The figure on the left shows a constant volume gas thermometer. The pressure gau
ID: 1510031 • Letter: T
Question
The figure on the left shows a constant volume gas thermometer. The pressure gauge reads absolute pressure P and the metal ball has a fixed volume V. Measurements were performed with n moles of an ideal gas in the device, the graph shows some of the results (points) and the straight line that is expected from the ideal gas law. a) According to the ideal gas law, at which temperature is the pressure equal to zero? b) According to the ideal gas law, what is the slope of the straight line representing the pressure as a function of temperature? c) Assume now that the device contain only nil moles of the gas and draw the corresponding straight line representing the pressure into the graph. d) If v_1 is the average (root mean square) speed of gas molecules at T_1, and v_2 is the average speed of gas molecules at T_2 = 2 T_1, calculate the ratio v_2/v_1.Explanation / Answer
a)
Pressure goes to Zero at a Temparature of T = -273.15 degrees Celsius
b)
PV = nRT
P = (nR/V) T
Slope = nR/V
c)
Slope would be Half of previous one.
d)
v2/v1 = sqrt (T2/T1)
v2/v1 = sqrt(2*T1/T1)
so, v2/v1 = Sqrt(2)