AP Chemistry – 1st Semester Final Exam Review Chapters 1 – 9 1. Ch3 #73. Benzene contains only carbon and hydrogen and is 7.74% H

by mass; the molar mass of benzene is 78.1 g/mol. Determine the empirical and molecular formulas of benzene.

Assume 100 g sample:

1. Ch3 #73. Benzene contains only carbon and hydrogen and is 7.74% H by mass; the molar mass of benzene is 78.1 g/mol. Determine the empirical and molecular formulas of benzene.

Assume 100 g sample:

1:1

Empirical Formula:

CH

Molecular Formula MassEmpirical Formula Mass

molCg

Cmolg

molHg

Hmolg

74.7 0.12

1 C 26.92

74.7 0.1

1 H 74.7

Ch3 #80) Balanced chem reactions:

a. Glucose (C6H12O6) reacts w oxygen…

b. Iron (III) sulfide reacts with gaseous hydrogen chloride …

Ch3 #100. Mercury and Bromine will react with each other to produce mercury (II) bromide

Hg(l) + Br2(l) HgBr2(s) 10.0 g 9.00 g

a. What mass of HgBr2 can be produced from the reaction of 10.0 g Hg and 9.00 g Br2? What mass of which reagent is left unreacted?

Hg is L.R.

22

22 Br 0563.0 Br 159.8

Br 1 Br 00.9

Hg 0499.0Hg 200.6

Hg 1 Hg 0.10

molg

molg

molg

molg

Ch3 #100. Mercury and Bromine will react with each other to produce mercury (II) bromide

Hg(l) + Br2(l) HgBr2(s) 10.0 g 9.00 g

a. What mass of HgBr2 can be produced from the reaction of 10.0 g Hg and 9.00 g Br2? What mass of which reagent is left unreacted?

Hg is L.R.

22

22 Br 0563.0 Br 159.8

Br 1 Br 00.9

Hg 0499.0Hg 200.6

Hg 1 Hg 0.10

molg

molg

molg

molg

2

22

HgBr 1mol Hg 1mo Hg 200.6

HgBr 360.4g HgBr 1mol Hg 1 Hg 0.10

g

molg

Br 1

Br 159.8 Br 0064.0

2

22

mol

gmol

100. Mercury and Bromine will react with each other to produce mercury(2) bromide

Hg(l) + Br2(l) HgBr2(s) 5ml 5ml

b. What mass of HgBr2 can be produced from the reaction of 5.00 mL mercury (density = 13.6 g/ml) and 5.00 mL bromine (density = 3.10 g/ml)?

HgBr 1mol Br 1molBr 159.8 Br 1ml

HgBr 360.4g HgBr 1mol Br 1 Br 3.10g Br 00.9

HgBr 1mol Hg 1mol Hg 200.6g Hg 1ml

HgBr 360.4g HgBr 1mol Hg 1mol Hg 6.13 Hg 00.5

222

22222

2

22

g

molg

gml

Ch4 #15.Calculate the molarity of each of these solutions. a. A 5.623g sample of NaHCO3 is dissolved in enough water

to make 250 ml of solution.

Ch4 #15.Calculate the molarity of each of these solutions. a. A 5.623g sample of NaHCO3 is dissolved in enough water

to make 250 ml of solution.

3

33

NaHCO 84.0g soln 0.250L

NaHCO 1mol NaHCO 5.623g

Ch4 #23. Describe how you would prepare 2.00 L of each of the following solutions.a. 0.250M NaOH from solid NaOHb. 0.250M NaOH from 1.00M NaOH stock solution

b. M1.V1 = M2

.V2

NaOH 1mol soln 1L

NaOH 40.0g NaOH 0.250molsoln 2L

Vsoln 1L

1.00mol

1

soln 2L

soln 1L

0.250mol2

Ch4 #43. A 100.0mL aliquot of 0.200 M aqueous potassium hydroxide is mixed with 100.0 mL of 0.200 M aqueous magnesium nitrate. a. Write a balanced chemical equation for any reaction that occurs. b. What mass of precipitate is produced? c. Calculate the concentration of each ion remaining in solution after precipitation is complete.

