1.if the pH value for a 10 mL solution containing 0.1M HA,after adding
5 mL 0.1M NaOH is 4.5,what is the pKa for HA?
選項有A)4.0 B)5.0 C)5.5 D)6.0
夭壽我算出來是7.5= =''
我的算法:
( 0.1x0.01－0.1x0.005)/0.015=0.033
x^2/(0.033-x)=Ka x = [H+] = 3.16x10^-5 代回前式,分母的x省略
求出來pKa就變成7.5了
請問我的算法/觀念是不是有問題@口@
2.what is the major species for H3A at pH = 6.0 ? (pKa1=2, pKa2=5, pKa3=9)
A) H+ B)H3A C)H2A- D) A3-
我是假設H3A的初始濃度是1M...Ka1=0.01 所以[H2A-]=0.1 [H3A]就是0.9了吧
我覺得是B欸
可是有幾個同學覺得是A的說,不過沒說為什麼@@
麻煩解答+提供解釋....謝謝!
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