Name KEY
AP Chemistry First Week Homework—This is the only time I’m going to type out your homework (our
textbooks will be assigned on Friday).
Monday 8/25/2014
1) A measurement is a quantitative observation involving both a number and a unit.
a) What is a qualitative observation? A descriptive or categorical measurement; does not include a number
b) What are the SI units for mass, length, and volume? Kilogram, meter, and liter, respectively
2) To determine the volume of a cube, a student measured one of the dimensions of the cube several times.
If the true dimension of the cube is 10.62 cm, give an example of four sets of measurements that would
illustrate the following.
a) imprecise and inaccurate data
15 g, 11 g, 9 g—not correct, not consistent
b) precise but inaccurate data
17.01 g, 16.99 g, 17.02 g—not correct, consistent
c) precise and accurate data
10.61 g, 10.63 g, 10.62 g—all close to the true value, and consistent
3) How many significant figures are there in each of the following values?
a) 6.07 x 10-15 3
d) 300
1
b) 17.00
4
e) 301
3
8
c) 8 x 10
1
f) 300.
3
4) How many significant figures are in each of the following?
a) 100
1
d) 0.00480
2
b) 1.0 x 10
2
e) 4.80 x 10-3
c) 0.0048
2
f) 4.800 x 10-3
3
3
4
5) Round off each of the following numbers to the indicated number of significant digits, and write the
answer in standard scientific notation.
a) 0.00034159 to three digits
0.000342
2
b) 103.351 x 10 to four digits
103.4 x 102 which is really 1.034 x 104
6) Use exponential notation to express the number 385,500 to
a) one significant figure
400,000
b) three significant figures
386,000
7) Evaluate each of the following, and write the answer to the appropriate number of significant figures.
a) 212.2 + 26.7 + 402.09 = 640.99  641.0 because addition problems rely on decimal places
b) 1.0028 + 0.221 + 0.10337 = 1.32717  1.327
c) 52.331 + 26.01 – 0.9981= 77.34
8) Perform the following mathematical operations, and express each result to the correct number of
significant figures.
0.102 x 0.0821 x 273
a)
= 2.26
1.01
b) 0.14 x 6.022 x 1023 = 8.4 x 1022
2.00 x 106
c)
= 6.67 x 1012
3.00 x 10−7
Tuesday 8/26/2014 (also prepare for safety “test” on Wednesday)
1) When a marble is dropped into a beaker of water, it sinks to the bottom. Which of the following is the
best explanation?
a) The surface area of the marble is not large enough to be held up by the surface tension of the water.
b) The mass of the marble is greater than the mass of the water.
c) The marble weighs more than an equivalent volume of water.
d) The force from dropping the marble breaks the surface tension of the water.
e) The marble has greater mass and volume than the water.
Justify your choice.
The marble displaces a volume of water equal to its own volume. However, it has a larger mass per unit
volume (density). The buoyant force of the water is smaller than the downward force (the marble’s weight);
the water cannot “hold up” the marble so the marble sinks.
2) Perform the following unit conversions.
a) 908 oz = 25.7 kilograms
16 oz = 1 lb, 1 kg = 2.205 lb
b) 12.8 L = 3.39 gallons
1 L = 1.06 quarts, 1 gallon = 4 quarts
c) 4.48 lb = 2030 grams
453.6 g = 1 lb
3) Mercury poisoning is a debilitating disease that is often fatal. In the human body, mercury reacts with
essential enzymes leading to irreversible inactivity of these enzymes. If the amount of mercury in a polluted
lake is 0.4 μg Hg/mL, what is the total mass in kilograms of mercury in the lake? (The lake has a surface
area of 100 mi2 and an average depth of 20 ft.) Show your work for credit.
100 square miles
(5280 ft)2
=
2.788 x 109 ft2
2
(1 mi)
2.788 x 109 ft2 surface x 20 ft depth = 5.576 x 1010 ft3 volume
5.576 x 1010 ft3
(12 in)3
(1 ft)3
(2.54 cm)3
(in)3
1 mL
1 cm3
4 x 10-7 g
1 mL
1 kg =
1000 g
6 x 105 kg
4) Convert the following Kelvin temperatures to Celsius and Fahrenheit degrees. C = K + 273.15, F = (9/5) C + 32
a) 233 K = -40.15 C = -40.27 F
b) 4 K = -269.15 C = -452.47 F
5) The density of pure silver is 10.5 g/cm3 at 20°C. If 5.25 g of pure silver pellets is added to a graduated
cylinder containing 11.2 mL of water, to what volume level will the water in the cylinder rise?
5.25 g / (10.5 g/cm3) = 0.500 cm3 = 0.500 mL
11.2 mL = 0.500 mL = 11.7 mL
6) Classify each of the following mixtures as homogeneous or heterogeneous.
a) Potting soil
Heterogeneous
b) Window glass
Homogeneous
c) Granite
Heterogeneous
7) Classify each of the following as a mixture or a pure substance.
a) Blood
Mixture
d) Brass
Mixture
b) The oceans Mixture
e) Uranium
Pure
c) Iron
Pure
f) Leather
Mixture
g) Table salt Pure
Wednesday 8/27/2014
1) Dalton assumed that all atoms of the same element were identical in all their properties. Explain
why this assumption is not valid.
Isotopes—same element, different numbers of neutrons and different masses
2) What happens to the ratio of the mass number to the atomic number of a stable isotope, as stable
isotopes become heavier?
It increases, because more neutrons are needed to keep the nucleus stable
3) What is the trend in metallic character (increasing/decreasing) as you go down group 4A?
4) What is the trend in metallic character (increasing/decreasing) as you move from left to right
across a period in the periodic table?