Ch4 #43. A 100.0mL aliquot of 0.200 M aqueous potassium hydroxide is mixed with 100.0 mL of 0.200 M aqueous magnesium nitrate. a. Write a balanced chemical equation for any reaction that occurs. b. What mass of precipitate is produced? c. Calculate the concentration of each ion remaining in solution after precipitation is complete. 2KOH + Mg(NO3)2 2K+ + 2NO3

- + Mg2+ + 2OH-

2KOH + Mg(NO3)2 Mg(OH)2(s) 0.200M 0.200M100ml 100ml

Ch457. Assign oxidation states for all atoms in each of the following compounds.

a. KMnO4 b. NiO2

e. P4O6 f. Fe3O4

h. SF4 i. CO

Ch457. Assign oxidation states for all atoms in each of the following compounds.

a. KMnO4 b. NiO2 (+1)+7(-8) +4(-4)

e. P4O6 f. Fe3O4

h. SF4 i. CO

Ch465. Balance the following oxidation-reductions reactions that occur in basic solutions.

a. Al(s) + MnO4-(aq) MnO2(s) + Al(OH)4

-(aq)

Ch462a. Specify if Cu(s) + 2Ag+(aq) 2Ag(s) +Cu2+(aq) is a oxidation-reduction reaction, and identify the oxidizing agent, the reducing agent, the substance being oxidized, and the substance being reduced.

Ch530. A balloon is filled to a volume of 7.00x102 mL at a temperature of 20.0°C. The balloon is then cooled at a constant pressure to a temperature of 1.00x102 K. What is the final volume of the balloon?

V1 = .700L V2 = ?P1 = const P2 = constT1 = 293K T2 = 100.K

V2 =K

V

K

L

T

V

T

V

100293

700.0

2

2

2

1

1

2

22

1

11

T

VP

T

VP

Ch538. What volume is occupied by 2.0 g of He at 25˚C and a pressure of 775 mm Hg?

P.V = n.R.T

Ch538. What volume is occupied by 2.0 g of He at 25˚C and a pressure of 775 mm Hg?

P.V = n.R.T

He mol 0.50He 4.0g

He 1mol He 2.0g

KTRn

PV

298 0.82060.50mol

1.02atm

KmolatmL

atm 02.1Hg 760mm

1atm Hg 775mm

Ch549. Calculate the volume of O2, at STP, required for the complete combustion of

125 g octane (C8H18) to CO2 and H2O.

2C8H18 + 25O2 16CO2 + 18H2O 125g ?L

55. Hydrogen cyanide is prepared commercially by the reaction of methane, CH4(g), ammonia, NH3(g), and oxygen, O2(g), at high temperature. The other product is gaseous water.a. Write a chemical equation for the reaction.

CH4 + NH3 + O2

b. What volume of HCN(g) can be obtained from 20 L CH4(g),

20 L NH3(g), and 20 L O2(g)? The volumes are all measured at the same temperature and pressure.

2CH4 +2NH3 +3O2 2HCN + 6H2O 20L 20L 20L ?L

At same temp and pressure, equal volumes contain equal number moles.(Assume STP, vol conv cancels out.)

b. What volume of HCN(g) can be obtained from 20 L CH4(g),

20 L NH3(g), and 20 L O2(g)? The volumes are all measured at the same temperature and pressure.

HCN 1mol O 3mol O 22.4L

HCN 22.4L HCN 2mol O 1mol O 20L

22

22

57. A gas consisting of only carbon and hydrogen has an empirical formula of CH2. The gas has a density of 1.65 g/L at 27oC and 734 torr. Determine the molar mass and molecular formula of the gas.

empirical formula: CH2 14.0 g/mol

molecular formula: CXH2X

d=1.65g/L T=300K

P=734torr0.966atm

57. A gas consisting of only carbon and hydrogen has an empirical formula of CH2. The gas has a density of 1.65 g/L at 27oC and 734 torr. Determine the molar mass and molecular formula of the gas.

empirical formula: CH2 14.0 g/mol

molecular formula: CXH2X

d=1.65g/L T=300K

P=734torr0.966atm

molg

KmolatmL

Lg

.1.42massmolar

0.966atm

300K0.082061.65massmolar

63. Consider the flasks diagrammed below, what are the partial pressures of H2 and N2 after the stopcock between the two flasks is opened? (Assume the final volume is 3 L) What is the final pressure in torr?

2.00 L H2 475 torr

1.00 L N2

0.200 atm

63.

2.00 L H2 475 torr

P1.V1 = P2

.V2 (475torr)(2.00L) = P2

.(3.00L) PH2 = 317torr (per 3L)

1.00 L N2

0.200 atm (152torr)

P1.V1 = P2

.V2 (152torr)(1.00L) = P2

.(3.00L)PN2 = 50.7torr (per 3L)

Ptotal =

65. The partial pressure of CH4(g) is 0.175 atm and that of O2(g) is 0.250 atm in a mixture of the two gasses.a. What is the mole fraction of each gas in the mixture?

b. If the mixture occupies a volume of 10.5 L at 65o C, calculate the total number of moles of gas in the mixture

c. Calculate the number of grams of each gas in the mixture.

