What your result means
Carbon dioxide is the mass of gas the reaction can make from what you put in. Gas volume is that same gas measured as a volume at room temperature — the number that matters in practice, because gas takes up roughly 700 times more room than the ingredients that made it.
Runs out first is the limiting ingredient: the one that stops the show. Whatever is left of the other is simply wasted, and adding more of it changes nothing. Fills your container compares the gas volume to the vessel, so anything above 1× means it is coming over the top.
Why this one is different
The reaction is limited by whichever of the two runs out first, and that is named outright — add more bicarbonate to a fixed amount of vinegar past a certain point and nothing further happens. Carbon dioxide is given by mass and by gas volume, then as the share of the container you said you were using.
How it works
Baking soda is sodium bicarbonate, a base. Vinegar is a dilute solution of acetic acid. Put them together and the acid hands a proton to the bicarbonate, which promptly falls apart into water and carbon dioxide. The gas has nowhere to dissolve once the liquid is saturated, so it leaves as bubbles — and if there is soap or protein around to hold thin films together, as foam.
The reaction is one-to-one by molecules, not by weight or spoonfuls, which is where kitchen intuition fails. One gram of baking soda needs only 0.71 g of pure acetic acid — but ordinary vinegar is 95% water, so that gram of soda actually needs about 14 ml of the bottle. Most volcano recipes are wildly soda-heavy, and that surplus soda just sits in the bottom as grit.
How to use this simulator
- Set your baking soda and vinegar amounts as you would actually measure them.
- Set the vinegar strength from the bottle label — this changes the answer more than anything else on the panel.
- Set the container size and check the fill figure before you find out on the carpet.
- Press use the exact ratio to have the soda adjusted so nothing is wasted, then compare the gas yield.
Formula
moles of soda: nₛ = mₛ ÷ 84.007
moles of acid: nₐ = ( V × ρ × a ÷ 100 ) ÷ 60.052
gas produced: n = min( nₛ , nₐ )
gas mass: m = n × 44.009
gas volume: Vᵧₐₛ = n × 24.055 L
- mₛ — mass of baking soda, in grams
- V — volume of vinegar, in millilitres; a — its acidity, in percent by mass
- ρ — density of vinegar, taken as 1.01 g/ml
- 84.007, 60.052, 44.009 — molar masses of sodium bicarbonate, acetic acid and carbon dioxide, in g/mol
- 24.055 L — the volume one mole of gas occupies at 20 °C and 1 atm
Example calculation
10 g of baking soda into 200 ml of 5% vinegar, in a 500 ml jar:
nₐ = ( 200 × 1.01 × 0.05 ) ÷ 60.052 = 0.1682 mol
limiting = soda, so n = 0.1190 mol
gas = 0.1190 × 44.009 = 5.24 g → 0.1190 × 24.055 = 2.863 L
fills the jar 5.7 × over, leaving 2.95 g of acetic acid unused
Those are the simulator's starting values and the panel shows the same figures. Balanced properly, 10 g of soda needs 141.6 ml of 5% vinegar — so the 200 ml in this example is about 58 ml more than the reaction can use.
The ratio that wastes nothing
Grams of baking soda per millilitre of vinegar for a complete reaction. A level teaspoon of baking soda is about 4.6 g, so at 5% each teaspoon wants roughly 65 ml of vinegar. Converting between spoons, grams and millilitres is what the recipe scaler and volume converter are for.
Frequently asked questions
What is the correct ratio of baking soda to vinegar?
For ordinary 5 percent vinegar it is about 0.071 grams of baking soda per millilitre, so roughly 1 teaspoon of soda to 60 millilitres of vinegar. Below that ratio you waste soda, above it you waste vinegar. Either way the fizz stops as soon as the first ingredient runs out, which is why adding more of the leftover one does nothing.
Why does my volcano fizz a lot but not for long?
Because the reaction is essentially instant once the two are in contact, so the whole gas yield arrives in a few seconds. Stretching it out means slowing the contact, for instance by using coarse soda, cold vinegar, or wrapping the soda in tissue. Adding washing-up liquid does not make more gas, it just traps the same gas as foam so you see more of it.
Is this reaction any good for cleaning?
Not as a mixture. Baking soda is a base and vinegar is an acid, so combining them neutralises both and leaves mostly salty water plus escaped carbon dioxide. The fizz can help lift loose debris mechanically, but each ingredient does far more work used on its own.
Related calculators
Assumptions & limitations
- The reaction goes to completion. In a real jar some gas stays dissolved in the liquid and some soda never meets acid, so the measured yield is a little lower.
- Gas volume is quoted at 20 °C and 1 atm. Warmer liquid gives more volume for the same mass of gas, and the bubbles carry water vapour with them.
- Vinegar is treated as acetic acid in water at 1.01 g/ml. Malt, balsamic and wine vinegars carry sugars and other acids that shift both density and strength.
- Baking soda is assumed pure. Baking powder is a different product — mostly filler and its own acid — and will not match these numbers.
- The timing and the bubbles are illustrative. Gas yield is exact chemistry; how quickly it arrives depends on grain size, stirring and temperature, so the animation shows a typical few-second fizz rather than a measured rate.
Further reading
Our guide to kitchen chemistry sets this reaction alongside curdling, caramel and egg-white foam, and draws out the one idea all four share. The rest of The Kitchen & Gut Lab covers what happens to food after it leaves the mixing bowl.
Sources & references
The molar masses, the gas volume and the vinegar composition used here come from the following, all specific to this reaction.
- PubChem — sodium bicarbonate, molar mass 84.007 g/mol
- PubChem — acetic acid, molar mass 60.052 g/mol and solution density
- NIST — the molar gas constant used for the 24.055 L molar volume at 20 °C
- US FDA compliance policy guide — vinegar must carry at least 4 g of acetic acid per 100 ml, the basis of the 5% table figure