* The water does get a little colder, but only because dissolving takes in heat. No new substance forms, so on its own this is not evidence of a reaction.
All readings are model values for 100 cm³ of liquid in a 250 cm³ conical flask at 20 °C, on a balance zeroed with the empty flask. Data-book values: NaHCO₃ 84.01 g/mol; dissolves about 9.6 g per 100 g of water at 20 °C; practically insoluble in ethanol and isopropyl alcohol. Gas volumes use 24 dm³/mol and assume all the CO₂ escapes (in reality a little stays dissolved). Alcohol slowly evaporating from an open flask is left out. With balloons the balances are ideal: a real balance reads up to about 0.7 g less for 571 cm³ of gas, because the air pushes up on the swollen balloon (buoyancy), even though no mass is lost.
Short answer to the question: baking soda does not react with ethyl alcohol or isopropyl alcohol. It does not even dissolve in them. The powder sinks, the liquid looks cloudy for a while, and then it clears with a white layer at the bottom: no bubbles, no temperature change, nothing new. To fizz, baking soda needs an acid that can hand over H⁺ ions, like the acetic acid in vinegar or the citric acid in lemon juice.
You see: cloudy, then a white layer settles. No bubbles. Temperature and mass do not change.
Why: the ions in baking soda cannot break away into ethanol, and ethanol gives no H⁺ ions. Filter it out and you get the same powder back.
You see: the same as ethanol, but it stays cloudy longer.
Why: isopropyl alcohol is about twice as thick (viscous) as ethanol, so the grains sink more slowly. Still nothing dissolves or reacts.
You see: mostly sinks; a little powder disappears. No bubbles.
Why: the 30% water can dissolve some baking soda (the alcohol makes even that much smaller). Still no acid, so no gas. The 70% ethanol sold for cleaning behaves the same way.
You see: the powder disappears, the liquid turns clear, it gets about 1 °C colder. No bubbles.
Why: water pulls the Na⁺ and HCO₃⁻ ions apart (dissolving takes in a little heat). The solution is weakly alkaline, pH about 8.3.
You see: strong fizzing, the liquid gets colder, a balloon fills, an open flask loses mass.
Why: NaHCO₃ + CH₃COOH → CH₃COONa + H₂O + CO₂. The bubbles are carbon dioxide. It stops when the baking soda or the acid runs out.
You see: fizzing much like vinegar.
Why: citric acid gives H⁺ too. 100 cm³ of lemon juice holds a little less acid than 100 cm³ of vinegar (enough for about 6.3 g of baking soda instead of 7.0 g), so with a big spoonful it gives a little less gas.
All the fizzing comes from one step: a hydrogen carbonate ion takes an H⁺ ion and falls apart into water and carbon dioxide, HCO₃⁻ + H⁺ → H₂O + CO₂. Acetic acid and citric acid give away H⁺ easily. Alcohols have an O–H group too, but they hold on to that H about as tightly as water does: they are not acids in this sense. No H⁺, no CO₂.
An acid turns HCO₃⁻ into CO₂ easily only if it is stronger than carbonic acid (pKa 6.4). (Citric acid’s third H, pKa 6.4, is borderline; it still reacts because the CO₂ keeps bubbling away.) Water can be quoted as 14 or 15.7 depending on the convention; either way the alcohols are about as weak, or a little weaker.
Baking soda is made of ions: Na⁺ and HCO₃⁻. To dissolve, a liquid has to pull the ions apart and surround each one. Water molecules are very polar and are excellent at this. Alcohol molecules are much less polar (relative permittivity: water about 80, ethanol about 25, isopropyl alcohol about 18), so they cannot hold the ions apart. The crystal stays a crystal, and the grains just sink.
How fast they sink depends on the grain size and on how thick the liquid is (Stokes’ law). Big grains reach the bottom in seconds; the finest dust takes several minutes, which is why the alcohol stays a little cloudy for a while.
The two flasks side by side: on the left nothing reacts, on the right a chemical reaction makes a new gas. Switch between the labeled diagram, a blank one to test your memory, and a quiz where you place each label yourself. You can also download both versions or print a label worksheet.
Tap a word, then tap the numbered box it belongs to (on the diagram or in the list below). Tap a filled box to take the word back. On a phone, swipe the diagram sideways to see every number.
Ten questions (from a bank of twenty) on what happens in each liquid, evidence of a chemical reaction, the equations and simple mole calculations.
Tap a card, then tap the box it belongs in. Check when all twelve are placed. Careful: some are tricky.
Put a spoonful of baking soda into six glasses: ethanol, isopropyl alcohol, rubbing alcohol, water, vinegar and lemon juice. Vinegar and lemon juice fizz at once and get colder. Water swallows the powder without a single bubble. The alcohols go milky for a while, then clear, with a white layer at the bottom, as if you had stirred sand into them. Scientists ask: did a new substance form? That is the difference between a chemical change and a physical change (or no change at all).
