Describe the reaction type and expected observations for the following chemical reactions: a) 2KBr(aq) + Cl2(g) → 2KCl(aq) + Br2(aq) b) CuO(s) + H2(g) → Cu(s) + H2O(l) c) CH2=CH2(g) + H2(g) → CH3CH3(g

Here are the short notes for each equation, including the reaction type and observations:

a) $\text{2KBr(aq)} + \text{Cl}_2\text{(g)} \longrightarrow \text{2KCl(aq)} + \text{Br}_2\text{(aq)}$

• Reaction Type: This is a displacement reaction (specifically, a halogen displacement) and a redox reaction. Chlorine, being more reactive than bromine, displaces bromine from potassium bromide.
• Observations: The colorless potassium bromide solution reacts with yellowish-green chlorine gas. The solution turns orange-brown as bromine is formed.

b) $\text{CuO(s)} + \text{H}_2\text{(g)} \longrightarrow \text{Cu(s)} + \text{H}_2\text{O(l)}$

• Reaction Type: This is a redox reaction. Hydrogen acts as a reducing agent, reducing black copper(II) oxide to pinkish-brown copper metal. Hydrogen itself is oxidized to water.
• Observations: Black solid copper(II) oxide turns into a pinkish-brown solid (copper metal). Colorless hydrogen gas is consumed, and colorless liquid water (or steam if heated) is produced.

c) $\text{CH}_2=\text{CH}_2\text{(g)} + \text{H}_2\text{(g)} \longrightarrow \text{CH}_3\text{CH}_3\text{(g)}$

• Reaction Type: This is an addition reaction, specifically hydrogenation. Ethene (an alkene) reacts with hydrogen in the presence of a catalyst (e.g., nickel) to form ethane (an alkane).
• Observations: Both reactants (ethene and hydrogen) and the product (ethane) are colorless gases. There are no visible changes in color or state. The reaction typically requires heating and a catalyst.

d) $\text{CH}_3\text{CH}_2\text{OH(aq)} + \text{CH}_3\text{COOH(aq)} \rightleftharpoons \text{CH}_3\text{COOCH}_2\text{CH}_3\text{(aq)} + \text{H}_2\text{O(l)}$

• Reaction Type: This is an esterification reaction. Ethanol (an alcohol) reacts with ethanoic acid (a carboxylic acid) to form ethyl ethanoate (an ester) and water. It is a reversible reaction, usually catalyzed by concentrated sulfuric acid.
• Observations: Both reactants are colorless liquids. The key observation is the formation of a new product, ethyl ethanoate, which has a characteristic sweet, fruity smell.