Metals & Their Reactions

When zinc reacts with hydrochloric acid, it forms zinc chloride and hydrogen gas. This is a typical example of a single displacement reaction, where zinc replaces hydrogen in the hydrochloric acid to form zinc chloride.

Sodium reacts most vigorously with cold water because it is a highly reactive alkali metal. When sodium comes into contact with water, it undergoes a violent reaction, producing hydrogen gas and sodium hydroxide. This reaction is exothermic and releases a large amount of heat. In contrast, iron, copper, and gold are less reactive and do not react with cold water.

Copper is a good conductor used in electrical wiring because it has a high electrical conductivity. This means that it allows electric current to flow through it easily. Copper is also ductile and malleable, making it easy to shape into wires. Additionally, copper has good thermal conductivity, which helps dissipate heat generated by the flow of electricity. These properties make copper an ideal choice for electrical wiring as it ensures efficient and safe transmission of electricity.

When magnesium reacts with nitric acid, it forms magnesium nitrate and hydrogen gas. This is because magnesium is a metal and nitric acid is an acid. The reaction between a metal and an acid typically produces a salt (in this case, magnesium nitrate) and hydrogen gas.

Copper hydroxide and nitric acid can be used to make copper nitrate. Copper hydroxide is a compound containing copper and hydroxide ions, while nitric acid is a strong acid containing nitrate ions. When these two chemicals react, the copper ions from copper hydroxide combine with the nitrate ions from nitric acid, forming copper nitrate. This reaction is a typical example of an acid-base reaction, where the hydroxide ions from copper hydroxide neutralize the hydrogen ions from nitric acid, resulting in the formation of water. The remaining copper and nitrate ions combine to form copper nitrate.

When zinc carbonate reacts with hydrochloric acid, it forms zinc chloride, carbon dioxide, and water. This is a typical example of a double replacement reaction, where the cations of the reactants switch places to form new compounds. In this case, the zinc cation from zinc carbonate combines with the chloride anion from hydrochloric acid to form zinc chloride. Simultaneously, the carbonate anion from zinc carbonate combines with the hydrogen cation from hydrochloric acid to form carbon dioxide and water.

Aluminium is the correct answer because it is more reactive than zinc. When heated with zinc oxide, aluminium can displace zinc from its compound and form zinc metal. This is known as a displacement reaction, where a more reactive metal displaces a less reactive metal from its compound. Magnesium, copper, and silver are all less reactive than zinc, so they cannot displace zinc from its compound and produce zinc metal.

Magnesium and copper can be separated from each other by adding dilute hydrochloric acid. This is because magnesium reacts with hydrochloric acid to form magnesium chloride and hydrogen gas, while copper does not react with hydrochloric acid. Therefore, when hydrochloric acid is added to the mixture of magnesium and copper, the magnesium will dissolve and separate from the copper.