Metallurgy

(a) Sodium amalgam, commonly denoted Na(Hg), is an alloy of mercury and sodium.

(b) Bauxite. The molecular formula is Al₂O₃.H₂O

(c) Amphoteric oxides

Eg. Al₂O₃ is an example of an amphoteric oxide

(d) Ball mill, is often used for grinding an ore and getting enough size reduction.

(e) Graphite is the only non-metal element that is a good conductor of electricity

(f) Aqua Regia, 1:3 mixture of concentrated nitric and hydrochloric acids can dissolve noble metals such as gold, palladium, and platinum.

(a) The process of extraction of the metals in pure form from their ores is termed as metallurgy.

(b) The minerals or deposits from which the metals can be extracted are called ores.

(c) The naturally occurring compounds of metals along with their impurities is termed as minerals.

(d) Ores contain metal compounds with some of the impurities such as sand and rocky materials and these impurities are called gangue.

Copper reacts with moist carbon dioxide in the air to form copper carbonate. The citric acid present in the lemon or tamarind neutralizes the basis copper carbonate and dissolves the layer. That is why tarnished copper vessels are cleaned with lemon or tamarind juice to give the surface of the copper vessel its characteristic shiny appearance.

Ionic compounds are formed from strong electrostatic interactions between ions, which result in higher melting points and electrical conductivity compared to covalent compounds.

Sodium is a very reactive metal. It is kept in kerosene to prevent it from coming in contact with oxygen and moisture. If this happens, it will react with the moisture present in air and form sodium hydroxide. This is a strongly exothermic reaction, and a lot of heat is generated.

Pine oil is used in froth flotation process because it does not have an affinity towards water (because of the hydrophobic chemicals as its constituents) and it attracts impurities which can be washed away.

This is because over time the graphite anode gets degraded and loses its ability to act as an electrode. Also, more impurities will stick to the electrode.

When Copper is dipped in silver nitrate solution, copper nitrate and silver metal are formed. A shining white deposit of silver metal is formed on the copper coin, which makes it glitter for some time.

eq:

From the configuration,

Metal A is Sodium or Na-2,8,1

Metal B is Calcium or Ca-2,8,8,1

Metal A i.e Sodium is more reactive than Calcium. Sodium metal reactive than calcium and it even reacts when kept open in the air.

Reaction With dil.HCl:

Sodium reacts vigorously with dilute hydrochloric acid to form sodium chlorides and hydrogen.

Calcium reacts less vigorously to form calcium chloride and hydrogen gas.

(a) 4Al(s) + 3O₂(l) → 2Al₂O₃(s)

The surface of the aluminum metal is covered with a thin layer of oxide that helps protect the metal from attack by air. So, normally, aluminum metal does not react with air. If the oxide layer is damaged, the aluminum metal is exposed to attack

(b) Iron is more electropositive than copper. It can displace Copper (Cu) from its salt Copper sulfate (CuSO4) and thus its colour changes from blue to green.

Fe + CuSO₄ → FeSO₄ + Cu

(c) The reaction of Ferric oxide and aluminum produces aluminum oxide and iron. The chemical equation is:

3Fe₃O₂ + 4Al → 2Al₂O₃ + 6Fe

(d) The electrode reactions are:

Anode reaction: 2O²- → O₂ + 4e^- (Oxidation)

Cathode reaction: Al³⁺→ Al (l)(Reduction)

(e) ZnO(aq)+2HCl(aq)→ZnCl₂(aq)+H₂O(l)

Zinc chloride and water are produced in the reaction.

(a) Silica, Ferric Oxide, and Titanium Oxide are the impurities or gangue in Bauxite

(b) By Hall’s and Bayer’s method, where finally the concentrated alumina can be obtained by the calcination process

(c) Halls Process:

(final calcination method)

(d) Since aluminum oxide is amphoteric in nature, it reacts with NaOH to form water-soluble Sodium aluminate

Highly Reactive metals: Na, Li, Ca

Moderately Reactive Metals: Mg, Zn, Fe

Less Reactive Metals: Cu