Question

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

Answer 1

Hint: 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.