The Gas Laws and the Ideal Gas Equation
Boyle's law, Charles's law and the pressure law are three slices of one relationship, pV = nRT, once the temperature is in kelvin. The equation gives any one of the four quantities when the other three are known.
What a learner can do afterwards
- Uses pV over T staying constant to compare one fixed mass of gas in two states
- Applies pV = nRT with the amount in moles and the temperature in kelvin
- Sketches p against V and p against T and says what the shape of each line shows
1 · Read
For a fixed mass of gas, p V over T stays constant. Squeeze it at fixed temperature and pressure climbs as volume falls. Heat a sealed can from 300 K to 600 K and the pressure doubles with it.
The full form is p V equals n R T. Amount goes in as moles, temperature in kelvin, and R is 8.31. Convert Celsius first, since 200 degrees is 473 K and skipping that step wrecks the answer.
Gas at 100 kPa fills 2.0 L, then expands to 4.0 L at fixed temperature. So 100 times 2.0 equals the new pressure times 4.0, giving 50 kPa. And 2.0 mol in 3.0 m3 at 300 K gives 2 times 8.31 times 300 over 3.0, which is 1662 Pa.
Read the graphs by shape. At fixed temperature, p against V is a falling curve. At fixed volume, p against T is a straight line through the origin. Mass over molar mass gives the moles to feed in.
Compare states with p V over T, solve all four with p V equals n R T in kelvin, and read curves for shape.
2 · Watch
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Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.