5) Now, what do you think “metallic character” means? Having metallic properties—malleable,
conducts electricity, lustrous, ductile
6) What is the difference between ionic and covalent bonding?
In ionic bonding, electrons are transferred from one atom to another, becoming a cation and an
anion. These are attracted to each other due to their opposite charges.
In covalent bonding, electrons are shared between two or more atoms. They are not always shared
equally.
7) What is the difference between an anion and a cation?
Anions are negatively charged; they have gained electrons.
Cations are positively charged; they have lost electrons.
8) Do salts (ionic compounds) form molecules? Explain. No, they form network/lattices.
In other words, they do not form discrete molecules.
9) If 1 L of H2 reacts with 1 L of Cl2 at the same temperature and pressure, what volume of HCl is
formed?
H2 + Cl2  2 HCl, so 2 L of HCl are formed
10) A sample of sulfuric acid contains 2.02 g hydrogen, 32.07 g sulfur, and 64.00 g oxygen. How many
grams of sulfur would be present in a second sample of sulfuric acid if it contained 7.27 g of
hydrogen?
115.42 g S
11) In a combustion reaction, 46.0 g of ethanol reacts with 96.0 g of oxygen to produce water and
carbon dioxide. If 54.0 g of water is produced, what mass of carbon dioxide is produced?
88 g of carbon dioxide are formed
12) What are the symbols of the following elements?
a. Sodium
Na
e. Chlorine
Cl
b. Radium
Ra
f. Sulfur
S
c. Iron
Fe
g. Oxygen
O
d. Manganese Mn
h. Phosphorous P
13) Classify the following as metals, metalloids, or nonmetals.
a. Mg
metal
f. Br
nonmetal
b. Bi
metal
g. Element #17 nonmetal
c. B
metalloid
h. Element # 63 metal
d. Ge
metalloid
i. Element #2
nonmetal
e. Am
metal
j. Element #55 metal
14) Color the periodic table to the right, giving
each group its own color according to the
list below. Use the list as a key by
circling/shading/highlighting each group
with the color you used.
a. Alkali metals
b. Alkali earth metals
c. Halogens
d. Noble gases
e. Transition metals
f. Inner transition metals
g. Other metals
h. Other nonmetals
15) Write the atomic symbol for an isotope where Z = 20 and the number of neutrons = 27. 4720Ca
16) How many protons and neutrons are in the nucleus of one atom of…
a. Cesium-133? p = 55
n = 78
b. Iron-57?
p = 26
n = 31
17) How many protons and electrons (total and valence) are in each of the following ions?
a. Ba2+
p = 56
total e= 54
valence e = 8
3b. N
p = 14
total e= 17
valence e = 8
3+
c. Co
p = 27
total e= 24
valence e = 6 (9-3)
18) Which groups of elements typically gain electrons when they become ions? Halogens, other nonmetals
Which groups typically lose electrons when they become ions? All metals, but some lose electrons
more readily than others.
Thursday 8/28/2014 Pg. 72-80
Fill out the following table.
Name
Sodium bromide
Strontium fluoride
Calcium sulfide
Potassium nitride
Mercury (I) oxide
Remember that mercury (I) is Hg22+
Tin (II) nitride
Cobalt (II) sulfide
Mercury (II) oxide
Cesium fluoride
Silver sulfide
Titanium (IV) oxide
Zinc Chloride
Tin (IV) bromide
Calcium phosphide
Potassium permanganate
Potassium dichromate
Chromium (III) hydroxide
Magnesium cyanide
Diboron trioxide
Arsenic Pentafluoride
Copper (I) iodide
Sodium hypochlorite
Ammonium nitrate
Acetic acid
Formula
NaBr
SrF2
CaS
K3N
Hg2O
Sn3N2
CoS
HgO
CsF
Ag2S
TiO2
ZnCl2
SnBr4
Ca3P
KMnO4
K2Cr2O7
Cr(OH)3
Mg(CN)2
B2O3
AsF3
CuI
NaOCl
NH4NO3
HC2H3O2
Lead (IV) phosphate
Potassium chlorate
(ClO3– is chlorate)
Tin (IV) oxide
Hypochlorous acid
(ClO– is hypchlorite)
Sulfate ion
Selenate ion
(just like SO42- is the sulfate ion—S and Se are the in same family)
Telluric acid
(just like H2SO4 is sulfuric acid—S and Te are in the same family)
Chloric acid
(ClO3– is chlorate)
Iodic acid
(IO3- is iodate)
Sulfur difluoride
Sodium dihydrogen phosphate
Ammonium acetate
Disulfur dichloride
Ammonia
Sodium oxide
Sodium peroxide
Nitrous acid
Iodous acid
Zinc sulfide
Silicon dioxide
Perbromic acid
Pb3(PO4)2
KClO3
SnO2
HClO
SO42SeO42H2TeO4
HClO3
HIO3
SF2
NaH2PO4
NH3C2H3O2
S2Cl2
NH3
Na2O
Na2O2
(just like hydrogen peroxide)
HNO2
HIO2
ZnS
SiO2
HBrO4
Each of the following compounds is incorrectly named. Circle the part that makes it incorrect, and write the
correct name for each formula. There may be more than one error in some of the names.
FeCl3
Iron_chloride
Correct name: Iron (III) chloride
NO2
Nitrogen (IV) oxide
Correct name: Nitrogen dioxide
Mg(C2H3O2)2 Magnesium diacetate
Correct name: Magnesium acetate
H2S
_Sulfuric acid
Correct name: Hydrosulfuric acid
FePO4
Iron (II) phosphide
Correct name: Iron (III) phosphate
Friday 8/29: Go over this key
Our Ch 1/2 Exam is on W 9/3. We will review T 9/2.