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

Two identical flasks contain O_{2} and H_{2} gas, respectively, at the same temperature and pressure.

**Analyze each statement:**

**(a) the average kinetic energy of H _{2} is greater than that of O**

- The temperature is the same so the average kinetic energy is the same.
**H**_{2}is lighter than O_{2}so this is FALSE.

**(b) the average speed of a H _{2} molecule is greater than that of an O**

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

$\overline{){\mathit{m}}{\mathit{o}}{\mathit{l}}{\mathbf{.}}{\mathbf{}}{\mathit{s}}{\mathit{p}}{\mathit{e}}{\mathit{e}}{\mathit{d}}{\mathbf{}}{\mathbf{=}}{\mathbf{}}\sqrt{\frac{\mathbf{3}\mathbf{R}\mathbf{T}}{\mathbf{M}}}}$

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.
**H**_{2}is lighter than O_{2}so this is TRUE.

Two identical flasks contain O_{2} and H_{2} 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 H_{2} is greater than that of O_{2}

(b) the average speed of a H_{2} molecule is greater than that of an O_{2}

(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

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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.

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