Evidence of a chemical reaction includes a new gas, a temperature change, a color change or a new solid (precipitate). In vinegar there is a new gas (it puts out a flame and fills a balloon), the temperature drops, and the balance shows mass leaving: NaHCO₃ + CH₃COOH → CH₃COONa + H₂O + CO₂. In water the Na⁺ and HCO₃⁻ ions just spread out between the water molecules: dissolving, a physical change, even though the water gets about 1 °C colder. In alcohol nothing happens to the ions at all: you can filter the powder out, dry it, and weigh the same mass again.
The fizzing step is HCO₃⁻ + H⁺ → H₂O + CO₂. It needs an acid stronger than carbonic acid (pKa 6.4): acetic acid (4.8) and citric acid (3.1) are; water and alcohols (pKa about 14–17) are not. One mole of NaHCO₃ gives one mole of CO₂, so 2.0 g (0.0238 mol) gives 0.57 dm³ and 1.05 g of CO₂, until either the baking soda or the acid runs out (the limiting reactant). Whether a salt dissolves depends on whether the liquid can surround its ions: water (very polar) can, alcohols (much less polar) cannot.
Before you add anything, fill in Predict first. Press Compare all six and watch the evidence checklist fill in. Switch the graph to Mass change: only the acids lose mass. Press Balloons on: now nothing loses mass. Pick ethanol and press Filter and dry: you get the same 2.00 g back. Then try Too much baking soda and keep adding spoonfuls to the vinegar until it stops fizzing.
| Liquid | What happens | Equation |
|---|---|---|
| Ethanol, isopropyl alcohol | no reaction, no dissolving: the powder settles (a mixture) | NaHCO₃(s) stays NaHCO₃(s) |
| Water (and the water in 70% alcohol) | dissolving: a physical change; takes in heat (+18.7 kJ/mol) | NaHCO₃(s) → Na⁺(aq) + HCO₃⁻(aq) |
| Vinegar (acetic acid) | chemical reaction: CO₂ gas, the liquid cools | NaHCO₃(s) + CH₃COOH(aq) → CH₃COONa(aq) + H₂O(l) + CO₂(g) |
| Lemon juice (citric acid) | chemical reaction: CO₂ gas; each citric acid can give 3 H⁺ | 3NaHCO₃(s) + C₆H₈O₇(aq) → Na₃C₆H₅O₇(aq) + 3H₂O(l) + 3CO₂(g) |
| Any acid (ionic equation) | the fizzing step | HCO₃⁻(aq) + H⁺(aq) → H₂O(l) + CO₂(g) |
| Strong heating (not in this lab) | thermal decomposition: slow from about 80 °C, fast at about 200 °C or in a flame | 2NaHCO₃(s) → Na₂CO₃(s) + H₂O(g) + CO₂(g) |
| Moles and gas | amount, then volume at room temperature and pressure | n = m ÷ M; V = n × 24 dm³/mol |
| Temperature change | heat taken in, then shared by the liquid | Q = n × ΔH; ΔT = Q ÷ (m × c) |
| Settling (Stokes’ law) | speed of a small grain sinking in a liquid | v = (ρgrain − ρliquid) g d² ÷ (18 μ) |
Alcohols and acetic acid both contain an O–H group, but in acetic acid the negative charge left behind after losing H⁺ is shared over two oxygen atoms (the acetate ion is stabilized), so it gives H⁺ away easily (pKa 4.76). An alkoxide ion such as ethoxide has no such help, so ethanol (pKa about 16) and isopropyl alcohol (about 17) behave like water: they practically never give H⁺ to HCO₃⁻. To make CO₂ from hydrogen carbonate readily, an acid must be stronger than carbonic acid (pKa 6.35); then H₂CO₃ forms and breaks down to H₂O + CO₂, which bubbles out. (Citric acid’s third H, pKa 6.40, is about as strong as carbonic acid; it still ends up reacting because the CO₂ escapes and pulls the reaction along. An alcohol, about 10 pKa units weaker, gives practically nothing.)
HCO₃⁻ can act as an acid (pKa 10.33) or as a base (it takes H⁺ to become H₂CO₃, pKa 6.35). For such an amphiprotic ion pH ≈ (6.35 + 10.33) ÷ 2 ≈ 8.3, whatever the concentration (in the usual range). In vinegar the pH climbs from about 2.4 towards the acetic acid/acetate buffer value (about 4.4 after 2 g), and jumps to about 8 only when the acid is used up.
From standard enthalpies of formation (kJ/mol, 25 °C): NaHCO₃(s) −950.81, Na⁺(aq) −240.12, HCO₃⁻(aq) −691.99, CH₃COOH(aq) −485.76, CH₃COO⁻(aq) −486.01, H₂O(l) −285.83, CO₂(g) −393.51. Dissolving: −240.12 − 691.99 + 950.81 = +18.70. Acid step: (−486.01 − 285.83 − 393.51) − (−691.99 − 485.76) = +12.40. Both positive (endothermic), which is why the fizzing liquid cools. The lab uses +12.4 for lemon juice too, which is close but not exact for citric acid.
