# Question 30599

Apr 3, 2016

Yes.

#### Explanation:

You're dealing with a decomposition reaction in which potassium chlorate, ${\text{KClO}}_{3}$, undergoes thermal decomposition to form potassium chloride, $\text{KCl}$, and oxygen gas, ${\text{O}}_{2}$.

Now, chemical formulas contain numbers written as subscripts. These subscripts are used to describe how many atoms of a certain element you get in one molecule or one formula unit of said compound.

In this case, potassium chlorate has the following chemical formula

${\text{KClO}}_{\textcolor{red}{3}}$

This means that one formula unit of potassium chlorate contains

• one atom of potassium, $1 \times \text{K}$
• one atom of chlorine, $1 \times \text{Cl}$
• three atoms of oxygen, $\textcolor{red}{3} \times \text{O}$

Notice that the $1$ is not written as a subscript. If a chemical formula contains a chemical symbol that is not followed by a subscript, then it is implied that the subscript is actually $1$.

In this case, the subscript $\textcolor{red}{3}$ follows the oxygen atom, so it belongs to oxygen exclusively.

Jeep in mind that you can have cases where a subscript belongs to more than one element in a chemical compound.

For example, magnesium hydroxide, "Mg"("OH")_color(blue)(2)#. Here the $\textcolor{b l u e}{2}$ subscript follows two elements, oxygen and hydrogen, grouped together by parentheses.

When that is the case, the subscript is distributed to both these elements. So one formula unit of magnesium hydroxide would contain

• one atom of magnesium, $1 \times \text{Mg}$
• two atoms of oxygen, $\textcolor{b l u e}{2} \times \text{O}$
• two atoms of hydrogen, $\textcolor{b l u e}{2} \times \text{H}$

Also, it's worth noting that stoichiometric coefficients are distributed to all the elements present in the chemical formula.

For example, the balanced chemical equation for the decomposition of potassium chlorate looks like this

$\textcolor{p u r p \le}{2} {\text{KClO"_ (3(s)) -> 2"KCl"_ ((s)) + 3"O}}_{2 \left(g\right)}$

Here the $\textcolor{p u r p \le}{2}$ stoichiometric coefficient tells you that you need two moles of potassium chlorate in order for the reaction to produce two moles of ptoassium chloride and three moles of oxygen gas.