Key to Review Worksheet for Exam I
Chem 101, Summer 2006
1. Give the type of measurement for each of the following:
a) The amount of space taken up by a substance is its
volume
b) The amount of matter contained in a substance is its
.
mass
.
c) The amount of thermal kinetic energy of a substance is its temperature .
2. Express the following measured numbers in scientific notation *Sig. Figs. Count
a) 680,000 km
6.8 x 105 km
b) 75.00 m
7.500 x 101 m
c) 0.0005 L
5 x 10-4 L
3. Complete the following metric relationships:
a) 1 g =
b) 1 mm =
c) 1 Ci =
1000
mg
0.001
106
m
Ci
4. A graduated cylinder initially contains 20.3 mL of water. If you add a 41.7 g piece of
silver metal (density of silver = 10.5 g/mL), what is the new volume of water (including
metal) that you would read on the graduated cylinder? *Sig. Figs. Count
d = m/V
Vsilver = m/d = 41.7 g/10.5 g/mL = 3.97 mL
Vtotal = Vwater + Vsilver = 20.3 mL + 3.97 mL = 24.3 mL
5. Write the symbols for the following elements:
Sodium
Na
Bromine
Br
Boron
B
Silver
Ag
6. Fill in the blanks with “precise” or “accurate”: The density of a sample of copper
was measured 10 times. The average value for the 10 measurements was close to the
literature value, so the results were _______accurate_______.
measurements
had
a
wide
range
of
values,
so
the
However, the 10
results
were
not
_________precise_________.
7. A top-fuel dragster can reach speeds over 330 mi/hr in only 0.250 miles. How fast is
that in km/hr? (1 km = 0.621 mi)
330 mi/hr x (1 km/0.621 mi) = 530 km/hr
8. Gallium has two naturally occuring isotopes. The isotope Ga-69 makes up 60.1 % of
the atoms and the isotope Ga-71 makes up 39.9 %. Calculate the atomic mass of
gallium. *Significant Figures Count.
Show your work.
(60.1/100) x 69 amu = 41.5 amu
(39.9/100) x 71 amu = 28.3 amu
atomic mass of gallium = 41.5 amu + 28.3 amu = 69.8 amu
9. Complete each of the following nuclear equations:
a)
11C

b)
35S

c)
14N
7Be
+
35Cl
+ 1n 
4He
+ e14C
+ 1H
10. If the half-life of 11C is 20.0 min, what will be the remaining activity, after 60.0 min,
of a sample of 11C with an initial activity of 0.100 mCi?
60/20 = 3 half-lifes
0.100 mCi/2 = 0.0500/2 = 0.0250/2 = 0.0125 mCi
11. If it takes 56 days for a sample of
approximate half-life of 32P?
32P
to decay from 250 Ci to 16 Ci, what is the
250/2 = 125/2 = 62.5/2 = 31.3/2 = 15.6 = 16 = 4 half-lifes
56 days/4 = 14 days
12. Give the maximum number of electrons that can be held in each of the following
shells:
1
2
2
8
3
18_____
13. Give the maximum number of electrons that can be in each of the following
subshells:
s
2
p
6
d
10_____
14. Identify each of the following elements (give the name and symbol):
a) Has atomic number 15:
Name
Phosphorus
Symbol
P___
Symbol
Mg___
Symbol
Cl___
b) Is in group 2A and has 3 electron shells:
Name
Magnesium
c) Has electron configuration 1s22s22p63s23p5:
Name
Chlorine
15. If the atomic number is 6 and the mass number is 13,
a) What is the element?
Carbon
b) How many electrons does it have?
6
c) How many neutrons does it have?
7
16. Write the electron configuration for potassium:
1s22s22p63s23p64s1
or
[Ar]4s1
17. Complete the following statements about metals and nonmetals:
a)
Nonmetals
are bad conductors of electricity.
b) When they form ions,
c)
Metals
metals
typically lose electrons.
usually form ionic bonds with
nonmetals
.
18. Write the electron-dot structures for the following ions and circle the ones with a
noble gas configuration:
a)
S
2-
b)
P
2-
c)
Ca2+
19. What type of bond would you expect to form for each of the following pairs of
atoms (ionic, polar covalent or nonpolar covalent)? (circle your answer)
a) C and Br
Ionic
Polar Covalent
Nonpolar Covalent
b) O and H
Ionic
Polar Covalent
Nonpolar Covalent
c) Ca and I
Ionic
Polar Covalent
Nonpolar Covalent
20. For each of the following molecules, write the dot structure and use VSEPR theory
to predict the shape (linear, bent, trigonal planar, pyramidal or tetrahedral). State
whether each molecule is overall polar or nonpolar:
Molecule Dot-Structure
Molecular Shape
Polar or Nonpolar
PCl3
Cl P Cl
Cl
Pyramidal
Polar
BCl3
Cl B Cl
Cl
Trigonal Planar
Nonpolar
Linear
Nonpolar
SiO2
O
Si
O
21. For each of the following pairs of compounds, circle the one with the higher boiling
point:
a)
CH4
CHCl3
b)
PCl3
H2O
c)
HCl
KCl
22. Identify the main type of interactive force that occurs between molecules in each of
the following substances.
a) HCl
b) NH3
c) PH3
d) H2S
e) F2
f) CO2
a) dipole-dipole b) h-bonding c) dispersion d) dipole-dipole e) dispersion f) dispersion
23. Given that for water:
heat of fusion = 80. cal/g, heat of vaporization = 540 cal/g, specific heat = 1.00 cal/g ºC
a) Calculate the amount of heat consumed (in kcals) when 25 g of ice at -15 ºC first
warms to 0.0 ºC and then melts (hint: 2 steps). Show your work.
25 g x 15 C x 1.00 cal/g C = 375 cal
25 g x 80. cal/g = 2000 cal
Total heat consumed = (375 cal + 2000 cal) x (1 kcal/1000 cal) = 2.4 kcal
b) Calculate the amount of heat consumed (in kcals) when the 25 g of liquid water
warms from 0.0 ºC to 100.0 ºC, vaporizes, and then warms to 120 ºC (hint: 3 steps).
Show your work.
25 g x 100.0 C x 1.00 cal/g C = 2500 cal
25 g x 540 cal/g = 13500 cal
25 g x 20 C x 1.00 cal/g C = 500 cal
Total heat consumed = (2500 cal + 13500 cal + 500 cal) x 1 kcal/1000 cal = 17 kcal
c) Draw a heating curve for the whole process occurring in parts a and b. It need not be
drawn to scale. (Label the x and y axes, the melting and boiling points and the physical
states: s, l and g.)
120
Temp.
gas
b.p. (liquid + gas)
100
( C)
liquid
0
-15
solid
m.p. (solid + liquid)
Heat Added