Dissolving baking soda in water creates a mildly alkaline solution with a pH around 8.3, not the dramatic fizzing volcano most people picture. The fizz only happens when an acid joins the party. That gentle alkaline solution, though, turns out to be surprisingly useful for everything from washing pesticides off apples to buffering acid in your blood, and the chemistry behind it explains why baking soda shows up in so many home remedies, cleaning tips, and even medical treatments.
What Actually Happens in the Glass
Baking soda is sodium bicarbonate, a white crystalline powder that dissolves readily in water. When it hits the water, it breaks apart into sodium ions and bicarbonate ions. That bicarbonate is a mild base, which nudges the water’s pH from neutral (around 7) up to roughly 8.3. You won’t see bubbles, foam, or any visible reaction. The water might look slightly cloudier for a moment as the powder disperses, but otherwise the change is invisible. The solution feels a bit slippery between your fingers, the way mildly alkaline solutions tend to.
This is the part that surprises people. Baking soda and water, by themselves, are uneventful. The compound just dissolves. It doesn’t decompose, doesn’t release carbon dioxide on its own at room temperature, and doesn’t generate heat you’d notice. The thermal decomposition of sodium bicarbonate requires temperatures well above what you’d get from a glass of tap water; researchers studying the breakdown of baking soda use differential thermal analysis at elevated temperatures in controlled systems to observe it falling apart into sodium carbonate, water, and carbon dioxide gas.1Elsevier / Journal of Inorganic and Nuclear Chemistry. Differential thermal analysis of the decomposition of sodium bicarbonate and its simple double salts At room temperature, you just get a clear alkaline solution sitting quietly in your glass.
Where the Fizz Comes From
The bubbling that people associate with baking soda only happens when you add an acid. Vinegar, lemon juice, cream of tartar in a batter, or the hydrochloric acid in your stomach all trigger the same basic reaction: the acid donates a hydrogen ion to the bicarbonate, forming carbonic acid, which quickly falls apart into water and carbon dioxide gas. That CO2 is the fizz.
Even then, the gas doesn’t escape as fast as you might expect. When researchers mixed sodium bicarbonate with hydrochloric acid in lab conditions mimicking the stomach, they found that even though the chemical reaction itself is nearly instantaneous, the carbon dioxide produced dissolves back into the surrounding water and is only slowly released into the gas phase.2PubMed. Gas production after reaction of sodium bicarbonate and hydrochloric acid This is why swallowing a teaspoon of baking soda in water for heartburn doesn’t cause an immediate balloon of gas in your stomach. The CO2 trickles out gradually, producing some belching but not the explosive release the chemistry on paper might suggest.
That slow off-gassing is also why baking soda works as a leavening agent in baking. Mixed into a batter with an acidic ingredient like buttermilk or yogurt, it generates CO2 bubbles that get trapped in the batter’s structure. Because the gas release is gradual rather than all-at-once, the bubbles expand as the batter heats in the oven, giving muffins and pancakes their rise. If the CO2 escaped instantly, it would all be gone before the batter set, and you’d end up with a flat, dense result.
Washing Pesticides Off Produce
One of the more practical things a baking soda and water solution can do is help remove pesticide residues from fruits and vegetables. A study testing different washing methods on apples found that a baking soda solution outperformed both plain tap water and dilute bleach at stripping surface pesticide residues. Using a solution of about one percent baking soda by weight, researchers were able to completely remove surface residues of two common pesticides, thiabendazole and phosmet, within 12 to 15 minutes of soaking. The baking soda appeared to help break down the pesticides chemically, not just physically wash them off.3PubMed. Effectiveness of Commercial and Homemade Washing Agents in Removing Pesticide Residues on and in Apples
There’s an important caveat, though. The baking soda wash worked well on residues sitting on the surface but was much less effective at removing pesticides that had already soaked into the peel. The deeper the chemical had penetrated, the less the wash helped. So if produce has been sitting with pesticides on it for a long time, even a thorough baking soda soak won’t get everything. It’s still a meaningful improvement over tap water alone, but it’s not a complete fix for residues that have migrated below the skin.
Controlling Odors
The old trick of keeping an open box of baking soda in your refrigerator is rooted in real chemistry. Bicarbonate can neutralize both acidic and basic odor molecules because it acts as a buffer, reacting with acids to form salts and with bases in a similar balancing act. In water solution, this buffering effect is even more accessible because the bicarbonate ions are free to interact with dissolved odor compounds directly.
