mass

D) percent composition

E) number of particles per mole

11)  What is conserved in the reaction shown below?

H2(g) + Cl2(g) Â 2HCl(g) 11)  _______

A) only mass, moles, and molecules

B) only mass, moles, molecules and volume

C) only mass

D) only mass and moles

12)  In a chemical reaction the mass of the products _____. 12)  _______

A) is equal to the mass of the reactants

B) has no relationship to the mass of the reactants

C) is greater than the mass of the reactants

D) is less than the mass of the reactants

13)  How many liters of chlorine gas can be produced when 0.98 L of HCl react with excess O2, at STP?

4HCl(g) + O2(g) Â 2Cl2(g) + 2H2O(g) 13)  _______

A) 0.98 L B)  0.49 L C)  2.0 L D)  0.25 L E)  3.9 L

14)  The calculation of quantities in chemical equations is called _____. 14)  _______

A) accuracy and precision

B) percent composition

C) dimensional analysis

D) stoichiometry

E) percent yield

15)  Iron(III) oxide is formed when iron combines with oxygen in the air.  How many grams of Fe2O3 are formed when 16.7 g of Fe reacts completely with oxygen?

4Fe(s) + 3O2(g) Â 2Fe2O3(s) 15)  _______

A) 95.6 g B)  267 g C)  23.9 g D)  12.0 g E)  47.8 g

16)  Glucose, C6H12O6, is a good source of food energy. When it reacts with oxygen, carbon dioxide, and water are formed.  How many liters of CO2 are produced when 126 g of glucose completely reacts with oxygen?

C6H12O6(s) + 6O2(g) Â 6CO2(g) + 6H2O(l) + 673 kcal 16)  _______

A) 94.1 L B)  185 L C)  5.33 L D)  4.21 L E)  15.7 L

17)  Calculate the number of moles of Al2O3 that are produced when 0.60 mol of Fe is produced in the following reaction.

2Al(s) + 3FeO(s) Â 3Fe(s) + Al2O3(s) 17)  _______

A) 1.8  mol B)  0.40 mol C)  0.20 mol D)  0.90 mol E)  0.60 mol

18)  Which of the following is NOT a true statement concerning limiting and excess reagents? 18)  _______

A) Adding more of the limiting reagent to the reaction chamber will cause more product to be produced.

B) The amount of product obtained is determined by the limiting reagent.

C) A balanced equation is necessary to determine which reactant is the limiting reagent.

D) Some of the excess reagent is left over after the reaction is complete.

E) The reactant that has the smallest given mass is the limiting reagent.

19)  How many grams of chromium are needed to react with an excess of CuSO4 to produce 27.0 g Cu?

2Cr(s) + 3CuSO4(aq) Â Cr2(SO4)3(aq) + 3Cu(s) 19)  _______

A) 14.7 g

B) 81.5 g

C) 18.0 g

D) 0.005 48 g

E) 33.2 g

20)  The equation below shows the decomposition of lead nitrate.  How many grams of oxygen are produced when 11.5 g NO2 is formed?

2Pb(NO3)2(s) Â 2PbO(s) + 4NO2(g) + O2(g) 20)  _______

A) 2.00 g B)  46.0 g C)  2.88 g D)  32.0 g E)  1.00 g

21)  Which physical state of nitrogen has the highest entropy? 21)  _______

A) gas B)  liquid C)  solid

22)  Why does a small particle size generally cause a reaction to proceed faster? 22)  _______

A) There are more collisions per second and the collisions are of greater energy.

B) There are more collisions per second only.

C) The collisions occur with greater energy.

23)  Which of the changes listed below would shift the following reaction to the right? 4HCl(g) + O2(g) <GRAPHIC> 2Cl2(g) + 2H2O(g) 23)  _______

B) increase of pressure

C) removal of O2

24)  Which one of the following systems has the highest entropy? 24)  _______

A) water at 95¶C B)  water at 100¶C

C) steam at 105¶C D)  steam at 100¶C

25)  If a reaction has an equilibrium constant just greater than 1, what type of reaction is it? 25)  _______

A) reversible, favoring reactants B)  irreversible

C) reversible, favoring products D)  spontaneous

26)  If a system is left to change spontaneously, in what state will it end? 26)  _______

A) the state with the maximum disorder

B) the same state in which it began

C) the state with the lowest possible energy consistent with the state of maximum disorder

