Question

The synthesis of an ester by the reaction of a carboxylic with an alcohol is an equilibrium reaction. H - R-OH HO ROH R OR, Recall from general chemistry that, according to Le Caiclista principle, an equilibrium can be shifted toward greater product formation by using an excess of reactant or by removal of a reaction product as it forms. 1. Are any products removed during the reaction period (the 1-hour reflux). if so which ones! 2. Using the quantities of carboxylic acid and alcohol in the experimental procedure, determine if sither reactant is used in molar excess. For this question assume the alcoholis 1-propanol. Show all calculations and clearly indicate if a reactant is used in excess (Note: the density of acetic acid and l-propanolare 1.049 g mland 0.900 g/ml, respectively). 3. What method, if any, will be used in this lab procedure to shit the reaction toward greater product formation 4. Based on your answer to question 2, what is the theoretical yield of ester in moles and grams? Show all additional calculations

acetic acid is 25 ml and alcohol is 20 ml

Answer 1

Ans 1:

During the esterification procedure water will be removed as soon as it is formed. This shifts the equilibrium to the right according to Le Chatelier’s principle.

Ans 2:

• According the balanced chemical equation for esterification, 1 mol of acetic acid demands 1 mol of 1-propanol (1:1 ratio). (refer the equation given in the question)

	Molar mass, M	density, d = m/V	Volume taken, V	Mass taken (m)	Mole taken m/M	Remark
Acetic acid CH3COOH	60.052 g/mol	1.049 g/ml	25 ml	26.225 g	0.4367 mol	Acetic acid is taken in excess CH3COOH: C3H7OH = 1.46:1
1-propanol C3H7OH	60.09 g/mol	0.900 g/ml	20 ml	18.00 g	0.2996 mol

• One of the reactant taken in excess also helps in pushing the equilibrium to the right increasing the product yield according to Le Chatelier’s principle.

Ans 3:

Using Dean–Stark apparatus one can easily remove water as soon as it forms.

It is a piece of laboratory glass apparatus used to collect water from a reaction vessel. It is used along with a reflux condenser and a batch reactor for removal of the water as soon as it is formed during a chemical reaction performed at reflux temperature.

Ans 4:

• Moles of acetic acid taken: 0.4367 mol
• Moles of 1-propanol taken: 0.2996 mol
• Limiting reagent (reagent which is in less amount than required) of the reaction: 1-propanol.
• Theoretically, during the reaction limiting reagent will be completely consumed to become the product. Accordingly, 1-propanol will be completely consumed.
• According the balanced chemical equation (refer the equation in question), 1 mol of 1-propanol gives 1 mol of ester i.e n-propylacetate (CH₃COOC₃H₇). So, 0.2996 mol of 1-propanol should form 0.2996 mol of ester.
• Molar mass of ester (n-propylacetate): 102.131 g/mol
• Mass of 0.2996 mol of ester = 102.131 x 0.2996 = 30.5984 g

Theoretical yield of ester = 0.2996 mol = 30.5984 g