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Lecture 86 Buffer Solutions.notebook
1
July 26, 2012
Feb 159:25 PM
1 If 50.0 g of formic acid (HCHO2, Ka = 1.8 x 104) and 30.0 g of sodium formate (NaCHO2) are dissolved to make 500 mL of solution, the pH of this solution is
A 4.76
B 3.76
C 3.35
D 4.12
E 3.02
Lecture 86 Buffer Solutions.notebook
2
July 26, 2012
Lecture 86 Buffer Solutions.notebook
3
July 26, 2012
Feb 159:29 PM
2 A buffer with a pH of 10.0 is needed. Which of the following should be used?
A acectic acid with a Ka of 1.8 x 105
B ammonia with a Kb of 1.8 x 105
C nitrous acid with a Ka 7.1 x 104
D H2PO4 and PO43 with a Ka of 4.5 x 1013
E dimethylamine with a Kb of 1.05 x 103
Feb 159:33 PM
3 A buffer has a pH of 4.87. If the buffer is made from a weak acid (Ka = 3.30 x 105), and its conjugate base, the [conjugate base]/[weak acid] ratio is
A 4.87
B 4.47
C 1.00
D 2.45
E 0.41
Feb 159:34 PM
4 pH is equal to pKa
A when [conjugate acid] = [conjugate base]
B at the endpoint of a titration
C in the buffer region
D in the Henderson Hasselbach equation
E at equilibrium
Feb 159:37 PM
5 Which of the following is the correct method for preparing a buffer solution?
A Mix the correct amounts of a weak acid and its conjugate base.
B Neutralize a weak base partially with strong acid.
C Neutralize a weak acid partially with a strong base.
D Add the appropriate amount of strong acid to an acid salt
E All of the above methods may be used to prepare buffers.