Question

Calculate the number of atoms present in 112 grams of N2 & also find its volume at STP?​

Answer 1

$\bigstar$ Answer $\bigstar$

$\checkmark$ Given:

112 g of N₂

$\checkmark$ To Find:

• Number of atoms
• Volume at STP

$\checkmark$ Solution:

We know that,

Gram Molecular Weight (GMW)

GMW of N₂ = 28 g

So,

28 g of N₂ is 1 mole

Therefore,

112 g of N₂ has x moles

Mathematically,

$\implies \rm 28 \ g = 1 \ mole$

$\implies \rm 112 \ g = x \ moles$

On Cross multiplication,

We get,

$\implies \rm x=\left(\dfrac{112 \times 1}{28}\right) \ moles$

Hence,

$\green{\implies \rm x=4 \ moles}$

We know that,

1 mole of a substance contains 6.023 x 10²³ molecules

So,

1 mole = 6.023 x 10²³ molecules

Therefore,

4 moles contains y molecules,

Mathematically,

$\rm \rightarrow 1 \ mole = 6.023 \times 10^{23} \ molecules$

$\rm \rightarrow 4 \ moles = y \ molecules$

On Cross multiplication,

We get,

$\implies \rm y=4 \times 6.023 \times 10^{23} \ molecules$

Hence,

$\implies \rm y=24.09 \times 10^{23} \ molecules$

Approximately,

$\red{\implies \rm y=24 \times 10^{23} \ molecules}$

According to question, we are also asked to find its volume at STP.

STP=Standard Temperature and Pressure

We know that,

1 mole of gas occupies 22.4 Litres

So,

1 mole = 22.4 Litres

Therefore,

4 moles = z Litres

Mathematically,

$\rm \implies 1 \ mole = 22.4 \ Litres$

$\rm \implies 4 \ mole = z \ Litres$

On Cross multiplication,

We get,

$\rm \implies z=4 \times 22.4 \ Litres \ at \ STP$

$\pink{\rm \implies z=89.6 \ L \ at \ STP}$