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BELLARMINE COLLEGE
DEPARTMENT OF CHEMISTRY AND PHYSICS
CHEM115 - GENERAL, ORGANIC, AND BIOLOGICAL CHEMISTRY II
EXAM #3
4/1 3/00
NAME:___________________________
Time: 50 minutes
Do all the following questions. Please read each question carefully and apportion your time according to the relative
worth of the question (shown in parenthesis after the question). Write legibly. Marks will be deducted for unclear,
messy and illegible work. You must show all calculations (including units) where appropriate. Also, remember to
show answers to the correct number of significant figures. Answer in the space provided after each question. The
total marks for this exam is 60.
1. Aqueous solutions of nitric acid are often made up by dissolving an appropriate amount of concentrated nitric
acid in the required amount of water. Concentrated nitric acid is 90.0% (v/v). How many milliliters of
concentrated nitric acid (HNO3) would you need to prepare 500.0 mL of a 0.850 M HNO3 solution? The density of
nitric acid is 1.574 g/mL. Hint: convert % (v/v) to mol/L first. (8)
(90.0 ml HNO3/100.0 mL sol.) x (1.574 g HNO3/ml HNO3) x (mol HNO3/63.01 g HNO3)
= 2.248 mol HNO3/100.0 mL sol.
(2.248 mol HNO3/100.0 mL solution) x 10 = 22.48 mol HNO3/1000 mL = 22.48 M HNO3
M1V1 = M2V2 and V1 = M2V2/M1 = (0.850 M x 500.0 mL)/22.48 M = 18.9 mL (to 3 SF)
2. You now need 1.50 L of a 0.150 M HNO 3 solution. How many milliliters of the 0.850 M HNO 3 solution you
made in Q1 would you need to make this new solution? (3)
M1V1 = M2V2 and V1 = M2V2/M1 = ((0.150 M x 1.50 L)/0.850 M) x (1000 mL/L) = 2.65 x 102 mL (to 3 SF)
3.
Identify the reactants as Lowry-Bronsted acids and bases in the following equations. (6)
a) H2PO4- + NH4+  H3PO4 + HN3
b) NH3 + H2O  NH4+ + OHc) CO32- + H2SO4  H2CO3 + SO42-
4.
What is the pH of the following solutions? Which ones are acidic and which ones are basic? (8)
a) [H3O+] = 3.46 x 10-3 M
2.46
acidic
b) [H3O+] = 8.15 x 10-11 M
10.09
basic
c)
[OH-] = 2.98 x 10-5 M
d) [OH-] = 7.00 x 10-10 M
[H3O+] = 3.36 X 10-10 M Ph = 9.47
basic
[H3O+] = 1.43 X 10-5 M
acidic
Ph = 4.85
5.
What are [H3O+] and [OH-] for the following solutions? (6)
a)
pH = 1.56
b) pH = 12.87
6.
[H3O+] = 0.0275 M
[OH-] = 3.63 x 10-13 M
[H3O+] = 1.35 x 10-13 M
[OH-] = 0.0741 M
Hypochlorous acid, HClO, is a weak acid. Write an equation for its ionization in water. (1.5)
HClO + H2O  ClO- + H3O+
7.
Write the balanced equation for the neutralization of HCl by Ba(OH)2. (2.5)
2HCl + Ba(OH)2  BaCl2 + 2H2O
8.
A 10.0-mL sample of H3PO4 (phosphoric acid) requires 35.7 mL of a 0.110 M NaOH for complete
neutralization. (6)
a)
Write the balanced chemical equation for the neutralization. Remember that H3PO4 has 3 acidic protons.
H3PO4 + 3NaOH  Na3PO4 + 3H2O
b) What is the molarity of the H3PO4 solution?
Moles NaOH = (0.110 mol NaOH/L) x 35.7 mL x (L/1000 mL) = 3.927 x 10 -3 mol NaOH
Moles H3PO4 = 3.927 x 10-3 mol NaOH x (1 mol H3PO4/ 3 mol NaOH) = 1.309 x 10-3 mol H3PO4
Molarity H3PO4 = (1.309 x 10-3 mol H3PO4/10.0 mL) x 1000 ml/L = 0.131 M H3PO4 (to 3 SF)
9.
Give 4 reasons why carbon (of all the elements) is unique in having its own field of chemistry (organic). Use
specific examples to illustrate each of your 4 reasons. (10)
See lecture notes
10. Match the following functional groups to the given organic compounds. (9)
FUNCTIONAL GROUP
CARBOXYLIC ACD
ALDEHYDE
ALKENE
KETONE
ALKYNE
ALCOHOL
COMPOUND
G
K
C
E
H
B
FUNCTIONAL GROUP
AROMATIC HYDROCARBON
ALKANE
HALOALKANE
PHENOL
ETHER
COMPOUND
A
J
F
I
D
O
CH3CH=CH2
CH3CH2OH
A.
B.
CH3OCH3
C.
CH 3
D.
O
E.
H
CCH 3
CH3CH2Cl
F.
CH 3
OH
HC
CH 3
CH 3
C
O
CH 3
CH 3
OH
H
CH 3
G.
H.
I.
J.
K.