Question

b)  Answer the following stoichiometry questions by referring to the equation below:

2        KClO₃  ---->  2 KCl + 3 O₂

i.        If 1.50 mol of KClO₃ decomposes, what is the mass of O₂ that will be produced?

ii.       If 80.0 grams of O₂ was produced, how many moles of KClO₃ are decomposed?

iii.    Find the mass of KClO₃ needed if we need to produce 2.75 mol of KCl.

Answer 1

From the equation;

i. Mass of $O_2$ produced

$1.50mol KClO_3$ $\times$ $3mol O_2\over 32.0gO_2$ $\times$ $122.5gKClO_2\over2mol KClO_2$ $=8.61gO_2$

ii. $x$ mol $KClO_3=80.0gO_2$ $\times$ $1mol O_2\over 32.0gO_2$ $\times$ $2mol KClO_3\over 3mol O_2$

$=1.67mol KClO_3$

iii. $x$ g $KClO_3$ $=2.75mol KCl$ $\times$ $2mol KCl\over 122.5gKClO_3$ $\times$ $74.55gKCl\over 2mol KCl$

$=1.67gKClO_3$