One equation predicts a diver's pain, a climber's fog, and a soda's hiss.
By the end you will predict dissolved gas from pressure, then break all three systems on purpose.
Partial pressure means the share of total pressure owned by one gas.
→ Do this: drag the pressure slider in panel 1 first, then come back and read.
Bottom line: dissolved gas follows the partial pressure of that same gas.
Dalton sets the share of each gas. Henry converts that share into dissolved concentration.
Temperature edits the exchange rate kH. Bubbles and blood decide what the number costs.
Some courses call this Henry's theorem; working divers and bottlers say Henry's law.
| Law | Job | Input → output |
|---|---|---|
| Dalton | splits total pressure | total P × fraction → partial P |
| Henry | dissolves each gas | partial P × kH → concentration |
| Temperature rule | shifts kH | warm liquid → smaller kH → less gas |
→ Do this: say aloud “Dalton splits, Henry dissolves” before touching any slider.
Bottom line: Henry never sees total pressure, only each gas and its own kH.
Every bench runs the same core math. Extremes are safe here and fatal outside.
Teaching model with illustrative tissue and altitude numbers. Not dive, flight, or medical guidance.
Depth pressure uses 10 m per atm (real seawater 10.3).
Same 30 m / 20 min dive, two ascents. Fast ascent seeds bubbles; slow ascent lets gas leave quietly.
One volume means one litre of CO2 gas (standard conditions) per litre of drink.
Big kH in C = kH·P means very soluble. Big KH in p = KH·x means barely soluble.
→ Do this: push every slider to both ends and watch which readouts scale in a straight line.
Bottom line: straight-line scaling with partial pressure is the signature you are hunting.
Learners multiply kH by total pressure and credit nitrogen with oxygen's pressure.
Henry bills each gas only for its own partial pressure: pN2 = 0.79 × Ptotal in air.
→ Do this: pick “wrong”, note the 27% overcharge, then switch back to “right”.
Bottom line: total pressure is shared; dissolved N2 only answers to the N2 share.
Checked folder niya: no files, no manifest, no pinned versions to verify against.
So nothing here names your files. The mapping below is where this math would live once you add code.
| If you add… | Put Henry logic in… | Pure function |
|---|---|---|
| dive planner | dive/henry.js | dissolved(N2, 0.79 × Pdepth) |
| altitude aid | physio/oxygen.js | dissolved(O2, frac × Palt) |
| carbonation tool | soda/carb.js | volumes(CO2, P, T) |
Keep simulation pure and DOM in one boot routine, exactly as this page does.
→ Do this: copy one pure function from this page into your first repo file.
Bottom line: an empty repo means the lesson stays standalone until you pin real code.
Three plants run on this law every day. Each has a knob, a cost, and a slider below.
At 30 m the pressure is ~4 atm, so blood N2 nears 4× the surface value. A fast ascent leaves no time to repay through the lungs, so N2 becomes bubbles in joints and blood.
The operator moves ascent speed and the safety stop. Dive computers penalise fast ascents with longer stops.
At 5,500 m total pressure halves, so inspired pO2 halves, alveolar follows, and hemoglobin saturation slides down its steep curve. Thinking slows before breathing feels hard.
The operator moves inspired O2: supplemental flow or cabin pressurisation restores pO2 without descending.
Doctors call the shortage hypoxia; many textbooks label this altitude case anoxia.
A plant chills syrup to ~4 °C and fills under 3–4 atm CO2, locking in ~3–4 volumes of fizz. A warm fill needs far more pressure for the same fizz and bursts out on opening.
The operator moves fill pressure and chill temperature. Cold saves gas and keeps caps on.
Every case is one pattern: pressure sets the dissolved dose, and a careless release turns dose into bubbles or deficit.
→ Do this: set WHY-2 to 5,500 m on air, then raise O2 until the status flips to safe.
Bottom line: control partial pressure and you control what the liquid must carry.
Eight questions, two per family: law, bends, anoxia, soda. Options shuffle each run.
→ Do this: answer all eight, then read the feedback on options you did not pick.
Bottom line: a pass means no family embarrasses you.
| Term | Meaning |
|---|---|
| Henry's law | dissolved concentration equals kH times that gas partial pressure at fixed temperature |
| partial pressure | total pressure times the fractional share of one gas |
| kH | Henry solubility constant in mol per litre per atm for C = kH × P |
| KH | alternate volatility constant in p = KH × x; large means insoluble |
| solubility | equilibrium dissolved amount at given pressure and temperature |
| bends | decompression sickness from N2 bubbles after fast ascent |
| anoxia | tissues starved of O2; here from low inspired pO2 at altitude |
| nucleation | seed site where dissolved gas gathers into a bubble |
| volumes CO2 | litres of CO2 gas at standard conditions per litre of drink |
| saturation | fraction of hemoglobin binding sites carrying O2 |
| ascent rate | vertical speed upward; fast values raise bubble risk |
| tissue loading | model N2 accumulated in a slow body compartment |
→ Do this: cover the table and define each term from the cards alone.
Bottom line: say it with partial pressure or do not say it.