65. The partial pressure of CH4(g) is 0.175 atm and that of O2(g) is 0.250 atm in a mixture of the two gasses.a. What is the mole fraction of each gas in the mixture?

b. If the mixture occupies a volume of 10.5 L at 65o C, calculate the total number of moles of gas in the mixture

Total =

c. Calculate the number of grams of each gas in the mixture.

425.0

250.0

425.0

175.024 OCH

338K 0.08206

0.175atm 10.5L

KmolatmL4CHn

338K 0.08206

0.250atm 10.5L

KmolatmL2On

4

44

CH 1mol

CH 16.0g CH 0.0662mol

2

22

O 1mol

O 32.0g O 0.0946mol

79. Consider three identical flasks filled with different gases.Flask A: CO at 760 torr and 0oC m = 26.0 g/molFlask B: N2 at 250 torr and 0oC m = 28.0 g/molFlask C: H2 at 100 torr and 0oC m = 2.0 g/mol

a. in which flask will the molecules have the greatest average kinetic energy? KEave = ½m.(uave)2

b. In which flask will the molecules have the greatest average velocity?

81. The effusion rate of an unknown gas is measured and found to be 31.50mL/min. Under identical experiment conditions, the effusion rate of O2 is found to be 30.50mL/min. If the choices are CH4, CO,NO,CO2, and NO2 what is the identity

of the unknown gas?

O2 : 32.0g/mol CH4 : 16.0g/molCO : 28.0g/mol NO : 30.0g/mol CO2 : 44.0g/molNO2 : 46.0g/mol

g/mol)in massmolar is (M 2 gasfor effusion of Rate

1 gasfor effusion of Rate

1

2

M

M

Ch6 #26. Consider the mixture of air and gasoline vapor in a cylinder with a piston. The original volume is 40. cm3. If the combustion of this mixture releases 950. J of energy, to what volume will the gases expand against a constant pressure of 650. torr if all the energy of combustion is conserved into work to push back the piston.

Ch6 #26. Consider the mixture of air and gasoline vapor in a cylinder with a piston. The original volume is 40. cm3. If the combustion of this mixture releases 950. J of energy, to what volume will the gases expand against a constant pressure of 650. torr if all the energy of combustion is conserved into work to push back the piston.

ΔV = (V2 – 0.040L)

q W = –950J (expands – gas doing work)

W = –P. ΔV

–950J = –(86.6kPa). ΔV ΔV = 10.97L

10.97L = (V2 – 0.040L)

kPa 6.68760torr

101.3kPa torr 650 P

29. The equation for the fermentation of glucose to alcohol and carbon dioxide is

C6H12O6(aq) → 2C2H5OH(aq) + 2CO2(g)

The enthalpy change for the reaction is -67kJ. Is the reaction exothermic or endothermic? Is energy, in the form of heat, absorbed or evolved as the reaction occurs?

34. The overall reaction in commercial heat packs can be represented as 4Fe(s) + 3O2(g) → 2Fe2O3(s) ΔH = -1652kJc. How much heat is released when 1.00 g iron is reacted with excess O2?

d. How much heat is released when 10.0 g Fe and 2.00 g O2 are reacted?

34. The overall reaction in commercial heat packs can be represented as 4Fe(s) + 3O2(g) → 2Fe2O3(s) ΔH = -1652kJc. How much heat is released when 1.00 g iron is reacted with excess O2?

d. How much heat is released when 10.0 g Fe and 2.00 g O2 are reacted?

released

Fe 4mol Fe 55.8g

1652kJ Fe 1mol Fe 1.00g

Fe 4mol Fe 55.8g

1652kJ Fe 1mol Fe 10.00g

Fe 3mol O 32.0g

1652kJ O 1.00mol O 2.00g

2

22

47.Consider the dissolution of CaCl2:

CaCl2(s) → Ca2+(aq) + 2Cl-

(aq) ΔH = -81.5 kJAn 11.0g sample of CaCl2 is dissolved in 125 g of water, with both substances at 25.0˚C. Calculate the final temperature of the solution assuming no heat lost to the surroundings and assuming the solution has a specific heat capacity of 4.18 J/˚C·g

