C.P. Chemistry I Midterm Review
Packet
1) When recording a measurement, how many significant digits should you record?
All digits known + 1 estimated digit
2) What is a significant digit?
All the digits that can be known precisely + 1 estimated digit
3) The volume of liquid in the graduated cylinder below is:
a) 3.3 ml
b) 3.30 ml
c) 3.4 ml
d) 3.60 ml
4) When multiplying or dividing numbers, how many significant digits can your answer
have? The same as the number in your problem with the least # of sig figs
5) The density of a block of wood is 3.20 g/cm3. Its length is 10.20 cm, its width is
4.50 cm, and its height is 3.2 cm. What is its mass recorded to the correct number of
sig figs? How many sig figs should your answer have?
Density = mass/volume
Volume = length x width x height
3.20 g/cm3 = mass/ (10.20 cm x 4.50 cm x 3.2 cm)
3.20 g/cm3 x 146.88 cm3 = 470 g
6) List and describe 5 methods of physical separation of substances.
Distillation, chromatography, filtration, crystallography, decanting, magnet, etc.
7) Which device would most accurately measure the volume of a liquid to one decimal
place?
A
8) Name five properties that a specific material can be identified by (only true for that
material). Density, melting point, boiling point, molar mass, etc.
9) The density of 1 gram of feathers is_______________ the density of 1 kg of feathers
at the same temperature?
a) same as
b) greater than
c) less than
d) can’t be determined
10) Perform the following conversions:
a) 5.60 X10-5 g --- kg
5.60 x 10-5 g x 10-3 kg = 5.6 x 10-8 kg
1g
b) 0.0060 kl --- ml
0.0060 kL x 1000 mL = 6000 mL
10-3 kL
11) Name the seven diatomic elements. Write their formulas. What does the term
“diatomic’ mean?
Hydrogen (H2), Oxygen (O2), Nitrogen (N2), Chlorine (Cl2), Bromine (Br2),
Iodine (I2), Fluorine (F2)
12) List 5 properties of metals. Where are metals located on the Periodic Table? Where
is the most reactive metal located?
Conduct heat and electricity, malleable, ductile, luster, solids at room temp.
Left of the zig-zag line.
Francium
13) List 5 properties of nonmetals. Where are the nonmetals located on the Periodic
Table? Where is the most reactive nonmetal located?
Brittle, don’t conduct, may be solids, liquids or gases, not ductile, not malleable
Right of the zig-zag line
Fluorine
14) Name and describe the two main classifications of matter.
Pure Substances (elements and compounds) and Mixtures
15) Name any two materials that can be classified as substances and give two ways that
they are different from each other.
Answers may vary
16) A combination of sugar and water would be classified as a:
a) pure substance
b) element
c) compound
d) mixture
17) When 8.0 g of magnesium burns in oxygen gas, what is the mass
of magnesium oxide formed?
2Mg + O2 2MgO
8.0 g Mg x 1 mole Mg x 2 mol MgO x 40.31 g MgO = 13 g MgO
24.31 g Mg 2 mol Mg
1 mole MgO
18) What are two types of energy transfer that can occur between a system and its
surroundings? Define each and give an example for each.
Endothermic Process—Absorbs Energy; A cold pack
Exothermic Process—Releases Energy; A fire
19) What is a physical property? Give 5 examples.
A quality or condition of a substance that can be observed or measured without changing
the substance’s composition. Color, size, shape, density, melting point, etc.
20) What is a chemical property? Give 5 examples.
The ability of a substance to undergo a specific chemical change. Flammability,
combustible, carcinogen, toxic, etc.
21) What is a physical change defined as? Give 5 examples.
A change during which some properties of a material change, but the composition of the
material does not change (you can easily return to the original substance). Melting,
freezing, cutting, boiling, etc.
22) What is a chemical change defined as? Give 5 examples.
A change the produces matter with a different composition than the original matter.
Combustion, reacting, precipitating, etc.
23) What are 5 good indications that a chemical change has occurred? Briefly
describe each one.
Odor, bubbles, energy change, precipitate, etc.
24) What are the three phases (states) of matter (excluding plasma)? Describe each in
regard to their volume, shape, kinetic energy, and the spacing of their molecules.
