Chapter 9: Q22P (page 209)

Calculate the fraction of association (α) for 1.00 × 10^-1, 1.00 ×10^-2, and 1.00 ×10^-12 M sodium acetate. Does α increase or decrease with dilution?

Short Answer

Expert verified

The fraction of dissociation, $a = 0.0076 %, 0.024 %, and 0.57 %$ .

Step by step solution

Definition of association.

It is defined as the aggregation of atoms or molecules into larger units.

Step: Consider a reaction.

${CH}_{3} {CO}_{2}^{-} + H_{2} O ⇌ {CH}_{3} {CO}_{2} H + {OH}^{-} [{CH}_{3} {CO}_{2}^{-}] = F - x [{CH}_{3} {CO}_{2} H] = [{OH}^{-}] = x$

Calculating value of Kb .

We will use this equation for following:

$K_{b} = \frac{x^{2}}{F - x} F = 10^{- 1} x = 7.6 \times 10^{- 6} F = 10^{- 2} x = 2.4 \times 10^{- 6} F = 10^{- 12},$

We can see that dilution is so high that $pH = 7$ we can use the following:

localid="1654945563356" $[HA] = \frac{K_{b} [A^{-}]}{[{OH}^{-}]} = 5.7 \times 10^{- 3} [A^{-}]$

Calculate fraction of dissociation.

$a = \frac{[HA]}{[HA] + [A^{-}]} = \frac{5.7 \times 10^{- 3} [A^{-}]}{(5.7 \times 10^{- 3} [A^{-}]) + [A^{-}]} a = 0.57 %$

Now, we can conclude that more the dilution of solution greater the fraction of dissociation.

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Calculate the fraction of association (α) for 1.00 × 10^-1, 1.00 ×10^-2, and 1.00 ×10^-12 M sodium acetate. Does α increase or decrease with dilution?

Short Answer

Step by step solution

Definition of association.

Step: Consider a reaction.

Calculating value of Kb .

Calculate fraction of dissociation.

One App. One Place for Learning.

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Calculate the fraction of association (α) for 1.00 × 10-1, 1.00 ×10-2, and 1.00 ×10-12 M sodium acetate. Does α increase or decrease with dilution?

Short Answer

Step by step solution

Definition of association.

Step: Consider a reaction.

Calculating value of Kb .

Calculate fraction of dissociation.

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Chemistry Textbooks

Making Measurements

Nuclear Chemistry

Chemical Analysis

Ionic and Molecular Compounds

Chemistry Branches

The Earths Atmosphere

Study anywhere. Anytime. Across all devices.

Calculate the fraction of association (α) for 1.00 × 10^-1, 1.00 ×10^-2, and 1.00 ×10^-12 M sodium acetate. Does α increase or decrease with dilution?