
If the value of the universal gas constant is , what will be the mean kinetic energy of 32 gm of oxygen at ?
A. 480 J
B. 4980 J
C. 2490 J
D. 100 J
Answer
499.2k+ views
Hint
The average kinetic energy of a gas is a measure of its temperature. As the temperature changes, the molecules of the gas start moving at different speeds colliding with one another and adding up to the kinetic energy.
, where is the mean kinetic energy of a substance with number of moles, is the universal gas constant and is the temperature of the gas.
Complete step by step answer
We are provided with a certain amount of oxygen in the question and are asked to find its mean kinetic energy. Let us look at the values that are given to us:
Universal gas constant
Mass of oxygen
Temperature [We convert the Celsius scale into Kelvin]
We are also aware that a single atom of oxygen with atomic number 8 has Atomic mass
So, we find the number of moles of oxygen in the given amount as:
Number of moles
Putting the values of and , we get:
To find the mean kinetic energy, we know that:
Substituting the values with correct units:
.
Hence, the average kinetic energy of 32 gm of oxygen is option (B) i.e. 4980 J.
Note
It is important to note that the question is talking about nascent oxygen (1 atom of oxygen) rather than molecular oxygen which has two atoms. This small detail would change the number of moles. Moles are used as a quantity for measuring the mass of atoms as they are very small in size.
The average kinetic energy of a gas is a measure of its temperature. As the temperature changes, the molecules of the gas start moving at different speeds colliding with one another and adding up to the kinetic energy.
Complete step by step answer
We are provided with a certain amount of oxygen in the question and are asked to find its mean kinetic energy. Let us look at the values that are given to us:
Universal gas constant
Mass of oxygen
Temperature
We are also aware that a single atom of oxygen with atomic number 8 has Atomic mass
So, we find the number of moles of oxygen in the given amount as:
Number of moles
Putting the values of
To find the mean kinetic energy, we know that:
Substituting the values with correct units:
Hence, the average kinetic energy of 32 gm of oxygen is option (B) i.e. 4980 J.
Note
It is important to note that the question is talking about nascent oxygen (1 atom of oxygen) rather than molecular oxygen which has two atoms. This small detail would change the number of moles. Moles are used as a quantity for measuring the mass of atoms as they are very small in size.
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