Introduction: a fizzy kitchen curiosity
Mixing lemon juice and baking soda is a classic kitchen experiment that delights children and adults alike. Add the two and you usually get a lively fizz, a scent of citrus, and a tiny cloud of bubbles that disappears almost as quickly as it began.
But behind that cheerful fizz is tidy chemistry with useful applications — from baking to cleaning — and a few safety notes worth knowing.
The chemistry, in plain language
At its heart this is an acid-plus-base reaction. Lemon juice contains citric acid, and baking soda is sodium bicarbonate — a gentle base.
When an acid meets bicarbonate, the acid donates protons; bicarbonate accepts them and soon produces carbon dioxide gas, water, and a salt called sodium citrate. The escaping carbon dioxide is the fizz you see.
A simple chemical equation
If you like formulas, it looks like this (simplified):
C6H8O7 (citric acid) + 3 NaHCO3 (sodium bicarbonate) → Na3C6H5O7 (sodium citrate) + 3 CO2 (carbon dioxide) + 3 H2O (water)
The reaction’s vigour depends on concentration, temperature, and surface area. Powdered acids with dry baking soda react faster than a splash of juice on clumps of soda.
What you’ll see and smell
Visuals are the fun part. Tiny bubbles form immediately where the liquid touches the powder and rise as fizzing foam.
You’ll also notice the lemon scent — the reaction doesn’t neutralise volatile citrus oils, so the aroma remains pleasantly bright.
Practical uses
Baking and leavening
This mixture is a kitchen star for leavening. In recipes that call for baking soda and an acidic liquid, the CO2 helps batters and doughs puff up while they cook.
That same effervescence is why many effervescent antacids and drink tablets use citric acid plus bicarbonate — the fizz carries the medicine and dissolves it quickly.
Cleaning and deodorising
The fizzing action can help lift gunk and neutralise odors on many surfaces. A paste of baking soda plus a squeeze of lemon juice is a popular scrub for cutting boards, sinks, and stained pans.
Be mindful of the surface: acid can dull or etch natural stone like marble and some countertops. When in doubt, test a small hidden area first.
Science demos and crafts
This is the go-to reaction for a backyard volcano or a quick classroom demo. It’s safe, visibly dramatic, and easy to control.
For a bigger show, use powdered citric acid instead of juice — it reacts more energetically and stores dry until you add water.
What forms after the fizz? (and is it safe?)
After fizzing stops the liquid contains mostly water and sodium citrate — a salty, mildly alkaline salt. It’s commonly used as a food additive and is generally safe in small amounts.
Consuming the amounts from a kitchen experiment is usually harmless, though the sodium content can be relevant for people on low-sodium diets. Also expect burping from that released CO2 if you drink it.
On the skin
Lemon juice is acidic and can irritate sensitive skin or cause photosensitivity in sunlight. Baking soda is alkaline and abrasive in scrubs.
Mixed together the acidity and alkalinity largely neutralize, but the mixture can still irritate. Avoid leaving it on delicate or broken skin, and skip using it on your face if you have sensitive skin.
In sealed containers
Never mix active fizzing batches in a tightly sealed container. The CO2 builds pressure and can cause the container to burst or spray its contents when opened.
Why this reaction matters beyond the kitchen
This acid-base interaction is a tidy example of neutralization — a concept that underpins everything from antacids to wastewater treatment.
If you’re curious about the general idea of acids meeting bases, I’ve written a friendly overview of what happens when an acid reacts with a base that goes deeper into the chemistry and everyday examples.
Common questions and useful tips
Will lemon juice destroy baking soda?
“Destroy” is a dramatic word, but acid does convert bicarbonate into other chemicals. You’ll lose the alkaline scrubbing power of the soda once it’s neutralized, but you gain fizz and a milder, salted liquid that still cleans in different ways.
Can you use the mixture to clean everything?
It’s effective on many stains and smells, but avoid using acidic mixtures on natural stone, certain metals, and unsealed wood. The acid may etch or discolor porous materials.
Is it the same as lemon plus milk curdling?
Lemon juice curdles milk by changing milk proteins with acid. That’s a protein reaction rather than a gas-producing neutralization, though both involve acid. If the curdling trick fascinates you, take a peek at my post about what happens when you mix lemon juice and milk.
How does this compare to other baking soda mixtures?
Different acids give different speeds and smells. Lemon adds aroma and mild flavor, while hydrogen peroxide produces extra bubbling and bleaching power in some cleaning mixes. For a look at another common baking-soda pairing, see what happens if you mix baking soda and hydrogen peroxide.
Simple experiments and recipes to try
Here are a few safe, simple things to try at home. Keep everything well-ventilated and don’t seal reaction vessels.
- Mini volcano: a cup of baking soda in a tray, add a little dish soap, then pour lemon juice slowly for a longer-lasting foam.
- Quick cleaner: sprinkle baking soda on a damp cutting board, rub with half a lemon, rinse and dry. It lifts odors and light stains.
- Fizzy drink (for adults or well-informed kids): a teaspoon of baking soda in a glass, add a tablespoon of lemon juice, top with water and stir. Expect bubbles and a salty-citrus taste; don’t overdo the baking soda.
Safety checklist
- Don’t mix in a closed bottle — pressure builds from CO2.
- Avoid contact with eyes and broken skin; rinse with water if irritation occurs.
- Don’t swallow large amounts; the sodium load and gas can be unpleasant.
- Test on hidden areas before using as a cleaner on delicate surfaces.
Wrap-up: a little chemistry, a lot of possibilities
Mixing lemon juice and baking soda is a small-scale lesson in chemistry that’s useful, harmless, and often charming. It shows neutralization, produces carbon dioxide you can see, and yields a practical cleaning and baking tool.
Use it for science demos, stain-fighting, or the occasional fizzy drink — and remember the simple safety notes so the experiment stays fun and trouble-free.
More Mixing Experiments
Love seeing what happens when everyday ingredients collide? Try these next: