Question

How is potassium dichromate prepared from a sample of chromite ore? Give balanced equations for the chemical reactions involved.

Answer 1

Potassium Dichromate, ${K_2}C{r_2}{O_7}$it is a most commonly oxidizing agent. It is harmful to health. It is a crystalline ionic solid with a very bright, red-orange color. It is odorless and insoluble in alcohol.

Complete step by step answer:
Chromite is a mineral that is an iron chromium oxide. It has a chemical formula of$FeC{r_2}{O_4}$. It is an oxide mineral. Its tenacity is brittle in nature, it weakly comprises magnetic properties. It is commonly found in a metamorphic rock. The chemical composition of chromite is$F{e^{2 + }}C{r_2}^{3 + }{O_4}$. Chromites have reactions with many gases such as $CO$ and $C{O_2}$. Due to its structure it is highly stable in nature. Let’s observed preparation of potassium dichromate from a sample of chromite ore:
Chromite ore is in the form of powdered and it is firstly heated with the sodium carbonate in the presence of air. By doing this, we get sodium chromate as a result. Now, sodium chromate is combining with the dilute sulphuric acid to form sodium dichromate. Lastly, if we want our product which is potassium dichromate then we have to treat it with $KCl$ so, sodium dichromate is combined with $KCl$ and we get our product named as potassium dichromate.
Step by step procedure:
Chromate ore is heated with the sodium carbonate in the presence of air.
$2FeC{r_2}{O_4} + 8NaOH + 7/2{O_2} \to 4N{a_2}C{r_2}{O_4} + F{e_2}{O_3} + 4{H_2}O$
Now, sodium chromate is added with dilute sulphuric acid to form sodium dichromate.
$2F{e_2}C{r_2}{O_4} + {H_3}S{O_4} \to N{a_2}C{r_2}{O_7} + N{a_2}S{O_4} + {H_2}O$
In the final step, Sodium chromate reacted with $KCl$and formed Potassium dichromate.
$N{a_2}C{r_2}{O_7} + 2KCl \to {K_2}C{r_2}{O_7} + 2NaCl$

Note:
Potassium dichromate is less soluble so its crystals are taken out first.