Baking Soda vs Baking Powder: The Chemistry That Makes Baked Goods Rise

Your muffins came out flat and dense, or they rose beautifully then collapsed, or they taste faintly soapy. Any of those symptoms points to the same category of problem: the leavening chemistry went wrong.

This happens more than people realize, and almost always because baking soda and baking powder got confused, swapped, or used in the wrong amount. They look nearly identical. They’re both white powders used in tiny amounts. But they work through different chemistry.

Baking Soda: Pure Reactant

Baking soda is sodium bicarbonate. That’s it. One ingredient. Its chemical formula is NaHCO3.

Sodium bicarbonate is a base. When it contacts an acid in a water-containing environment, it reacts to release carbon dioxide gas. The CO2 forms bubbles in the batter. Those bubbles expand in the oven, which makes your muffin or pancake rise. Then the structure sets around them through starch gelatinization and protein coagulation, and you have a light, porous crumb.

The reaction looks like this:

NaHCO3 + acid → CO2 + water + a salt

No acid present means no CO2. No CO2 means no rise.

This is the first thing most people don’t realize: baking soda only works if there’s something acidic in the recipe. The acids that activate it include buttermilk, yogurt, sour cream, lemon juice, vinegar, honey, molasses, natural (non-Dutch-process) cocoa powder, and brown sugar. These are common enough that many recipes include them without the baker understanding why.

There’s another critical timing issue. Baking soda reacts the moment it contacts moisture and acid. The CO2 starts releasing immediately. This is why quick breads and pancakes say to mix the wet and dry ingredients until just combined and cook right away. If you let a baking soda batter sit, you lose much of the gas before the heat can set the structure around it. Flat results.

Baking Powder: Self-Contained

Baking powder is baking soda plus a dry acid (usually cream of tartar, sodium aluminum sulfate, or monocalcium phosphate) plus a starch buffer to keep the two from reacting in the container. It’s a complete leavening system in one jar.

Because the acid is built in, baking powder doesn’t need an acidic ingredient in the recipe to work. Drop it into a batter with water, and the reaction starts. This is why neutral-tasting recipes — vanilla cake, plain scones, white bread — typically use baking powder rather than baking soda.

Most commercial baking powder is double-acting. The name refers to two separate reactions happening at two different times.

The first reaction happens at room temperature when the powder hits moisture. A portion of the CO2 releases.

The second reaction happens at oven temperature. The heat activates the second acid component, releasing more CO2 just as the batter is going into structural changes (starch gelatinizing, gluten setting). This second burst of gas does the most useful work because the batter is thickening around it.

The practical benefit: you have a bit of flexibility with baking powder batters. A batter that sits for 10-15 minutes before baking won’t lose all its lift because the majority of the CO2 is yet to come.

Why Substitution Goes Wrong

Baking soda is roughly 3-4 times more potent than baking powder. When you substitute one for the other without accounting for this, the results fail predictably.

Baking soda used instead of baking powder: Too much leavening. The CO2 is released so fast that the batter over-rises and then collapses before the structure sets. There’s also no acid in a neutral batter to react with, so much of the baking soda stays unreacted. That unreacted baking soda leaves sodium carbonate in the finished product, which tastes soapy and bitter.

Baking powder used instead of baking soda: Not enough leavening power. The baked good is denser than intended. If the recipe contained acidic ingredients that were supposed to react with baking soda, the excess acid remains unreacted, giving the food an overly tart flavor.

If you genuinely need to substitute and don’t have the right ingredient, here’s how to do it correctly:

When Recipes Use Both

Some recipes list both baking soda and baking powder, which looks redundant. It isn’t.

The baking powder does the primary leavening work. The baking soda has a different job: neutralizing excess acid in the recipe.

This matters for two reasons. First, flavor. Acidic batters taste sharper. Baking soda neutralizes the excess acid, making the overall flavor more balanced.

Second, color. Acid affects the Maillard reaction. Acidic environments suppress browning, so baked goods stay paler. Baking soda raises the pH, which accelerates browning. This is why Dutch-process chocolate cake recipes often don’t use baking soda (Dutch-process cocoa is already neutralized and alkaline), while natural cocoa recipes do (natural cocoa is acidic). The baking soda keeps the cake dark and rich-looking. Without it, the cake would be lighter brown.

Recipes that contain buttermilk, brown sugar, or molasses often include baking soda alongside baking powder for exactly this flavor and color management reason, not just for extra lift.

Too Much of Either

Using too much baking soda causes CO2 to release very fast. The batter can’t trap the gas quickly enough, and a lot of it escapes before the structure is set. The result: an aggressive initial rise, then a collapse in the oven. The surface might look cratered.

Too much baking powder causes similar over-rising. It also adds a bitter metallic taste from the acid salts. You’ll notice this most in baked goods with a delicate flavor profile, like a plain vanilla cake.

The amounts in tested recipes are calibrated. One level teaspoon vs a heaping teaspoon matters here in a way it doesn’t with many other ingredients. Use the measuring-spoon-leveled-flat approach for any leavening agent.