Explain why?
(a) The number of atoms in a certain volume of hydrogen is twice the number of atoms in the same volume of helium at the same temperature and pressure.
(b) When stating the volume of a gas, the pressure and temperature should also be given.
(c) Inflating a balloon seems to violate Boyle's law.
a) When hydrogen is present in the molecular form, then in one mole of hydrogen molecules, number of hydrogen molecules = 6.022×1023
One molecule of hydrogen has 2 atoms of hydrogen. Therefore, in 1 mole of hydrogen (diatomic), the number of moles of hydrogen gas = 2
Helium is monoatomic gas. So, at same temperature and pressure, hydrogen has twice the number of atoms than helium
b)Rate of change of volume of gas depends on the rate of change of temperature and pressure. We can get this information from the ideal gas equation PV=nRT. The gas expands as temperature and pressure change. Volume is how much space the gas has occupied, so if the temperature/pressure changes, the gas will expand or come closer together, altering its volume. Gas has no definite volume, which is why we must specify temperature and pressure.
c)When air is blown into a balloon, the volume and the pressure inside the balloon increases. Here Boyle's law is not violated because the law is valid for a definite mass.