12.3 Equation of state for an ideal gas NC Flashcards
What 3 laws do we need to combine to get pV/T = constant (k)
Boyle Law = pV = k
Pressure Law = p/t = k
Charles Law = V/t = k
what is the constant k and what do we have to assume to make pV = nRT
k is the universal molar gas constant. To form this equation we assume the mass is 1 mole and is fixed
Is this equation the same for all gases?
Yes, all ideal gases
What is the equation for ideal gases in terms of moles? What does each symbol stand for and what are the units?
pV = nRT p = pressure (Pa or Nm^-2) V = volume (m^3) n = number of moles (no unit) R = universal molar gas constant (8.31JK^-1mol^-1) T = temperature (K)
What is the value of the universal molar gas constant?
8.31 JK^-1mol^-1
What is a mol?
SI base unit of a substance, it is 6x10^23 particles/molecules
What is another way of expressing this relationship of pV = nRT?
Using the boltzmann constant.
What is the boltzmann constant defined as? What does each symbol stand for?
k = R/Na k = constant R = universal molar constant Na = avogadro constant
What is the avogadro constant (word definition)?
number of molecules in 1 mole of a substance
How can we determine the equation pV = NkT?
We substitute k =r/Na into pv = nRt.
pV = nNakt
n x Na is moles x number of molecules per mole, hence it equals total number of molecules
In the equation pV = NkT what does each symbol stand for?
p = pressure (Pa or Nm^-2) V = volume (m^3) N = number of molecules (no unit) k = boltzmann constant(JK^-1) T = temperature (K)
What is the value of the Boltzmann constant?
1.38x10^-23 JK^-1
What is an ideal gas?
A gas obeying these equations and the 3 laws under all conditions .
Is there such a thing as an ideal gas?
No, but in practice most gases obey laws and the equations given that their pressure is low and temperature is high(above the critical temperature).
Is the critical temperature usually quite low or high for gases?
Generally low e.g. -118 celsius for oxygen
