Perform a rxn to obtain 5 g ethyl bromide. Assuming that a normal percentage yield is 85%, what min quantity of materials needed to give desired product

Question

Density of ethyl bromide is 1.47 g/cm3

Molecular mass of ethyl bromide is 108.97 g/mol

 

I need the answer in mL ethanol and mL phosphorus tribromide

Answer 1

In order to solve this problem, you need to know the densities of phosphorus tribromide and ethanol:

ρ PBr₃ = 2.852 g/mL

ρ EtOH = 0.789 g/mL

 

The balanced equation is as follows:

3CH₃CH₂OH + PBr₃ -->  3CH₃CH₂Br + HPO(OH)₂

 

The answers are obtained as follows:

 

mL_PBr3 =  5 g_EtBr(1 mol_EtBr/108.9651 g_EtBr)(1 mol_PBr3/3 mol_EtBr)(270.6858 g_PBr3/mol_PBr3)(100/85)(1 mL_PBr3/2.852 g_PBr3) = 1.71 mL

 

mL_EtOH = 5 gEtBr(1 molEtBr/108.9651 gEtBr)(3 mol_EtOH/3 mol_EtBr)(46.0684 g_EtOH/mol_EtOH)(100/85)(1 mL_EtOH/0.789 g_EtOH) = 3.15 mL