Chemistry Question快 40分!
2011-03-27 2:32 am
1. 30.0cm3 of 0.1 M KOH is completely neutralized by20.0 cm3 of dilute H2 So4to form K2 So4 solution. What is the molarity of the salt solutionobtained? 2. 3.15 gof a solid tribasic acid is dissolved in some distilled water. The solution isthen diluted to 250.0 cm3.25.0 cm3 of the diluted solution require 20.0 cm3 of 0.25 M sodium hydroxide for completeneutralization. What is the molar mass of the tribasic acid?
回答 (2)
2011-03-27 2:57 am
✔ 最佳答案
1. 2KOH + H2SO4 ---> K2SO4 + 2H2ONo. of moles of KOH = 0.1 * 30/1000 = 3.333 mol
No. of moles of K2SO4 = 3.333/2 = 1.667 mol
Molarity of the salt solution K2SO4
= 1.667 * 50/1000
= 0.08333M
2. Let the formula of the tribasic acid be H3A
H3A + 3NaOH ---> Na3A + 3H2O
No. of moles of NaOH
= 0.25 * 20/1000
= 5*10^-3 mol
No. of moles of H3A after dilution
= 5*10^-3 / 3
= 1.667*10^-3 mol
No. of moles of H3A before dilution
= 1.667*10^-3 * 10
= 0.01667 mol
Molar mass of the tribasic acid
= 3.15/0.01667
= 189 g mol^-1
2011-03-26 19:11:25 補充：
Correction
1. No. of moles of KOH = 0.1 * 30/1000 = 3*10^-3 mol
No. of moles of K2SO4 = 3*10^-3 / 2 = 1.5*10^-3 mol
Molarity of the salt solution K2SO4
= 1.5*10^-3 / (50/1000)
= 0.03M
Sorry!
參考: Knowledge is power.
2011-03-27 2:45 am
收錄日期: 2021-04-20 00:18:32
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