An unknown alkene weighing 5.04 g completely discolors 100 g of a 9.6% solution

An unknown alkene weighing 5.04 g completely discolors 100 g of a 9.6% solution of bromine in carbon tetrachloride. Find the molecular formula for alkene.

1. Let’s compose the reaction equation for alkene bromination:

CnH2n + Br2 → CnH2nBr2;

2. find the mass of bromine:

m (Br2) = w (Br2) * m (solution) = 0.096 * 100 = 9.6 g;

3.Calculate the chemical amount of bromine:

n (Br2) = m (Br2): M (Br2) = 9.6: 160 = 0.06 mol;

4.According to the reaction equation, the amount of alkene coincides with the amount of added bromine:

n (CnH2n) = n (Br2) = 0.06 mol;

5.Calculate the molar mass of the alkene:

M (CnH2n) = m (CnH2n): n (CnH2n) = 5.04: 0.06 = 84 g / mol;

M (CnH2n) = 12n + 2n = 14n;

6.we equate the obtained molar masses and determine n:

14n = 84;

n = 6;

7.Substitute the found value of the index and write the formula:

C6H6.

Answer: hexene C6H6.