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Potassium dichromate acts as a strong ox...

Potassium dichromate acts as a strong oxidising agent in the acidic medium. When heated with a metal chloride and conc. sulphuric acid, it gives orange red fumes. On passing these fumes through sodium hydroxide, it gives a yellow solution (X) and this acidified solution gives yellow precipitate (Y) with lead acetate. On heating potassium dichromate with KOH, it forms a yellow solution (Z) which on acidification changes to orange colour. Acidified solution of dichromate ion gives deep blue colour with `H_2O_2` due to the formation of (P)
The yellow precipitate (Y) corresponds to

A

`PbS`

B

`PbCO_3`

C

`PbCrO_4`

D

`PbSO_4`

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The correct Answer is:
To solve the problem step-by-step, we will analyze the information provided and deduce the required answers systematically. ### Step 1: Understand the Reaction of Potassium Dichromate Potassium dichromate (K₂Cr₂O₇) acts as a strong oxidizing agent in acidic medium. When it is heated with a metal chloride and concentrated sulfuric acid, it produces orange-red fumes. The orange-red fumes are primarily due to the formation of chromyl chloride (CrO₂Cl₂). **Hint:** Remember that potassium dichromate in acidic conditions can lead to the formation of chromyl chloride when reacted with metal chlorides. ### Step 2: Passing Fumes Through Sodium Hydroxide When these orange-red fumes are passed through sodium hydroxide (NaOH), a yellow solution (X) is formed. This yellow solution is sodium chromate (Na₂CrO₄). **Hint:** The reaction of chromyl chloride with sodium hydroxide leads to the formation of sodium chromate, which is yellow in color. ### Step 3: Reaction with Lead Acetate The yellow solution (X) obtained from the previous step is treated with lead acetate (Pb(CH₃COO)₂). This reaction produces a yellow precipitate (Y), which corresponds to lead chromate (PbCrO₄). **Hint:** Lead acetate reacts with sodium chromate to form a yellow precipitate, which is characteristic of lead chromate. ### Step 4: Heating Potassium Dichromate with KOH When potassium dichromate is heated with potassium hydroxide (KOH), it forms another yellow solution (Z), which is potassium chromate (K₂CrO₄). Upon acidification, this yellow solution turns orange due to the formation of potassium dichromate again. **Hint:** Heating potassium dichromate with KOH results in the formation of potassium chromate, which is also yellow. ### Step 5: Reaction with Hydrogen Peroxide The acidified solution of dichromate ions reacts with hydrogen peroxide (H₂O₂) to give a deep blue color due to the formation of a compound (P), which is likely to be a chromium species such as Cr³⁺ in a complex form. **Hint:** The deep blue color indicates the presence of a specific chromium ion complex formed in the reaction with hydrogen peroxide. ### Final Answer The yellow precipitate (Y) corresponds to **lead chromate (PbCrO₄)**.
To solve the problem step-by-step, we will analyze the information provided and deduce the required answers systematically. ### Step 1: Understand the Reaction of Potassium Dichromate Potassium dichromate (K₂Cr₂O₇) acts as a strong oxidizing agent in acidic medium. When it is heated with a metal chloride and concentrated sulfuric acid, it produces orange-red fumes. The orange-red fumes are primarily due to the formation of chromyl chloride (CrO₂Cl₂). **Hint:** Remember that potassium dichromate in acidic conditions can lead to the formation of chromyl chloride when reacted with metal chlorides. ### Step 2: Passing Fumes Through Sodium Hydroxide ...
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Potassium dichromate acts as a strong oxidising agent in the acidic medium. When heated with a metal chloride and conc. sulphuric acid, it gives orange red fumes. On passing these fumes through sodium hydroxide, it gives a yellow solution (X) and this acidified solution gives yellow precipitate (Y) with lead acetate. On heating potassium dichromate with KOH, it forms a yellow solution (Z) which on acidification changes to orange colour. Acidified solution of dichromate ion gives deep blue colour with H_2O_2 due to the formation of (P) The oxidation state of Cr in compound P

Potassium dichromate acts as a strong oxidising agent in the acidic medium. When heated with a metal chloride and conc. sulphuric acid, it gives orange red fumes. On passing these fumes through sodium hydroxide, it gives a yellow solution (X) and this acidified solution gives yellow precipitate (Y) with lead acetate. On heating potassium dichromate with KOH, it forms a yellow solution (Z) which on acidification changes to orange colour. Acidified solution of dichromate ion gives deep blue colour with H_2O_2 due to the formation of (P) The orange red fumes obtained on heating potassium dichromate with a metal chloride and conc. H_2SO_4 is due to the formation of

Knowledge Check

  • Potassium dichromate acts as a strong oxidising agent in the acidic medium. When heated with a metal chloride and conc. sulphuric acid, it gives orange red fumes. On passing these fumes through sodium hydroxide, it gives a yellow solution (X) and this acidified solution gives yellow precipitate (Y) with lead acetate. On heating potassium dichromate with KOH, it forms a yellow solution (Z) which on acidification changes to orange colour. Acidified solution of dichromate ion gives deep blue colour with H_2O_2 due to the formation of (P) The yellow solution (X) is

    A
    `K_2CrO_4`
    B
    `Na_2CrO_4`
    C
    `CrCl_3`
    D
    `Cr(OH)_3`

  • Potassium dichromate acts as a strong oxidising agent in the acidic medium. When heated with a metal chloride and conc. sulphuric acid, it gives orange red fumes. On passing these fumes through sodium hydroxide, it gives a yellow solution (X) and this acidified solution gives yellow precipitate (Y) with lead acetate. On heating potassium dichromate with KOH, it forms a yellow solution (Z) which on acidification changes to orange colour. Acidified solution of dichromate ion gives deep blue colour with H_2O_2 due to the formation of (P) The yellow solution (Z) on acidification gives

    A
    `K_2CrO_4`
    B
    `K_2Cr_2O_7`
    C
    `K_2SO_4`
    D
    `(CH_3COO)_2Pb`

  • Potassium dichromate acts as a strong oxidising agent in the acidic medium. When heated with a metal chloride and conc. sulphuric acid, it gives orange red fumes. On passing these fumes through sodium hydroxide, it gives a yellow solution (X) and this acidified solution gives yellow precipitate (Y) with lead acetate. On heating potassium dichromate with KOH, it forms a yellow solution (Z) which on acidification changes to orange colour. Acidified solution of dichromate ion gives deep blue colour with H_2O_2 due to the formation of (P) The blue colour of compound P fades due to the formation of

    A
    `Cr^(3+)` and `O_2`
    B
    `CrO_4^(2-)` and `Cr^(3+)`
    C
    `Cr_2O_7^(2-)` and `Cr^(3+)`
    D
    `CrO_3`

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