Chemistry Semester Two Exam Review
Name___________________________
The test will consist of 50 multiple choice questions over the following topics.
1) Measuring (1): Triple beam balance, graduated cylinder, thermometer, ruler
2) Writing Rx & State Symbols (5):
A) Solid aluminum hydroxide decomposes when it is heated.
2Al(OH)3
Al2O3 + 3H2O
Decomposition Rxn
B) A solution of iron (III) nitrate reacts with a solution of ammonium carbonate.
2Fe(NO3)3 + 3(NH4)2(CO3)
6(NH4)(NO3) + Fe2(CO3)3
Precipitation Rxn
C) Solid sodium carbonate decomposes when it is heated.
Na2(CO3)
Na2O + CO2
Decomposition Rxn
D) A chunk of lithium reacts with a solution of sodium hydroxide.
Li + Na(OH)
Na + Li(OH)
Single Replacement Rxn
8CO2 + 10H2O
Combustion Rxn
E) Gaseous C4H10 burns.
2C4H10 + 13O2
F) Solid iron (III) reacts with fluorine.
2Fe + 3F2
2FeF3
Synthesis/Composition Rxn
3) Periodic Trends (6):
A) Electron affinity across a period and down a family...why? Increase from left to right (fewer
electrons needed to fill up orbital spaces) and decreases down (atomic radius is becoming larger).
B) Electronegativity across a period and down a family…why? Increase from left to right (fewer
electrons needed to fill up orbital spaces – wants to gain electrons) and decreases down (atomic radius
is becoming larger).
C) Ionization energy across a period and down a family…why? Increase from left to right (atomic radius
becoming smaller, more energy needed to remove an electron) and decreases down (atomic radius is
becoming larger, less energy needed to remove electron).
D) Atomic radius across a period and down a family…why? Increase from right to left (fewer protons in
nucleus – not as strong of a pull to center) Increase down (more energy levels)
E) Chemical behavior & resulting oxidation number for each family – Alkali metals very reactive metals
(+1), Alkali earth metals not as reactive as alkali metals (+2), Halogens very reactive nonmetals (-1),
Nobel Gases inert/nonreactive nonmetals (0), Transition and Inner transition metals not as reactive as
alkali or alkali earth variable oxidation
F) Most reactive metal & most reactive nonmetal…why? Most reactive metal – Francium (largest
atomic radius – easily loses valence electron), most reactive nonmetal – Fluorine (smallest atomic radius
– easily gains valence electron due to large electronegativity)
5) Nuclear Reactions (2):
A) Thorium-291 emits a beta particle what is the resulting atom? Protactinium-291
B) Lead-204 emits an alpha particle what is the resulting atom? Mecury-200
Alpha particle – similar to a helium atom without electrons. Easily stopped by paper, clothing, skin,
space. Contains two protons and two neutrons.
Beta decay – an electron emitted from nucleus at the same time a neutron is changed to a proton.
6) Law of Conservation of Mass/Balancing Equations (2)
7) Weighted Averages (3):
A) 13.00 g 25.0%
B) 300.00 g
33.00%
14.00 g 70.0%
301.00 g
52.00%
15.00 g
302.00 g
13.8 g – Weighed average
300.82 g – Weighed average
8) LR/ER (7): Study Test 6-2 and/or Practice Problems for 6-2
9) Atoms and Molecule Drawings (3)
10) Protons, Neutrons, Electrons (3):
A) How many protons, neutrons, electrons & valence electrons does a neutral
atom of arsenic-73 have? P = 33, E= 33, N = 40, Valence e’s = 5
B) Please write the isotopic notation for an atom of strontium.
88
0
Sr
38
C) Please give the name, atomic number, atomic mass, oxidation number, number of protons, number
of neutrons & number of electrons for these atoms. Identify the type of ion & the type of isotope.
54 +4
Fe
26
124 -2
Te
52
Iron-54, AN = 26, AM = 54, ON = +4, P = 26, N = 28, E = 22, cation, light isotope
Tellurium – 124, AN = 52, AM = 124, ON = -2, P = 52, N = 72, E = 54, cation, light isotope
D) Please give the isotopic notation, name, type of ion & type of isotope for each of these atoms.
76 protons, 130 neutrons, 71 electrons
Osmium – 206, cation, light isotope
206
+5
Os
76
52 protons, 80 neutrons, 53 electrons
Tellurium – 132, anion, heavy isotope
132
-1
Te
52
11) Empirical/Molecular Formulas (3):
A) A compound contains 43.638% phosphorus & 56.362% oxygen. Its molar mass is 283.88 g. What is its
empirical formula? What is its molecular formula?
