Download Review Exam for Chemistry

Review Exam for Chemistry
1. Which of the following is not a chemical change?
a. nitrogen gas is cooled until it becomes a liquid
b. H2 and O2 combine to produce H2O2
c. grape juice is fermented to produce wine
d. natural gas is burned to produce energy
e. mercury (II) oxide is heated until liquid mercury and oxygen gas are formed
2. Select the correct statement about subatomic particles:
a. electrons are negatively charged and are the heaviest subatomic particle
b. the nucleus is not charged and has a very high density
c. neutrons are found in the nucleus of the atom
d. the protons and electrons are spread out evenly throughout the atom
e. None of the above are correct.
3. In which of the following is the symbol for the ion and the number of electrons given correctly?
+
a. H has one electron
b. Cl has 17 electrons
3+
+
c. Al has 16 electrons
d. Na has 10 electrons
e. None of the above are written correctly.
12
14
4. How do the isotopes Carbon - 12 ( C) and Carbon-14 ( C) differ?
a. Carbon-14 has two more electrons than Carbon - 12
b. Carbon-14 has 8 protons; Carbon - 12 has six
c. Carbon-14 has 8 neutrons; Carbon - 12 has six
d. Carbon - 12 has 12 protons; Carbon-14 has 14
-
5. Which element forms an anion with a 3 charge?
a. Al b. P
c. S
d. Na
e. Mg
6. Which of these is an incorrect interpretation of this balanced equation?
3 Ni (s) + N2 (g) → Ni3N 2 (s)
a. 3 g Ni + 1 g N2 → 1 g Ni3N2
b. 3 moles Ni + 1 mole N2 → 1 mole Ni3N 2
c. 3 atoms of Ni + 1 molecule of N2  1 molecule of Ni3N2
d. All of the above are correct
7. In the reaction: Al2S3 + 6HCl → 2AlCl3 + 3H2S How many moles of HCl are used for each
mole of AlCl3 formed?
a. 1
b. 1.5
c. 2
d. 3
e. 6
26
8. How many moles of silver atoms are there in 1.8 x 10 atoms of silver?
-4
2
a. 3.0 x 10
moles
c. 3.0 x 10 moles
-3
44
b. 3.3 x 10
moles
d. 1.1 x 10 moles
9. How many hydrogen atoms are in 10 molecules of isopropyl alcohol, C 3H7O?
23
a. 6.022 x 10 atoms
c. 70 atoms
25
b. 10 atoms
d. 2 x 10 atoms
10. How many grams of lead are there in 4.32 moles of lead?
3
a. 8.95 x 10 g
c. 48.0 g
b. 207.2 g
d. 0.0208 g
11. All of the following are empirical formulas except:
a. Na2SO4
b. C6H5Cl
c. C6H12O6
19
e. 895 g
d. Sn3(PO4)4
12. What is the mass in grams of 4.32 x 10 molecules of the solvent cyclohexene, C6H10?
-5
6
-3
-7
a. 7.7 x 10 g
b. 1.14 x 10 g
c. 5.89 x 10 g
d. 8.72 x 10 g
13. Which of the following has the highest mass percent of hydrogen?
a. CH 4 b. SnH4
c. SiH4
d. All have the same mass % of hydrogen
14. A freon propellant from an aerosol can was analyzed. The empirical formula of Freon was
found to be CCl2F2 and the molar mass was known to be 240g/mole. What is the molecular
formula of freon?
a. CCl2F2
c. CCl2F4
b. C2Cl4F4
d. CCl3F6
For questions 15-16, match the sample element description with the appropriate answer
15. You hammer an element sample and find that it shatters. This element would also likely be
16. You measure the conductivity of this element and find that it is high. This element is also
probably
a. dull and a poor conductor
b. malleable and shiny
c. dull and a liquid
24
17. The nuclide Na has a half-life of 15 hours. If a sample that originally contained 180. mg of
24
Na now only contains 22.5 mg, how many hours have elapsed?
a. 7.5 h
b. 15 h
c. 30 h
d. 45 h
e. 60 h
18. Write the balanced nuclear equation for the reaction that occurs when
60
Co produces a beta particle
27
Part II- Reactions (4 points each)
For each of the following reactions:
a. State the type of reaction b. Predict the products
c. Balance the equation
d. Give the states of matter
TYPE OF REACTION
REACTION
1.
