Question

How much $KN{{O}_{3}}$ must be heated to give as much $O$, as required to burn 16 g of $S$ into $S{{O}_{2}}$?
$[N=14,O=16,K=39,S=32]$
A. 100 g
B. 101 g
C. 91 g
D. 99.1 g

Answer 1

Hint: $KN{{O}_{3}}$ is known by the name potassium nitrate which is a chemical compound and known as an ionic salt of potassium ions represented by the symbol ${{K}^{+}}$and nitrate ions $N{{O}_{3}}^{-}$. It generally occurs in nature as a mineral.

Complete answer:
A mole of a substance or particle can be defined as containing exactly $6.02214076 \times {10^{23}}$ particles which may be atoms, molecules or ions where $6.02214076 \times {10^{23}}$ is known as the Avogadro’s number.
$S+{{O}_{2}}\to S{{O}_{2}}$
Moles of sulfur can be calculated by the formula
$\dfrac{Given\ \text{mass}\ }{Molar\ \text{mass}}$; Molar mass is 32 and given is 16
$Moles\ of\ \text{sulphur =}\dfrac{16}{32}=0.5mole$
This suggests that 0.5 mol of sulfur requires 0.5 mol of oxygen.
Now we know that sulphur burns in 0.5 mol oxygen.
Then the thermal decomposition of Potassium nitrate is given by the following reaction:
$2KN{{O}_{3}}\to 2KN{{O}_{2}}+{{O}_{2}}$
This suggests that 1 mol of oxygen​ is produced by 2 mol of $KN{{O}_{3}}$​
We can also say that 0.5mol of oxygen​ will be produced by 1 mol of $KN{{O}_{3}}$​
Thus, 1 mole of $KN{{O}_{3}}$​ is required to produce the given amount of oxygen.
1 mol of $KN{{O}_{3}}$​= molar mass of $KN{{O}_{3}}$
Molar mass of $KN{{O}_{3}}$can be calculated by $K+2\times N+3\times O=39+14\times 2+16\times 3=101$

Hence, option B is correct.

Note:
Mole is generally represented by the symbol mol. It is generally described as the unit of measurement for the amount of substance in SI where SI stands for International System of units. It is defined on the basis of Avogadro’s number.