Question

Problem PageQuestion A student prepares a aqueous solution of butanoic acid . Calculate the fraction of butanoic acid that is in the dissociated form in his solution. Express your answer as a percentage. You will probably find some useful data in the ALEKS Data resource.

Answer 1

Answer:

Incomplete question: A student prepares a 0.54 mM aqueous solution of butanoic acid...

The answer is: The percentage of dissociation is 15.4%

Explanation:

Given:

Ka = 1.51x10⁻⁵

Concentration = 0.54 mM = 0.54x10⁻³M

The reaction is:

                   C₄H₈O₂               =             C₄H₇O₂⁻          +           H⁺

I                    0.54x10⁻³                             0                                0

E                   0.54x10⁻³(1-x)                      0.54x10⁻³x                0.54x10⁻³x

Where x is the degree of dissociation

$Ka=\frac{[H^{+}][C_{4}H_{7}O_{2}^{-} }{[C_{4}H_{8}O_{2} } \\1.51x10^{-5} =\frac{0.54x10^{-3}x^{2} }{1-x} \\x^{2} +0.028x-0.028=0\\x_{1} =0.154\\x_{2} =-0.182$

We will choose the positive value

x = 0.154

The percentage of dissociation is 15.4%