Question

QUESTION 1

Distillation is commonly used in the organic laboratory as a way to:

	a.	remove a reaction solvent.
	b.	purify an organic liquid.
	c.	separate the components of a liquid mixture.
	d.	all of the above.

1 points   

QUESTION 2

Fractional distillation gives a better separation than simple distillation because _________.

	a.	the fractionating column used in fractional distillation contains more theoretical plates.
	b.	the fractionating column used in fractional distillation contains less theoretical plates.
	c.	does not require as much heat as simple distillation.
	d.	simple distillation is better because it requires less glassware.

1 points   

QUESTION 3

Consider the following solvent pairs: ethanol and water; methylene chloride and water; chloroform and water; toluene and water. In which solvent pair would the organic layer be the top layer?

	a.	toluene and water
	b.	chloroform and water
	c.	methylene chloride and water
	d.	ethanol and water

1 points   

QUESTION 4

A crude product mixture dissolved in diethyl ether contains acetic acid. Which of the following would be the first step in the extraction procedure used to remove the acidic acid from the ether layer?

	a.	Extract the ether layer with water.
	b.	Extract the ether layer with a solution of hydrochloric acid.
	c.	Extract the ether layer with a solution of sodium hydroxide.
	d.	Extract the ether layer with a different solvent such as methylene chloride.

1 points   

QUESTION 5

Which piece of glassware is commonly used to recrystallize a solid organic compound?

	a.	Beaker
	b.	Separatory funnel
	c.	Test tube
	d.	Erlenmeyer flask

1 points   

QUESTION 6

What is a theoretical plate?

	a.	Utensil used for eating.
	b.	One condensation-vaporization cycle.
	c.	An electrode found in a storage battery.
	d.	Utensil used for the collection of an offering.

1 points   

QUESTION 7

Why is it necessary to remove the stopper from a separatory funnel when the liquid is being drained through the stopcock?

	a.	To prevent the build up of pressure.
	b.	To prevent the formation of an emulsion.
	c.	To prevent the formation of a vacuum, which will prevent the liquid from draining.
	d.	To prevent the separatory funnel from imploding.

1 points   

QUESTION 8

The ideal crystallization solvent is one that ______________

	a.	does not react with the solute.
	b.	dissolves the solute when hot but not when cold.
	c.	is non-toxic, readily available, and inexpensive.
	d.	all of the above.

1 points   

QUESTION 9

Which of the following statements is not one of the disadvantages of using sublimation as a purification technique?

	a.	Sublimation can not be used for solids that have extremely low vapor pressures.
	b.	The solid being sublimed usually needs to be heated under the presence of a vacuum.
	c.	Sublimation is faster and cleaner than recrystallization.
	d.	Solid impurities must have a lower vapor pressure than the solid being sublimed.

1 points   

QUESTION 10

Extraction is an effective method for separating compounds, which can be treated with an acid or base and made to differ in:

	a.	boiling point
	b.	molecular weight
	c.	water solubility
	d.	optical activity.

Answer 1

Q1) Distillation is commonly used in the organic laboratory as a way to:
d.   all of the above.

Because all the conditions mentioned are used in the orgo-lab.

Q2) Fractional distillation gives a better separation than simple distillation because:
a.   the fractionating column used in fractional distillation contains more theoretical plates.

Q3) Consider the following solvent pairs: ethanol and water; methylene chloride and water; chloroform and water; toluene and water. In which solvent pair would the organic layer be the top layer?
DCM and Chloroform have a higher density than water and hence they will be always as a lower layer. Whereas toluene has a lower density than water and hence toluene (the organic layer) will be a top layer.
Thus the answer is a.   toluene and water

Q4) A crude product mixture dissolved in diethyl ether contains acetic acid. Which of the following would be the first step in the extraction procedure used to remove the acidic acid from the ether layer?
AcOH + NaOH ---> AcONa(aq) + H2O
Thus answer is option:
c.   Extract the ether layer with a solution of sodium hydroxide.  

Q5) Which piece of glassware is commonly used to recrystallize a solid organic compound?
Answer: option d.   Erlenmeyer flask

Q6) What is a theoretical plate?
Answer is option: b.   One condensation-vaporization cycle.

Q7) Why is it necessary to remove the stopper from a separatory funnel when the liquid is being drained through the stopcock?
Answer is an option: c.   To prevent the formation of a vacuum, which will prevent the liquid from draining.

Q8) The ideal crystallization solvent is one that:
d.   all of the above.

Q9) Which of the following statements is not one of the disadvantages of using sublimation as a purification technique?
c.   Sublimation is faster and cleaner than recrystallization.

Q10) Extraction is an effective method for separating compounds, which can be treated with an acid or base and made to differ in:
c.   water solubility.