Question

Potassium dichromate and concentrated $HCl$ are heated together.
${K_2}C{r_2}{O_7} + HCl \to KCl + ..... + ..... + {H_2}O$
A. $2{K_2}C{r_2}{O_7} + 12HCl \to 4KCl + 4CrC{l_3} + 7{H_2}O + 3C{l_2} \uparrow $
B. ${K_2}C{r_2}{O_7} + 12HCl \to 2KCl + 2CrC{l_3} + 7{H_2}O + 3C{l_2} \uparrow $
C. $2{K_2}C{r_2}{O_7} + 14HCl \to 4KCl + 4CrC{l_3} + 7{H_2}O + 3C{l_2} \uparrow $
D. ${K_2}C{r_2}{O_7} + 14HCl \to 2KCl + 2CrC{l_3} + 7{H_2}O + 3C{l_2} \uparrow $

Answer 1

Hint: In order to the question, to know the exact balanced reaction of potassium dichromate and a concentrated acid results in evolution of chlorine gas, we will do reaction between them and then fill the blank site with the exact compound which is as product.

Complete step by step answer:
${K_2}C{r_2}{O_7} + 14HCl \to 2KCl + 2CrC{l_3} + 7{H_2}O + 3C{l_2} \uparrow $ is the exact balanced reaction of potassium dichromate and a concentrated acid results in evolution of chlorine gas.
This reaction is actually called the chromyl chloride test for the chloride anion, \[C{l^ - }\] .
The idea is that when you heat a compound that contains chloride (a solid salt, not a solution that contains the solvated anion) with potassium dichromate and concentrated sulphuric acid, the reaction produces chromyl chloride, a red fuming liquid.
Potassium dichromate \[\left( {{K_2}C{r_2}{O_7}} \right)\] is an inorganic chemical reagent that is normally used as an oxidizer in industrial and laboratory applications. It is used to oxidize alcohols and convert primary alcohols to aldehydes and sometimes carboxylic acids. Unlike similar processes that use permanganate, only carboxylic acids result. The secondary alcohols are converted into ketones and no further oxidation is required. Potassium dichromate does not oxidize tertiary alcohols. The chemical is potentially harmful to human health and is a crystalline ionic solid that is a bright, red-orange color.

So, the correct answer is Option D.

Note: It's well known that the chemical element potassium is very important for a wide variety of biological functions in the human body. However, the chemical compound potassium dichromate is quite the opposite - it is very harmful to our health.