Question

What would the initial pH of a carbonic acid - bicarbonate (Ka=4.27 x 10-7) buffer be if the ratio of conjugate base to acid is 0.366 to 1?
A.
1.67
B.
1.81
C.
5.79
D.
5.85
E.
5.93

Answer 1

Answer:

E. 5.93

Explanation:

#Plato

Use the Henderson-Hasselbalch equation:

pH = pKa + log$(\frac{[A^-]}{[HA]})$, where A^- is the concentration of the conjugate base of the weak acid & HA is the concentration of the acid.

                    Quick note: A^- = bicarbonate and HA = carbonic acid.

Plug the known numbers into the equation:  

pH = 4.27 x 10^-7 + log$(\frac{0.366}{1} )$

Remember, the 4.27 x 10^-7 is Ka, to change it to pKa use: -log[Ka] and pKa will be 6.37.

Thus,

pH = 6.37 + log(0.366) = 5.93305321

5.93 is the intial pH

Answer 2

5.93 is the initial pH. Hence, option E is correct.

What is pH?

A figure expressing the acidity or alkalinity of a solution on a logarithmic scale on which 7 is neutral, lower values are more acid and higher values more alkaline.

Use the Henderson-Hasselbalch equation:

pH = pKa + log$\frac{[A^-]}{[HA]}$, where $A^-$is the concentration of the conjugate base of the weak acid & HA is the concentration of the acid.

Quick note: $A^-$ = bicarbonate and HA = carbonic acid.

Plug the known numbers into the equation:  

pH = 4.27 x $10^{-7}$ + log$\frac{[0.366]}{[1]}$

Remember, the 4.27 x $10^{-7}$ is Ka, to change it to pKa use:

-log[Ka] and pKa will be 6.37.

Thus,

pH = 6.37 + log(0.366) = 5.93305321

5.93 is the intial pH

Learn more about pH here;

brainly.com/question/12294404

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