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Boiling Point Experiment

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Organic Chemistry: CHP 225
Thomas Hsieh

Experiment 2: Boiling Points

o Date experiment was performed: September 16, 2011

o Objective: To determine the boiling point of organic compounds such as tert-butyl alcohol, sec-butyl alcohol, n-butyl alcohol, and an unknown.

o Principle: Boiling point is the temperature at which gas and liquid phases coexist in equilibrium. At this temperature, the vaporization rate and the condensation rate are equal. The liquid and vapor reach a state of dynamic equilibrium: liquid molecules evaporate and vapor molecules condense at the same rate. The boiling point of a liquid is the temperature at which its vapor pressure equals atmospheric pressure. While a gas is forming, the vapor pressure within …show more content…

6. Stop heating once you have obtained a constant rate of bubbling. The experimenter will soon observe that gas bubbling will gradually subside. Once the bubbling has subsided, liquid has entered the capillary. The experimenter must record this temperature; this is the beginning of the boiling point range. 7. Very soon the capillary will be filled up with the liquid tert-butyl alcohol. Heat the water bath again until the last bubble comes out of the capillary. Once this last bubble is observed, record this temperature. This temperature is the end of the boiling point range. *Note: This method can only be utilized for compounds whose boiling points are below 100oC because that is the boiling point of water and a temperature of higher than 100oC is not possible.

Part B: Reflux Method

1. Obtain an aluminum dish and fill the dish with sand and put it on a hotplate. 2. Acquire a test tube and fill it with sec-butyl alcohol to 1-2 cm high. Place the test tube in the sand bath on the hotplate. Clamp a thermometer in the test tube about 1-2 cm above the sec-butyl alcohol. 3. Turn on the hotplate and moderately heat the hotplate. Keep heating until liquid has begun boiling. Once liquid is boiling, the experimenter should observe a vapor that has collected around the mercury bulb. Once a vapor has collected around the mercury bulb, lower the heating of

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