Question

You transfer 10.0 mL of a 0.5 M solution of urea (CH4N2O) into a beaker. How many molecules of urea does it contain?

Answer 1

Volume of Urea = 10 ml

Concentration of urea = 0.5 M

Moles of urea = 10 x 0.5 / 1000 = 0.005 Moles

The number of molecules in one mole of urea (or any substance), equal to 6.023 × 10²³ which known as  Avogadro's number.

No of molecules of urea = 0.005 x 6.023 × 10²³ = 3.0115 x 10²¹ Molecules

Hence the total no of urea molecules present in the beaker is  3.0115 x 10²¹