Advertisements
Advertisements
Question
Estimate the average thermal energy of a helium atom at the temperature of 10 million Kelvin (the typical core temperature in the case of a star).
Advertisements
Solution
At temperature, T = 107 K
Average thermal energy `= 3/2` kT
`= 3/2 xx 1.38 xx 10^(-23) xx 10^7`
= 2.07 × 10–16 J
Hence, the average thermal energy of a helium atom at the core of a star is 2.07 × 10–16 J.
RELATED QUESTIONS
The figure shows the plot of PV/T versus Pfor 1.00×10–3 kg of oxygen gas at two different temperatures.
(a) What does the dotted plot signify?
(b) Which is true: T1 > T2 or T1 < T2?
(c) What is the value of PV/T where the curves meet on the y-axis?
(d) If we obtained similar plots for 1.00 ×10–3 kg of hydrogen, would we get the same value of PV/T at the point where the curves meet on the y-axis? If not, what mass of hydrogen yields the same value of PV/T (for low pressure high temperature region of the plot)? (Molecular mass of H2 = 2.02 u, of O2 = 32.0 u, R = 8.31 J mo1–1 K–1.)
Estimate the total number of air molecules (inclusive of oxygen, nitrogen, water vapour and other constituents) in a room of capacity 25.0 m3 at a temperature of 27 °C and 1 atm pressure
Three vessels of equal capacity have gases at the same temperature and pressure. The first vessel contains neon (monatomic), the second contains chlorine (diatomic), and the third contains uranium hexafluoride (polyatomic).
Is the root mean square speed of molecules the same in the three cases? If not, in which case is vrms the largest?
At what temperature is the root mean square speed of an atom in an argon gas cylinder equal to the rms speed of a helium gas atom at – 20 °C? (atomic mass of Ar = 39.9 u, of He = 4.0 u).
What do you understand by gas?
During the practical session in the lab when hydrogen sulphide gas having offensive odour is prepared for some test, we can smell the gas even 50 metres away. Explain the phenomenon.
Give reasons for the following:
Gas fills the vessel completely in which it is kept.
A gas occupies 500 cm3 at a normal temperature. At what temperature will the volume of the gas be reduced by 20% of its original volume, the pressure is constant?
Correct the following statement:
0°C is equal to zero Kelvin.
Name or state the following:
The standard pressure of a gas in cm. of mercury corresponding to one atmospheric pressure.
Give reason for the following:
Temperature remaining constant the product of the vol. & the press, of a given mass of dry gas is a constant.
The average energy per molecule is proportional to ______
Show that for monoatomic gas the ratio of the two specific heats is 5:3.
Show that for diatomic gas the ratio of the two specific heats is 7:5.
Gases exert pressure on the walls of the container because the gas molecules ______
The equation of state for 2g of oxygen at a pressure 'P' and temperature 'T', when occupying a volume 'V' will be ______.
Three vessels of equal capacity have gases at the same temperature and pressure. The first vessel contains neon (monatomic), the second contains chlorine (diatomic), and the third contains uranium hexafluoride (polyatomic).
Do the vessels contain an equal number of respective molecules?
Which of the following diagrams (Figure) depicts ideal gas behaviour?
 (a) |
 (b) |
 (c) |
 (d) |
At room temperature, a diatomic gas is found to have an r.m.s. speed of 1930 ms-1. The gas is ______.
P ∝ T at constant volume is the statement of ______.
