# Chemistry - Ideal Gases

For Ideal Gases, the important assumptions are as below:

1. The intermolecular forces (Attractive Force or Repulsive Force) between the gas molecules are entirely negligible.

2. The volume occupied by the gas molecules themselves is entirely negligible relative to the volume of the container.

By the assumptions above, we can sure that there are no "Ideal Gas" in our real world.

However, scientists formulate the concept of Ideal Gases to make sure some gas law will always true. Or else, more errors will present in our calculations or data.

On the other hand, errors do exist when we dealt with Real Gases. We shall discuss this later.

If you are well with Ideal Gases, then here is the Ideal Gas Law:

$$PV=nRT$$

$$P$$ is for Pressure, with the unit $$Pa$$.

$$V$$ is for Volume, with the unit $$m^3$$.

$$n$$ is the Number of moles, with the unit $$mol$$.

$$R$$ is a Constant, which is $$8.314 m^3mol^{-1}K^{-1}$$.

$$T$$ is for Temperature, with the unit $$K$$.

Now, there is an example:

At a standard status (we mean by $$P=1 \text{atm}$$ and $$T=0^\circ C$$), what is the volume of a $$25g$$ $$O_2$$?

First, we convert the units.

$$P=1 \text{atm}=101325 Pa$$

$$T=0^\circ C=(0+273)K=273K$$.

We now have all the details we wanted, by the formula we have

$$PV=nRT$$

$$(101325)V=\frac{25}{32}\times8.314\times273$$

$$V=0.0175m^3$$

Thus, the volume is $$0.0175m^3$$.

Note by Christopher Boo
4 years, 5 months ago

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## Comments

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It has been a long time since my last post. This is because I went to my hometown to celebrate Chinese New Year. However, Anish and Vishnuram had post some chemistry notes on Electrochemistry and Organic Chemistry. Check it out here!

- 4 years, 5 months ago

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This is good stuff Christopher. Keep it up!

Staff - 4 years, 5 months ago

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Superb. Waiting for gas law problems.

- 4 years, 5 months ago

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Happy Chinese New Year!! ^^

- 4 years, 5 months ago

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Can I know what is this topic?

- 4 years, 5 months ago

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Hi Welthan, this topic is about about the laws governing ideal gases as defined by Christopher. It helps us to link up the temperature, volume and pressure of the gases along with the mass i.e. the number of moles. It is derived from the various gas laws given by Boyle, Charles, Gay-Lussac, etc. It has its applications in various fields.

- 4 years, 5 months ago

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I've noticed I missed our many thing too. I will try my best to edit it. :)

- 4 years, 5 months ago

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This is quite of a common sense once you get the intuition for it. ^^ But this formula, is very useful in physics and chemistry. (y) A chemistry toolkit that is used a lot in thermodynamics. ^^ I guess, that's a bit on the application side. Hahhaa. =)

- 4 years, 5 months ago

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