# Butin was subjected to incomplete chlorination, calculate the mass fraction of chlorine in the final product

**Butin was subjected to incomplete chlorination, calculate the mass fraction of chlorine in the final product, name this substance.**

Given:

C4H6

To find:

ω (Cl in C4H6Cl2) -?

Solution:

The mass fraction of an element in a given substance is the ratio of the relative atomic mass of a given element, multiplied by the number of its atoms in a molecule, to the relative molecular mass of a substance.

1) Write the equation of a chemical reaction:

C4H6 + Cl2 => C4H6Cl2;

2) Using the periodic system of D.I.Mendeleev, calculate the relative molecular weight of C4H6Cl2:

Mr (C4H6Cl2) = Ar (C) * 4 + Ar (H) * 6 + Ar (Cl) * 2 = 12 * 4 + 1 * 6 + 35.5 * 2 = 125;

2) Calculate the mass fraction of Cl in C4H6Cl2:

ω (Cl in C4H6Cl2) = N * Ar (Cl) * 100% / Mr (C4H6Cl2) = 2 * 35.5 * 100% / 125 = 56.8%.

Answer: Mass fraction of Cl in C4H6Cl2 is 56.8%.