NapkinCalc

Physics 4 — Thermo & Fluids

The ideal gas law

P·V = n·R·T ties a gas's pressure, volume, amount and temperature into one rule. A scuba tank: 12 L at 230 atmospheres — how many moles of air?

Rgas=8.314R_{gas} = 8.314 gas constant (J/mol·K)
Ptank=230⋅101325P_{tank} = 230 \cdot 101325 = 2.3305×1072.3305 \times 10^{7} pressure (Pa)
Vtank=0.012V_{tank} = 0.012 volume (m³)
Ttank=293T_{tank} = 293 room temperature (K) — gas laws need KELVIN
nmol=Ptank⋅VtankRgas⋅Ttankn_{mol} = \frac{P_{tank} \cdot V_{tank}}{R_{gas} \cdot T_{tank}} = 114.8016114.8016 about 115 mol — over 3 kg of air