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Chemistry Final Exam Review

Write all answers to questions on a separate sheet of paper.

Properties of Matter

Physical Properties of Matter

Do not change the identity of the substance.

Chemical Properties

The potential to cause a

chemical reaction.

mass

volume

density

(mass per

volume)

melting point

conductivity

color

malleability

(metals)

ductility

(metals)

boiling point

luster

reactivity

oxidation

flammability

Chemical and Physical Changes

1) A chemical change occurs when something new is made. Words associated with this type of changes are:

rotting, decomposing, burning, digestion, rusting.

2) A physical change occurs when nothing new has been made. Words associated with this type of changes

are: tearing, cutting, painting.

Evidence of a chemical change:

Precipitate formed

Evolution of gas (bubbles)

Color change

Energy change (energy given off or absorbed)

Atomic Structure

Proton – positive charge

Neutron – neutral charge

Electron – negative charge

Atomic number = number of

protons.

Mass number = number of

protons and neutrons in the

nucleus of an atom.

Number of neutrons = mass

number minus number of

atomic number.

Protons and neutrons are found in the nucleus of an atom.

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Metals Nonmetals

solid (with the exception of Hg, a liquid).

shiny, good conductors of electricity and

heat.

ductile (they can be drawn into thin wires).

malleable (they can be easily hammered

into very thin sheets).

good conductor of heat and electricity

lose electrons to combine with other

elements

not solid (with the exception Hg, a liquid).

shiny, good conductors of electricity and

heat.

ductile (they can be drawn into thin wires).

malleable (they can be easily hammered

into very thin sheets).

good conductor of heat and electricity

lose electrons to combine with other

elements

Periodic Table

3) Metals are found on what side of the periodic table? Left of the zigzag line

4) Nonmetals are found on what side of the periodic table? Right of the zigzag line

5) Where are the metalloids located? Adjacent to the zigzag line

6) What is the group number of the alkali metals? Group IA

7) What is the group number of the alkaline earth metals? Group IIA

8) What is the group number of the halogens? Group VA

9) What is the group number of the noble gases? Group VIIA

10) The noble gases are chemically non-reactive (do not combine with other elements). Why? Noble gases

have 8 valence electrons. The outermost energy level is filled.

Periodic Trends

Electronegativity is a measure of an atom's ability to attract electrons to itself.

11) Which atom in each pair has the larger atomic radius?

a) Li or K* b) Ca* or Ni c) Ga* or B d) O or C* e) Cl or Br* f) Be or Ba* g) Si* or S

h) Fe* or Au

12) What is the periodic trend for atomic size from top to bottom in a group? from left to right in a period?

Atomic radius increases top to bottom. Atomic radius decreases left to right.

13) Which element in each pair has a higher electronegativity value?

a) Cl, F* b) C, N* c) Mg*, Ne d) As*, Ca

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Dalton’s Atomic Theory

All matter composed of atoms.

All atoms of an element are identical.

Atoms cannot be divided, created, or destroyed.

We now know:

Atoms can be divided into smaller particles.

Atoms of the same element can have different masses.

Electron configurations

Electron configuration - the arrangement of electrons in an atom around the nucleus of atoms. Electrons are

not placed at fixed positions in atoms, but we can predict approximate positions of them. These positions are

called energy levels of atoms.

Energy level n=1, 2, 3, 4, 5, 6, 7

Sublevels s, p, d, f

s has 1 orbital

p has 3 orbitals

d has 5 orbitals

f has 7 orbitals

Each orbital can hold at most 2 electrons.

Example

Chlorine 17 e-

1s2 2s2 2p6 3s2 3p5

14) Write long-hand and short-hand electron configurations with orbital notation for each of the following

elements.

A. nitrogen B. iodine C. calcium D. barium E. copper

A. 7e- 1s2 2s2 2p3

B. 53e- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p5 I 53e- [Kr] 5s2 4d10 5p5

C. 20e- 1s2 2s2 2p6 3s2 3p6 4s2 Ca 20e- [Ar] 4s2

D. 56e- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 Ba 56e- [Xe] 6s2

Ions are formed from the gain or loss of electrons. Metals lose electrons to form cations, positive ions.

Nonmetals gain electrons to form anions, negative ions.

15) For each of the following elements, state whether the element will form cations or anions and the

number of electrons gained or loss.

F. Potassium G. Bromine H. Strontium I. Sulfur J. Aluminum

Element Electrons gained Electrons lost cation or anion

K 1 cation

Br 1 anion

Sr 2 cation

S 2 anion

Al 3 cation

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Chemical Bonding

An ionic bond is formed from the transfer of electrons between a metal and a nonmetal.

A covalent bond is formed from the sharing of electrons between a nonmetal and a nonmetal.

16) Classify each of the following compounds as ionic or covalent. Write the name of each compound.