___C5H12 (g) +
2.
___Al(OH)3 (aq) +
3.
___Cu (s) + ___HNO3 (aq) →
(use copper(II))
4.
___Li (s) +
5.
___ O2 (g) →
___H2SO4 (aq) →
___O2 (g) →
* aqueous copper (II) nitrate and aqueous potassium carbonate react
Part III - Problem Solving
Make sure all of your answers contain the correct units and that you use significant
figures and scientific notation (when appropriate).
1. Fill in the blanks with the appropriate symbol (including both numbers on the left) and write which type
of process is described (α decay, β decay, positron emission, electron capture, fission, or fusion).
Reaction Type
a.
10
B +
-->
257
Lr
+
21n
b. Lead-210 undergoes β-decay, and has a half-life of 20 years.
c. Write the nuclear reaction showing the beta-decay of lead-210.
d. If Jan were given a lead ball the day she was born, what per cent of the lead-210 in it would still be there
now? Jan is now 15 years old. Show your work and box your final answer with units!
2. A green patina is made when copper metal reacts with oxygen from the air (20).
a. Write balanced reaction equations for the formation of the two different possible forms of
copper oxide: Cu2O or CuO.
Rxn possibility #1:
Rxn possibility #2:
b. Suppose you start with 10.00 g of copper and your final product has a mass of 12.52 g and you are sure
all of the Cu has oxidized. What is the empirical formula of this copper oxide?
3. You are given that 8.0695 x 10
20
molecules of X4H10 weighs 0.07145 grams. (10 points)
a. What is the molar mass of X4H10 ? (Hint: molar mass is g/mole!) Show work.
b. What is the identity of the unknown element X and how did you come to this
conclusion?
Write the balanced chemical equation including states for each of the following. Be careful: some
reactants and/or products must be deduced from the given situation.
4. Iron ore (primarily ferric oxide), is mixed with carbon and heated to produce melted iron and carbon
monoxide.
5. When lead sulfide is heated to high temperatures in a stream of pure oxygen gas, lead oxide forms and
sulfur dioxide gas is produced.
6. Thallium (III) oxide and carbon dioxide react to form thallium (III) carbonate.
7. Baking soda (sodium bicarbonate) is used to neutralize a spill of hydrochloric acid, releasing CO2
bubbles.
Do it in reverse: First, BALANCE the reaction. Then describe the process that each of the following
chemical equations represents.
8.
Fe (s) +
O2
(g)
=
Fe2O3 (s)
9.
K2SO4 (aq) +
10.
CO2 (g) +
AlCl3
(aq)
=
H2O (l) =
KCl (aq) +
Al2(SO4)3 (s)
C6H12O6 (aq) +
O2 (g)
11. 27.0 g of K2CO3 was added to a solution containing 19.5 g H3PO4 (20).
The equation for the reaction that occurred is as follows. Use it to answer the following questions
3K2CO3 (aq) + 2H3PO4 (aq) → 3CO2 (g) + H2O (l) + 2K3PO4 (aq)
Which of the above chemicals have:
a) Only covalent bonds:
b) Only ionic bonds:
c) Calculate the number of grams of CO2 you expect to be produced (theoretical yield).
