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pH After Titrations - Ionic Equilibria

1. Calculate the pH after 25.0 mL of .20 M HF (Ka=6.8 10-4) are titrated with 15.0 mL of .10 M NaOH?

2. Calculate the pH after 25.0 mL of 2.0 M HF is titrated with 50.0 mL of 1.0 M NaOH?

Solution Preview

1. Calculate the pH after 25.0 mL of 0.20 M HF (Ka=6.8à?10-4) are titrated with 15.0 mL of 0.10 M NaOH?

It would have be nice to see how you worked your solutions, nevertheless, here we go!

HF + NaOH ----> NaF + H2O

(0.025 L)(0.20 mol/L) = 0.005 moles HF to start

(0.015 L)(0.10 mol/L) = 0.0015 moles NaOH added

Therefore, after the reaction is over, we have 0.005 - 0.0015 = 0.0035 moles HF leftover and 0.0015 moles NaF formed. Of course, there's no NaOH in the solution since we haven't made it to the equivalence point yet. Therefore, all the NaOH got used up.

We're left with a ...

Solution Summary

Almost 400 words and many lines of calculations to solve 2 problems calculating the pH of a solution after titration.

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