Researchers tested baking soda’s ability to control odor from stored food waste and found that spreading about 50 grams of baking soda at the bottom of a food waste bin reduced odor by roughly 70 percent over a week. More isn’t always better, though. Using too much, above 100 grams per kilogram of waste, pushed the pH above 9.0, which actually caused ammonia to volatilize and produce its own sharp smell.4PubMed Central. Preliminary observation on the effect of baking soda volume on controlling odour from discarded organic waste This is a useful general principle: baking soda works as an odor neutralizer in moderate amounts, but overdoing it can backfire by creating alkaline conditions that release different unpleasant compounds.
As a Gentle Abrasive for Teeth
Baking soda dissolved or partly dissolved in water has been used as a tooth-cleaning agent for well over a century, and it shows up in many commercial toothpastes today. A review in the Journal of the American Dental Association concluded that baking soda has an inherently low-abrasive nature because it is significantly softer than both tooth enamel and dentin.5PubMed. Baking soda as an abrasive in toothpastes: Mechanism of action and safety and effectiveness considerations When you make a paste of baking soda and water and brush with it, the crystals break down quickly on contact with moisture, so they don’t scratch enamel the way harder abrasives can.
Its mild alkalinity also helps here. Cavity-causing bacteria thrive in acidic environments, and raising the pH of the mouth even slightly can create less hospitable conditions for them. A baking soda rinse, just a teaspoon stirred into a glass of water, is sometimes recommended after vomiting or acid reflux to help neutralize the acid coating the teeth before brushing, since brushing acid-softened enamel can cause wear.
Using It in the Garden
Gardeners sometimes spray a dilute baking soda solution on plant leaves as a homemade fungicide, particularly against powdery mildew. The theory is that the alkaline pH on the leaf surface discourages fungal growth. There’s some basis for this: raising the surface pH does make conditions less friendly for certain fungi. However, field research comparing baking soda sprays with other treatments found that baking soda was not especially effective on its own. In trials on pumpkins with powdery mildew, milk-based sprays consistently outperformed baking soda, suggesting that simply buffering leaf pH isn’t enough to explain effective disease control.6Crop Protection. The effect of milk-based foliar sprays on yield components of field pumpkins with powdery mildew Baking soda sprays may provide a mild benefit, but they’re not a reliable standalone treatment for serious fungal problems.
Another thing to keep in mind is that repeated baking soda applications can raise soil pH over time. For plants that prefer acidic soil, like blueberries or azaleas, this is the opposite of what you want. Occasional light sprays are unlikely to cause problems, but heavy or frequent use could shift the soil chemistry in ways that hurt more than they help.
What Happens When You Drink It
When you swallow baking soda dissolved in water, the alkaline solution meets the hydrochloric acid in your stomach, and the neutralization reaction begins. This is why baking soda has been used for generations as a cheap antacid. It raises stomach pH, which can provide quick relief from heartburn or indigestion. The CO2 produced causes belching, which some people find uncomfortable but is generally harmless in small amounts.
Beyond the stomach, the bicarbonate that gets absorbed into the bloodstream has broader effects. Your blood has its own tightly controlled pH buffer system, and adding bicarbonate pushes it slightly more alkaline, a state called metabolic alkalosis. In healthy people who take a small amount, the kidneys quickly correct this by excreting the excess bicarbonate in urine. But this temporary shift is exactly what some athletes are chasing.
Exercise Performance
During intense exercise, muscles produce hydrogen ions that lower the pH of the surrounding tissue, contributing to the burning sensation and fatigue you feel during an all-out effort. Ingesting baking soda before exercise raises the concentration of bicarbonate in the blood, which increases the body’s ability to buffer that acid. Since bicarbonate can’t cross directly into muscle cells, it works by pulling hydrogen ions out of the muscle and into the bloodstream, where they get neutralized.7PubMed Central. International Society of Sports Nutrition position stand: sodium bicarbonate and exercise performance
The International Society of Sports Nutrition has recognized sodium bicarbonate as having ergogenic (performance-enhancing) potential, particularly for high-intensity efforts lasting one to several minutes, the kind of activity where acid buildup is a major limiter. The typical dose studied is about 0.3 grams per kilogram of body weight, taken 60 to 90 minutes before exercise. For a 70-kilogram person, that’s roughly 21 grams, a substantial amount that commonly causes gastrointestinal discomfort, including nausea, bloating, and diarrhea. The stomach issues are a real trade-off and the main reason this strategy hasn’t gone mainstream despite decades of research supporting a modest performance benefit.
Kidney Health
In people with chronic kidney disease, the kidneys lose their ability to excrete acid efficiently, and the blood gradually becomes more acidic than it should be. This low-grade acidosis itself appears to accelerate kidney damage, creating a vicious cycle. Oral sodium bicarbonate supplements, essentially baking soda in pill or dissolved form, have been studied as a way to break that cycle.
