纯净物与混合物

区分纯净物和混合物，认识配方产品是组成精确的有用混合物，并利用熔点和沸点来检验物质的纯度。

Distinguish between pure substances and mixtures, identify formulations as useful mixtures with precise compositions, and use melting and boiling points to test for purity

学习证据 / Evidence

• 解释为什么纯净物具有固定而明确的熔点，而混合物则在一个温度范围内熔化。
• 识别常见的配方产品（药物、合金、油漆、燃料）是刻意配成的混合物。
• 解释杂质对熔点和沸点的影响。
• 在微粒层面上区分混合物与化合物。

• Explains why a pure substance has a sharp, fixed melting point but a mixture melts over a range
• Identifies common formulations (medicines, alloys, paints, fuels) as deliberate mixtures
• Explains what impurities do to melting and boiling points
• Distinguishes mixtures from compounds at the particle level

评估问题 / Assessment

如果{{name}}想检验一份水样是否纯净，他们能否说明一种可以做的检测，并说出什么结果能让他们确定它是纯净的，而不是混合物？

If {{name}} was checking whether a sample of water was pure, could they explain one test they could do — and say what result would tell them it was definitely pure versus a mixture?