Question

Write the balanced chemical equation for the reaction \[{K_2}C{r_2}{O_7}\] and Ferrous sulfate.
A.\[C{r_2}{O_7}^{2 - } + 6F{e^{ + 2}} + 14{H^ + } \to 2C{r^{ + 3}} + 6F{e^{ + 3}} + 7{H_2}O\]
B.\[2C{r_2}{O_7}^{2 - } + 6F{e^{ + 2}} + 16{H^ + } \to 2C{r^{ + 3}} + 6F{e^{ + 3}} + 8{H_2}O\]
C.\[C{r_2}{O_7}^{2 - } + 8F{e^{ + 2}} + 16{H^ + } \to 2C{r^{ + 3}} + 8F{e^{ + 3}} + 8{H_2}O\]
D.None of these

Answer 1

Hint: A chemical equation represents the substances that are involved in a chemical reaction i.e. reactants and products. The balanced chemical equation is the one that has the same number of atoms on both sides of a reaction.

Complete step by step answer:
To balance the reaction, we can use the law of conservation of mass. Hit and trial method is used to balance the number of atoms on both, left and right side of the reaction. The mass of products in a chemical reaction must be equal to the mass of reactants.
The atomic number of irons is 26 and hence its electronic configuration is \[1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}4{s^2}3{d^6}\]. Hence, the iron atom can achieve 2 oxidation states, viz. +2 and +3.
The atomic number of chromium is 24 and hence its electronic configuration is \[1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}4{s^1}3{d^5}\]. Hence, the chromium atom can achieve many oxidation states, among them +6 and +3.
Now, \[{K_2}C{r_2}{O_7}\] is a strong oxidizing agent, it will oxidize the ferrous into ferric.
Here oxidation and reduction takes place, so it is a redox reaction.

Now to balance a chemical reaction there are so many methods. For redox reactions in an acidic medium, the steps of balancing reaction are,
1.First, write down the oxidation and reduction reaction from the given reaction.
2.Then balance the number of oxygen and hydrogen of the oxidation and reduction reaction. Add \[{H^ + }\] to make an equal number of hydrogen and add water to make an equal number of oxygens.
3.Then balance the charge of each oxidation and reduction reaction by the electron.
4.After that multiply the number with the reaction to make an equal number of electrons in each reaction.
5.Finally, summarize the reaction to establish a balanced reaction.
So, considering all these steps the overall balanced equation, for the reaction \[{K_2}C{r_2}{O_7}\] and Ferrous sulfate. Is,
 \[C{r_2}{O_7}^{2 - } + 6F{e^{ + 2}} + 14{H^ + } \to 2C{r^{ + 3}} + 6F{e^{ + 3}} + 7{H_2}O\]

So, the correct option is A.

Note: The coefficient means the number of molecules of a reaction is present. it is the number in front of the chemical formula of the compound in a reaction equation.
Iron and chromium are the d- block metal. The d block elements are found in the group 3,4,5,6,7,8,9,10,11 and 12 of the periodic table. These are also known as transition metals. The d orbital is filled with an electronic shell $n - 1$. There are a total of 40 d block elements.