A systematic review of long-term trials found that alkali therapy, primarily oral bicarbonate, was associated with a meaningful slowing of kidney function decline. Patients receiving bicarbonate treatment showed a significantly slower drop in their kidney filtration rate compared to controls, and long-term studies found a substantial reduction in the likelihood of needing dialysis.8American Journal of Nephrology. Short- and Long-Term Effects of Alkali Therapy in Chronic Kidney Disease: A Systematic Review A later and larger meta-analysis confirmed these trends, finding that oral sodium bicarbonate significantly slowed the decline in kidney filtration and raised serum bicarbonate levels.9PubMed Central. The Effects of Oral Sodium Bicarbonate on Renal Function and Cardiovascular Risk in Patients with Chronic Kidney Disease: A Systematic Review and Meta-Analysis
This is a medically supervised therapy, not a DIY remedy. The doses used in these trials are carefully calibrated to each patient’s blood chemistry, and the sodium load that comes with the bicarbonate can worsen blood pressure and fluid retention, which are already concerns in kidney disease patients. A review of the evidence noted that while the results are promising, the treatment comes with real side effects and potential complications that need monitoring.10PubMed. Bicarbonate therapy for prevention of chronic kidney disease progression
When Baking Soda Water Becomes Dangerous
The risks of drinking baking soda dissolved in water are real and escalate quickly with dose. A teaspoon in a glass of water as an occasional antacid is generally tolerated by healthy adults. But people who use it routinely or in large amounts can develop severe metabolic alkalosis, a condition where the blood becomes dangerously alkaline. Case reports in emergency medicine describe patients arriving with blood pH values well above normal, dangerously high sodium levels, and low potassium, all from excessive baking soda intake.11PubMed. Severe metabolic alkalosis and hypernatremia induced by excessive sodium bicarbonate intake: A case report and literature review
Symptoms of bicarbonate overdose are unpredictable and can include seizures, abnormal heart rhythms, and in extreme cases, cardiac arrest.12PubMed. Severe metabolic alkalosis due to baking soda ingestion: case reports of two patients with unsuspected antacid overdose The variability in how people present makes it especially tricky: some patients show up with confusion or muscle twitching, while others go into respiratory failure. Emergency physicians have noted that baking soda overdose is sometimes missed because clinicians don’t think to ask about it, treating the metabolic derangements without identifying the cause.
There’s also the gas problem at the extreme end. While the slow release of CO2 from a normal dose is benign, taking a very large amount of baking soda on a full stomach can produce enough gas to cause gastric distention. At least one case in the medical literature documents spontaneous stomach rupture in a healthy adult following sodium bicarbonate ingestion.13PubMed. Spontaneous rupture of the stomach in a healthy adult man after sodium bicarbonate ingestion This is extremely rare, but it underscores that “natural” and “safe at any dose” are not the same thing.
Why the Temperature of the Water Matters
Baking soda dissolves more readily in warm water than cold, which is why most recipes and cleaning tips suggest using warm or hot water when making a solution. At room temperature, you can dissolve roughly 9 to 10 grams of sodium bicarbonate per 100 milliliters of water. Heating the water increases solubility modestly, letting you get more baking soda into solution without leaving undissolved grit at the bottom.
If you heat the solution enough, something else starts to happen. Above roughly 50 degrees Celsius (about 120°F), baking soda begins to decompose into sodium carbonate, water, and carbon dioxide. Sodium carbonate, commonly called washing soda, is a stronger alkali. This is actually the basis of an old cleaning trick: baking a layer of baking soda in the oven converts it to washing soda, which is a more aggressive cleaner for things like greasy ovens or heavily soiled laundry. When you dissolve baking soda in boiling water, some of this conversion happens in the pot, giving you a solution that’s more alkaline than what you’d get with cold water. For cooking purposes this rarely matters, but for cleaning, using hot water with baking soda gives you a mildly stronger solution.
How Long the Solution Lasts
A freshly mixed baking soda solution is stable at room temperature for days, as long as it’s kept in a closed container and nothing acidic is introduced. The bicarbonate ions stay dissolved and don’t break down spontaneously at normal temperatures. Over time, especially if the container is left open, dissolved CO2 from the air can shift the equilibrium slightly, but in practical terms, a sealed jar of baking soda water will still be effective for cleaning or rinsing a week later.
Dry baking soda, by contrast, has a very long shelf life because it’s chemically stable as a solid. The main thing that degrades it over time is moisture in the air, which can cause it to clump and slowly react. If your box of baking soda has been sitting open in the pantry for years, it may have partially converted to sodium carbonate and lost some of its potency. The classic test still works: drop a spoonful into vinegar. If it fizzes vigorously, it’s still good. If it barely reacts, it’s time for a fresh box.