Write short notes on the oxidation of Cu to CuO.

This is an oxidation reaction where copper metal reacts with oxygen to form copper(II) oxide. Copper loses electrons, and its oxidation state increases from 0 to +2.

$$2\text{Cu}(s) + \text{O}_2(g) \rightarrow 2\text{CuO}(s)$$

This is an esterification reaction. Methanol, an alcohol, reacts with ethanoic acid, a carboxylic acid, to produce methyl ethanoate, an ester, and water. This reaction is typically catalyzed by a strong acid and is reversible.

$$\text{CH}_3\text{OH}(l) + \text{CH}_3\text{COOH}(l) \xrightarrow{\text{H}^+, \text{heat}} \text{CH}_3\text{COOCH}_3(l) + \text{H}_2\text{O}(l)$$

This is also an esterification reaction. Ethanol, an alcohol, reacts with ethanoic acid to form ethyl ethanoate, an ester, and water. This reaction is also acid-catalyzed and reversible.

$$\text{CH}_3\text{CH}_2\text{OH}(l) + \text{CH}_3\text{COOH}(l) \xrightarrow{\text{H}^+, \text{heat}} \text{CH}_3\text{COOCH}_2\text{CH}_3(l) + \text{H}_2\text{O}(l)$$