酸和碱的电离
化学物质的电离是中性分子在暴露于溶液时分解成带电离子的过程。根据 Arrhenius 理论,酸是在水介质中离解产生氢离子 H +的物质。因为大多数电离发生在水介质中,阿伦尼乌斯的理论在解释酸和碱电离方面很重要。酸和碱的强度可以根据酸和碱的电离程度来定义。此外,电离程度在酸性和碱性物质之间有所不同。在水性介质中,少数酸,如盐酸 (HCl) 和高氯酸 (HClO 4 ),完全解离成它们的组成离子。
Arrhenius 酸碱电离的解释
该响应表明酸解离平衡是动态的,质子转移发生在正向和反向。因为HA比H 3 O +具有更大的产生质子的倾向,所以与H 3 O +相比,它表现为强酸。因为更强大的酸将质子捐赠给更强大的碱。平衡转向产生较弱的酸和较弱的碱。强酸具有较弱的共轭碱,而强碱具有较弱的共轭酸。由于强酸和强碱的高度电离,会发生这种情况。
化合物的电离
另一方面,碱是在水性介质中提供羟基离子 OH –的化学物质。酸和碱的电离程度有助于它们的强度。电离程度可能因酸性和碱性物质而异。
酸的电离
电离度是指酸或碱的酸度或碱度。强酸在水中完全电离,而弱酸只是部分电离。由于酸的电离程度不同,弱化程度也不同,可以定量表示。因为弱酸的电离是一个平衡过程,所以化学方程式和平衡常数的表达式如下:
HA (aq) + H 2 O -> H 3 O + (aq) + A –
K a = [H 3 O + ] [A – ] / [HA]
酸电离常数由酸电离的平衡常数 (K a ) 定义。然而,酸电离常数越大,酸越强。因此,强酸是优良的质子供体。由于产物在 Ka 分子中的浓度,酸电离常数越大,酸 (K a )越强。
碱基的电离
在水溶液中,一些碱,如氢氧化锂或氢氧化钠,完全解离成它们的离子,称为强碱。结果,这些碱的电离产生盐酸离子,表示为(OH - )。对于碱基,等效的短语是:
A + H 2 O ⇢ OH - + HA +
K b = [OH – ] [HA + ] / [A]
碱基电离常数,缩写为 K b ,是碱基电离的平衡常数。因此,强碱意味着良好的质子受体,而强酸意味着良好的质子供体。弱酸和弱碱在水中的离解如下:
CH 3 COOH + H 2 O ⇔ CH 3 COO ‾ + H 3 O +
NH 3 + H 2 O ⇔ NH 4 + (aq) + OH ‾ (aq)
示例问题
问题 1:您对碱基电离了解多少?
回答:
In an aqueous media known as a strong base, some bases, such as lithium hydroxide and sodium hydroxide, are totally dissociated into ions. As a result, the ionisation of these bases results in the formation of hydrogen chloride ions, such as (OH–).
问题2:酸和碱的坏处是什么?
回答:
Chemicals, both acids and bases, can be corrosive if tasted or touched. Acids and bases can cause skin burns. Acids are sourer and have a dry or gritty sensation, whereas bases are bitter and have a slippery or soapy feel.
问题 3:什么是酸和碱?
回答:
Acids have a highly sour flavour. Orange juice and lemon juice are two examples of acids. Acetic acid is found in lemons and other citrus fruits. As a result, anything with a sour flavour can be classified as an acid. Bases have a more harsh flavour. As an example of a base, consider soap (made of magnesium hydroxide or potassium salts). As a result, everything with a bitter flavour is a base.
问题4:您对酸电离的理解是什么?
回答:
The degree of ionisation is determined by the acid or base strength. Strong acids are totally ionised in water, whereas weak acids are just partially ionised. Because the degree of acid ionisation varies, so does the degree of weakening.
问题 5:您如何知道某物是否完全电离?
回答:
The degree of ionisation value indicates whether or not the substance is totally ionised. The ratio of the number of molecules undergoing dissociation to the total number of molecules is referred to as the degree of ionisation. When the degree of dissociation value is 1, the molecule is totally ionised.