1. 20 cm3 of methanoic acid (Ka = 1.8 x 10-4 moldm-3) of concentration 0.10 moldm-3 is titrated against sodium hydroxide of concentration 0.05 moldm-3.
a) Calculate the pH of the solution:
i) initially
i've redone this so many times i'm not sure why im getting it wrong.
The answer on the site said it was pH 2.37
ALEVEL CHEMISTRY QUESTION!!! ph initially?
2017-05-05 6:38 pm
回答 (1)
2017-05-05 6:59 pm
✔ 最佳答案
In order to calculate the initial pH - that is the pH of the acid - user the Ka equation to calculate H+. HCOOH dfissociates
HCOOH ↔ H+ + HCOO-
Ka = [H+] [HCOO-] /[HCOOH]
[H+] = [HCOO-] and the dissociation is small , we can write
1.8*10^-4 = [H+]² / 0.10
[H+]² = (1.8*10^-4)*0.1
[H+]² = 1.8*10^-5
[H+] = 4.2*10^-3M
pH = -log [H+]
pH = -log ( 4.2*10^-3)
pH = 2.37
收錄日期: 2021-04-24 00:25:13
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20170505103852AA8SpkU