Download Review Stations - ANSWER KEY - Liberty Union High School District

Midterm Review Day 1: Units 1 – 3 Review Stations – ANSWER KEY
Station #1: Measurement & Dimensional Analysis
1. The most common unit used for mass in the chemistry laboratory is grams. This unit is commonly
abbreviated as the letter g.
2. Convert 85.3 grams (g) to kilograms (kg). 0.0853 kg
3. Convert 120.8 grams (g) to ounces (oz.). 4.261 oz
4. The most common unit used for volume in the chemistry laboratory is liters. This unit is commonly
abbreviated as the letter L.
5. Convert 784 liters (L) to milliliters (mL). 784,000 mL
6. The most common unit used for length in the chemistry laboratory is meters. This unit is commonly
abbreviated as the letter m
7. Convert 13.4 centimeters (cm) to nanometers (nm). 134,000,000 nm
Station #2: Scientific Notation & Significant Figures
1. Convert 987,600 to scientific notation. 9.876 x 105
2. Convert 5.688 x 10-4 to standard form.
0.0005688
3. Convert 0.000360 to scientific notation. 3.60 x 10-4
4. Determine the number of significant figures in each example
3030
0.007080
10.00
320.
8.6703
3
4
4
3
5
5. Solve each example + round to the correct number of significant figures
43.2 + 18.01 – 6.035 = 55.175  55.2
160 ÷ 10.5 = 15.238095  15
86.2 x 0.032 = 2.7584  2.8
17.3 – 0.005 + 0.10048 – 11 = 6.39548  6
178.1 ÷ 8.003 = 22.254154  22.25
36.2 ÷ 5 x 4.3 + 2.01 = 33.142  30
5. Which measurement is reported to a greater degree of accuracy: 0.009 cm or 0.00900 cm?
6. Calculate the percent error for a density that was measured by a student to be 9.80 g/mL, if the
accepted value is 10.00 g/mL.
(10.00 – 9.80) x 100 = 2.00%
10.00
Station #3: History of the Atom
1. What is the difference between Democritus’ and Dalton’s Model of the Atom? Very similar – both thought that
atoms made up everything and were very small. Democritus named them, atomos, and Dalton said they were
indivisible.
2. How did Rutherford build on Thomson’s discovery? Describe each of their experiments and what the outcomes
were. Thomson used the cathode ray to determine that there was substructure to an atom (positive + negative
charge) and described it as “plum pudding.” Rutherford shot alpha particles (positive charges) at a piece of gold
foil and discovered the nucleus (where all the mass is contained) and that electrons were around it outside (all
the space).
3. What are the similarities between the Bohr model and the electron cloud model? What are the differences?
Very similar – both say the nucleus has all the mass (made of protons and neutrons) and both say electrons orbit
the nucleus. Bohr said in a circle (planetary model) and the electron cloud model says that the orbits are not all
circular in shape.
4. Who is credited with discovering the nucleus? Why? Rutherford. When he shot the alpha particles at the piece
of foil they bounced back only in the center (the nucleus) where it was a dense concentration of protons.
Station #4 – The Atom
Complete the following table.
Element
Symbol
Atomic
#
Atomic
Mass
# protons
#
neutrons
#
electrons
Cadmium
Cd
48
112
48
64
48
Praseodymium Pr
59
140
59
81
59
Lead
Pb
82
207
82
125
82
Tungsten
W
74
184
74
110
74
Nuclear
Symbol
112
Cd
48
140
Pr
59
207
Pb
82
184
W
74
Station #5 – The Ion
Complete the following table.
Element
Ion
Symbol
Atomic #
Atomic
Mass
# protons
# neutrons
# electrons
Cobalt
Co2+
27
59
27
32
25
Aluminum
Al3+
13
27
13
14
10
Palladium
Pb2+
46
106
46
60
44
Iodine (-1)
I-
53
127
53
74
54
Nuclear Symbol
(include charge)
59
Co2+
27
27 3+
Al
13
106
Pb2+
46
127 I
53
Station #6 – The Isotope
Complete the following table.
Element
Hyphen Notation
Atomic #
Atomic Mass
# protons
# neutrons
# electrons
Vanadium
Vanadium-52
23
52
23
29
23
Barium
Barium-139
56
139
56
83
56
Lead
Lead-209
82
209
82
127
82
Silver
Silver-109
47
109
47
62
47
Nuclear
Symbol
52
V
23
209
Pb
82
209
Pb
82
109
Ag
47
Station #7 – Weighted Average Atomic Mass
Solve the following problems + round your answer to the correct number of significant figures.
1. What is the average atomic mass of silicon
given the following abundance information
on the isotopes of silicon?
Mass number
Si-28
Si-29
Si-30
1.
2.
3.
4.
2. What is the average atomic mass of hafnium
given the following information about the number of
atoms of its isotopes?
Abundance
Mass number
# Atoms
Hf-176
35
Hf-177
100
Hf-178
45
Hf-179
250
Hf-180
120
92.21 %
4.70 %
3.09 %
Turn abundance percentages into decimals (to make all relative to 1)
Multiple by mass
Add up
Sig Figs!
0.9291 (28) = 26.0148
0.0471 (29) = 1.3659
0.0309 (30) = 0.927
28.3077  28 amu
1.
2.
3.
4.
Turn # atoms into decimals (to make all relative to 1) by dividing by total number of atoms.
Multiple by mass
Add up
Sig Figs!
35 + 100 + 45 + 250 + 120 = 550 total atoms
35/550 = 0.06364 (176) = 11.201
100/500 = 0.18182 (177) = 32.182
45/550 = 0.081818 (178) = 14.564
250/550 = 0.45455 (179) = 81.364
120/550 = 0.21818 (180) = 39.273
178.584  179 amu