Acid_base


ANSWERS ARE GIVEN IN BOLD!

Start Date:     24 Jul 2008 at 01:00 PM
Due Date:     31 Jul 2008 at 01:00 AM
Student Access after Due Date:    Yes. View Only
Graded:    Yes

EOC Problem 9.4

Give the formula for the conjugate base of each acid.
a. H2CO3
HCO3-
b. HCO-3
CO32-
c.H2SO4
HSO4-
d. H2PO4-
PO43-

EOC Problem 9.10

Identify the Brønsted-Lowry acids and bases for the forward and reverse reactions of each.
a. PO43-(aq) + NH4+(aq) <=> NH3(aq) + HPO42-(aq)?

Forward reaction
acid: NH4+
base: PO43-
b. PO43-(aq) + NH4+(aq) <=> NH3(aq) + HPO42-(aq)?

Reverse reaction
acid: HPO42-
base:  NH3
c. HCN(aq) + H2PO4-(aq) <=> CN-(aq) + H3PO4(aq)

Forward reaction
acid: HCN
base: H2PO4-
d. HCN(aq) + H2PO4-(aq) <=> CN-(aq) + H3PO4(aq)

Reverse reaction
acid: H3PO4
base: CN-

EOC Problem 9.14

Which of the following statements are correct at equilibrium?

 a. The forward and reverse reactions stop.

b. The concentration of reactants and products does not change.

c. The rate of the forward reaction is greater than the rate of the reverse reaction.

EOC Problem 9.30

Calculate the H3O+ concentration present in water when
a. [OH-] = 5.8 x 10-7 M
*1 M

Significant digits are disabled; the tolerance is +/-2%

b. [OH-] = 7.8 x 10-7 M
*1 M

Significant digits are disabled; the tolerance is +/-2%

c. [OH-] = 4.8 x 10-8 M
*1 M

Significant digits are disabled; the tolerance is +/-2%

EOC Problem 9.34

Calculate the OH- concentration present in water when
a. [H3O+] = 5.9 x 10-8 M
*1 M

Significant digits are disabled; the tolerance is +/-2%

b. [H3O+] = 5.2 x 10-2 M
*1 M

Significant digits are disabled; the tolerance is +/-2%

c. [H3O+] = 5.6 x 10-8 M
*1 M

Significant digits are disabled; the tolerance is +/-2%

EOC Problem 9.36

Indicate whether each solution is acidic, basic, or neutral, when
a. [H3O+] = 4.7 x 10-8 M
b. [H3O+] = 9.8 x 10-8 M
c. [H3O+] = 6.0 x 10-7 M


EOC Problem 9.68

If you wish to maintain a pH of 6.0, which is the better buffer, H2CO3 and HCO3- or H2PO4- and HPO42-?

H2PO4- and HPO42-

H2CO3 and HCO3-

EOC Problem 9.70

At which pH is the H2CO3/HCO3- buffer system most effective?
*1 -*2

Answer *1: significant digits are disabled; the tolerance is +/-2%
Answer *2: significant digits are disabled; the tolerance is +/-2%



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