ANSWERS to Review Question for Mid-Year Chemistry Exam
1. Which of the following is not a chemical change?
a. nitrogen gas is cooled until it becomes a liquid
b. H2 and O2 combine to produce H2O2
c. grape juice is fermented to produce wine
d. natural gas is burned to produce energy
e. mercury (II) oxide is heated until liquid mercury and oxygen gas are formed
2. Select the correct statement about subatomic particles:
a. electrons are negatively charged and are the heaviest subatomic particle
b. the nucleus is not charged and has a very high density
c. neutrons are found in the nucleus of the atom
d. the protons and electrons are spread out evenly throughout the atom
e. None of the above are correct.
3. In which of the following is the symbol for the ion and the number of electrons given
correctly?
a. H+ has one electron
b. Cl- has 17 electrons
3+
c. Al has 16 electrons
d. Na+ has 10 electrons
e. None of the above are written correctly.
4. How do the isotopes Carbon - 12 (12C) and Carbon-14 (14C) differ?
a. Carbon-14 has two more electrons than Carbon - 12
b. Carbon-14 has 8 protons; Carbon - 12 has six
c. Carbon-14 has 8 neutrons; Carbon - 12 has six
d. Carbon - 12 has 12 protons; Carbon-14 has 14
5. Which element forms an anion with a 3- charge?
a. Al
b. P
c. S
d. Na
e. Mg
6. Which of these is an incorrect interpretation of this balanced equation?
3 Ni (s) + N2 (g) → Ni3N2 (s)
a. 3 g Ni + 1 g N2 → 1 g Ni3N2
b. 3 moles Ni + 1 mole N2 → 1 mole Ni3N2
c. 3 atoms of Ni + 1 molecule of N2  1 molecule of Ni3N2
d. All of the above are correct
7. In the reaction: Al2S3 + 6HCl → 2AlCl3 + 3H2S How many moles of HCl are used for
each mole of AlCl3 formed?
a. 1
b. 1.5
c. 2
d. 3
e. 6
8. How many moles of silver atoms are there in 1.8 x 1026 atoms of silver?
a. 3.0 x 10-4 moles
c. 3.0 x 102 moles
-3
b. 3.3 x 10
moles
d. 1.1 x 1044 moles
9. How many hydrogen atoms are in 10 molecules of isopropyl alcohol, C3H7O?
a. 6.022 x 1023 atoms
c. 70 atoms
b. 10 atoms
d. 2 x 1025 atoms
10. How many grams of lead are there in 4.32 moles of lead?
a. 8.95 x 103 g
c. 48.0 g
b. 207.2 g
d. 0.0208 g
e. 895 g
11. All of the following are empirical formulas except:
a. Na2SO4
b. C6H5Cl
c. C6H12O6
d. Sn3(PO4)4
12. What is the mass in grams of 4.32 x 1019 molecules of the solvent cyclohexene,
C6H10?
a. 7.7 x 10-5 g
c. 5.89 x 10-3 g
6
b. 1.14 x 10 g
d. 8.72 x 10-7 g
13. Which of the following has the highest mass percent of hydrogen?
a. CH4
b. SnH4
c. SiH4
d. All have the same mass % of hydrogen
14. A freon propellant from an aerosol can was analyzed. The empirical formula of Freon
was found to be CCl2F2 and the molar mass was known to be 240g/mole. What is the
molecular formula of freon?
a. CCl2F2
c. CCl2F4
b. C2Cl4F4
d. CCl3F6
For questions 15-16, match the sample element description with the appropriate answer
15. You hammer an element sample and find that it shatters. This element would also
likely be A
16. You measure the conductivity of this element and find that it is high. This element is
also probably B
a. dull and a poor conductor
b. malleable and shiny
c. dull and a liquid
17. The nuclide 24Na has a half-life of 15 hours. If a sample that originally contained
180. mg of 24Na now only contains 22.5 mg, how many hours have elapsed?
