CHEM MC

2007-03-03 3:46 am
Which of the following concerning pure ethanoic acid is INCORRECT?

A. It is souble in water
B. It contains hydrogen ions
C.It does not react with magnesium
D.It does not turn dry pH paper red

回答 (2)

2007-03-03 4:10 am
✔ 最佳答案
我會寫 B

A.acid當然soluble in water 啦-.- 唔洗解釋 呢句岩
B.因為e家係 pure ethanoic acid ,即係冇水 pure ethanoic acid 係simple molecular structure,所以o係冇水既情況下 只會有molecule而冇ions 呢句錯
C.pure ethanoic acid 冇水 = 冇h+ 冇h+又點會有反應呢 呢句岩
D.都係果句 冇水...ph paper係度 H+ 濃度 冇水=冇h+ 又點會turns red呢

希望幫到你啦^^"
參考: me
2007-03-03 4:10 am
答案係b
a:凡酸都可以溶o係水
c:冇溶o係水o既酸係冇酸o既特性,唔會同金屬有反應
d:冇溶o係水o既酸唔會有H+,唔會用石蕊試紙o既chemical反應變成紅色

點解係b??
因為純酸係以共價鍵(covalent bond)存在
水可以將酸離子化(ionize),生成氫離子hydrogen ion

2007-03-02 20:14:36 補充:
有更正..純酸係以共價結構存在總括黎講純酸完全冇酸o既特性,唔會有H
參考: 中四化學常識


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