Initial volume of 2-methyl-2-butanol: 5 mL Final volume of 2-chloro-2-methylbuta
ID: 635583 • Letter: I
Question
Initial volume of 2-methyl-2-butanol: 5 mL Final volume of 2-chloro-2-methylbutane: 1 mL
Attached is the reagents used during the experiment.
Need to use the density to calculate the theoretical yield from initial volume of 2-chloro-2-butanol (?) Explaination/calculation would be greatly appreciated.
o Place the seperatory funnel into a the ring stand and make sure the seperatory funnel is closed. o Add 5 mL of 2-methyl-2-butanol to the seperatory funnel. o Add 12.5 mL of concentrated HCl to the seperatory funnel and swirl to combine o Put the glass stopper on the seperatory funnel, and while holding the stopper one with a finger or two, carefully invert the seperatory funnel and vent immediate o Close the stopcock and vigorously shake the seperatory funnel for 20 seconds or so and then vent once again. Close the stopcock and repeat shaking and venting again. Place the seperatory funnel back into the ring stand, remove the glass stopper, and drain the bottom (aqueous) layer into an erlenmeyer flask. ° Add 10 mL of sodium bicarbonate solution slowly as gas will be produced. Swirl the seperatory funnel until the bubbling stops then put the glass stopper on, invert the seperatory funnel and immediately vent. o Close the stopcock and shake the seperatory funnel 20 seconds and the vent once again. o Place the seperatory funnel back into the ring stand, remove the glass stopper, and drain the bottom (aqueous) layer into the same erlenmeyer flask containing the first aqueous extract (bubbling in the erlenmeyer may occur, so perform this second draining slowly). These aqueous extracts are waste, but do not dispose of them until you have completed the entire experiment. Perform a second wash (repeat the last 3 steps) but using sodium chloride solution this time. Perform a third wash with 10 mL of distilled water Drain the organic layer into a clean erlenmeyer flask, add about 4 spatulas of anhydrous sodium sulfate, and swirl the flask for about 15 seconds. Pipet the liquid into a teared beaker and weigh to obtain the mass. Use a drop of the liquid to obtain the IR spectrum. Perform the silver nitrate and sodium iodide tests. o o o o o
Explanation / Answer
Sol . As density of 2-methyl -2- butanol = 0.815 g/ml
And volume of 2-methyl-2-butanol = 5 ml
So , mass of 2-methyl-2-butanol = density × volume
= 0.815 × 5 = 4.075 g
As molar mass of 2-methyl-2-butanol = 88.15 g / mol
So , moles of 2-methyl-2-butanol = mass × molar mass
= 4.075 / 88.15 moles
As from the reaction : 2-methyl -2 -butanol + HCl ----> 2-chloro-2-methylbutane
So , moles of 2-chloro-2-methylbutane = 4.075 / 88.15 moles
As molar mass of 2 - chloro - 2- methylbutane = 106.593 g/mol
So , mass of 2- chloro - 2- methylbutane = moles × molar mass = (4.075 ×106.593 )/88.15 = 4.928 g
Therefore , theoretical yield = 4.928 g
Now , final volume of 2-chloro - 2- methylbutane = 1ml
density of 2-chloro - 2- methylbutane = 0.866 g/ml
So , mass of 2-chloro-2-methylbutane = 1 × 0.866 = 0.866 g
Experimental yield = 0.866 g
So , percentage yiled = experimental yield/Theoretical yiled ×100
= 0.866/4.928 × 100 = 17.57 %