9) Consider the reaction of C6H6 Br2 C6H5Br HBr a. What is the theoretical yield of C6H5Br if 42.1 g of C6H6 react with 73.0 g of Br2

The theoretical yield of the reaction has been 0.457 mol.

The balanced chemical equation for the reaction can be given by:

Accordingly, 1 mole of benzene will give 1 mole of Bromobenzene and 1 mole of Hydrobromide.

The moles can be calculated as;

Moles =

Moles in 42.1 grams Benzene:

Moles of Benzene =

Moles of Benzene = 0.540 mol

Moles of Bromine =

Moles of Bromine = 0.457 mol.

The limiting reactant in the reaction has been the one that has been present in the lesser quantity as the other reactant to continue to the product formation.

The 1 mole of Benzene requires 1 mole of bromine. So, 0.54 mol of benzene requires. 0.54 mol of bromine. Since the available bromine has been 0.457 mol, Bromine has been the limiting reactant.

The theoretical yield of the reaction will be based on the concentration of Bromine.

Thus, 1 mol of Bromine forms 1 mol of Bromobenzene.

0.457 mol of Bromine will form 0.457 mol of bromobenzene.

The theoretical yield of the reaction has been 0.457 mol.

For more information about theoretical yield, refer to the link:

link

71.7 g of C₆H₅Br are produced at the theoretical yield.

Explanation:

The reaction is:

C₆H₆ + B₂ → C₆H₅Br + HBr

This is an easy excersie, stoichiometry is 1:1

We determine moles of reactants:

42.1 g / 78g/mol = 0.540 moles of benzene

73 g / 159.80 g/mol = 0.457 moles of hydrogen bromide

Certainly, the HBr is the limiting reactant, because I need 0.540 moles of HBr for 0.540 moles of benzene and I only have, 0.457 moles.

0.457 moles of HBr will produce 0.457 of bromobenzene, at the 100 % yield reaction (theoretical yield)

We convert the moles to mass: 0.457 g . 157 g/mol = 71.7 g  

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.