Solid—Definite Volume/Definite Shape/Molecules packed together
Liquid—Definite Volume/No Definite Shape/Molecules farther apart than
solids/Flow
Gas—No Definite Volume/No Definite Shape/High Energy/Molecules apart as much
as they can
25) Elements are represented by:
a) equations
b) symbols c) moles
d) formulas
26) Compounds are represented by:
a) Equations
b) symbols c) moles
d) formulas
27) Which subatomic particle is involved in a chemical reaction?
electrons
28) When metals react they (lose/gain) electrons forming (positive/negative) ions
called
(cations/anions).
29) When nonmetals react they (lose/gain) electrons forming (positive/negative) ions
called (cations/anions).
30) Atoms react to become ___stable____________ like the __noble
gases_________ which are in Group VIII or 18. This Group has a full outer shell
called an ____octet___________. Since they are stable and do not want to react their
oxidation number (charge) is __0____________.
31) Predict the oxidation number (charge) of the following ions:
a) Sodium +1
b) Barium +2
c) Aluminum +3
d) Chloride -1
e) Helium 0
32) An atom that loses three electrons will have an oxidation number (charge) of
___+3____________ (give number and sign).
33) An atom that gains two electrons will have an oxidation number (charge) of
_____-2__________ (give number and charge).
34) How do the following differ from their neutral atom?
a)
b)
c)
d)
Bromide gained 1 electron
tin (IV) lost 4 electrons
magnesium ion lost 2 electrons
oxide gains 2 electrons
35) Give the correct formula and oxidation number (charge) for the following
polyatomic ions:
a) sulfate
SO4-2
b) hydroxide OHc) ammonium NH4+
d) chlorate ClO3e) phosphate PO4-3
f) acetate
C2H3O2g) nitrate
NO3h) carbonate CO3-2
36) What is the oxidation number (charge) of sulfur in SO42-?
37) What is the oxidation number (charge) of phosphorous in H3PO4? -3
38) Give the correct formulas for the following compounds:
a) iron (III) sulfide
Fe2S3
b) sodium hydroxide
NaOH
c) copper (II) chloride
CuCl2
d) sulfuric acid
H2SO4
e) hydrochloric acid
HCl
f) nickel (IV) sulfate (aq)
Ni(SO4)2
39) Give the correct names for the following compounds:
a) Ca(OH)2
calcium hydroxide
b) HNO3(aq)
nitric acid
c) Al2O3
aluminum oxide
d) PbCl2
lead(II) chloride
e) Sn(ClO3)2
tin chlorate
f) H2S (g)
hydrosulfuric acid
40) What is the characteristic ion present in water solutions of all acids? H+
41) What is the characteristic ion present in water solutions of all bases? OH42) What are the 5 main reactions types and how do you recognize each type?
Synthesis: 1 product
Decomposition: 1 reactant
Single-Replacement: element + compound  element + compound
Double-Replacement: compound + compound compound + compound
Combustion: O2 is a reactant
a) nickel + chlorine ---
Ni + Cl2  NiCl2
b) aluminum hydroxide ---
2Al(OH)3  Al2O3 + 3H2O
c) magnesium sulfate + sodium hydroxide ---
MgSO4 + 2NaOH  Na2SO4 + Mg(OH)2
d) calcium + water ---
Ca + 2H2O  Ca(OH)2 + H2
e) lead + sulfuric acid ---
Pb + H2SO4  PbSO4 + H2
f) mercury (II) bromide ---
HgBr2  Hg + Br2
g) ammonium hydroxide ----
2NH4OH  (NH4)2O + H2O
h) tin (II) carbonate ---
SnCO3  SnO + CO2
i) strontium + iron (II) chloride ---
Sr + FeCl2  SrCl2 + Fe
j) fluorine + potassium iodide ---
F2 + 2KI  2KF + I2
43) In a chemical reaction, the name(s) of the material(s) that you start with are called
the reactants and appear on the left side of the arrow,
44) In a chemical reaction, the name(s) of the material(s) that you end with are called
the products and appear on the right side of the arrow.
45) In a chemical reaction, the mass of reactants should be _______________ mass of
the products.
a) equal to
b) greater than
c) less than e) can’t be determined
46) Question # 44 is true due to what law? Law of Conservation of Mass
47) Knowing that all potassium compounds are soluble, and that most hydroxides are
insoluble, write the correct word and balanced equation for the addition of an
aqueous solution of cobalt (II) sulfate to an aqueous solution of potassium hydroxide.
