Place the tip of the thermometer below the surface of the
solution, but do not allow the tip to touch the walls or the bottom of the flask. Why?
If the solution is being stirred with a magnetic stir bar,
do not allow the stir bar to come in contact with the thermometer. If necessary,
GENTLY clamp the thermometer in place.
A student has clamped a thermometer into a solution which is being
heated on a stirplate. Is the placement of the thermometer correct in
the picture? Answer
Taking readings
Determine the temperature by reading the scale on the thermometer
at eye level. Read the temperature by using all certain digits and one
uncertain digit. Certain digits are determined from the calibration marks
on the thermometer. The uncertain digit (the last digit of the reading)
is estimated. On most thermometers encountered in a general chemistry
lab, the tenths place is the uncertain digit. Some example readings are
shown below on a Celsius thermometer:
