Question

When one gram mole of $KMn{O_4}$ reacts with $HCl$, the volume of chlorine liberated at NTP will be:
A. 11.2 litres
B. 22.4 litres
C. 44.8 litres
D. 56.0 litres

Answer 1

Potassium permanganate, a strong oxidizing agent is used as a reactant for producing manganese compounds. When potassium permanganate ($KMn{O_4}$) reacts with concentrated hydrochloric acid ($HCl$), the products formed are manganese(II) chloride, potassium chloride, water and chlorine gas.

Formula used: As derived from ideal gas law,
$V = n \times 22.4L$
$n$= moles of the gas produced
$V =$ Volume of the gas at NTP

Complete step by step answer:
The chemical reaction between potassium permanganate and concentrated hydrochloric acid is shown below.
$2KMn{O_4} + 16HCl \to 2KCl + 2MnC{l_2} + 8{H_2}O + 5C{l_2}$
As per chemical equation above, 2 moles of potassium permanganate ($KMn{O_4}$) reacts with 16 moles of hydrochloric acid to produce 2 moles of potassium chloride, 2 moles of manganese chloride, 8 moles of water and 5 moles of chlorine gas were released.
Therefore, if 1 mole of $KMn{O_4}$ reacted with 8 moles of $HCl$, then the amount of chlorine gas that will liberate is $\dfrac{5}{2} = 2.5moles$.
At NTP, one mole of any gas will occupy 22.4L of volume.
Now, to calculate the volume of 2.5 moles of chlorine gas at NTP, we have to use the following formula.
$V = n \times 22.4L$
On substituting the values in the formula, we get,
$V = 2.5 \times 22.4L$
$\therefore V = 56L$
Therefore, the volume of chlorine gas at NTP will be 56L or 56 litres.

So, the correct answer is Option D.

Additional information:
The formula used for calculating the volume of chlorine gas at NTP is derived from the ideal gas law equation.
According to the ideal gas law,
$PV = nRT$
We know that, at NTP,
$P = 1atm$
$n = 1mole$
$R = 8.314J/mol.{K^{ - 1}}$
$T = 273K$
On putting these values in ideal gas law equation, we get
$V = 22.4L$

Note: Students might get confused about STP and NTP. There is a difference between STP and NTP. STP is Standard Temperature and Pressure and NTP is Normal Temperature and Pressure. As stated by IUPAC, at STP, temperature is considered as 0$^\circ$C and pressure is 1 bar. At NTP, pressure is 1 atm and temperature is 20$^\circ$C.