# What volume of oxygen gas is released at STP if 10.0g of potassium chlorate is decomposed? The molar mass of KCIO_3 is 122.55 g/mol?

Sep 7, 2016

$K C l {O}_{3} \left(s\right) + \Delta \rightarrow K C l \left(s\right) + \frac{3}{2} {O}_{2} \left(g\right)$

Approx. $3 L$ of dioxygen gas will be evolved.

#### Explanation:

We assume that the reaction as written proceeds quantitatively.

Moles of $K C l {O}_{3} \left(s\right)$ $=$ $\frac{10.0 \cdot g}{122.55 \cdot g \cdot m o {l}^{-} 1}$ $=$ $0.0816 \cdot m o l$

And thus $\frac{3}{2} \times 0.0816 \cdot m o l$ dioxygen are produced, i.e. $0.122 \cdot m o l$.

At $\text{STP}$, an Ideal Gas occupies a volume of $22.4 \cdot L \cdot m o {l}^{-} 1$.

And thus, volume of gas produced $=$ $22.4 \cdot L \cdot m o {l}^{-} 1 \times 0.0816 \cdot m o l \cong 3 L$

Note that this reaction would not work well without catalysis, typically $M n {O}_{2}$.