Calcium hydroxide, commonly known as slaked lime, is often used in agriculture and construction. When it reacts with nitric acid (HNO₃), it forms calcium nitrate and releases water. This reaction is not just about producing fertilizers but also has historical significance. Calcium nitrate has been used since ancient times to enhance crop growth, showing that people have been making effective use of chemistry for centuries!

The second reaction you presented involves iron and water, leading to the formation of iron(IV) oxide. A common problem when dealing with iron and moisture is rust formation, often caused by a lack of oxygen access to the iron surface. To avoid this, simple solutions like applying oil or paint can create a protective barrier, preventing moisture from reaching the iron and thereby reducing corrosion significantly!