Cliffs AP Chemistry, 3rd Edition

8. A solution is prepared by adding 0.600 liter of 1.0 × 10 –3M HCl to 0.400 liter of
   1.0× 10 –3M HNO 3. What is the pH of the final solution?

A. 1.00

B. 2.00

C. 3.00

D. 4.00

E. 5.00

Answer: C

First, determine the volume of the mixture.

0.600 liter + 0.400 liter = 1.000 liter

Next, determine the concentration of each acid.

HCl:.

..

100.

0 600 1 0 10

liter 0 000600

liter M

M

##^3

=

HNO 3 :.

..

liter.

liter M

100 M

0 400 1 0 10

0 000400

##^3

=

Because both acids are strong (and monoprotic), the H+concentration is equal to the
concentration of the acid. Therefore, [H+] = 6.00 × 10 –4M + 4.00 × 10 –4M = 1.00 × 10 –3M,
and pH = −log[H+] = 3.00.

9. Suppose that 0.500 liter of 0.0200 M HCl is mixed with 0.100 liter of 0.100 M Ba(OH) 2.
   What is the pH in the final solution after neutralization has occurred?

A. 3.00

B. 5.00

C. 7.00

D. 9.00

E. 12.00

Answer: E

Step 1: Write a balanced reaction.

2 HCl + Ba(OH) 2 →BaCl 2 + 2 H 2 O

Step 2: Calculate the number of moles of H+.

..

0 500

1

liter 0 0200 100 10

liter

##mole= -+^2 mole H

Part II: Specific Topics