Question
What is the number of molecules in 11.2 L of O2 at STP? [Ans. 3.011 × 1023]
Answer
Step 1: Calculation of number of moles
moles of O2 = Given Volume\ of\ O_2 \over 22.4
= 11.2 \over 22.4
= 0.5 mol
Step 2: Calculation of number of molecules
number of molecules of O2 = moles of O2 × Avogadro’s number
= 0.5 × 6.022 × 1023
= 3.011 × 1023 molecules
Therefore, the number of molecules in 11.2 L of O2 at STP is 3.011 × 1023 molecules.