A student recorded the boiling point of butanone, which has a literature boiling
ID: 1067398 • Letter: A
Question
A student recorded the boiling point of butanone, which has a literature boiling point of 79.64 degree C. Her thermometer read 75.0 degree C for the vapor temperature, which is lower than she expected. The student asks you for advice. Provide answers for her following three questions to you "Maybe the liquid wasn't pure butanone. Could impurities have lowered the boiling point?" "Maybe there is liquid condensing on the thermometer, and that is lowering the temperature. Would condensation of liquid make the thermometer read higher or lower?" "Maybe my thermometer isn't accurate. How should i calibrate my thermometer? How do cover the thermometer reading into a calibrated value?"Explanation / Answer
a. There are various factors that affect the boiling point of a liquid. The presence of Impurities is one of the factor that affect the boiling point of the liquid and presence of impurities elevates it. In this case, the boiling point has decreased. Pressure is also another factor that affects the boiling point of the liquid. Boiling takes place when the vapour pressure of liquid equals the pressure surrounding it. The lesser the surrounding pressure the lesser the boiling point. So, boiling point needs to be checked at corresponding pressure.
b. No. No condensation phenomena takes place in thermometer to affect the thermometer reading. Mercury is thus used in the thermometer to avoid the inaccurate readings due to condensation, freezing etc since it is liquid for wide range of temperature. So, there is no chance of inaccurate readings due to condensation on thermometer.
c. Ice Point Method is easiest way to callibrate your thermometer. Crush ice in one container and add clean tap water into the container full of ice. Stirr the ice water mixture well and insert the thermometer probe into the mixture. Wait for 30 seconds to show the temperature to 00 C. Hold the Callibration nut securely with wrench or other tool & rotate the head of thermometer untill it reads 00 C.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.