# Question 9fdaf

Feb 1, 2015

The mass of potassium chloride is $\text{3.8 g}$.

Take the balanced chemical equation

$2 K C l {O}_{3} \to 2 K C l + 3 {O}_{2}$

Look at the mole ratio you have between potassium chlorate and potassium chloride; what you will see is that every $\text{2 moles}$ of potassium chlorate will produce $\text{2 moles}$ of potassium chloride, i.e. you have a $\text{1:1}$ mole ratio between the two compounds.

The number of moles of $\text{KCl}$ will mirror the number of moles of ${\text{KClO}}_{3}$, regardless of what that number is. This means that you know how many moles of $\text{KCl}$ you'll have - exactly how many moles of ${\text{KClO}}_{3}$ you have.

Since you were given the mass of ${\text{KClO}}_{3}$, you can determine how many moles you have by using its molar mass

$\text{6.3 g KClO"_3 * ("1 mole")/("122.6 g") = "0.051 moles}$

Automatically, the number of $\text{KCl}$ moles produced will be

n_("KCl") = n_("KClO"_3) = "0.051 moles"#

Now use $\text{KCl}$'s molar mass to determine how many grams you'll get

$\text{0.051 moles KCl" * ("74.6 g")/("1 mole") = "3.8 g}$

The reaction you are dealing with is the decomposition of potassium chlorate (more here: http://socratic.org/questions/what-does-kclo3-decompose-into).