Metals and Non-Metals — Important Questions

Electrolysis

Step 1: Highly reactive metals like sodium, potassium, and magnesium have very high affinity for oxygen. Step 2: These metals cannot be reduced using carbon because they are more reactive than carbon. Step 3: Electrolysis is used where electric current is passed through molten salts of these metals. Step 4: During electrolysis, metal ions gain electrons at the cathode and are reduced to form pure metals. Step 5: For example, sodium is obtained by electrolysis of molten NaCl: Na⁺ + e⁻ → Na at cathode.

Hydrated iron oxide (Fe₂O₃.xH₂O)

Step 1: Rust is the reddish-brown substance formed when iron corrodes in the presence of oxygen and moisture. Step 2: The chemical formula of rust is Fe₂O₃.xH₂O, which is hydrated ferric oxide. Step 3: The 'x' represents variable number of water molecules associated with each Fe₂O₃ unit. Step 4: Rust formation requires both oxygen and water - removing either prevents rusting. Step 5: The formation of rust weakens iron structures and is a major economic problem, which is why rust prevention methods are important.

Graphite

Step 1: Generally, non-metals are poor conductors of electricity because they don't have free electrons. Step 2: Graphite is an exception - it's the only non-metal that conducts electricity well. Step 3: In graphite's structure, each carbon atom is bonded to three other carbon atoms, leaving one electron free to move. Step 4: These free electrons make graphite a good conductor of electricity. Step 5: This property makes graphite useful in making electrodes, pencil leads, and dry cell batteries.

Zinc chloride and hydrogen gas are formed

Step 1: Zinc is more reactive than hydrogen, so it can displace hydrogen from dilute acids. Step 2: The chemical equation is: Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g). Step 3: This reaction produces zinc chloride (a salt) and hydrogen gas. Step 4: You can observe effervescence (bubbling) due to hydrogen gas evolution. Step 5: This is a typical metal-acid reaction where the metal displaces hydrogen to form a salt and hydrogen gas.