CaCl2(s) water

Ca2+(aq) + 2Cl-

(aq) + 81.5 kJ m=11g m=125g Ti = 25C Ti = 25C per 1 mol CaCl2

47. CaCl2(s) water

Ca2+(aq) + 2Cl-

(aq) + 81.5 kJ m=11g m=125g Ti = 25C Ti = 25C per 1 mol CaCl2

q = – m.cp.ΔT

22

22

CaCl mol 1 CaCl 111.1g

81.5kJ CaCl mol 1 CaCl 11.5g

T

Cg

C25-T 136g J 4.188436

f

o

ofJ

55. Given the following data:

2O3(g) → 3O2(g) ΔH = -427 kJO2(g) → 2O(g) ΔH = +495 kJ

NO(g) + O3(g) → NO2(g) + O2(g) ΔH = -199 kJ

calculate ΔH for the reaction

55. Given the following data:

2O3(g) → 3O2(g) ΔH = -427 kJO2(g) → 2O(g) ΔH = +495 kJ

NO(g) + O3(g) → NO2(g) + O2(g) ΔH = -199 kJ

calculate ΔH for the reaction

2NO(g) + 2O3(g) → 2NO2(g) +2O2(g) ΔH = -398 kJ 3O2(g) → 2O3(g) ΔH = +427 kJ

2O(g) → O2(g) ΔH = -495 kJ2NO(g) + 2O(g) → 2NO2(g) ΔH = -466 kJ

NO(g) + O(g) → NO2(g) ΔH = -233 kJ

61. Use the values of ΔHf

o in Appendix 4 to the calculate ΔHo for the following reactions.

a. 2NH3(g) + 3O2(g) + 2CH4(g) → 2HCN(g) + 6H2O(g) 2mol(-46kJ/mol)+ 3(0) + 2mol(-75kJ/mol) 2mol(135.1kJ/mol) + 6mol(-242kJ/mol)

ΔHo

reaction =

43. It takes 7.21 x 10-19 J of energy to remove an electron from an iron atom. What is the maximum wavelength of light that can do this? IE

e-1

nucleus

43. It takes 7.21 x 10-19 J of energy to remove an electron from an iron atom. What is the maximum wavelength of light that can do this? IE

e-1

nucleus

JE

hchcE

19s

m834

7.21x10

)s)(3x10J(6.626x10

45. Calculate the de Broglie wavelength for each of the following.a. a proton with a velocity 90.% of the speed of light

45. Calculate the de Broglie wavelength for each of the following.a. a proton with a velocity 90.% of the speed of light

)107.2)((1.67x10

6.626x10827-

-34

smxkg

sJ

49. Calculate the wavelength of light emitted when each of the following transition occur in the hydrogen atom.

a. n=3 n=2

n=4

n=3

n=2

n=1

JxJxE

JxJxE

n

ZJxE

192

218

2

192

218

3

2

218

1043.52

110178.2

1041.23

110178.2

10178.2

49. Calculate the wavelength of light emitted when each of the following transition occur in the hydrogen atom.

n=4

n=3

n=2

n=1

a. n=3 n=2

1041.2 1036.1 193

194 JxEJxE

E

hchcE

83. Arrange the following groups of atoms in order of increasing size.a. Be, Mg, Ca

85. Arrange the atoms in order of increasing first ionization energy.a. Be, Mg, Ca

87. In each of the following sets, which atom or ion has the smallest radius?

c. O+, O, O-

d. S, Cl, Kr

121) The successive ionization energies for an unknown element are:I1 = 896kJ/mol

I2 = 1752 kJ/molI3 = 14,807 kJ/mol

I4 = 17948 kJ/molTo which family in the periodic table does the unknown element most

likely belong?

122) An unknown element is a nonmetal and has a valence electron configuration of ns2np4

a) How many valence electrons does this element have?b) What are some possible identities for this element?c) What is the formula of the compound this element would form

with potassium?d) Would this element have a larger or smaller radius than barium?e) Would this element have a greater or smaller ionization energy

than fluorine?

Ch81. Explain the electronegativity trends across a row and down a column of the periodic table. Compare these trends with those of ionization energies and atomic radii. How are they related?

21. Without using Fig. 8.3, predict which bond in each of the following groups will be the most polar.a. C---F, Si---F, Ge---F

most

b. P---Cl, S---Cl most

c. S---F, S---Cl, S---Br most

d. Ti---Cl, Si---Cl, Ge---Cl most

64. Lewis structures that obey octet rule for each. (1st atom is central atom.)a. POCI3, SO4

2- , XeO4, PO43- , CIO4

-