Chem 1721/1821
Name ___________________________________
Quiz 2 (25 points)
1.
2.
Which of the following correctly matches a class of solids with a characteristic property? Circle the one best answer.
a. ionic solids - malleable and ductile
c. metallic solids - good conductors
b. covalent-network solids - low melting point
d. molecular solids - high melting point
Consider the pictures of unit cells shown below to answer questions a - c:
A
3.
4.
February 6, 2014
NA = 6.022 x 1023 mol−1
C = kP
B
C
a.
What fraction of a particle on the corner of unit cell A is inside of the unit cell?
__________________
b.
How many atoms are contained inside unit cell B?
__________________
c.
Which unit cell {A, B, or C} has particles that touch along the body diagonal?
__________________
Indicate whether each of the following substances should have greater solubility in ethanol (C2H5OH), or pentane
(C5H12).
a.
XeF4
___________________
b.
PCl3
___________________
c.
a biologically active compound that is fat soluble (i.e. lipophilic)
___________________
Multiple choice - circle the one best answer for each of the following.
a.
What is the hybridization of each carbon atom in diamond?
sp3d
b.
sp2
none of these
greater than 18.8 g/L
equal to 18.8 g/L
Which type of unit cell contains the least empty space?
face-centered cubic
d.
sp4
The solubility of Ba(OH)2 in water at 25ºC is 18.8 g/L. At a temperature of 40ºC, what should be the solubility of
Ba(OH)2?
less than 18.8 g/L
c.
sp3
body-centered cubic
simple cubic
it is the same for all of these
Which of the following is the correct definition of molarity?
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5.
In the solid state, silver has a face-centered cubic unit cell; the volume of the unit cell is 6.89 x 10–23 cm3. Determine the
atomic radius (in pm) of silver, and the density (in g/cm3) of silver.
radius = _________________ pm
density = _________________ g/cm3
6.
Fish generally need an O2 (g) concentration in water of at least 4.00 mg O2/L solution for survival.
a.
Determine this required concentration of O2 in water in parts per billion (ppb), and molar concentration.
Assume that for the solution, density = 1.00 g/mL
___________________ ppb
___________________ M
b.
Determine the partial pressure (in atm) of O2 (g) above water necessary to achieve this required concentration. For
O2 in water at 25ºC, Henry's Law constant k = 1.31 x 10–3 mol/L•atm
PO2 = ___________________ atm
7.
Lactose (C12H22O11) is a sugar that is found naturally in mammalian milk. A 0.335 M solution of lactose in water has
density = 1.0432 g/mL. Determine the mole fraction of lactose (χC12H22O11), the mass percent of lactose, and the molal
concentration of this solution.
mass % = _____________________
molality = _____________________
mole fraction = _____________________