Thank you for your help. Post Lab Questions For each of the following pairs of s

Question

Thank you for your help.

Post Lab Questions For each of the following pairs of solute and solvent, predict whether the solute would be soluble or insoluble. Explain why. Malic acid in water Naphthalene in water Amphetamine in ethyl alcohol Succinic acid in hexane Predict whether the following pairs of liquids would be miscible or immiscible. If immiscible, indicate which will be the top layer. Water and methyl alcohol Hexane and benzene Methylene chloride and benzene Water and toluene Methylene chloride and water Hexane and water Toluene and water Diethyl ether and water Suppose solute A has a partition coefficient of 4.0 between diethyl ether and water. If 5.0g of A in 100 mL of water solution were extracted with two 25mL portion of diethyl ether, how many grams of A will remain in the water solution? If the solution were extracted with one 50mL portion of diethyl ether, how many grams of A will still remain in water?

Explanation / Answer

1.

Malic acid is soluble in water bacause of both are polar molecules hence exists hydrophilic interaction.

Naphthalene is a non-polar molecule, this is insoluble in a polar solvent like water.

Amphetamine will be soluble in ethyl alcohol because of its polar -NH2 group in amphetamine and ethyl alcohol is a polar solvent.

Succinic acid is a very polar molecules, thus will be insoluble in non-polar solvent hexane.

2.

Water and methyl alcohol bothe being plar are miscible.

Hexane and benzene being non-polar both are misscible.

Methylene chloride is moderately polar, where as benzene is non-polar, thus they will be immiscible or very partially miscible.

Water and toluene are immiscible as they are polar and non-polar liquids respectively.

Methylene chloride and water will be miscible, but not in very high degree like two polar solvents, because methylene chloride is moderately polar unlike highly polar water.

Hexane and water will be immiscible as hexame is a non-polar solvent where as water is very much polar.

Toluene and water will be immiscible ,as water is a polar solvent and toluene is non-polar.

Diethyl ether is non-polar where as water is polar, so are unlikely to get miscible.

3.

"A" has a partition coefficient of 4.0 between diethyl ehter and water.

It means ratio of "A" in diethyl ehter to water is 4.

Now, volume of water= 100 ml

Amount of "A" = 5 .0 g

Total volume of diethyl ether for first extraction = 25ml

So, amount of "A" in diethyl ether in first extraction= (5/5)*4*25/100 = 1.0 g

For second time extraction in diethyl ehter, amount of "A" in diethyl ether = (4/5)*4*25/100 = 0.8 g

Thus, amount of "A" in water after extraction = 5-(1+0.8) = 3.2 g

In case 2: where volume of diethyl ether for extraction = 50 ml

Amount of "A" in diethyl ether = 4*50/100 = 2.0 g

Thus, amount of "A" in water after extraction = 5-2 = 3.0 g

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