Calculate the pH of a solution that results from t

Question

Calculate the pH of a solution that results from the mixing of 25.00 ml of 0.028 M benzoic acid with 15.00 ml of 0.025 M NaOH (  the Ka for benzoic acid is 6.3 x 10-5)

Jules Bruno · Accepted Answer

Reaction:  HC7H5O2 (aq) + NaOH(aq) ⇌ NaC7H5O2(aq) + H2O (l)molarity (volume) → molesRecall:M=molLmoles HC7H5O2=25 mL×10-3 L1 mL×0.028 mol HC7H5O2L= 7.00 x 10-4 mol HC7H5O2moles NaOH=15.00 mL×10-3 L1 mL×0.025 mol NaOH1 L= 3.75 x x 10-4 mol NaOHICF Chart:After the reaction is complete the solution contains:▪3.75 x 10-4 mol NaC7H5O2 → salt of onjugate baseNaC7H5O2 → Na+ + C7H5O2-▪ 3.25 x 10-4 mol HC7H5O2 → weak acid▪ weak acid + conjugate base = we still have a bufferHenderson-Hasselbalch Equation to calculate for pH of buffers: pH=pKa+logconjugate baseweak acidpKa=-log KapH=-log Ka+log conjugate baseweak acidpH=-log 6.3×10-5+log 3.75×10-4 mol3.25×10-4 molpH=4.20+log (1.154)pH=4.20+(0.062)pH = 4.26The pH of the resulting solution after titration of benzoic acid with NaOH is 4.26.

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Calculate the pH of a solution that results from the mixing of 25.00 ml of 0.028 M benzoic acid with 15.00 ml of 0.025 M NaOH ( the Ka for benzoic acid is 6.3 x 10-5)

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Calculate the pH of a solution that results from the mixing of 25.00 ml of 0.028 M benzoic acid with 15.00 ml of 0.025 M NaOH ( the Ka for benzoic acid is 6.3 x 10-5)

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