A. NO2 B. MgBr2 C. N2O3 D. SO2 E. CaO F. CuCl2 G. Fe2O3 H. NaCl I. O2

covalent ionic covalent covalent ionic ionic ionic ionic covalent

Law of Conservation of Matter

The Law of Conservation of Matter states:

matter is neither created not destroyed in a chemical reaction.

the mass and number of atoms of the products of a reaction must equal the mass and number of

atoms of the reactants.

17) Which of the following questions obey the Law of Conservation of Matter? Circle your answers.

A. NH4F + AlCl3 → NH4Cl + AlF3

B. **3 Na2CO3 + 2 H3PO4 → 2 Na3PO4 + 3 H2O + 3 CO2

C. **Mg + Co(NO2)2 → Mg(NO2)2 + Co

D. **H2SO4 + 2 NaOH → 1 Na2SO4 + 2 H2O

E. C4H8O + 11 O2 → CO2 + H2O

F. **AgMnO4 + Sr → Ag + SrMnO4

G. 2 LiBr + 1 H2SO4 → 1 LiHSO4 + 2 HBr

Types of Reactions

Synthesis reaction = one product

Decomposition reaction = one reactant

Single replacement reaction = one element replaces another element in a compound

Double replacement reactions = the two reactants are ionic compounds. The positive ions trade partners.

Combustion reaction = a hydrocarbon compound reacts with oxygen to produce water and carbon dioxide.

Neutralization reaction = an acid reacts with a base to produce a salt and water

18) State the type of each reaction. Then balance the equations.

A. Decomposition 2HgO 2 Hg + O2

B. Single replacement 2Al + 3Pb(NO3)2 2 Al(NO3)3 + 3Pb

C. Double replacement 2 AgNO3 + K2SO4 Ag2SO4 + 2 KNO3

D. Combustion 2CH3OH + 3O2 2CO2 + 4H2O

E. Double replacement Zn(OH)2 + 2HNO3

Zn(NO3)2 + 2 H2O

F. Decomposition 2 H2O 2H2 + O2

G. Single replacement Cu + 2AgNO3 Cu(NO3)2 + 2Ag

H. Synthesis N2 + 2H2O NH4NO2

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Percent Composition % = part/whole x 100

19) Calculate the percent composition for each of the following compounds.

A. hydrochloric acid HCl

H 1 x 1g = 1g

Cl 1 x 35g = 35g

36g

1gH/36g HCl x 100 = 2.78% H

35gCl/36g x 100 = 97.22% Cl

B. sulfuric acid H2SO4

H 2 x 1g = 2g

S 1 x 32g = 32g

O 4 x 16g = 64g

98g

2g H/98g H2SO4 x 100 = 2.04% H

32g S/98g H2SO4 x 100 = 32.65% S

64g O/98g H2SO4 x 100 = 65.31% O

C. nitric acid HNO3

H 1 x 1g = 1g

N 1 x 14g = 14g

O 3 x 16g = 48g

63g

1g H/63g HNO3 x 100 = 1.59% H

14g N/63g HNO3 x 100 = 22.22% N

48g O/63g HNO3 x 100 = 76.19% O

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Empirical and Molecular Formulas

Molecular

Formula

Empirical

Formula

H2O H2O

CH3COOH CH2O

CH2O CH2O

C6H12O6 CH2O

Empirical Formula - the formula of a compound expressed

as the smallest possible whole-number ratio of subscripts of

the elements in the formula.

Molecular Formula - the formula of a compound in which

the subscripts give the actual number of each element in the

formula.

The molecular formula and the empirical formula can be identical.

20) Write the empirical formulas for the following compounds.

A. A compound is found to have (by mass) 48.38% carbon, 8.12% hydrogen and oxygen.

What is its empirical formula?

48.38g C 1 mol C

=

4.032 mol C

= 1.14 Empirical Formula C1H2O1

12 g C 3.53

8.12g H 1 mol H

=

8.12 mol H

= 2.3

1 g H 3.53

56.50 g O 1 mol O

=

3.53 mol O

= 1

16 g O 3.53

B. A compound is known to have an empirical formula of CH and a molar mass of 78.11 g/mol.

What is its molecular formula?

Molar mass CH = 13 g/mol 78.11g/13g = 6 Molecular Formula C6H6

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Mole Calculations

1 mole = the molar mass of the substance 1 mole = 6.02 x 1023 atoms, ions, molecules

21) Make the following mole calculations.

