(a) When concentrated sulphuric acid was added to an unknown salt present in a test tube a brown gas (A) was evolved. This gas intensified when copper turnings were added to this test tube. On cooling, the gas (A) changed into a colourless solid (B).

(i) Identify (A) and (B).

(ii) Write the structures of (A) and (B).

(iii) Why does gas (A) change to solid on cooling?

(b) Arrange the following in the decreasing order of their reducing character :
HF, HCI, HBr, HI

(c) Complete the following reaction :
$X e F_{4} + S b F_{5} \to$

Open in App

Solution

(a) Salt + Conc. $H_{2} S O_{4} \to$ Brown gas (A)

Salt + conc. $H_{2} S O_{4} + c u ⟶ B r o w n g a s (A) i n t e n s i f i e d$

Brown gas (A) $C o o l i n g - --- \to$ Colourless Solid (B)

(i) A = $N O_{2}$ gas ; B = $N_{2} O_{4}$ Solid

(iii) Because $N O_{2}$ dimerises as $N_{2} O_{4}$ due to the fact that $N O_{2}$ is an odd electron species\\

(b) HI > HBr > HCI > HF

(c) $X e F_{4} + S b F_{5} ⟶ [X e F_{3}]^{+} [S b F_{6}]^{-}$

Suggest Corrections

Similar questions

Q. When concentrated sulphuric acid was added to an unknown salt present in a test tube a brown gas(A) was evolved. This gas intensified when copper turnings were added to this test tube. On cooling, the gas(A) changes into a colourless solid(B).
Why does gas(A) change to solid on cooling?

Q. When concentrated sulphuric acid was added to an unknown salt present in a test tube a brown gas (A) was evolved. This gas intensified when copper turning were added to this test tube. On cooling, the gas(A) changed into a colourless solid(B).
Write the structures of (A) and (B).

Q. A dilute solution of sodium carbonate was added to two test tubes - one containing dilute

H C l

(A) and the other containing dilute

N a O H

(B). The correct observation was

Q. Iron powder and sulphur powder were mixed together and divided into two parts A and B. When part A was heated strongly over a burner, then a substance C was formed. The part B was, however, not heated at all. When dilute hydrochloric acid was added to substance C, then gas D was evolved and when dilute hydrochloric acid was added to part B then gas E was evolved.

(a) What type of substance is B ?
(b) What type of substance is C ?
(c) Name the gas (i) D, and (ii) E ?
(d) State one characteristic property of gas D.
(e) Write one test to identify gas .E

Iron powder and sulphur powder were mixed together and divided into two parts A and B. When part A was heated strongly over a burner, then a substance C was formed. The part B was, however, not heated at all. When dilute hydrochloric acid was added to substance C, then gas D was evoled and when dilute hydrochloric acid was added to part B then gas E was evolved.

(a) What type of substance is B ?

(b) What type of substance is C ?

(d) State one characteristic property of gas D.

(e) Write one test to identify gas E.

Join BYJU'S Learning Program