Problem: Two identical flasks contain O2 and H2 gas, respectively, at the same temperature and pressure. In comparing the two flasks, which of the following is not a true statement.(a) the average kinetic energy of H2 is greater than that of O2(b) the average speed of a H2 molecule is greater than that of an O2(c) the number of impacts/(unit area)/(unit time) are different for the two gases(d) the number of moles is the same(e) total mass of each gas is different

FREE Expert Solution

We are asked which of the statements are NOT TRUE given: 

Two identical flasks contain O2 and H2 gas, respectively, at the same temperature and pressure.

Analyze each statement:

(a) the average kinetic energy of H2 is greater than that of O2

  • The temperature is the same so the average kinetic energy is the same.
  • H2 is lighter than O2 so this is FALSE.


(b) the average speed of a H2 molecule is greater than that of an O2

Recall that the molecular speed of a gas is given by:


mol. speed = 3RTM


where R = gas constant, T = temperature, and M = molar mass of the gas.


  • We can see that the molar mass is in the denominator. 
  • This means that the lower the molar mass the faster the molecule is. 
  • H2 is lighter than O2 so this is TRUE.


82% (11 ratings)
View Complete Written Solution
Problem Details

Two identical flasks contain O2 and H2 gas, respectively, at the same temperature and pressure. In comparing the two flasks, which of the following is not a true statement.

(a) the average kinetic energy of H2 is greater than that of O2

(b) the average speed of a H2 molecule is greater than that of an O2

(c) the number of impacts/(unit area)/(unit time) are different for the two gases

(d) the number of moles is the same

(e) total mass of each gas is different

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Kinetic Molecular Theory concept. You can view video lessons to learn Kinetic Molecular Theory. Or if you need more Kinetic Molecular Theory practice, you can also practice Kinetic Molecular Theory practice problems.

What professor is this problem relevant for?

Based on our data, we think this problem is relevant for Professor Bateman's class at BUFFALO STATE.