A. Calculate the mass of 2.50 moles of aluminum hydroxide.

2.50 mol Al(OH)3 1 mol Al(OH)3

= 0.03 mol Al(OH)3

78 g Al(OH)3

B. Calculate the mass of 0.0125 moles of dinitrogen pentoxide.

0.0125 moles N2O5 108 g N2O5

= 1.35 g N2O5

1 mol N2O5

C. Calculate the mass of 3.12 x 1021 ions of iron (III) sulfide

3.12 x 1021 ions Fe2S3 1 mol Fe2S3 208 g Fe2S3

= 1.078 g Fe2S3

6.02 x 1023 Fe2S3 1 mol Fe2S3

D. Calculate the mass of 4.30 x 1027 molecules of carbon monoxide gas.

4.30 x 1027 mlc CO 1 mol CO 28 g CO

= 2.00 x 105 g CO

6.02 x 1023 CO 1 mol CO

E. Calculate the number of moles in 1.25 grams of strontium nitrate.

1.25 g Sr(NO3)2 1 mol Sr(NO3)2

= 0.006 mol Sr(NO3)2

212 g Sr(NO3)2

F. Calculate the number of moles in 0.570 g of chlorine gas.

0.570 g Cl2 1 mol Cl2

= 0.008 mol Cl2

70 g Cl2

G. How many ions are in 225 g of lithium oxide?

225 g Li2O 1 mol Li2O 6.02 x 1023 Li2O

= 4.52 x 1024 Li2O

30 g Li2O 1 mol Li2O

H. How many molecules are in 15.0 g of silicon tetrafluoride?

15.0g SiF4 1 mol SiF4 6.02 x 1023 mlc SiF4

= 8.68 x 1022 mlc SiF4

104g SiF4 1 mol SiF4

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Stoichiometry

Stoichiometry is the relationship between the relative quantities of substances taking part in a reaction or

forming a compound.

22) Make the following calculations.

A. N2 + 3H2 2NH3

How many moles of NH3 at STP is produced if 25.0 g of N2 is reacted with an excess of H2?

25.0 g N2 1 mol N2 2 mol NH3

=

28 g N2 1 mol N2

B. 2KClO3 2KCl + 3O2

If 5.0g of KClO3 is decomposed, how many moles of O2 is produced at STP?

5.0 g KClO3 1 mol KClO3 3 mol O2

= 0.123 mol O2

122 g KClO3 2mol KClO3

C. H2SO4 + 2NaOH 2H2O + Na2SO4

How many molecules of water are produced if 2.0g of sodium sulfate are produced in the above

reaction?

2.0 g Na2SO4 1 mol Na2SO4 2 mol H2O 6.02 x 1023 mlc H2O

= mol H2O

142 g Na2SO4 1 mol Na2SO4 1 mol H2O

D. H2SO4 + NaOH Na2SO4 + H2O

If 30.0 g of H2SO4 reacts with sodium hydroxide, what mass of water is produced?

30.0 g H2SO4 1 mol H2SO4 1 mol H2O 18 g H2O

= 5.5 g H2O

98 g H2SO4 1 mol H2SO4 1 mol H2O

Gases

Absolute zero - lowest theoretical temperature, all particle motion would stop.

Absolute zero = 0 Kelvin = -273o C __

o

C + 273 = __ K

Boyle’s Law – V1P1 = V2P2

Charles Law

V1

=

V2

Combined Gas Law

V1P1

=

V2P2

T1 T2 T1 T2

Ideal Gas Law PV = nRT Universal Gas Constant 0.0821 L • atm

mol • K

23) Make the following calculations.

A. A gas occupies 3.5L at 2.5 mm Hg pressure. What is the volume at 10 mm Hg at the same

temperature?

Boyle’s Law – V1P1 = V2P2

3.5 L x 2.5 mm Hg = V2 x 10 mm Hg

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B. A constant volume of oxygen is heated from 100C to 185C. The initial pressure is 4.1 atm. What is

the final pressure?

G-L Law

(Combined Gas Law)

V1P1

=

V2P2 4.1 atm P2

= 5.034 atm

T1 T2 373 K 458 K

C. An ideal gas occupies 400ml at 270 mm Hg and 65C. If the pressure is changed to 1.4 atm and the

temperature is increased to 100C, what is the new volume?

G-L Law

(Combined Gas Law)

V1P1

=

V2P2 (400 mL)( 0.355 atm)

=

(V2)( 1.4 atm) = 111.93

T1 T2 338 K 373 K mL

D. What is the pressure of 23g of neon gas at 1C and a volume of 2L?

Ideal Gas Law PV = nRT

23.0 g Ne 1 mol Ne

= 1.15 mol Ne

20 g Ne

P =

(2 L) (1.15 mol) (0.0821 L • atm)

(274 K) (mol • K)

E. A 600mL balloon is filled with helium at 700mm Hg barometric pressure. The balloon is released

and climbs to an altitude where the barometric pressure is 400mm Hg. What will the volume of the

balloon be if, during the ascent, the temperature drops from 24 to 5C?

