2015-16 AP CHEMISTRY SUMMER ASSIGNMENT Practice ProblemsSelected Topics from Chapters 1-3
For #1-10, determine the number of significant figures. For #11-20 calculate and round your answer off to the correct
number of significant digits.
1.
5.280 =
_______________
11.
2,560 + 13.3 =
_______________
2.
2,000 =
_______________
12.
0.0009 / 12.5 =
_______________
3.
15 =
_______________
13.
8,900,000 * 0.00564 =
_______________
4.
6,589,000 =
_______________
14.
0.0920 + 0.5 + 4.50 =
5.
70,400,000,000 = _______________
15.
6,300 / 3 =
6.
0.00263 =
_______________
16.
7.
0.00589 =
_______________
17. (245.38)*(3.5 x 10-4) = ____________________
8.
0.006 =
_______________
18. 45.01 + 30. + 32.1 = _____________
9.
0.400 =
_______________
19. 6.022 x 1023 * 3.5 = _______________
10.
0.08060 =
_______________
20. 4.184 * 0.785 = ________________
_______________
_______________
0.500 /2.5 = ____________
Make the following Metric System conversions using “unit analysis” (you may use scientific notation):
1.
100 mg
=_______________ g
2.
20 cm
= _______________ m
3.
50 L
= _______________ kL
4.
22 g
= _______________ cg
5.
825 cm
= _______________ km
6.
2,350 kg
= _______________ g
7.
19 mL
= _______________ cL
8.
52 mL
= _______________ L
9.
36 m
= _______________ cm
10.
18 cm
= _______________ mm
Atoms, Ions, Isotopes
1.
2.
Give the mass number of each of the following atoms:
(a) an iron atom with 30 neutrons
(d) nitrogen with 8 neutrons
(b) zinc with 34 neutrons
(e) xenon with 75 neutrons
(c) an americium atom with 148 neutrons
(f) a tungsten atom with 110 neutrons
How many electrons, protons, and neutrons are there in an atom of:
(a) carbon-13, 13 C
(b) copper-63, 63 Cu
(c) bismuth-205,
3.
205
Bi
Fill in the blanks in the table (one column per element).
Symbol
65
Cu
86
Kr
Number of protons
78
Number of neutrons
117
46
Number of electrons
in the neutral atom
Name of element
36
4.
Radioactive americium-241 is used in household smoke detectors and in bone mineral analysis. Give the number
of electrons, protons, and neutrons in an atom of americium-241.
19
9
X , 209 X , 189 X , and
5.
Which of the following are isotopes of element “X”, with atomic number of 9:
6.
Verify that the atomic mass of magnesium is 24.31 amu, given the following information:
24
Mg , mass = 23.985042 amu; percent abundance = 78.99%
7.
25
Mg , mass = 24.985837 amu; percent abundance = 10.00%
26
Mg , mass = 25.982593 amu; percent abundance = 11.01%
63
Copper has two stable isotopes, Cu and
65
21
9
X.
Cu , with masses of 62.939598 amu and 64.927793 amu, respectively.
Calculate the percent abundances of these isotopes of copper.
Sr , 87 Sr , and
reasonably abundant. Which of these more abundant isotopes predominates? How can you tell?
8. Strontium has four stable isotopes, Strontium-84 has a very low natural abundance, but
86
88
Sr are all
Beginning Stoichiometry
I. Molar Masses
Given a periodic table, you should be able to calculate the molecular mass (in amu) or the molar mass (in
grams) for any element or compound. Round off answers to the correct number of significant figures.
1. NaOCl
2. MgSO4
3. H2O
4. Cl2
5. ZnF2
II. Fraction and Percent Composition
It is useful to determine how much of a compound’s mass is made up of each element. Water, H2O, for
example has a molar mass of 18.02 g. The H’s mass is 2(1.008) = 2.02 g. The O’s mass is 16.00 g.
2.02
16.00
We can set up fractions for each element: H =
= 0.112 = 11.2%.
O=
= 0.888 = 88.8%.
18.02
18.02
This is called the percent composition. The fraction composition is a good in-between step.
Determine the fraction and percent composition of each element below:
1. H2SO4
2. Ca(OH)2
3. HC2H3O2
4. CO2
III. Empirical and Molecular Formula Determination
Research the process for empirical and molecular formula determination and complete the following:
Define: Empirical Formula_______________________________________________________________
Molecular Formula_______________________________________________________________
Determine the empirical formula for the following:
A compound that contains 43.4% Na, 11.3% C and 45.3% O
A compound that contains 68.4% chromium and 31.6% oxygen
A compound containing only carbon, hydrogen, and oxygen is 63.16% C and 8.77% H. Mass spectrometry shows that the
compound has a molar mass of 114 g/mol. What is its empirical formula and its molecular formula?
Writing Formulas and Naming Compounds
Introduction
Writing formulas and naming compounds can be confusing because there are different types of compounds that follow
different rules. Additionally, some compounds (H2O, NH3, CH4, etc.) simply have common names that must be
memorized.
The two types of compounds we will focus on first are ionic compounds (formed from positive and negative ions) and
binary nonmetal compounds (molecular compounds). Later we will add acids. So… you must recognize the type of
compound before you try to name it. [Note: + ion = “cation” and – ion = “anion”.]
Formula
Naming
I.
