Question

a) What is meant by corrosion? Name any two methods used for the prevention
of corrosion.

(b) Suppose you have to extract metal M from its enriched sulphide ore. If M is in the middle of the reactivity series, write various steps used in extracting this metal.

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100 points​

Answer 1

Hey mate...

...1...Corrosion is General destruction of metals due to chemical reaction with water and oxygen.. Prevention can be through oiling and Greasing.

....2....ᴛʜᴇ ᴍᴇᴛᴀʟs ɪɴ ᴛʜᴇ ᴍɪᴅᴅʟᴇ ᴏғ ᴛʜᴇ ʀᴇᴀᴄᴛɪᴠɪᴛʏ sᴇʀɪᴇs ᴀʀᴇ MODERATELY REACTIVE. THESE ARE ᴜsᴜᴀʟʟʏ ᴘʀᴇsᴇɴᴛ ᴀs sᴜʟᴘʜɪᴅᴇs ᴏʀ ᴄᴀʀʙᴏɴᴀᴛᴇs ɪɴ ɴᴀᴛᴜʀᴇ ᴛʜᴇ ᴍᴇᴛᴀʟ sᴜʟᴘʜɪᴅᴇs ᴀɴᴅ ᴄᴀʀʙᴏɴᴀᴛᴇs ᴍᴜsᴛ ʙᴇ ᴄᴏɴᴠᴇʀᴛᴇᴅ ɪɴᴛᴏ ᴍᴇᴛᴀʟ ᴏxɪᴅᴇs.

Thus this impure metal ‘M’ undergoes purification. The process of purifying impure metal is called refining. The most widely used method for refining is electrolytic refining.

Hope this helps❤

Answer 2

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[A]

Corrosion is a process in which metal reacts with substances present in the environment to form surface compounds. Due to corrosion metals become unfit for use.

Prevention :

(i) Galvanisation is a process to prevent corrosion of iron.

(ii)Electroplating is also used to prevent corrosion.

[B]

(i) Concentration of ores : Sulphide ore will be concentrated by froth- floatation process. Sulphide ore will be collected in froth whereas gangue will be left behind.

(ii) Roasting : Sulphide ore is heated strongly in the presence of O2 to form metal oxide and sulphur dioxide.

$\sf{2MS + 3O2 \: \: \longrightarrow \: 2MO + 2SO_ {2}}$

(iii) Reduction : MO reacts with carbon (acts as reducing agent) to form metal and CO.

$\sf{MO + C \: \longrightarrow \: M + CO}$