Nicotine contains 74.9% carbon, 8.7% hydrogen and 17.3% nitrogen. it is known that this compound contains two nitrogen atoms per molecule. what are the empirical and molecular formulas of nicotine?

             Empirical Formula  =  C₅H₇N₁

             Molecular Formula  =  C₁₀H₁₄N₂

Solution:

Step 1: Calculating Moles of Elements as;

For C;

                          Moles of C  =  %age of C ÷ At.Mass of C

                          Moles of C  =  74.9 ÷ 12

                          Moles of C  =  6.24

For H:

                          Moles of H  =  %age of H ÷ At.Mass of H

                          Moles of H  =  8.7 ÷ 1

                          Moles of C  =  8.7

For N;

                          Moles of N  =  %age of N ÷ At.Mass of N

                          Moles of N  =  17.3 ÷ 14

                          Moles of N  =  1.23

Step 2: Simplifying the mole ratio as;

                                   C             :            H           :            N

                           6.24/1.23        :        8.7/1.23     :       1.23/1.23

                                 5                :            7           :             1

So, The Empirical Formula is;

                                                       C₅H₇N₁

Step 3: Finding out Molecular Formula;

The Molecular mass of Nicotine is 162.23 g.mol⁻¹, So, the Molecular formula is calculated as,

                          n  =  Molecular Mass ÷ Empirical formula Mass

As,

          Empirical formula Mass  =  C₅H₇N₁ = (12)₅+(1)₇+(14)₁ = 60+7+14 = 81

So,

                          n  =  162 ÷ 81

                          n  =  2

Now, Multiply Empirical Formula by 2 as;

                          (C₅H₇N₁) × 2 = C₁₀H₇N₂

both adhesion and cohesion are attractions.

they are different in that adhesion is the force of attraction between the molecules of two different substances, whereas cohesion is the force of attraction between molecules of the same substance.

possible examples include capillary action, in which the adhesion between water and glass causes the water to rise in a narrow tube against the force of gravity.

because of hydrogen bonding, water is extremely cohesive.

this causes molecules on the surface of water to be drawn inward, which is why drops of water form beads on smooth surfaces.

hope this .