Metallurgy, Metals, Non-Metals & Alloy RRB PYQ

Galvanization is a method of protecting iron from rusting by coating it with a thin layer of zinc. This zinc layer acts as a protective barrier, preventing moisture and oxygen from reaching the iron surface. Additionally, even if the coating is damaged, zinc will preferentially corrode instead of the iron, offering sacrificial protection.

The electrolyte used in the electrolytic refining of copper is CuSO4. The electrolyte is specifically an acidified solution of copper sulphate, which allows for the smooth flow of copper ions between electrodes. During electrolysis, a thick block of impure copper is made the anode, while a thin strip of pure copper is made the cathode. Impure copper from the anode dissolves into the solution and an equivalent amount of pure copper from the solution is deposited onto the cathode.

In a displacement reaction, a more reactive metal replaces a less reactive metal from its salt solution. The less reactive metal is released in its elemental form, while the more reactive metal combines with the non-metal part of the salt to form a new compound. This reaction is commonly used in the extraction of metals from their ores. For example, zinc displaces copper from copper sulfate solution, showing that zinc is more reactive than copper.

Food cans are coated with tin and not zinc because zinc is more reactive than tin. Zinc is more reactive and can react with the food inside the can, potentially causing contamination and affecting food quality. Tin, being less reactive, provides a more stable and safe coating for preserving the food.

Iron is more reactive than copper, so it can displace copper from a copper sulfate (CuSO4) solution. This is called a displacement reaction or single replacement reaction. In the displacement reaction, iron (Fe) reacts with copper sulfate (CuSO4) solution to form iron sulfate (FeSO4) and copper (Cu): Fe + CuSO4 → FeSO4 + Cu. This reaction shows the reactivity series of metals, where iron is placed above copper, meaning iron is more reactive and can replace it from its compound.

Malachite is an ore of copper. It is a green mineral composed of copper carbonate hydroxide (Cu2CO3(OH)2). Malachite has been historically significant as a source of copper and is also used as a decorative stone due to its vibrant green color.

Corrosion means metals slowly break down because they react with their surroundings. It usually happens when there is moisture or acids, which make oxides, hydroxides, or sulfides on the metal surface. Common examples are the rusting of iron and the tarnishing of silver. Corrosion is a natural change that turns pure metals into more stable forms like oxides or hydroxides.

When potassium reacts with water, we observe a bright flame and rapid reaction. Potassium is an alkali metal that reacts violently with water to produce potassium hydroxide and hydrogen gas, releasing enough heat to ignite the hydrogen immediately. The characteristic lilac-coloured flame seen during this reaction is due to the excitation of potassium ions by the intense heat of the exothermic process. The reaction is so vigorous that the potassium metal skims across the water's surface, hissing and sparking until it completely dissolves or explodes.

The bubbling of hydrogen gas will be the fastest for magnesium. In the reactivity series, the higher a metal is, the more readily it reacts with acids to displace hydrogen gas. Magnesium is the most reactive metal, followed by aluminium, zinc, and iron. The faster the reaction, the greater the bubbling of hydrogen gas.

The attempt to extract magnesium from magnesium oxide using carbon fails because carbon is less reactive than magnesium. Magnesium is a highly reactive metal located above carbon in the reactivity series, meaning it has a stronger affinity for oxygen than carbon does. Because of this high affinity, carbon is not a strong enough reducing agent to displace magnesium from its oxide form to obtain the pure metal. Chemical reduction using carbon only works for moderately reactive metals like iron, zinc, or lead, whose bonds with oxygen are weaker than those of magnesium.