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In part of the lab, I will b doing the following for measuring "Ka" for ethanoic acid using the indicator method:

1- Mix ethanoic acid (0.02M, 5cm3) and sodium ethanoate (0.02M, 5cm3).

2- Add bromocresol green (10 drops) and mix thoroughly.

And, in the introduction to the lab, I'm given this information:

Hln(aq) <-----> H+(aq) + ln-(aq)

ka(Hln) = [H+][ln-] / [Hln]

ka(Hln) for bromocresol green = 2 x 10^-5 mol dm-3

Provided that, how can I answer those questions:

1- What is the ratio of [ln-]/[Hln] in the CH3COOH/CH3COONa mixture?

2- Using this equation "ka(Hln) = [H+][ln-] / [Hln]", calculate [H+] in the CH3COOH/CH3COONa mixture.

3- What is the value of Ka for ethanoic acid?

Thanks.