omework assignment is worth 20 points. HOL Consider the titration of 20.0 mL of
ID: 1038961 • Letter: O
Question
omework assignment is worth 20 points. HOL Consider the titration of 20.0 mL of a 0.100 M aqueous solution o strong monoprotic acid) with a 0.12 base). Calculate the pH of the solution at each of thè following points: f hydrochloric acid (HCI: a queous solution of sodium hydroxide (NaOH: a strong HCL 20wlO.IM Na0. 1. Before any base has been added to the solution. 2. Halfway to the equivalence point. 3. At the equivalence point. 4. After the addition of 10.0 mL of base past the equivalence point. 5. Sketch the form of the titration curve with important points.Explanation / Answer
1) before addition of NaOH ,
pH = -log(H3O+)
= -log(0.1)
= 1
2) no of mol of HCl taken = 20*0.1 = 2 mmol
at halfway to the equivalence point
no of mol of NaOH added = 1 mmol
volume of NaOH added = 1/0.12 = 8.33 ml
concentration of excess HCl = (2-1)/(28.33) = 0.0353 M
pH = -log(H3O+)
= -log(0.0353)
= 1.45
3) at equivalence point
pH = 7 (because HCl,NaOH - are strong acid,bases)
4) no of mol of HCl taken = 20*0.1 = 2 mmol
no of mol of NaOH required to reach equivalence point = 20*0.1 = 2 mmol
volume of NaOH required to reach equivalence point = 2/0.12 = 16.66 ml
concentration of excess NaOH = (10*0.12)/(20+26.66) = 0.026 M
pH = 14 - (-log(OH-))
= 14 - (-log(0.026))
= 12.4
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