Question

2 mol of ${H_2}S$ and 11.2 L $S{O_2}$ at N.T.P. reacts to form x mol of sulphur; x is
$S{O_2} + 2{H_2}S \to 3S + 2{H_2}O$
(A) 1.5
(B) 3
(C) 11.2
(D) 6

Answer 1

Here, first we have to calculate the number of moles of each compound needed to form another compound. This can be calculated from the equation by the substitution method. We have to convert $S{O_2}$into moles and get the number of moles to calculate the no. of moles of Sulphur. Then, we determine the limiting agent and according to it the number of moles can be calculated.

Complete step by step answer:
The equation is,
$S{O_2} + 2{H_2}S \to 3S + 2{H_2}O$
Given data is:
2 mol of ${H_2}S$ 11.2 L $S{O_2}$ at N.T.P.
Let us find out no. of moles of $S{O_2}$
No. of moles of $S{O_2}$
=$\dfrac{{11.2}}{{22.4}} = 0.5$
According to this equation 1 mole of $S{O_2}$ reacts with 2 moles of ${H_2}S$.
In this question we have 2 mol of ${H_2}S$ and 0.5 mol of $S{O_2}$. So $S{O_2}$
is a limiting agent which is 0.5 moles.
So 1 moles of $S{O_2}$ reacts with 2 moles of ${H_2}S$.
So 0.5 moles of $S{O_2}$ reacts with 1 mole of ${H_2}S$.
So 1 moles of $S{O_2}$ reacts with 3 moles of S.
So 0.5 moles of $S{O_2}$ reacts with $3 \times 0.5$=1.5 moles of S.

So, the correct answer is Option A.

Additional information:
Moles are the unit of measurement in chemistry. It is defined as the given weight by molecular weight. It is important as it bridges between the atom and the macroscopic amounts of material. It helps in measuring the weights of different substances.
One mole of a substance is equal to $6.022 \times {10^{23}}$
units of that substance (such as atoms, molecules, or ions). $6.022 \times {10^{23}}$
is known as Avogadro's number or Avogadro's constant.

Note: It is to be noted that STP and NTP are not the same. STP stands for standard temperature and Pressure and NTP stands for normal temperature and pressure. According to IUPAC, STP is for 0 degree Celsius (temperature) and 1 atm or 100 kPa (pressure) and NTP is for 20 degree Celsius and 101.325 kPa.