Question

Chemistry Charles's Law Post-Laboratory Questions

1. Serveral students performed this experiment without paying adequate attention to the details of the procedure. Briefly explain what effect each of the following procedural changes would have ont the size of the volume-to-temperature ratio calculated by the students.

A) One student failed to replenish the boiling water in the boiling-water bath as the flask was being heated. At the end of the 6 min of heating, the boiling water in the bath was only in contact with the lower portion of the flask.

B) Following the proper heating of the flask in the boiling water, a student removed the flask from the boiling-water bath but only partially immersed the flask in the ice-water bath during the cooling period.

C) A student neglected to close the pinch clamp before removing the flask from the boiling-water bath and immersing it in the ice-water bath.

D) One student neglected to measure the volume of the flask before leaving the laboratory. Because the procedure called for a 125-mL Erlenmeyer flask, the student used 125 mL as the volume of the flask.

Answer 1

A) One student failed to replenish the boiling water in the boiling-water bath as the flask was being heated. At the end of the 6 min of heating, the boiling water in the bath was only in contact with the lower portion of the flask.
Effect: The temperature in the upper portion of flask will be lower than the temperature that could have been obtained when entire flask was immersed in boiling bath. Thus the actual temperature was lower than the assumed temperature and the volume-to-temperature ratio calculated by the students will be lower than the actual volume-to-temperature ratio.
B) Following the proper heating of the flask in the boiling water, a student removed the flask from the boiling-water bath but only partially immersed the flask in the ice-water bath during the cooling period.
Effect: The temperature in the upper portion of flask will be higher than the temperature that could have been obtained when entire flask was immersed in ice-water bath. Thus the actual temperature was higher than the assumed temperature and the volume-to-temperature ratio calculated by the students will be higher than the actual volume-to-temperature ratio.
C) A student neglected to close the pinch clamp before removing the flask from the boiling-water bath and immersing it in the ice-water bath.
Effect: Some air will enter the flask and measured volume will be higher than actual volume. The volume-to-temperature ratio calculated by the students will be higher than the actual volume-to-temperature ratio.
D) One student neglected to measure the volume of the flask before leaving the laboratory. Because the procedure called for a 125-mL Erlenmeyer flask, the student used 125 mL as the volume of the flask.
Effect: The volume may be higher or lower than 125-mL. The volume-to-temperature ratio calculated by the students may be higher or lower than the actual volume-to-temperature ratio.