CoSO4(aq) + 2KOH(aq)  Co(OH)2(s) + K2SO4(aq)
48) Calculate the total number of atoms in the following compounds:
a) Ni3(PO4)4
3 + 4 + 16 = 23
b) (NH4)2SO4 2 + 8 + 1 + 4 = 15
49) Calculate the number of oxygen atoms in 3Al(Cr2O7)3. What is the total number
of atoms in 3Al(Cr2O7)3 ? 63 oxygen atoms, 84 total atoms
51) Calculate the number of hydrogen atoms in Ba(OH)2  8H2O. This compound is
known as a hydrate (barium hydroxide octahydrate). 18 hydrogen atoms
52) What are the four pieces of information that a coefficient gives you and give
conditions, if necessary.
Ratio of moles, molecules, atoms or formula units
53) Which of the following represents 4 moles of chlorine
a) 4 Cl
b) Cl4
c) Cl4
d) 4 Cl2
54) What is the empirical formula for C4H6O4? C2H3O2
55) Name the three subatomic particles, their charge, and their location within the atom.
Electron, -1, outside the nucleus
Proton, +1, inside the nucleus
Neutron, +1, inside the nucleus
56) What is an isotope? Atoms of the same element, with the same number of protons
but different numbers of neutrons
57) In what way are carbon - 12 and carbon -14 the same? In what way are they
different?
Carbon-12 and carbon-14 have the same number of protons, but different numbers of
neutrons
58) What is the composition of a nucleus of 131 I?
53 protons, 78 neutrons
59) A monatomic ion containing 18 electrons, 20 protons, and 20 neutrons. What is the
charge of this ion? +2
60) Which group contains the same number of electrons?
a) O2-, S2-, Se2b) Cl1-, Ar, K1+
c) F, Ne, Na d) Ca2+, Fe2+, Zn261) How many neutrons are present in 131I? 78
62) Combustion of methane occurs according to the following equation:
CH4 + 2O2 ---- CO2 + 2H2O
How many molecules of water can be produced from 4 moles of methane?
4 moles CH4 x 2 mol H2O x 6.02 x 1023 molecules H2O = 5 x 1024 molecules
1 mol CH4
1 mole H2O
63) When the following chemicals are mixed together in lab, the following results
occurred:
Powder
A
B
C
D
Unknown
Liquid I
bubbles
some mixing
bubbles
some mixing
bubbles
Liquid II
orange color
black color
bubbles
blue color
black color
What is the identity of the unknown?
a) A & B
b) A & D
c) B & C
64) Given the equation:
Pb(NO3)2(aq) + 2NaI(aq)
→
Liquid III
some mixing
some mixing
bubbles
some mixing
some mixing
d) C & D
2NaNO3(aq) + PbI2(s)
Which of the following is the correct net ionic equation for the reaction:
a. Pb2+(aq) + 2NO3-(aq) + 2Na+(aq) + 2I-(aq)
→
2Na+(aq) + 2NO3-(aq) + PbI2(s)
→ PbI2(s)
c. Pb2+(aq) + 2I-(aq) → PbI2(s)
d. 2Na+(aq) + 2NO3-(aq) → 2NaNO3(s)
b. Pb2+(aq) + I2-(aq)
65) A sample of sodium metal is available in lab along with water, calcium chloride, and
a Bunsen burner. Using any combination of these substances and common lab
equipment, suggest a procedure below which will produce at least one new
compound. Write a reaction to show how the new compound(s) form(s). Also,
identify the formula for the new compound. NOTE: There are several acceptable
procedures which will produce different results, but only one needs to be supplied
for credit for this answer.
4Na + O2  2Na2O
2Na + 2H2O  2NaOH + H2
66) A student is supplied a sample of an oxide of aluminum. Explain how the
number of molecules of aluminum oxide could be determined in this sample. The
following equipment is available: Balance, ruler, calculator, pencil, funnel, periodic
table and beaker.
Measure the mass of aluminum oxide using a balance. Use molar
conversions to convert to molecules.
67) Explain how a student could separate any mixture of dyes, such as the
mixtures used to obtain markers, pens, or food dyes. Be sure to describe
what supplies and equipment might be necessary. Also, what property
(or properties) of the dyes allow for the separation.
Chromatography