D) the state with lowest possible energy

27)  Exergonic reactions _____. 27)  _______

A) release free energy

B) produce energy that can be used to do useful work

C) are spontaneous

D) all of the above

28)  If a catalyst is used in a reaction _____. 28)  _______

A) the reaction rate does not change

B) the energy of activation increases

C) different reaction products are obtained

D) the reaction rate increases

29)  What is the rate law for the following reaction? A + 2B Â C + D 29)  _______

A) rate = k[A]2[B] B)  rate = k[A]2[B]2

C) rate = k[A][B] D)  rate = k[A][B]2

30)  In a first-order reaction, what is the rate constant if the rate is 0.01M/s and the reactant concentration is 0.01M? 30)  _______

A) 0.1/s B)  0.01/s C)  1/s D)  10/s E)  100/s

31)  The products of self-ionization of water are _____. 31)  _______

A) H3O+ and H2O B)  HO- and H+

C) HO- and OH+ D)  HO+ and H-

32)  What is the name of H2SO3? 32)  _______

A) hydrosulfite acid

B) sulfuric acid

C) hyposulfuric acid

D) sulfurous acid

E) hydrosulfuric acid

33)  Which of these acids is monoprotic? 33)  _______

A) H2SO4 B)  CH3COOH C)  H2PO with (superscript (stacked) and subscript (~%3))  D)  H3PO4

34)  What type of acid or base is the ammonium ion? 34)  _______

A) conjugate acid B)  Arrhenius base C)  conjugate base

35)  A 0.12M solution of an acid that ionizes only slightly in solution would be termed _____. 35)  _______

A) dilute and weak B)  strong and dilute

C) concentrated and strong D)  concentrated and weak

36)  What type of acid is sulfuric acid? 36)  _______

A) triprotic B)  diprotic C)  monoprotic

37)  What is the formula for phosphoric acid? 37)  _______

A) HPO4 B)  HPO2 C)  H2PO3 D)  H3PO4 E)  HPO3

38)  The pH of a solution with a concentration of 0.01M hydrochloric acid is _____. 38)  _______

A) 2.0 B)  12.0 C)  10-2 D)  10-12

39)  How many free hydrogen ions are there in one liter of water? 39)  _______

A) approximately 10-1 mol B)  none; they are all hydrated

C) approximately 10-7 mol D)  approximately 100 mol

40)  What characterizes a strong acid or base? 40)  _______

A) presence of a hydroxide or hydrogen ion

B) polar covalent bonding

C) complete ionization in water

D) ionic bonding

41)  The solubility product constant for zinc carbonate is 10-10. If 0.1M sodium carbonate and 0.1M zinc nitrate are mixed, what happens? 41)  _______

A) No precipitate forms.

B) A sodium nitrate precipitate forms.

C) A zinc carbonate precipitate forms.

42)  What is the solubility product constant equal to? 42)  _______

A) the equilibrium constant times the concentration of undissolved solid

B) the equilibrium constant

C) the equilibrium constant of water

D) the equilibrium constant times the concentration of water

43)  If a stock solution of hydrochloric acid is 3.0N, how many milliliters are needed to make 200.0 mL of 0.10N HCl? 43)  _______

A) 1.5 mL B)  67 mL C)  6.7 mL D)  150 mL E)  15 mL

44)  How many equivalents are in 2 L of 2M sulfuric acid? 44)  _______

A) 10 equiv B)  2 equiv C)  8 equiv D)  4 equiv E)  6 equiv

45)  Which substance when dissolved in water will produce a solution with a pH greater than 7? 45)  _______

A) NaCl B)  NaC2H3O2 C)  HCl D)  CH3COOH

46)  How many equivalents are there in 60 mL of 0.1N sodium hydroxide? 46)  _______

A) 0.001 6 equiv B)  6 equiv

C) 0.006 equiv D)  1.6 equiv

47)  What is the concentration of sulfuric acid if 50 mL of acid is neutralized by 10 mL of 0.2N sodium hydroxide? 47)  _______

A) 1M B)  0.02M C)  0.010M D)  0.5M

48)  Calculate the concentration of silver ion when the solubility product constant of AgI is 10-16. 48)  _______

A) 10-2M B)  10-4M C)  10-8M D)  10-16M

49)  What type of reaction is an acid-base reaction? 49)  _______

A) decomposition B)  single replacement

C) double replacement D)  combination

50)  What does a buffer do? 50)  _______

A) keeps the sodium concentration constant

B) keeps the pH of a solution constant

C) keeps the chloride concentration constant

D) keeps the salt concentration of a solution constant