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Chemistry II
Distillation Test
| Question | Answer |
|---|---|
| The escape of molecules from the liquid phase to the gas phase | Evaporation |
| This pressure is characteristic of the liquid | Equilibrium vapor pressure |
| The measure of vapor depends on what? | The nature of the liquid and the temperature |
| The temperature at which the vapor pressure is equal to the atmospheric pressure | Boiling point |
| The process of heating a liquid to its boiling point, condensing the vapors Two processes: Heating Cooling | Distillation |
| Two purposes of distillation | 1. Determination of its boiling point for the purpose of identification 2. Purification- separating two liquids |
| The boiling point determination | Simple distillation |
| Starting flask | Distilling flask |
| Where distillate is collected Can be put into an ice bath for further condensation | Receiving flask |
| The liquid collected during distillation when the evaporated substance condenses | Distillate |
| Describes two liquids that will mix with each other and have different boiling points | Miscible |
| When a substance is not able to mix with another substance Oil and water | Immiscible |
| Simply a glass column that contains a packing or condensing surface | Fractionating column |
| Two mixture liquids that behave upon distillation as through they were a pure substance Caused by loose intermolecular attractions between molecules | Azeotrope |
| Compare the volumes obtained in each temperature range for the simple distillation and the fractional distillation and explain the differences observed. | Fractional distillation had smaller amounts because temp went up faster. |
| Was fractional distillation more effect give than simple distillation in separating acetone and water? | Yes, you got more at the range of acetone's boiling point. |
| In the fractional distillation, what is the composition of the liquid collected in the first receiving flask? What is the composition of the liquid that remained in the distilling flask? | Acetone is in the receiving flask and water in the distilling flask |
| The entire mercury bulb of the thermometer must be below the level of the side arm in order o obtain an accurate reading of the distillation temperature. Why is this so? | It wouldn't accurately read the temperature of the collecting vapors. |
| Why is cold water circulated through the condenser from the bottom rather than from the top? | To make sure the vapor condenses before entering the receiving flask |
| In the simple distillation why did you add the acetone and water through a long-stem funnel rather than pouring it into the neck of the distilling flask directly from the graduated cylinder? | So it didn't accidently go down the arm of the condenser |
| Suppose the acetone- water mixture were distilled through the fractionating column as quickly as possible. What effect would this have had on the efficiency of the distillation? | It wouldn't separate as well and it would be less efficient . |
| What was the boiling point of acetone as indicated by your graph? How does the compare with the true boiling point of acetone? If the barometric pressure were lower than normal, what effect would this have on your observed boiling point? | According to the graph the simple boiling point was higher than normal, and fractional was the normal boiling point. If the barometric pressure was lower you'd have a lower boiling point. |
| The total volume of liquid obtained is not equal to the volume that was introduced into the distillation flask. What are the possible sources of loss in this procedure? | Acetone evaporates faster and some residue was left in the distilling apparatus |
| Why should the liquid sample fill from one-third to two-thirds of the volume of the distilling flask prior to distillation? | So it doesn't go over the arm |
| What is the purpose of boiling stones in a distillation | To stop bumping and prevent superheating stones absorb the energy |
| Why should a sample being distilled never be heated to dryness? | Some substances can leave explosive residues |
| Can you suggest a reason why a compound having an extremely high boiling point might be distilled under reduced pressure? | Lower pressure equals lower boiling therefore lower temperature and uses less energy |
Created by:
Drake Archer Peterson