Question

Consider the following reactions $ A + HCl + H_2SO_4 \rightarrow CrO_2Cl_2$ + Side Products Little amount $ CrO_2Cl_2(vapour) + NaOH \rightarrow B + NaCl + H_2O $ $ B + H^+ \rightarrow C + H_2O $ The number of terminal 'O' present in the compound 'C' is ______

Hint:

Identify the chromium-containing species formed in each reaction. Chromyl chloride (\( CrO_2Cl_2 \)) reacts with NaOH to form chromate ions (\( CrO_4^{2-} \)), which in acidic solution convert to dichromate ions (\( Cr_2O_7^{2-} \)). Draw the structure of the dichromate ion to count the terminal oxygen atoms.

Answer 1

Correct Answer: 6

\( Cr_2O_7^{2-} + HCl + H_2SO_4 \rightarrow CrO_2Cl_2 \) 

\( CrO_2Cl_2(vapour) + NaOH \rightarrow Na_2CrO_4 + NaCl + H_2O \)

\( Na_2CrO_4 + H^+ \rightarrow Na_2Cr_2O_7 + H_2O \) 

\( 2Na_2CrO_4 + 2H^+ \rightarrow Na_2Cr_2O_7 + 2Na^+ + H_2O \) 

\( CrO_4^{2-} \xrightarrow{H^+} Cr_2O_7^{2-} \)

No of terminal "O" = 6