Potassium Permanganate

Part 3 of the series (d- and f- block). Question mode: Flashcards only. Answer mode: Answer with definition. Suitable for JEE Mains, I don't know about JEE Advanced. Catered towards NCERT and IAT.

What (ore) is potassium permanganate prepared from?

Pyrolusite ($MnO_2$)

What are the steps of preparation of potassium permanganate from pyrolusite?

1. Conversion of pyrolusite into potassium manganate

2. Conversion of potassium manganate into potassium permanganate by oxidation

What is the colour of $KMnO_4$?

purple or violet

How do you convert pyrolusite to potassium manganate?

By treating it with something like potassium hydroxide or potassium carbonate in the presence of air ($O_2$)

What is the chemical equation for the reaction of pyrolusite with potassium hydroxide?

What is the chemical equation for the reaction of pyrolusite with potassium carbonate?

What is the colour of $K_2MnO_4$?

green :)

How is potassium manganate converted to potassium permanganate?

potassium manganate undergoes chemical or electrochemical oxidation to form potassium permanganate

Give one example of a chemical reaction of potassium manganate undergoing chemical oxidation to form potassium permanganate.

When potassium manganate undergoes electrolytic oxidation, what is the anode and what is the cathode?

the anode is nickel

the cathode is iron

When potassium manganate undergoes electrolytic oxidation, what is the electrolytic solution?

it is an aqueous solution of $K_2MnO_4$.

When potassium manganate undergoes electrolytic oxidation, at which electrode is permanganate formed?

anode

When potassium manganate undergoes electrolytic oxidation, which gas is evolved at the cathode?

hydrogen gas

In the laboratory, a salt of manganese (II) is oxidised by what to form permanganate?

peroxodisulphate

What is the chemical equation for formation of permanganate from a salt of Manganese (II)?

What is the chemical formula of peroxodisulphate? What is the oxidation state?

$$S_2O_8^{-2}$$

Is it true that $KMnO_4$ is structurally similar to $KClO_4$?

yea

Is $KMnO_4$ soluble in water?

not very

What is the melting point of $KMnO_4$?

513 K

Is $KMnO_4$ paramagnetic or diamagnetic?

diamagnetic, sometimes paramagnetic but not very much and it’s not really in syllabus so just say diamagnetic

What is the structure of the manganate ion?

What is the structure of the permanganate ion?

Is the manganate ion diamagnetic or paramagnetic?

paramagnetic, it has one unpaired electron

What is the chemical equation for the heating (decomposition) of $KMnO_4$?

What is the chemical equation for reacting $KMnO_4$ with $KOH$?

What is the chemical equation for reacting $KMnO_4$ with concentrated sulphuric acid?

2KMnO₄ + 2H₂SO₄ ⟶ 4MnO₂ + 3O₂ + 2KHSO₄ + H₂O

In acidic medium, $KMnO_4$ is a _______ oxidising agent.

(strong, mild, weak)

strong

In neutral medium, $KMnO_4$ is a _______ oxidising agent.

(strong, mild, weak)

mild

In basic medium, $KMnO_4$ is a _______ oxidising agent.

(strong, mild, weak)

weak

When $KMnO_4$ reacts in acidic medium, what is the new oxidation state of manganese?

$$+2$$

When $KMnO_4$ reacts in neutral medium, what is the new oxidation state of manganese?

$$+4$$

When $KMnO_4$ reacts in basic medium, what is the new oxidation state of manganese?

$$+6$$

What is the chemical equation for reacting $KMnO_4$ with regular unconcentrated sulphuric acid?

What is the chemical equation for when $KMnO_4$ oxidises $I^-$ in acidic medium?

What is the chemical equation for when $KMnO_4$ oxidises $Fe^{+2}$ to $Fe^{+3}$ in acidic medium?

What is the chemical equation for when $KMnO_4$ oxidises the oxalate ion to carbon dioxide in acidic medium at 333 K?

What is the chemical equation for when $KMnO_4$ oxidises $H_2S$ to sulphur in acidic medium? There are two steps.

What is the chemical equation for when $KMnO_4$ oxidises sulphurous acid (or sulphite in acidic medium) to sulphuric acid (or sulphate in acidic medium)?

What is the chemical equation for when $KMnO_4$ oxidises nitrite to nitrate in acidic medium?

Generally when $MnO_4^-$ oxidises something in acidic medium, what is the form of the equation?

[thing to be oxidised] + [$H^+$ ions] + [$MnO_4^-$ moledules] → [thing that is oxidised now] + [bunch of water molecules] + [$Mn^{2+}$ ions]

What is the chemical equation for when $KMnO_4$ oxidises $I^-$ in neutral medium?

iodate is formed

What is the chemical equation for when $KMnO_4$ oxidises thiosulphate in neutral medium?

sulphate is formed

What is the chemical equation for when the permanganate ion oxidises a manganese salt in neutral medium

What is the catalyst used in this reaction?

zinc sulphate or zinc oxide

Generally when $MnO_4^-$ oxidises something in neutral medium, what is the form of the equation?

[thing that will be oxidised] + [water molecules] + [$MnO_4^-$ molecules] → [thing that has been oxidised now] + [$MnO_2$ molecules] + [hydroxide ions]

When a $KMnO_4$ oxidises in an acidic medium, what form is the manganese in after the reaction?

$$Mn^{+2}$$

When a $KMnO_4$ oxidises in a neutral medium, what form is the manganese in after the reaction?

$$MnO_2$$

When a $KMnO_4$ oxidises in an basic medium, what form is the manganese in after the reaction?

$$K_2MnO_4$$

What are the three practical uses of $KMnO_4$?

1. used in analytical chemistry

2. excellent oxidant in organic chemistry

3. bleaching / decolourisation of stuff