Analytical Chemistry Question 286
Question: Which of the following statement(s) is (are) correct when a mixture of $ NaCl $ and $ K_2Cr_2O_7 $ is gently warmed with conc. $ H_2SO_4 $
[IIT 1998; CPMT 1988; AMU 1984; MP PMT 2002]
Options:
A) A deep red vapour is evolved
B) The vapour when passed into $ NaOh $ solution gives a yellow solution of $ Na_2CrO_4 $
C) Chlorine gas is evolved
D) Chromyl chloride is formed
Show Answer
Answer:
Correct Answer: A
Solution:
Chromyl chloride test $ 4NaCl+K_2Cr_2O_7+3H_2SO_4\xrightarrow{heat} $
$ K_2SO_4+2Na_2SO_4+\underset{\text{chromyl chloride (orange }\text{red)}}{\mathop{2CrO_2Cl_2+3H_2O}} $
$ 4NaOH+CrO_2Cl_2\to \underset{Sod\text{. chromate }\text{(Yellow)}}{\mathop{2NaCl\ +Na_2CrO_4+2H_2O}} $
$ Na_2CrO_4+\ {{(CH_3COO)}_2}Pb\to 2CH_3COONa+ $
$ \underset{\begin{smallmatrix} \text{Lead chromate} \\ \text{(yellow ppt}\text{.)} \end{smallmatrix}}{\mathop{PbCrO_4\downarrow }} $
BETA
