Acids and Alkalis | 酸与碱

📚 Acids and Alkalis | 酸与碱

Acids and alkalis are two important groups of chemicals that we meet in everyday life and in the laboratory. They have opposite properties, and understanding them helps explain processes from cooking to cleaning to digestion.

酸和碱是我们在日常生活和实验室中都会遇到的两类重要化学物质。它们性质相反，理解它们有助于解释从烹饪、清洁到消化等许多过程。

1. What Are Acids and Alkalis? | 什么是酸和碱？

An acid is a substance with a pH lower than 7. In solution, acids release hydrogen ions, H⁺. Many acids taste sour, but you should never taste chemicals in the laboratory.

酸是 pH 值低于 7 的物质。在溶液中，酸会释放氢离子 H⁺。许多酸尝起来是酸的，但在实验室中绝不能品尝化学药品。

An alkali is a soluble base with a pH higher than 7. Alkalis release hydroxide ions, OH⁻, in solution. They often feel soapy and can be just as hazardous as acids.

碱是一种可溶于水的碱类物质，pH 值高于 7。碱在溶液中会释放氢氧根离子 OH⁻。它们通常摸起来有滑腻感，并且可能和酸一样危险。

Common laboratory acids include hydrochloric acid, sulfuric acid and nitric acid. Common laboratory alkalis include sodium hydroxide and potassium hydroxide.

常见的实验室酸包括盐酸、硫酸和硝酸。常见的实验室碱包括氢氧化钠和氢氧化钾。

2. Everyday Acids and Alkalis | 生活中的酸和碱

Acids are found in many foods and cleaning products. Lemons and oranges contain citric acid, vinegar contains ethanoic acid, and fizzy drinks often contain carbonic acid.

许多食物和清洁用品中都含有酸。柠檬和橙子含有柠檬酸，食醋含有乙酸，汽水通常含有碳酸。

Alkalis are common in cleaning materials. Soap, bleach, oven cleaner and drain cleaner are often alkaline. They help break down grease and dirt.

碱常见于清洁用品中。肥皂、漂白剂、烤箱清洁剂和下水道清洁剂通常呈碱性。它们有助于分解油污和污垢。

Remember that whether a chemical is an acid or an alkali is not the same as whether it is dangerous. Some weak acids and alkalis are safe to eat, while strong ones can burn skin.

请记住，一种化学品是酸还是碱，与它是否危险并不相同。有些弱酸和弱碱可以安全食用，而强酸和强碱会灼伤皮肤。

3. The pH Scale | pH 值标度

The pH scale runs from 0 to 14 and measures how acidic or alkaline a solution is. A pH of 7 is neutral, meaning the solution is neither acidic nor alkaline.

pH 值标度从 0 到 14，用于衡量溶液的酸性或碱性程度。pH 值为 7 表示中性，即溶液既不是酸性也不是碱性。

Solutions with pH less than 7 are acidic. The lower the pH, the more acidic the solution. Solutions with pH greater than 7 are alkaline; the higher the pH, the more alkaline the solution.

pH 值小于 7 的溶液呈酸性。pH 值越低，溶液酸性越强。pH 值大于 7 的溶液呈碱性；pH 值越高，溶液碱性越强。

For example, pure water has a pH of about 7, lemon juice about pH 2, and oven cleaner about pH 13. Each pH unit change means the solution is ten times more acidic or alkaline.

例如，纯水的 pH 值约为 7，柠檬汁的 pH 值约为 2，烤箱清洁剂的 pH 值约为 13。pH 值每变化 1 个单位，溶液的酸性或碱性就改变十倍。

4. Using Indicators | 使用指示剂

An indicator is a substance that changes colour depending on pH. Litmus is a simple indicator: it turns red in acidic solutions and blue in alkaline solutions.

指示剂是一种会随 pH 值改变颜色的物质。石蕊是一种简单的指示剂：它在酸性溶液中变红，在碱性溶液中变蓝。

Universal indicator is more useful because it

Published by TutorHao | KS3 Chemistry Revision Series | aleveler.com

更多咨询请联系16621398022（同微信）