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How to Calculate the Moles of AR Present

As with all gases, the number of moles of argon in a sample determines its volume. The number of moles of atoms is directly proportional to the amount of space that the gas needs. Two other factors, however, also define a gas's volume, and you must take them into account when calculating the amount of argon present. A sample with twice as much pressure contains twice as many moles per volume, and a sample with double the pressure has half as many.

Instructions

- 1
  Multiply argon's volume, measured in cubic meters, by its pressure, measured in Pascals. If, for instance, a sample has a volume of 0.4 cubic meters and a pressure of 200,000 Pascals -- 0.4 --- 200,000 = 80,000.
- 2
  Divide the answer by argon's temperature, measured in Kelvin. If, for instance, it has a temperature of 300 K -- 80,000 ÷ 300 = 266.7.
- 3
  Divide the result by 8.3145, which is the universal gas constant that relates these different factors -- 266.7 ÷ 8.3145 = 32.076, or just over 32 moles of argon.

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