Volume correction factor (VCF) is a tool chemists often use in their calculations to correct a random volume of gas in their equations to a standard volume. The result of the math is the ratio of the two volumes. Certain calculations depend on using a standard volume, such as determining energy content. The equation for determining VCF uses mostly standard quantities, including the freezing point of water in Kelvin, as well as standard atmospheric pressure.

- Skill level:
- Moderate

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### Things you need

- Ambient air pressure, in bars
- Actual pressure of a gas meter reading of the gas's pressure, in bars
- Gas temperature, in Kelvin
- Gas law deviation factor, if given

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## Instructions

- 1
Add the ambient pressure and the gas meter pressure. For example, assume the ambient pressure is 1 bar and the gas meter pressure reading is 2 bars, giving a result of 3 bars.

- 2
Multiply the previous step's result by 273.15 Kelvin, which is the freezing point of water in Kelvins. For example, 3 times 273.15 is 819.45 Kelvin-bars.

- 3
Multiply the gas temperature by the standard atmospheric pressure, 1.01325 bars. For example, 400 Kelvin times 1.01325 bars is 405.3 Kelvin-bars.

- 4
Multiply the previous step's result by the gas law deviation factor, if given. The gas law deviation factor is a dimensionless measure of the gas's deviation from the ideal gas law due to extreme pressures. Under ideal conditions, its value is one.

- 5
Divide the second step's result by the previous step's result to obtain the volume correction factor. For example, 819.45 Kelvin-bars divided by 405.3 Kelvin-bars yields a VCF of 2.022.