WEBVTT

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Here is the problem: What volume does 3 mol of an ideal gas occupy at 0.8 atm and 20 °C?

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Solve PV equals nRT for V, with pressure in atm, volume in litres, amount in moles and temperature in kelvin.

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Convert the temperature to kelvin. The gas law needs absolute temperature.

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Choose the gas constant to match the units. Pressure is in atm and volume in litres.

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Rearrange PV equals nRT for V and substitute.

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So the answer is V equals 90.2067 L.

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An ideal gas obeys PV equals nRT: pressure times volume is proportional to the amount of gas and its absolute temperature. Real gases follow it closely at low pressure and high temperature.

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PV equals 72.1654 and nRT equals 72.1654, which agree.