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DISTILLATION The PreLab Exercise A mixture of 40 mL of methylbutyrate (MW=1021 g

ID: 884626 • Letter: D

Question

DISTILLATION The PreLab Exercise A mixture of 40 mL of methylbutyrate (MW=1021 gmold-o 89 g and 10 mL butyric acid (MW-88.1 gmol, d-0.96 g/ Calculate the mole percent of each component, and , d-0.89 g/mL) - mL) is distilled pe rcents and the figure below, answer the following questions: of each component, and u using these mole 1. What is the initial boiling point of this mixture? 2. What is the composition of the vapor in equilibrium with this lquid? What is the composition of the initial condensate from simple distillation' 3. Instead of a simple distiliation, you set up a fractional distillation Assuming three theoretical plates, what is the composition of the first fraction collected? 170 170 160 150 140 Gas 140 Temp C)130 130 120 120 110 100 Liquid 0 80 20 100 methyl butyrate butyric acid 80 100 LLATION liquid state, the molecules that make up any compound are packe in a relatively close space. These molecules have a certain energy, ar constant motion. In the liquid phase, molecules are held together forces, which include London forces, dipole attractions, a en bonding. It is the strength of these attractive forces that determines er lecular nnint nf a liquid. At any temperature, some of these molecules h nd nter the gas phase

Explanation / Answer

Volume of methyl butyrate = 40 mL

Density of  methyl butyrate = 0.89 g/mL

Mass of  methyl butyrate = 40*0.89

= 35.6 g

moles of methyl butyrate = 35.6 / 102.1

= 0.3486

Volume of butyric acid = 10 mL

Density of butyric acid = 0.96 g/mL

Mass of  butyric acid = 10*0.96

= 9.6 g

moles of butyric acid = 9.6 / 88.1

= 0.109

mole percent of methyl butyrate = 0.3486 / (0.3486 + 0.109) * 100

= 76.18%

mole percent of butyric acid = 0.109 / (0.3486 + 0.109) * 100

= 23.82%

The total pressure is P=Pa + Pb

methyl butyrate Pa = (0.3486 * 40 / 0.3486 + 0.109)    (since vapour pressure of methyl btyrate= 40 mm Hg)

                            = 30.47 mm Hg

butyric acid Pb = (0.109 * 43 / 0.3486 + 0.109)    (since vapour pressure of butyric acid = 43 mm Hg)

                            = 9.53 mm Hg

P = Pa + Pb = 30.47 + 9.53

= 39.99 mm Hg