Chapter 9: Q6P (page 208)

Find theand fraction of dissociation ( a ) of a $0.100 M$ solutionof the weak acid $HA$ with $Ka = 1.00 \times 10^{- 5}$

Short Answer

Expert verified

The pH of the weak acid HA is 3.0.

The fraction of disassociation (α) is 9.95 × 10^-3.

Step by step solution

Step: Definition of disassociation and pH.

Disassociation is the process of breaking up of compound into simpler form that are capable of re-combing under other conditions.

pH is defined as a quantitative measure of acidity and basicity. Compounds having pH more than 7 is acidic in nature while pH when shown above than 7 is basic in nature. When comes 7, compound is said to be neutral.

Step: Consider value of [HA].

The value of $Ka = 1.00 \times 10^{- 5}$ is given in the question.

So,

We will consider that:

$x = [H^{+}] = [A^{-}] 0.1 - x = [HA]$

Step: Calculating pH

$K_{A} = \frac{x^{2}}{0.1 - x} 1.00 \times 10^{- 5} = \frac{x^{2}}{0.1 - x} x = 9.95 \times 10^{- 4} M$

Now, consider that

$X = [H^{+}] = [A^{-}],$

the pH would be:

$pH = - \log (X) pH = - \log [H^{+}] pH = - \log (9.95 \times 10^{- 4}) = 3.00$

Calculate fraction of disassociation.

$X = [A^{-}] = 9.95 \times 10^{- 4} 0.1 - X = [HA] 0.1 - (9.95 \times 10^{- 4}) a = \frac{[A^{-}]}{[A^{-}] + [HA]} = \frac{9.95 \times 10^{- 4}}{9.95 \times 10^{- 4} + (0.1 - 9.95 \times 10^{- 4}))} a = 9.95 \times 10^{- 3}$

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Find theand fraction of dissociation ( a ) of a $0.100 M$ solutionof the weak acid $HA$ with $Ka = 1.00 \times 10^{- 5}$

Short Answer

Step by step solution

Step: Definition of disassociation and pH.

Step: Consider value of [HA].

Step: Calculating pH

Calculate fraction of disassociation.

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Find theand fraction of dissociation ( a ) of a 0.100Msolutionof the weak acid HAwith Ka=1.00×10-5

Short Answer

Step by step solution

Step: Definition of disassociation and pH.

Step: Consider value of [HA].

Step: Calculating pH

Calculate fraction of disassociation.

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Chemistry Textbooks

Kinetics

Chemistry Branches

Chemical Reactions

The Earths Atmosphere

Ionic and Molecular Compounds

Organic Chemistry

Study anywhere. Anytime. Across all devices.

Find theand fraction of dissociation ( a ) of a $0.100 M$ solutionof the weak acid $HA$ with $Ka = 1.00 \times 10^{- 5}$