Sodium Bicarbonate vs Sodium Carbonate (Soda Ash)

Sodium bicarbonate and sodium carbonate (soda ash) are both sodium salts of carbonic acid and both are mild-to-moderate alkalis, so they are often confused. They are different chemicals with different strength, pH and uses:

Product	CAS	Formula	pH (solution)	Relative alkalinity
Sodium bicarbonate	144-55-8	NaHCO₃	about 8.3 (1% solution)	Mild
Sodium carbonate (soda ash)	497-19-8	Na₂CO₃	about 11 (1% solution)	Stronger

The relationship: sodium bicarbonate is the half-neutralised form; heating it drives off CO₂ and water and leaves sodium carbonate (2 NaHCO₃ -> Na₂CO₃ + CO₂ + H₂O). Soda ash is therefore the stronger alkali and the “parent” of bicarbonate in the soda family.

Head-to-head comparison

Property	Sodium bicarbonate (NaHCO₃)	Sodium carbonate (Na₂CO₃)
pH of solution	About 8.3	About 11
Strength	Mild base	Stronger base
CO₂ release with acid	Strong (the source of leavening and effervescence)	Also releases CO₂ with acid, but less per unit used as a leavener
Food additive number	E500(ii)	E500(i)
Main uses	Food/leavening, feed buffer, flue-gas, buffering, effervescent	Glass, detergents, pH control, bulk alkali, water softening
Handling	Mild; safe in food	More alkaline and irritating
Cost per unit alkalinity	Higher (weaker)	Lower (stronger)

Because soda ash is a stronger base, less of it is needed to reach a given pH; bicarbonate is chosen where a gentle, safe base or a controllable CO₂ source is wanted.

How to choose

Food, leavening or a mild buffer? Choose sodium bicarbonate (E500(ii)).
Need strong alkalinity per tonne (glass, detergents, bulk pH)? Choose soda ash (E500(i) for food use, technical otherwise).
Need a safe CO₂ source or effervescence? Bicarbonate, balanced against an acid.
pH control where over-shooting is a risk? Bicarbonate buffers gently near pH 8; caustic or soda ash can overshoot.
Cost per unit of alkalinity? Soda ash is cheaper per unit; bicarbonate buys mildness and safety.

Can one replace the other?

Sometimes, but not blindly. Substituting soda ash for bicarbonate gives a much stronger, more alkaline result and can change flavour, texture and safety; substituting bicarbonate for soda ash usually under-treats the system and costs more per unit of alkalinity. Where a recipe or process specifies one, use that one – and if you must change, adjust the dose on the chemistry and confirm by test.

Other alkalis in the soda family

Sodium bicarbonate and soda ash are not the only related alkalis. Buyers sometimes also consider sodium sesquicarbonate (CAS 533-96-0, the mineral trona, Na₂CO₃.NaHCO₃.2H₂O), potassium carbonate and caustic soda. Sesquicarbonate sits between bicarbonate and carbonate in strength and is used as a buffer and a milder alkali; caustic soda (NaOH) is far stronger and is handled as a corrosive. When a process is sensitive to over-alkalisation, the milder bicarbonate or sesquicarbonate is preferred; when raw alkalinity per tonne is wanted, soda ash or caustic wins on cost.

Frequently Asked Questions

Is baking soda the same as soda ash?

No. Baking soda is sodium bicarbonate (NaHCO₃, E500(ii)); soda ash is sodium carbonate (Na₂CO₃, E500(i)), a stronger alkali.

Which is stronger?

Sodium carbonate is stronger (about pH 11 vs about pH 8.3 for a 1% solution).

Can I use soda ash instead of baking soda in food?

Not as a direct substitute – it is much more alkaline and can be harmful at the same dose. Use the product a recipe specifies.

Which is cheaper?

Soda ash is generally cheaper per unit of alkalinity; bicarbonate is used where its mildness and CO₂ release are needed.

Do you supply both?

We supply sodium bicarbonate; contact us for your requirement and grade.