BACCALAURÉAT S
ÉPREUVE SPÉCIFIQUE « SECTION EUROPÉENNE »
SCIENCES PHYSIQUES ET CHIMIQUES – ANGLAIS
Task: Do the following exercise
Esterification
Scented esters like methylbenzoate are often used in the perfume industry.
Methylbenzoate C6H5-COO-CH3 is obtained by reaction between benzoic acid
C6H5-COOH and a chemical called A, in presence of sulphuric acid.
1) Qualitative analysis.
1. What is an esterification? What kind of chemical families are involved?
2. What is the use of sulphuric acid?
3. Give the name and the chemical family of A. Draw its structural formula.
4. Draw the semi-developed formula of a benzoic acid molecule.
2) Quantitative analysis.
In the case of an esterification obtained from an equimolar mixture of reactants
(1.0 mol of A and 1.0 mol of benzoic acid):
1. Draw the progress table of the chemical transformation.
2. Express the reaction quotient Qr. Deduce the equilibrium constant of this
reaction knowing that the progress at equilibrium is xeq = 0.66 mol. Define and
determine the yield of the reaction.
Now we realise a new experiment with 3.0 mol of A and 1.0 mol of benzoic acid.
3. Using the reaction quotient, determine how the transformation evolves.
3) Increasing the yield of the esterification.
1. Could you find another way to increase the yield of the transformation?
2. Write the structural formula of the chemicals involved.
ANG CHIORG 106759777
Page 1 sur 1