a. 7.5 h
b. 15 h
c. 30 h
d. 45 h
18. Write the balanced nuclear equation for the reaction that occurs when
60
0
Co ------->
27
e
-1
60
+
Ni
28
e. 60 h
Part II- Reactions (4 points each)
For each of the following reactions:
a. State the type of reaction
b. Predict the products
c. Balance the equation
d. Give the states of matter
TYPE OF REACTION
REACTION
1. Combustion
C5H12 (g) +
2. Double replacement
acid- base
8O2 (g) → 5CO2 + 6H2O
2Al(OH)3 (aq) + 3H2SO4 (aq) → Al2(SO4)3 + 6H2O
3. single replacement
Cu (s) + 2HNO3 (aq) → Cu(NO3) 2 + H2 (g)
(use copper(II))
4. synthesis
4Li (s) +
5. Double replacement*
aqueous copper (II) nitrate and aqueous potassium carbonate react
O2 (s) → 2Li2O
Cu(NO3)2 + K2CO3
CuCO3 (s) + 2KNO3 (aq)
Part III - Problem Solving
Make sure all of your answers contain the correct units and that you use
significant figures and scientific notation (when appropriate).
1. Fill in the blanks with the appropriate symbol (including both numbers on the left) and
write which type of process is described (α decay, β decay, positron emission, electron
capture, fission, or fusion).
Reaction Type
10
249
B +
5
Cf
98
1
-------> 2 n
0
257
+
Lr
103
Fusion
b. Lead-210 undergoes β-decay, and has a half-life of 20 years.
c. Write the nuclear reaction showing the beta-decay of lead-210.
210
Pb ------->
82
0
e
-1
+
210
Bi
83
d. If Jan were given a lead ball the day she was born, what per cent of the lead-210 in it
would still be there now? Jan is now 15 years old. Show your work and box your final
answer with units!
Nt = N0 /2n
you will be given this in the exam
Nt = amount of radioactive material left
N0 = original amount of material
n
= number of half lives
n =t / t 1/2 = 15/20 = 0.75
Nt = 100% /(2)0.75
=
59.46%
2. A green patina is made when copper metal reacts with oxygen from the air (20).
b. Write balanced reaction equations for the formation of the two different possible
forms of copper oxide: Cu2O or CuO.
Rxn possibility #1: 4Cu
(s) + O2 (g) → 2Cu2O (s)
Rxn possibility #2: 2Cu
(s) + O2 (g) → 2CuO (s)
b. Suppose you start with 10.00 g of copper and your final product has a mass of 12.52 g
and you are sure all of the Cu has oxidized. What is the empirical formula of this copper
oxide?
Cu + O2 → CuxOx
mass of copper = 10.00g
Cu + O2 → CuxOx
nCu =10.00g / 63.55 gmol-1 = 0.157 mol of Cu
(1)
mass of O in final sample = 12.52g – 10.00g = 2.52g
(1)
nO =2.52g / 16 gmol-1 = 0.1575 mol of O
(1)
molar ratio = Cu0.157 O0.157 = Cu0.157/0.157 O0.157/0.157 = Cu1 O1
CuO
(1)
3. You are given that 8.0695 x 1020 molecules of X4H10 weighs 0.07145 grams. (10
points)
a. What is the molar mass of X4H10 ? (Hint: molar mass is g/mole!) Show work.
Moles of X4H10 = 8.0695 x 1020 / 6.022 x 1023 = 0.00134 moles
n = mass / molar mass
molar mass = 0.07145g / 0.00134mol = 53.32 g/mol
b. What is the identity of the unknown element X and how did you come to this
conclusion?
molar mass of X4H10 = 53.32 g/mol
10 grams is due to H
43.32 g is due to X
mass of X = 43.32/4 = 10.83g boron
X4H10 = B4H10
4. 27.0 g of K2CO3 was added to a solution containing 19.5 g H3PO4 (20).
