为什么soap和detergent是alkali?

mini-torres

alkali是compound that produce OH ion when dissolve in water ...
soap和detergent dissolve in water时有produce OH ion吗？

@res

有啊

mini-torres

有咩  举一个例子：sodium palmitate  CH3(CH2)14COONa怎样PRODUCE OH ion???

@res

这应该要用lewis acid theory来解释。不过我不会解释 不好意思

morphv02c01

Let your sodium palmitate be R-COONa (makes me easy to type)
R-COONa will dissociate into R-COO- and Na+
R-COO- is a strong conjugate base of it's acid (R-COOH) (weak acid)
Therefore hydrolysis occurs : R-COO- + H2O ---> R-COOH + OH-  the presence of excess OH- ions makes the solution alkaline..

staycool

当soap和detergent是固体＝neutral
但是参了水（H2O）就变成液体才有属性
H2O分解去 H ion+OH ion.....那么就有OH ion了

-HwLnG-

原帖由 morphv02c01 于 8-6-2008 02:20 PM 发表
Let your sodium palmitate be R-COONa (makes me easy to type)
R-COONa will dissociate into R-COO- and Na+
R-COO- is a strong conjugate base of it's acid (R-COOH) (weak acid)
Therefore hydrolysis occ ...

good explaination. *clap*

staycool

哦。。。

恶天使

原帖由 morphv02c01 于 8-6-2008 02:20 PM 发表
Let your sodium palmitate be R-COONa (makes me easy to type)
R-COONa will dissociate into R-COO- and Na+
R-COO- is a strong conjugate base of it's acid (R-COOH) (weak acid)
Therefore hydrolysis occ ...

R-COOH(Carboxylic acid)又会不会再分解出H+ ions?

科学就是未来

原帖由 mini-torres 于 5-6-2008 12:15 PM 发表
alkali是compound that produce OH ion when dissolve in water ...
soap和detergent dissolve in water时有produce OH ion吗？

美国里有 acidic detergent

detergent =/= alkaline

原帖由 恶天使 于 3-8-2008 05:44 PM 发表


R-COOH(Carboxylic acid)又会不会再分解出H+ ions?

R-COOH can produce H+ in water, but just a reverseible reaction, so it is a weak acid

[ 本帖最后由 科学就是未来 于 3-8-2008 08:10 PM 编辑 ]

kokleong89

原帖由 mini-torres 于 6-6-2008 10:17 PM 发表
有咩  举一个例子：sodium palmitate  CH3(CH2)14COONa怎样PRODUCE OH ion???

来让我叫大家一个简单的辨认salt是acidic, basic 或neutral。

CH3(CH2)14COO - 是来自非常弱的acid(CH3(CH2)14COOH). it's weak acid.
Na+ 是来自非常强的base(NaOH). it's strong base.
当 CH3(CH2)14COOH + NaOH =  CH3(CH2)14COONa + H2O
              acid                        base                    salt
它的salt就是basic， 也就是碱性。（我们要看它来自哪一个比较强）

[ 本帖最后由 kokleong89 于 27-12-2008 12:53 PM 编辑 ]

TKCboy

soap and detergent 不一定是alkali de, acid also can de..