Question

At constant temperature and pressure, 5.0 L of SO2 is combined with 3.0 L of O2 according to the equation:

2SO2 + O2=2SO3
After SO3 formation is complete, what is the volume of the mixture?

Answer 1

Answer : The volume of mixture is, 4.99 liters.

Explanation :

First we have to calculate the moles of
`SO_2` and
`O_2`.

As we know that at STP, 1 mole of substance contains 22.4 L volume of substance.

As, 22.4 L volume of
`SO_2` present in 1 mole of
`SO_2`

So, 5 L volume of
`SO_2` present in
`(5)/(22.4)=0.223` mole of
`SO_2`

And,

As, 22.4 L volume of
`O_2` present in 1 mole of
`O_2`

So, 3 L volume of
`O_2` present in
`(3)/(22.4)=0.134` mole of
`O_2`

Now we have to calculate the limiting and excess reagent.

The balanced chemical reaction is,

`2SO_2+O_2\rightarrow 2SO_3`

From the balanced reaction we conclude that

As, 2 mole of
`SO_2` react with 1 mole of
`O_2`

So, 0.223 moles of
`SO_2` react with
`(0.223)/(2)=0.1115` moles of
`O_2`

From this we conclude that,
`O_2` is an excess reagent because the given moles are greater than the required moles and
`SO_2` is a limiting reagent and it limits the formation of product.

Now we have to calculate the moles of
`SO_3`

From the reaction, we conclude that

As, 2 mole of
`SO_2` react to give 2 mole of
`SO_3`

So, 0.223 moles of
`SO_2` react to give 0.223 moles of
`SO_3`

Now we have to calculate the volume of
`SO_3`.

As, 1 mole of
`SO_3` gas occupy 22.4 L volume of
`SO_3`

So, 0.223 mole of
`SO_3` gas occupy
`0.223* 22.4=4.99L` volume of
`SO_3`

Therefore, the volume of the mixture is 4.99 liters.

Answer 2

The balanced chemical reaction is:

2SO2 + O2=2SO3

We are given the amounts of the reactants to be consumed in the reaction. These amounts are the starting point for the calculations.

5.0 L SO2 ( 1 mol / 22.4 L ) = 0.2232 mol SO2
3.0 L O2 ( 1 mol / 22.4 L ) = 0.1339 mol O2

From the chemical reaction, the mole ratio of the reactants 2:1. Therefore, the limiting reactant is SO2.

0.2232 mol SO2 ( 1 mol SO3 / 2 mol SO2) ( 22.4 L / 1 mol ) = 2.4998 L SO3