Boiling Point Determination

• 1. Prepare two capillaries and seal one end of both tubes.
• 2. Introduce about 20 drops of ethyl alcohol into a culture tube.
• 3. Attach the culture tube to a thermometer by means of a string. The tip of the thermometer and bottom of the culture tube must be side by side (See Figure 4, p. 21).
• 4. Place one capillary tube into the culture tube containing ethyl alcohol with the open end immersed in the liquid sample.
• 5. Prepare 20 mL of a water bath in a beaker. Suspend the culture tube- thermometer assembly into the water bath with the use of a clamp.
• 6. Raise the temperature of the water bath until a rapid and continuous stream of bubbles is observed in the alcohol sample.
• 7. While eyes are still on the stream of bubbles, remove the flame and allow the bath to cool. Read the thermometer at the instant bubbles cease to come out of the capillary tube and just before the liquid sample enters the capillary tube. This is the experimental boiling point of ethyl alcohol.
• 8. Determine the boiling point of a 50-50 mixture of ethyl alcohol and water by repeating steps 2 to 7.
•  Calculate the % error for ethyl alcohol if its true boiling point is 78°C.