Some CO₂ stays dissolved (about 1.5 g per dm³ at 25 °C under 1 atm of CO₂), so you collect a little less gas than calculated. A growing balloon is pushed up by the air around it (buoyancy): 571 cm³ of extra balloon displaces about 0.7 g of air, so a real balance reads up to about 0.7 g less even though no mass is lost. That is why teachers often show conservation of mass with a rigid closed container instead, such as a strong plastic soda bottle with only a small amount of powder (opened slowly afterwards). Open flasks of alcohol slowly evaporate, so their reading creeps down unless covered. And “practically insoluble” is not exactly zero: handbooks list baking soda as insoluble or only very slightly soluble in alcohol, far too little to see in this experiment.
Many videos show baking soda and sugar on a pile of sand soaked in alcohol, which is then lit: a black “snake” grows out of it. This is not a reaction between baking soda and alcohol. The alcohol is only the fuel: it burns and supplies heat. The heat makes baking soda decompose (2NaHCO₃ → Na₂CO₃ + H₂O + CO₂) and turns the sugar into black carbon. The carbon dioxide and steam puff the soft, burning sugar up into a long, light, crumbly snake. Without heat (as in the lab above) baking soda and alcohol do nothing to each other.
No. Baking soda (sodium hydrogen carbonate, NaHCO₃) does not react with ethyl alcohol (ethanol) or isopropyl alcohol (isopropanol). It does not dissolve in them either: the powder makes the liquid cloudy for a while, then settles as a white layer. There are no bubbles, no temperature change and the mass stays the same. You can filter the powder out, dry it and get the same baking soda back.
Key takeaway: no bubbles, no new substance: baking soda and alcohol just form a mixture.Practically not. Handbooks list sodium hydrogen carbonate as insoluble, or only very slightly soluble, in ethanol, far too little to notice. Alcohol molecules are much less polar than water molecules, so they cannot pull the Na⁺ and HCO₃⁻ ions apart. In water, by contrast, about 9.6 g dissolves in 100 g at 20 °C.
Key takeaway: baking soda dissolves in water, not in alcohol.The fizz is carbon dioxide made when hydrogen carbonate ions take H⁺ ions from an acid: HCO₃⁻ + H⁺ → H₂O + CO₂. Vinegar contains acetic acid, which gives H⁺ easily. Alcohols have an O–H group, but they hold on to the H about as tightly as water does (pKa about 16–17), so they are not acids here and no CO₂ forms.
Key takeaway: fizzing needs an acid to supply H⁺ ions.Carbon dioxide, CO₂. The word equation is sodium hydrogen carbonate + acetic acid → sodium acetate + water + carbon dioxide. You can show it is CO₂ and not air or hydrogen: it puts out a small flame, it turns limewater milky, and a balloon on the flask fills with it.
Key takeaway: the bubbles are carbon dioxide.At school level, no: it is a physical change. The ions separate and spread out, but no new substance forms, and you can get (most of) the baking soda back as white crystals by letting the water evaporate slowly at room temperature (heating would break it down). The water does get a little colder (about 1 °C for 2 g in 100 g), which shows that a temperature change on its own is not proof of a reaction.
Key takeaway: dissolving is a physical change, even when the temperature changes.The reaction is endothermic: it takes in heat from the liquid. Together, dissolving the baking soda and the acid step take in about 31 kJ per mole of NaHCO₃. For 2 g in 100 cm³ of vinegar that is about 1.8 °C of cooling; a 5 g teaspoon gives about 4.5 °C.
Key takeaway: the reaction takes in heat, so the liquid cools.Yes. Lemon juice contains citric acid (about 5%), which gives H⁺ ions, so it fizzes with carbon dioxide just like vinegar: 3NaHCO₃ + C₆H₈O₇ → Na₃C₆H₅O₇ + 3H₂O + 3CO₂. 100 cm³ of lemon juice can react with about 6.3 g of baking soda, a little less than the 7.0 g for 100 cm³ of 5% vinegar.
Key takeaway: lemon juice is acidic, so it fizzes too.Rubbing alcohol (and the 70% ethanol sold for cleaning, for example “álcool 70” in Brazil) is about 30% water. A little baking soda dissolves in that water, but most of it still sinks, and there are no bubbles, because there is no acid.
Key takeaway: a little dissolves in the water part; still no fizz.A level teaspoon is about 5 g, which is 5 ÷ 84.01 = 0.0595 mol. With enough acid (100 cm³ of 5% vinegar is enough for 7 g) that makes 0.0595 mol of CO₂: about 1.4 dm³ at room temperature and 2.6 g. That is why a balloon on the flask grows to about the size of a grapefruit.
Key takeaway: about 1.4 dm³ of CO₂ from 5 g.There the alcohol is only the fuel. When it burns, the heat makes baking soda decompose (2NaHCO₃ → Na₂CO₃ + H₂O + CO₂) and chars the sugar into carbon; the gas puffs the carbon up into a snake. Baking soda and alcohol still do not react with each other. It is a fire demonstration for adults only, outdoors, and should not be tried at home.
Key takeaway: alcohol = fuel; heat breaks down the baking soda.