Question

One mole of potassium chlorate $\left(KCl{O}_3\right)$ is thermally decomposed and excess of aluminium is burnt in the gaseous product. How many moles of aluminium oxide $\left(A{l}_2{O}_3\right)$ are formed?

• A. $1$
• B. $1.5$
• C. $2$
• D. $3$

Answer 1

Answer: (A)

$1$

Chemical equation for thermal decomposition of $KCl{O}_3$:

$2KCl{O}_3\underset{}{\overset{\Delta }{\to }}2KCl+3O_2.........\left(1\right)$

Chemical equation for reaction between $Al$ and $O_2$

$4Al+3O_2\to 2A{l}_2{O}_3......\left(2\right)$

The overall reaction can be deduced by combining both equations-

$2KCl{O}_3⟶2KCl+3O_2$

$4Al+3O_2\to 2A{l}_2{O}_3$

$\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_$

$2KCl{O}_3+4Al+3O_2\to 2KCl+2A{l}_2{O}_3+3O_2$

$\therefore$ Overall reaction $KCl{O}_3+2Al\to KCl+A{l}_2{O}_3$

From the above reaction, $1$ mole $KCl{O}_3$, produces $1$ mol of $A{l}_2{O}_3$

$\therefore$ Option $A=1$ is correct.