G-L Law

(Combined

Gas Law)

V1P1

=

V2P2 (600 mL)( 700mm Hg)

=

(V2)( 400mm Hg)

T1 T2 297 K 278 K = 982.83 mL

F. A 500 mL metal cylinder holding 0.100 moles of helium gas is known to rupture at a pressure of 10

atmospheres. At what temperature, in °C, will the container fail?

Properties of Water

Polarity is the unequal sharing of electrons within the water molecule between the hydrogens and the

oxygen. The oxygen end of the molecule is slightly negative. The hydrogen end slightly positive. Water is

known as the universal solvent because of its polarity.

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Solutions, Molarity, Dilutions

Molarity – a measure of concentration in moles per liter

Molarity =

moles Solution = solute + solvent

liters

24) Calculate the molarity of each of the following. *Volumes must be in Liters.

A. What is the molarity of a solution that contains 1.724 moles of H2SO4 in 2.50 L of solution?

0.690 M H2SO4 =

1.724 moles

2.5 L

B. What is the molarity of a solution prepared by dissolving 25.0 g of HCl (g) in enough water to make

150.0 mL of solution?

0.694 mol

= 4.63 M HCl

0.150 L

C. How many grams of potassium carbonate are needed to make 200 mL of a 2. 5 M solution?

2.5 M K2CO3 =

x mol x = 0.5 mol

0.200 L

D. What is the concentration of a solution with a volume of 2.5 L containing 60 moles calcium

phosphate?

24 M Ca3(PO4)2 =

60 moles

2.5 L

Dilutions

Mc x Vc = Md x Vd M1 x V1 = M2 x V2

25) Make the following calculations.

A. If you add 25 mL of water to 125 mL of a 0.15 M NaOH solution, what will the molarity of the

dilution be? (0.15 M) (0.125 L) = (0.150 L) (Md)

B. If 45 mL of water are added to 250 mL of a 0.75 M K2SO4 solution, what will the molarity of the diluted

solution be? (0.75 M) (0.250 L) = (0.295 L) (Md)

C. How much 0.075 M NaCl solution can be made by diluting 450 mL of 9.0 M NaCl?

(9.0 M) (0.450 L) = (0.075 M) (Vd)

Solubility is the maximum amount of a substance that will dissolve in a given amount of solvent at a

specific temperature.

Insoluble compounds form a precipitate.

Saturated solution – a solution that contains the maximum amount of solute at a given temperature.

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Factors that increase the solubility of a solid in a

liquid.

Factors that increase the solubility of a gas in a

liquid.

Nature of the solute and solvent

Temperature increase. (There are exceptions.)

Size of the particles.

Stirring, agitation.

Amount of solute already in the solution.

Temperature decrease.

Pressure increase.

Electrolytes and Nonelectrolytes

An electrolyte is a chemical compound that dissociates into ions in water. Capable of conducting electricity.

Ionic compounds are electrolytes. examples: NaCl, KI, Ca(OH)2

A nonelectrolyte is a chemical compound that does not dissociate in water. Not capable of conducting

electricity.

Covalent compounds are nonelectrolytes. examples: CO2, N2O3, SO2

26) During lab a student made the following observations. Which of the following groups of substances

contains only electrolytes?

Substance Observations

A. CH3OH and CCl4

HCl Bright light

B. HCl, MgCl2 and CCl4

CH3OH No light

C. CH3OH, NaOH and CH3COOH

MgCl2 Some light

D. **HCl, MgCl2, NaOH and CH3COOH

NaOH Bright light

CH3COOH Some light

CCl4 No light

Acids and Bases

Characteristics of Acids Characteristics of Bases

Taste sour

pH less than 7

Acids effects indicators:

o Acids turn blue litmus to red

o Phenolphthalein is colorless

[H+ ] > [OH-]

Electrolytes

React with metals to produce H2

Taste bitter

pH greater than 7

Bases effect indicators:

o Bases turn red litmus blue

o Phenolphthalein is pink-purple

[OH-] > [H+ ]

Electrolytes

Feel slippery

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pH – A measure of hydrogen concentration.

Neutralization Reaction

Acid + Base

a Salt + water example HCl + NaOH

NaCl + H2O

Neutralization reactions are also double replacement reactions.

27) Predict the products for each of the following types of reactions. Write a complete balanced equation for

each reaction.

A. Ca(OH)2 + H3PO4

Ca3(PO4) + H2O

B. HCl + KOH

KCl + H2O

C. Al(OH)3 + HCl

AlCl3 + H2O

28) State whether each of the following is an acid, base or salt.

A. HCl B. NaOH C. NH4Cl D. HNO3 E. Ca(NO3)2

F. H2SO4 G. H2C2H3O2 H. KOH I. H3PO4 J. Al(OH)3

A. acid B. base C. salt D. acid E. salt

F. acid G. acid H. base I. acid J. base