Question | Answer |
What does the separation of two or more liquid compounds by distillation depend? | Boiling point differences |
What is mean by the term vapor pressure | THe pressure exerted by a liquid on it's environment |
How is boilint point of a pure liquid defined? | THemp. where the liquid vapor pressure equals the pressure exerted by the atmosphere. |
In a collection of compounds of similar molecular weight which will have the higher boiling points and which will have the lower bpt? | polar compounds have higher, non-polar compounds are lower. |
Upon what does the boiling point of a mixture depend? | Wpon the vapor pressures of the various components |
What affects can impurities have on the observed boiling point? | the observed boiling point will be either higher or lower (determined only by experimentation) |
What distinguished simple distillation from fractional distillation? | 1. The # of vaporizations- condensation cycles.
2.Simple distillations typically have 1 to 2 vaporization- condensation cycles.
3. Fractional distillations have 3 or more vaporization- condensation cycles. |
What is meant by the term distiallate? | Distillate refers to the condensed liquid. |
During distillation how does the composition of the liquid remaining in the distilling flask change? | The liquid remaining in the distilling flask becomes richer in the less volatile component. |
During distillation how does the boiling point of the liquid remaining in the distilling flask change? | The boiling point of the liquid remaining in the distilling flask rises during the course of the distillation. |
Under what circumstances is simple distillation commonly employed? | 1.to purify an organic compound and determine its boiling point.
2. to seperate a high boiling organic compound from a low boiling organic solvent. |
The what level should one fill the distilling flask prior to starting a simple distillation? | The distilling flask should be no more than 1/3 to 1/2 full. |
How does one know whether or not the hermometer is positioned correctly in the distilling head of a distillation apparatus? | The top of the thermometer bulb should be level w/ bottom of the side arm. |
How should the distilling flask/three-way adapter assembly be positioned? | The distilling flask/ three-way adapter should be vertical. |
How is heat input to the distilling flask from the heating mantle controlled? | Via a variable transformer. |
When should a distillation be stopped? | Before the distilling flask reaches dryness. |
Upon what does the efficiency of a fractionating column depend? | The effect of a fractionating column depends upon the number of vaporization-condensation cycles. |
What rate of distillate collection indicates a slow, steady distiallation? | A slow, steady distillation is characterized by a distillation rate of 1 drop every 2-3 sec. |
How does the use of excessvie heat affect fractional distillation? | The number of possible vaporization-condensation cycles decreases and speration is compromised. |
How does the use of too little heat affect fraction distillation | The fractionating column loses more heat than the ascending. |
What advantage are associate with the use of steam distillation? | Complex vacuum steps are not required. |
What industries make use of steam distiallation? | Perfume industry
flavor industry |
Upon what does steam distillation depend? | The immiscibility of organic compounds w/water (Can't mix) |