1) Write an equation for the relationship between the temperature (T) in kelvins and the average molecular speed (v_avg) in a gas (which may contain a numerical constant).
2) Describe the relationship in words between the Temperature (T) and the average molecular speed (v_avg). (i.e. linear, inverse, squared, no relationship at all, etc.)
Any help and explanations you can provide would be awesome! Thanks!
2) Describe the relationship in words between the Temperature (T) and the average molecular speed (v_avg). (i.e. linear, inverse, squared, no relationship at all, etc.)
Any help and explanations you can provide would be awesome! Thanks!
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I think all that is really required is:
1) T = A(v_avg)^2 where A is a constant
2) Temperature is proportional to v_avg squared.
This follows from the definition of thermodynamic temperature, T: T is proportional to the average kinetic energy of the particles, which in turn isproportional to v_avg squared.
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But here is a more detailed analysis to answer you concerns.
1)The answer to question 1 is a bit ambiguous.
Often the rms speed is used synonymously with average speed. This is technically incorrect. However it gives (assuming we are dealing with an ideal gas):
(3/2)kT = (1/2)m(v_avg)^2 where m is mass of a single particle (molecule)
This can be reduced to an equation with a single numerical constant, A, say:
T = A(v_avg)^2
where A = m/(3k)
The true average speed depends on the speed distribution (Maxwell-Boltzmann) and is given by
v_avg = sqrt(8RT/(πM)) (M being molar mass) (e.g. see just before halfway down the link)
Introducing a single numerical constant, B, this would become:
T = B(v_avg)^2
where B = πM/(8R) (= πm/8k)
However, v_rms is the ‘best’ value to use, as T is defined in terms of average kinetic energy; and average kinetic energy = (1/2)m(v_rms)^2.
Note that you CANNOT have a relationship between v_avg (however defined) and T unless the constant (A or B) incorporates molar mass or the mass of a molecule.
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2) The relationship is that (for a given gas):
1) T = A(v_avg)^2 where A is a constant
2) Temperature is proportional to v_avg squared.
This follows from the definition of thermodynamic temperature, T: T is proportional to the average kinetic energy of the particles, which in turn isproportional to v_avg squared.
______________________________________…
But here is a more detailed analysis to answer you concerns.
1)The answer to question 1 is a bit ambiguous.
Often the rms speed is used synonymously with average speed. This is technically incorrect. However it gives (assuming we are dealing with an ideal gas):
(3/2)kT = (1/2)m(v_avg)^2 where m is mass of a single particle (molecule)
This can be reduced to an equation with a single numerical constant, A, say:
T = A(v_avg)^2
where A = m/(3k)
The true average speed depends on the speed distribution (Maxwell-Boltzmann) and is given by
v_avg = sqrt(8RT/(πM)) (M being molar mass) (e.g. see just before halfway down the link)
Introducing a single numerical constant, B, this would become:
T = B(v_avg)^2
where B = πM/(8R) (= πm/8k)
However, v_rms is the ‘best’ value to use, as T is defined in terms of average kinetic energy; and average kinetic energy = (1/2)m(v_rms)^2.
Note that you CANNOT have a relationship between v_avg (however defined) and T unless the constant (A or B) incorporates molar mass or the mass of a molecule.
______________________________________…
2) The relationship is that (for a given gas):
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keywords: Kinetic,Gases,Theory,question,of,Physics,Physics Kinetic Theory of Gases question