Question

Question 1 1. 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 2 1. A reaction workup for an aqueous reaction mixture calls for extraction with diethyl ether and then an extraction with saturated aqueous sodium chloride. What is the purpose of the saturated sodium chloride extraction? a. To remove any unreacted starting material. b. To remove huge amounts of water. c. To remove trace amounts of water. d. To force the desired product into the organic layer. 1 points

Question 3 1. At the end of an experiment, the product is a mixture of the starting material, which is benzoic acid and the product, which is benzaldehyde, both of which are dissolved in diethyl ether. The reaction mixture is best separated by a. extraction with a solution of hydrochloric acid, separating the layers, followed by drying and evaporating the organic layer. b. extraction with a solution of sodium bicarbonate, separating the layers, followed by drying and evaporating the organic layer. c. Drying and evaporating the organic layer. d. extraction with a solution of sodium bicarbonate, separating the layers, add diethyl ether to the aqueous layer, extracting with a solution of hydrochloric acid, filtering and recrystallization the solid product. 1 points

Question 4 1. 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 5 1. The best separation possible with simple distillation is ______________. a. a complete separation of the components of the mixture b. a separation that is enriched in the less volatile component c. a separation that is enriched in the more volatile component d. a separation that is in the exact composition as the starting mixture. 1 points

Question 6 1. 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 7 1. 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 8 1. 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 9 1. A crude nonacidic 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 10 1. 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.

Answer 1

Question 1 1. Which piece of glassware is commonly used to recrystallize a solid organic compound?

Erlenmeyer flask : as it is designed to provent contact with impurities

Question 2 1. A reaction workup for an aqueous reaction mixture calls for extraction with diethyl ether and then an extraction with saturated aqueous sodium chloride. What is the purpose of the saturated sodium chloride extraction? b. To remove huge amounts of water.

Question 3 b. extraction with a solution of sodium bicarbonate, separating the layers, followed by drying and evaporating the organic layer.

Question 4 1. 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?

Depends upon the density of organic solvent, Here the density of toluene is less than water

a. toluene and water

ethanol and water will mix with each other

Question 5 1. The best separation possible with simple distillation is ______________. a separation that is enriched in the more volatile component , as it will distill off easily.

Question 6 1. 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.

Question 7 1. Fractional distillation gives a better separation than simple distillation because _________. a. the fractionating column used in fractional distillation contains more theoretical plates.

Question 8 1. What is a theoretical plate? b. One condensation-vaporization cycle.

Question 9 1. A crude nonacidic 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?c. Extract the ether layer with a solution of sodium hydroxide. which will form salt of acetic acid , soluble in water

Question 10 1. Why is it necessary to remove the stopper from a separatory funnel when the liquid is being drained through the stopcock? c. To prevent the formation of a vacuum, which will prevent the liquid from draining.