明代诗人于谦有一首流传千古的名篇《石灰吟》:“千锤万凿出深山,烈火焚烧若等闲。粉身碎骨浑不怕,要留清白在人间。”可以说这是对石灰的最高赞赏。石灰是我们学习中常碰到的物质,通常分为生石灰和熟石灰两种。生石灰就是氧化钙(CaO),能吸收空气中的水气,因此,常常用作空气干 Yu Qian, a poet of the Ming Dynasty, had a famous rendition of “limestone”: “If a thousand hammers are made out of the mountains, if the fire burns, wait. It’s not afraid to get rid of it. Let’s leave it in the world.” It can be said that this is the highest appreciation for lime. Lime is a substance we often encounter in our studies. It is usually divided into quicklime and hydrated lime. Lime is calcium oxide (CaO), which absorbs moisture from the air and is therefore often used as air.