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课程 7 · 年级 7–9
Reactions: acids, bases, pH
📖 课程
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🎯 测验——选择翻译
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✅ 本课已完成
A chemical reaction rebuilds atoms: reactants → products. Acids taste sour (lemon, vinegar, cola), bases feel soapy (soap, baking soda, cleaners). The pH scale runs 0–14: below 7 acid, 7 neutral (water), above base. Acid + base = salt + water: neutralization.
- ●pH 0–6: cola ~2.5, lemon ~2, rain ~5.5
- ●pH 7: pure water and blood (nearly, ~7.4)
- ●pH 8–14: soap ~10, bleach ~13
🥼 Red-cabbage indicator: the juice shifts red with acid, green with base. A home lab!