The equation for the reaction that occurred is as follows. Use it to answer the following
questions
3K2CO3 (aq) + 2H3PO4 (aq) → 3CO2 (g) + H2O (l) + 2K3PO4 (aq)
Which of the above chemicals have:
a) Only covalent bonds:
b) Only ionic bonds:
CO2
H2O
None of these pure ionic would be NaCl
c) Both ionic and covalent bonds: K2CO3 (aq) H3PO4 (aq) K3PO4 (aq)
I don’t expect you to know this yet
d) Calculate the number of grams of CO2 you expect to be produced (theoretical yield).
3K2CO3 (aq) + 2H3PO4 (aq) → 3CO2 (g) + H2O (l) + 2K3PO4 (aq
moles K2CO3 = 27.0 g / 138.2 g/mol
= 0.195 moles K2CO3
moles H3PO4 = 19.5 g / 98 g/mol
= 0.198 moles H3PO4
3K2CO3 (aq) + 2H3PO4 (aq
0.195 moles K2CO3 x 2/3 = 0.13 moles H3PO4 therefore K2CO3 is the limiting reactant
moles CO2 = 0.195 moles x 1 = 0.195 moles
mass CO2 = 0.195 moles x 44 g/mol = 8.58 g
Yet more problems!!!!
Write the balanced chemical equation including states for each of the following. Be
careful: some reactants and/or products must be deduced from the given situation.
A. When butane C4H10 burns in air, carbon dioxide and one other compound are
produced.
B. Iron ore (primarily ferric oxide), is mixed with carbon and heated to produce melted
iron and carbon monoxide.
C. When lead sulfide is heated to high temperatures in a stream of pure oxygen gas, lead
oxide forms and sulfur dioxide gas is produced.
D. Thallium (III) oxide and carbon dioxide react to form thallium (III) carbonate.
E. Baking soda (sodium bicarbonate) is used to neutralize a spill of sulfuric acid,
releasing CO2 bubbles.
Do it in reverse: First, BALANCE the reaction. Then describe the process that each
of the following chemical equations represents.
F.
Fe (s) +
O2
(g)
=
Fe2O3 (s)
G.
K2SO4 (aq) + AlCl3 (aq)
=
H.
CO2 (g)
H2O (l) =
+
KCl (aq) +
Al2(SO4)3 (s)
C6H12O6 (aq) +
O2 (g)
Yet more problems!!!!
Write the balanced chemical equation including states for each of the following. Be
careful: some reactants and/or products must be deduced from the given situation.
A. When butane C4H10 burns in air, carbon dioxide and one other compound are
produced.
2C4H10 (g) +
13O2 (g) → 8CO2 + 10H2O
B. Iron ore (primarily ferric oxide), is mixed with carbon and heated to produce melted
iron and carbon monoxide.
2 Fe2O3 (s) + 3C (g) =
4 Fe (l) + 3CO (g)
C. When lead (II) sulfide is heated to high temperatures in a stream of pure oxygen gas,
lead oxide forms and sulfur dioxide gas is produced.
2 PbS (s) + 3O2 (g) =
2 PbO
(l)
+ 2SO2 (g)
D. Thallium (III) oxide and carbon dioxide react to form thallium (III) carbonate.
Th2O3 (s) + 3CO2 (aq)
=
Th2(CO3)3 (s)
E. Baking soda (sodium bicarbonate) is used to neutralize a spill of hydrochloric acid,
releasing CO2 bubbles.
NaHCO3 (aq) + HCl (aq)
=
H2O
(l)
+ NaCl (aq) +
CO2 (g)
Do it in reverse: First, BALANCE the reaction. Then describe the process that each
of the following chemical equations represents.
F.
4 Fe (s) + 3 O2 (g) =
2 Fe2O3 (s)
G.
3 K2SO4 (aq) + 2 AlCl3
(aq)
H.
6 CO2 (g)
+
=
6 KCl (aq) + Al2(SO4)3 (s)
6 H2O (l) = C6H12O6 (aq) +
6 O2 (g)