
The ratio between the root mean square velocity of at 50K and that of at 800K is:
(a) 0.25
(b) 1
(c) 2
(d) 4
Answer
156.3k+ views
Hint: The root mean square velocity is the measure of the speed of a particle in a gas. We can solve the above problem by using the formula
Complete step by step answer:
1: The root mean square velocity or is directly proportional to the square root of temperature and is inversely proportional to the square root of molecular weight.
2: Now, we calculate of at 50K using the formula
Where, R is the universal gas constant (8.314 J mol-1 K-1 )
T is the temperature, here it is 50K
M is the molecular mass which is 2 g/mol for H2
∴ for is
(Since R is common in both and we need to calculate the ratio, we will leave it as R for simplicity and it will get cancelled at the end.)
3: Similarly, for is (Since molecular mass of IS 32 g/mol)
4: Now taking the ratio between and , we get:
Thus, the correct option is (a).
Note:
We mostly use instead of because for a typical gas sample, the net velocity is zero. This is because the particles are moving randomly constantly in all directions. This is a key formula as the velocity of the particles is what determines both the diffusion and effusion rates. The faster the root mean square velocity, the faster the diffusion. Effusion occurs by a difference of pressures while diffusion occurs due to difference in concentrations.
Complete step by step answer:
1: The root mean square velocity or
2: Now, we calculate
Where, R is the universal gas constant (8.314 J mol-1 K-1 )
T is the temperature, here it is 50K
M is the molecular mass which is 2 g/mol for H2
∴
(Since R is common in both and we need to calculate the ratio, we will leave it as R for simplicity and it will get cancelled at the end.)
3: Similarly,
4: Now taking the ratio between
Thus, the correct option is (a).
Note:
We mostly use
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