chem buffer

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When the following solutions are mixed, which will act as a buffer? (check all that apply)

A. 50 mL of 0.05M sodium hydroxide and 50 mL of 0.1M nitrous acid

B. 50 mL of 0.1M ammonia and 50 mL of 0.1M ammonium acetate

C. 50 mL of 0.1M ammonia and 50 mL of 0.05M nitric acid

D. 50 mL of 0.1 M sodium chloride and 50 mL of 0.1M sodium acetate

E. 50 mL of 0.05M sodium hydroxide and 50 mL of 0.1M nitric acid

• chem buffer -

A buffer is a solution of
a. a weak acid and its base (salt).
b. a weak base and its acid(salt).
Acetic acid/sodium acetate
NH3 and NH4Cl

• chem buffer -

A. 50 mL of 0.05M sodium hydroxide and 50 mL of 0.1M nitrous acid

First, write the equation, then set up an ICE chart.
NaOH + HNO2 ==> NaNO2 + H2O
2.5....5.0...... 0.......0 initial
-2.5...-2.5......+2.5....+2.5 change
0......2.5.......2.5.....2.5 final

The table with the equation comes from the following data:
mmoles NaOH = 50 x 0.05 = 2.5 mmoles.
mmoles HNO2 = 50 x 0.1 = 5 mmoles.

From the final solution, you can see you have some HNO2 and its salt; that is a weak acid and its salt. Therefore, this is a buffered solution.

• chem buffer -

abcd

• chem buffer -

A & D

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