Ionic
cation before anion
ex: NaCl (NH4)2SO4 Al2S3 CuSO4
Name of cation + name of anion
sodium chloride
ammonium sulfate
aluminum sulfide
copper(II) sulfate*
*
note, transition metal ions with more than one
possible charge must be identified in the name
with the roman numeral indicating the charge on
the metal cation. See flashcards or ion list to
learn which metals are in this category.
Binary Nonmetal
usually the less electronegative atom is first
ex: CO
CO2
N2O
Indicate the number (mono, di, tri, and kind of atoms. First
element is simply name of element. Second element name ends
with “ide”
carbon monoxide
carbon dioxide
dinitrogen monoxide
Writing Ionic Formulas
Cl
NO3
S2
CO32
N3
PO43
Na+
NH4+
Sn2+
Hg22+
Al3+
Sn4+
II.
Naming Ionic Compounds
Cation
Anion
Cu2+
OH
Ba2+
SO42
NH4+
Cr2O72
Ag+
C2H3O2
Fe3+
S2
Formula
Name
OH
mono
III.
di
tri
Formula
hexa
hepta
octa
Name
nona
deca
Formula
nitrogen trifluoride
phosphorus trichloride
nitrogen monoxide
phosphorus pentachloride
nitrogen dioxide
sulfur hexafluoride
dinitrogen tetroxide
disulfur decafluoride
dinitrogen monoxide
xenon tetrafluoride
Naming Binary Nonmetal Compounds
Name
V.
penta
Writing Formulas of Binary Nonmetal Compounds
Name
IV.
tetra
Formula
Name
Formula
CCl4
HBr
P4O10
N2F4
ClF3
XeF3
BCl3
PI3
SF4
SCl2
Practice for Both Types of Compounds
Formula
Name
Formula
Name
HCl
carbon dioxide
PCl5
ammonium carbonate
K 2S
sulfur dichloride
NiSO4
calcium iodide
ClF3
boron trifluoride
OF2
phosphorus triiodide
Al(OH)3
magnesium perchlorate
NCl3
potassium permanganate
(NH4)3PO4
aluminum phosphate
S2Cl2
dioxygen difluoride
Beginning Stoichiometry
1 mole = 6.02 x 1023 molecules = 22.4 L (@ STP)
1.
Calculate the mass of 1.58 moles CH4.
2.
What volume will 7.29 moles of CO2 gas occupy at STP?
3.
How many molecules are there in a 0.00583 mole sample of H2O?
4.
What mass of CO2 gas occupies a volume of 100. Liters at STP?
5.
How many molecules are in a 35.0 gram sample of H2O2?
6.
What volume will 5.25 x 1022 molecules of N2 occupy at STP?
7.
Calculate the mass of 2.19 moles C6H12O6.
8.
What volume will 2.22 moles of CO2 gas occupy at STP?
9.
How many molecules are there in a 0.127 mole sample of N2O?
10.
What mass of NO2 gas occupies a volume of 395 Liters at STP?
11.
How many molecules are in a 0.250 gram sample of H2O?
12.
What volume will 3.01 x 1022 molecules of C2H4 occupy at STP?
13.
Calculate the mass of 7.23 moles NOCl.
14.
What volume will 9.35 moles of CO gas occupy at STP?
15.
What mass of CO2 gas occupies a volume of 10.8 Liters at STP?
Balancing Equations
Balance the following equations. Identify the reaction as: double displacement, single displacement, synthesis,
decomposition, or combustion. For the combustion reactions at the bottom, complete and balance.
1.
__ZnS + __HCl  __ZnCl2 + __H2S
2.
__HCl + __Cr  __CrCl2 + __H2
3.
__Al + __Fe3O4  __Al2O3 + __Fe
4.
__H2 + __Br2  __HBr
5.
__Na2S2O3 + __I2  __NaI + __Na2S4O6
6.
__LaCl3 + __Na2CO3  __La2(CO3)3 + __NaCl
7.
__NH4Cl + __Ba(OH)2  __BaCl2 + __NH3 + __H2O
8.
__Ca(OH)2 + __H3PO4  __Ca3(PO4)2 + __H2O
9.
__La2(CO3)3 + __H2SO4  __La2(SO4)3 + __H2O + __CO2
10.
__Na2O + __(NH4)2SO4  __Na2SO4 + __H2O + __NH3
11.
__C4H10 + __O2  __CO2 + __H2O
12.
__C7H6O2 + __O2  __CO2 + __H2O
13.
__P4O10 + __H2O  __H3PO4
14.
__FeS2 + __O2  __Fe2O3 + __SO2
15.
__NH3 + __O2  __NO + __H2O
16.
__Fe + __HCl  __H2 + __FeCl2
17.
__PbO2 + __HCl  __H2O + __PbCl2 + __Cl2
18.
__Fe2O3 + __H2SO4  __Fe2(SO4)3 + __H2O
19.
__NO2 + __H2O  __NO + __HNO3
20.
__C2H6S + __O2  __CO2 + __H2O + __SO2
Write complete, balanced combustion reactions for the following organic molecules, combustion reactions always have
oxygen gas as a reactant, and when the other reactant is a hydrocarbon, the products are carbon dioxide and water:
21.
C6H14
22.
C2H5OH
23.
C3H7OH
24.
C6H6
25.
C17H35COOH