Practical 7 - Estimation of absolte zero by use of the gas laws

Question 1

Which law do we use for this practical?

Answer 1

Charles’ law

Question 2

What does charles’ law state?

Answer 2

That the volume and temperature of a gas are proportional provided that the pressure is constant

Question 3

Describe the air column trapped in the tube used in this practical

Answer 3

Constant cross sectional area

Question 4

What is the length of the air column proportional to and why?

Answer 4

The volume
Has a constant cross sectional area

Question 5

Method

Answer 5

-place the capillary tube mounted to the ruler in the water bath
-allow the recapture to equalise
-note temperature T (in Celsius) and length of air column l
-switch on the water bath and keep an eye on the temperature
-note the length l at varying intervals of T
-a suitable range would be from the initial temperature and noting l at 10 degrees Celsius intervals
-plot a graph of T (Celsius) on the x-axis, projecting the axis back to at least -300 degrees Celsius, and length l (mm) on the y-axis, extending the axis to zero

Question 6

Factors that could affect the accuracy in this practical

Answer 6

-scale resolution of the ruler
-gas not ideal
-parallax
-variation in atmospheric pressure
-gas and liquid at different temperatures