# Potassium chlorate, KClO_3, decomposes to form potassium chloride, KCl and oxygen gas. How do you write a balanced equation for this decomposition reaction?

Dec 8, 2015

$\text{2KClO"_3("s")" + heat}$$\rightarrow$$\text{2KCl(s)" + "3O"_2("g")}$

#### Explanation:

$\text{KClO"_3("s")" + heat}$$\rightarrow$$\text{KCl(s)" + "O"_2("g")}$

Notice that the number of atoms of $\text{K}$ and $\text{Cl}$ are the same on both sides, but the numbers of $\text{O}$ atoms are not. There are 3 $\text{O}$ atoms on the the left side and 2 on the right. 3 and 2 are factors of 6, so add coefficients so that there are 6 $\text{O}$ atoms on both sides.

$\text{2KClO"_3("s")" + heat}$$\rightarrow$$\text{KCl(s)" + "3O"_2("g")}$

Now the $\text{K" and "Cl}$ atoms are not balanced. There are 2 of each on the left and 1 of each on the right. Add a coefficient of 2 in front of $\text{KCl}$.

$\text{2KClO"_3("s")" + heat}$$\rightarrow$$\text{2KCl(s)" + "3O"_2("g")}$

The equation is now balanced with 2 $\text{K}$ atoms, 2 $\text{Cl}$ atoms, and 6 $\text{O}$ atoms on both sides.