Empirical = P2O5
Molecular = P4O10
B) A compound contains 27.631 g carbon, 4.880 g hydrogen, 6.446 g nitrogen & 11.043 g oxygen. Its
molar mass is 434.66 g. What is its empirical formula? What is its molecular formula?
Empirical = C10H21N2O3
Molecular = C20H42N4O6
C) What is the empirical formula of this copper compound?
Before any reactions: Mass of crucible & lid
50.000 g
Mass of crucible & lid + Cu
54.436 g
After several reactions & drying: Mass of crucible & lid + CuxOy
56.000 g
If estimate 1.5 instead of the 1.4
Empirical formula would be Cu2O3
12) % yield lab problems (2):
Please calculate the % yield of oxygen based upon these lab results.
2 K(ClO3) (s)
2 KCl (s) + 3 O2 (g)
Before heating:
Mass of crucible & cover
50.000 g
Mass of crucible & cover + K(ClO3)
52.644 g
After heating:
Mass of crucible & cover + contents
51.527 g
%Yield = Actual/Theoretical (have to do stoichiometry to get!!!) X 100
Actual amount = 1.117 g, Theoretical = 1.036 g
% yield = 108%
13) Names & Formulas of Compounds (5):
A) Cu3(PO4) Copper (I) phosphate
B) N2O7 Dinitrogen heptoxide
C) F2 Fluorine gas
D) Ca+2 Calcium ion
E) Phosphide ion P-3
F) Trisulfur heptoxide S3O7
G) Ammonium sulfate (NH4)2(SO4)
H) Hydrogen H2
I) Zinc (IV) bromide ZnBr4
J) Aluminum sulfate Al2(SO4)3
14) Moles (2):
A) How many molecules does 15.0 L of sulfur dioxide gas contain?
4.03 X 1023 molecules sulfur dioxide
B) What is the density of 1 mole of Cl2O7 at STP?
D= M/V
8.17 g/L
C) What volume will 3.25 X 1024 formula units of chlorine gas have at STP?
121 L
D) What is identical in 1 mole of water and 1 mole of sugar? What is different? Number of molecules
present – 6.02 X 1023. Grams and volume are different
E) 1 mole of N2 = 14.007 g = 22.4 L = 6.02 X 1023 molecules.
F) 1 mole of Au = 196.967 g = 6.02 X 1023 atoms.
16) Acids and Bases (1):
A) What is the pH range for a strong acid? 0-3
B) What is the pH range for a strong base? 11-14
C) What is the pH range for a weak acid? 4-just below 7
D) What is the pH range for a weak base? 10-just above 7
17) Stoichiometry Problems (2):
Use the equation below to answer A-C
Al4C3 (s) + 12 H2O (g)
4 Al(OH)3 (s) + 3 CH4 (g)
A) Assuming excess amounts of water vapor present, how many atoms of methane gas would be
produced from 26.9 g aluminum carbide?
3.37 X 1023 atoms methane gas
B) If 45.7 g of aluminum hydroxide were produced, what mass of water was needed?
31.7 g water
C) Assuming excess amounts of aluminum carbide, how many grams of methane gas would be produced
from 35.7 L of water vapor?
6.39 g methane gas
18) Density, mass and volume (3):
A) Please arrange these substances as they would appear in a graduated cylinder:
Alcohol density = 0.62 g/ml
Mercury density = 13 g/ml
Water
Air density = 0.0257 g/ml
air, alcohol, water, mercury
B) What happens to the mass, volume and density of air that is compressed in a syringe? Why?
Mass remains the same (not adding anything), volume decreases (added force), density increases (more
mass in a smaller space)
C) What happens to the density of a wooden block when it is cut in half? Why?
Density stays the same – the volume decreased the same proportion as the mass
D) Please give an example of two objects with the same masses and different volumes.
1 kg bricks and 1 kg feathers
E) Please give an example of two objects with the same volumes and different masses.
1 L ketchup and 1 L helium
H) The density of air is 2.71 mg/L. How many kL will a sample of air occupy if it has a mass of 0.755 dkg?
(1000 mg = 1 g, 100 g = 1 dkg, 1000 L = 1kL)
27.9 kL
J) A rock has a mass of 10.0 g and causes the water level in a graduated cylinder to rise from 15.0 ml to
21.0 ml. What is its density?
10g/6mL = 1.67 g/mL