Question 1: Define a metal hydroxide and describe how it is generally formed in a chemical reaction.

Answer: A metal hydroxide is an inorganic compound consisting of a metal cation and hydroxide anion (OH−). It is generally formed when a metal reacts with water or when a metal oxide reacts with water.

Question 2: Explain what happens when a metal hydroxide reacts with an acid.

Answer: When a metal hydroxide reacts with an acid, it undergoes a neutralisation reaction, producing a salt and water.

Question 3: Which of the following is a typical characteristic of most metal hydroxides? A) They are acidic B) They are insoluble in water C) They are basic and form alkaline solutions D) They are gases at room temperature

Answer: C) They are basic and form alkaline solutions

Question 4: Fill in the blank: When aluminium reacts with water to form aluminium hydroxide, the process is described as a ______ reaction.

Answer: hydrolysis

Question 5: Describe the typical physical state and solubility of most metal hydroxides.

Answer: Most metal hydroxides are solid at room temperature and are usually insoluble or only slightly soluble in water, forming alkaline solutions.

Question 6: Calculate the concentration (in mol/L) of a sodium hydroxide solution if 0.5 mol of NaOH is dissolved in 2 litres of solution.

Answer: 0.25 mol/L

Question 7: Why are metal hydroxides important in the manufacturing of soap and detergents?

Answer: Metal hydroxides such as sodium hydroxide are used in soap making because they saponify fats and oils, producing soap and glycerol.

Question 8: Identify the gas evolved when aluminium hydroxide reacts with excess sodium hydroxide solution and explain its significance.

Answer: Hydrogen gas is evolved, indicating that aluminium hydroxide can act as a source of hydrogen in reactions and is involved in metal extraction processes.

Question 9: Propose a simple experimental method to test whether a solution contains a metal hydroxide.

Answer: Add a few drops of universal pH indicator or litmus paper to the solution. If the solution turns blue or pH is above 7, it indicates the presence of a basic substance like a metal hydroxide.

Question 10: Discuss the environmental impact of using metal hydroxides in industry, including any potential hazards and how they are managed.

Answer: Metal hydroxides can cause environmental harm if discharged untreated, leading to alkalinity in water systems which can harm aquatic life. Proper waste treatment, neutralisation, and regulatory controls are essential to minimise environmental impact.