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Solved: (a) Explain why in a gas of N molecules, the
Chapter 18, Problem 87P(choose chapter or problem)
CALC (a) Explain why in a gas of \(N\) molecules, the number of molecules having speeds in the finite interval \(v\) to \(v+\Delta v\) is \(\Delta N=N \int_{v}^{v+\Delta v} f(v) d v\). (b) If \(\Delta v\) is small, then \(f(v)\) is approximately constant over the interval and \(\Delta N \approx N f(v) \Delta v\). For oxygen gas ( \(\mathrm{O}_{2}\), molar mass 32 \(\mathrm{gm} / \mathrm{mol}\) at \(T=300 \mathrm{~K}\), use this approximation to calculate the number of molecules with speeds within \(\Delta v=20 \mathrm{~m} / \mathrm{s}\) of \(v_{m p}). Express your answer as a multiple of (c) Repeat part (b) for speeds within \(\Delta v=20 \mathrm{~m} / \mathrm{s}\) of \(7 v_{m p}\) (d) Repeat parts (b) and (c) for a temperature of . (e) Repeat parts (b) and (c) for a temperature of . (f) What do your results tell you about the shape of the distribution as a function of temperature? Do your conclusions agree with what is shown in Fig. ?
Equation Transcription:
Text Transcription:
N
v
v+ delta v
delta N=N integral _v^v+v f (v)dv
delta v
f(v)
delta N approx N f(v) delta v
O_2
T=300 K
delta v=20 m/s
v_mp
delta v=20 m/s
7 v_mp
gm/mol
deltav=20 m/s
v_mp
Questions & Answers
QUESTION:
CALC (a) Explain why in a gas of \(N\) molecules, the number of molecules having speeds in the finite interval \(v\) to \(v+\Delta v\) is \(\Delta N=N \int_{v}^{v+\Delta v} f(v) d v\). (b) If \(\Delta v\) is small, then \(f(v)\) is approximately constant over the interval and \(\Delta N \approx N f(v) \Delta v\). For oxygen gas ( \(\mathrm{O}_{2}\), molar mass 32 \(\mathrm{gm} / \mathrm{mol}\) at \(T=300 \mathrm{~K}\), use this approximation to calculate the number of molecules with speeds within \(\Delta v=20 \mathrm{~m} / \mathrm{s}\) of \(v_{m p}). Express your answer as a multiple of (c) Repeat part (b) for speeds within \(\Delta v=20 \mathrm{~m} / \mathrm{s}\) of \(7 v_{m p}\) (d) Repeat parts (b) and (c) for a temperature of . (e) Repeat parts (b) and (c) for a temperature of . (f) What do your results tell you about the shape of the distribution as a function of temperature? Do your conclusions agree with what is shown in Fig. ?
Equation Transcription:
Text Transcription:
N
v
v+ delta v
delta N=N integral _v^v+v f (v)dv
delta v
f(v)
delta N approx N f(v) delta v
O_2
T=300 K
delta v=20 m/s
v_mp
delta v=20 m/s
7 v_mp
gm/mol
deltav=20 m/s
v_mp
ANSWER:
Solution to 87P
Step 1
is the probability that a particle has a speed between and . Thus is the fraction of particle whose speed is in that range.
If there are N number of particle, then the fraction of particle having the speed in between and is given by
(a)