Download Practice Test 3

BRCC
CHM 101
PRACTICE TEST 3
PAGE 1 OF 6
Show your calculations on all mathematical problems! Answers with no work shown will receive no
points even if correct. Incorrect answers for which work is shown may receive partial credit.
1.
The gas pressure in an aerosol can is 1.5 atm at 25 °C. If the can were thrown into a fire and the
contents heated to 450 °C, what would the new pressure be? (Combined Gas Laws)
Given that the can is likely to explode at pressures above 3 atm, will the can explode?
Yes
No
2.
An inflated balloon has a volume of 6.0 L and a pressure of 1.0 atm at sea level. The balloon is allowed
to ascend in altitude until the pressure is 0.45 atm. During the ascent the temperature of the gas cools
from 22 °C to - 21 °C. What is the volume of the balloon at its final altitude? (Combined Gas Laws)
3.
How many moles of an ideal gas occupy a volume of 24 L at a pressure of 0.75 atm and a temperature of
125 °C? (Ideal Gas Law) note: R = 0.0821 L-atm/K-mol
BRCC
CHM 101
PRACTICE TEST 3
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4.
What is the volume occupied by 13.7 grams of Cl2 gas at 45 °C and 745 mmHg? (Molar Mass of Cl2 =
70.9 g/mol) (Ideal Gas Law) note: 1 atm = 760 mmHg
5.
Normal saline solution contains 9.000 grams of NaCl per liter. The formula weight of NaCl is 58.443
g/mol. Calculate the molar concentration of NaCl in normal saline.
6.
You want to make up 750.0 mL of D5W (Dextrose 5% in Water). How many grams of dextrose do you
need to use?
BRCC
CHM 101
PRACTICE TEST 3
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7.
You have on hand a bottle of 10.00% aqueous NaCl solution, and you need 1500 mL of normal
saline (0.900% NaCl). How many mL of the 10.00% NaCl do you need to dilute?
8.
MATCHING
Colloid
Homogeneous mixture
Miscible liquids
Nonelectrolyte
Saturated Solution
Strong Electrolyte
Supersaturated Solution
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
A solution is an example of one.
Solute particles will settle out.
Milk is an example.
Dissociates completely into ions in solution.
Individual parts can be seen with the naked eye.
More dissolved solute is present than theoretically possible.
Conducts electricity by movement of neutrons.
More solute can be dissolved if desired.
Two liquids which are mutually insoluble.
Exists in solution mostly as molecules, with a few ions.
Exists in solution entirely as dissolved ions.
Exists in solution entirely as dissolved molecules.
No more solute will dissolve.
Two liquids which are mutually soluble in all proportions.
Suspension
Unsaturated solution
Weak Electrolyte
9.
If we add 215 g of methanol to 1000g of water, what will be the freezing point of the solution?
BRCC
CHM 101
PRACTICE TEST 3
PAGE 4 OF 6
11. What is the osmolarity of a 3.3% w/v Na3PO4 solution?
12. MULTIPLE CHOICE QUESTIONS. Select the one most correct answer for each.
A.
A weak electrolyte:
a.
b.
c.
d.
e.
B.
A strong electrolyte:
a.
b.
c.
d.
e.
C.
Is translucent (cloudy) and exhibits the Tyndall effect.
Is opaque; solute particles settle out readily.
Is the same thing as a true solution.
Is the same thing as a heterogeneous mixture.
Is transparent (clear) and does not exhibit the Tyndall effect.
In a hypotonic solution, red blood cells:
a.
b.
c.
d.
e.
E.
Forms no ions at all when it dissolves in water.
Will not dissolve in water at all.
Will always be highly toxic in solution.
Forms a very few ions in aqueous solution, but mostly dissolves as molecules.
Breaks up completely into ions in aqueous solution.
A colloid (colloidal dispersion):
a.
b.
c.
d.
e.
D.
Forms no ions at all when it dissolves in water.
Will not dissolve in water at all.
Will always be highly toxic in solution.
Forms a very few ions in aqueous solution, but mostly dissolves as molecules.
Breaks up completely into ions in aqueous solution.
Neither shrink nor swell.
Are poisoned by lack of O2.
Become dehydrated.
Undergo crenation.
Undergo hemolysis.
In an isotonic solution, red blood cells:
a.
b.
c.
d.
e.
Neither shrink nor swell.
Are poisoned by lack of O2.
Become dehydrated.
Undergo crenation.
Undergo hemolysis.
BRCC
CHM 101
PRACTICE TEST 3
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13. Fill in the missing acid or base in the conjugate acid-base pairs:
Acid
Base
Acid
Base
-
H2O
CH3COO
+
-
NH4
Br
HCOOH
H2O
14. Complete the following table:
+
[H3O ]
-
pH
[OH ]
-4
1.0 x 10
-7
5 x 10
10.3
15.
The pKa of acetic acid (CH3COOH) is 4.75. What is the pH of a CH3COOH/CH3COO- buffer
system in which [CH3COOH] is twice as much as [CH3COO-]? (Use the HendersonHasselbalch equation.)
16.
a. What is the equivalent weight of Ca(OH)2 ? (hint: formula weight of Ca(OH)2 = 74.10
g/mol.)
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CHM 101
PRACTICE TEST 3
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b. How many equivalents are in 20 grams of Ca(OH)2 ?
c. What is the normality of a solution made by dissolving 5.0 grams of Ca(OH)2 in enough
water to make 450 mL of solution? (Use the normality equation on the help sheet.)
17.
A 25.0 mL solution of an unknown base was titrated with 0.150 N HCl, and 22.0 mL of acid
was needed to reach the end point of the titration. What was the normality of the base? (Use
the titration equation on the help sheet.)
Helpful Information
PV = nRT
Ideal Gas Law
m
MW
PV =
Combined Gas Law
Molarity of a solution:
Percent (wt/vol) solution:
R = 0.0821 L-atm/K-mol
P1V1
T1
=
RT
where m = mass and MW = molecular weight
P2V2
T2
M=
Mols solute
Liter of solution
%=
grams solute
100 mL of solution
Dilution equation:
M1V1 = M2V2
where
=
X 100%
M1 = original concentration
V1 = mLs of original to use
M2 = desired diluted concentration
V2 = desired volume of solution
pH calculations:
To calculate the pH of a solution whose H3O+ concentration is given:
Enter H3O+ concentration
Press the LOG key
Press the +/- key (The answer should always be between 0 and 14!)
To calculate the H3O+ concentration of a solution whose pH is given:
Enter the pH value
Press the +/- key
Press the 10x key (or 2nd LOG).
To calculate H3O+ or OH- concentration when one of the two is given:
Enter 1 EE -14 (that is the same as 1 x 10-14)
Press ÷ (divide key)
Enter the concentration you are given.
Press =
Henderson-Hasselbalch equation
pH = pKa + log
[ A− ]
[ HA]
Normality, N
equivalents of solute
N = -------------------------Liters of solution
Titration Equation
Vacid X Nacid = Vbase X Nbase
where V = volume and N = normality
grams solute
FW solute X Liter of solution