酸、碱与pH值

根据氢离子浓度定义酸和碱，描述pH值刻度（0–14），并解释如何使用指示剂来识别和测量酸碱性。

Define acids and alkalis in terms of hydrogen ion concentration, describe the pH scale (0–14), and explain how indicators are used to identify and measure acidity or alkalinity

学习证据 / Evidence

• 能说明酸的pH值低于7，碱的pH值高于7，pH值为7时呈中性。
• 能解释氢离子（H⁺）与酸性之间的关系。
• 能说出常见指示剂（石蕊、万能指示剂）并描述其颜色变化。
• 能识别日常生活中的常见酸（醋、柠檬汁）和常见碱（漂白水、小苏打）。

• States that acids have pH below 7, alkalis have pH above 7, and neutral is pH 7
• Explains what hydrogen ions (H⁺) have to do with acidity
• Names common indicators (litmus, universal indicator) and describes colour changes
• Identifies everyday acids (vinegar, lemon juice) and alkalis (bleach, bicarbonate of soda)

评估问题 / Assessment

如果{{name}}用一片万能指示剂试纸测试柠檬汁和小苏打溶液，能否预测它们各自会变成什么颜色，并解释这说明了这两种物质分别具有什么性质？

If {{name}} used a piece of universal indicator paper to test lemon juice and baking soda solution, could they predict what colour each would turn and explain what that tells you about each substance?