pH of the acid sample

A 0.0200 mol dm⁻³ H2SO4sample was prepared. What was the pH of the acid sample?

H2SO4 is a dibasic strong acid. 1 mole of H2SO4completely ionized in water to give 2 moles of hydrogen ions.
H2SO4(aq) → 2H⁺(aq) + SO4²⁻(aq)

Conc. of H2SO4 = 0.0200 mol dm⁻³
Conc. of H⁺ ions produced, [H⁺] = 0.0200 x 2 =0.0400 mol dm⁻³

Hence, pH = -log[H⁺] = -log(0.0400) = 1.4


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sea water and tap water的pH是不是neutral的7呢？

ThepH of seawater and that of tap water depend on the substances dissolved inthem.

The pH of seawater is typically limited to a range between 7.5 and 8.4.

The pH of tap water varies from town to town. In Hong Kong, chlorine andhydrated lime are added to drinking water for disinfection and pH adjustment.The pH of tap water in Hong Kong is around 6 to 8.

2014-08-08 14:15:05 補充：
點解一睇就知要寫條equation出黎? 我只係見到....sample was prepared ……點知佢係用dissociation in H2O 呢個case?麻煩你了！

題目給了 H2SO4 的 molarity，但要知道 the molariyt of hydrogen ions 先至計算到 pH 。因此要寫出 equation，目的是要知道 1 M 的 H2SO4 會 ionizes/dissociates 出多少 M 的 hydrogen ions。

2014-08-08 14:21:46 補充：
concentration of hydrogen ions of that solution 同concentration of that solution有分別嗎？係咪其中一個高,第二個就都會高呢？

前者是指在 solution 中 hydrogen ions 的 concentration。

後者是指在 solution 中 solute (本題是 H2SO4) 的 concentration。

後者 ionizes/diissociates 產生前者。因此，後者愈高，前者愈高。

haha如果可以,你也可回答我剛post出來的問題!
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