What Happens When You Mix Baking Soda and Water

No, this isn’t science class. It’s your handy dandy, favorite cooking blog. Today, we’re talking about what happens when you mix baking soda and water. Essentially, baking soda reacts to water to produce heat and carbonic acid, ultimately creating carbon dioxide.

Hey, there! My name is Michelle, and I’m a little bit fascinated with baking, even when it comes down to the more intrusive and exhausting elements like science. While I’m not the biggest science nerd out there, I still know a thing or two about baking soda science experiments.

Have you ever been curious about what really happens when you mix baking soda and water? It might not be as exciting as mixing baking soda with an acid, such as vinegar, but it’s still plenty interesting – and that’s what this article is here to teach you today.

Who’s ready to dive into the world of science?

What Happens When You Mix Baking Soda and Water?

When baking soda, also referred to as sodium bicarbonate (NaHCo3), is combined with water, heat and carbonic acid are formed. This type of heat is known as an exothermic reaction rather than an endothermic reaction because:

  • An endothermic reaction requires heat to be added to cause the reaction
  • Exothermic reactions occur when there is heat leftover

Therefore since there is no heat being added to the water, it is an exothermic reaction. At this point, the carbonic acid is unable to remain “stable”. This is where the classic “fizziness” comes into play. When baking soda reacts in water, carbon dioxide is formed, causing the iconic fizz.

It comes down to this scientific equation: NaHCo3 + H2O = NaOH + H2CO3

Is Baking Soda Added to Water a Chemical or Physical Change?

When discovering what happens when you mix baking soda and water, a common question is whether the reaction is chemical or physical. The fact is, baking soda mixed with water is a chemical change. Here’s why.

  • A physical change only alters the appearance rather than the chemical composition.
  • A chemical change, on the other hand, transforms a substance into something new (also referred to as a chemical reaction)

Since adding baking soda to water causes a change to the water, it is a chemical change. Aside from the slight and fast-acting fizziness, the physical composition of the water is not altered. Therefore it is not a physical change.

Does Baking Soda Warm Water?

Another common question is whether or not adding baking soda to water increases the temperature. Well, the answer is – only slightly. It all roots back to baking soda and water having an exothermic reaction. 

When baking soda mixes with water, an exothermic reaction takes place. The chemical bonds of each product bind and release energy. This energy then causes the temperature of the water to rise, although insignificantly. 

For example: you won’t be able to boil a pot of coffee just by mixing baking soda and water. The change is so slight it is hardly noticeable.


Well, bakers and scientists, now you know everything you need to know about what happens when you mix baking soda and water. If your mind still isn’t satisfied and you want to learn more, though, check out these frequently asked questions below. 

What does mixing baking soda with water do?

If you are asking about what baking soda with water does when it’s consumed, it’s a great remedy for calming indigestion – but not regularly. To ease indigestion every so often, mix ¼ teaspoon of baking soda with a full glass of water. 

Is mixing water and baking soda a chemical change?

Yes, mixing water and baking soda is a chemical change because it changes the composition of the water. However, it does not alter the appearance of the water, which would render a physical change. 

What are the side effects of baking soda and water?

While drinking baking soda and water can ease indigestion, overconsumption can be incredibly harmful. Short-term side effects can be worsening indigestion, gas, nausea, diarrhea, and stomach pain. Over time, hypokalemia, hypochloremia, and hypernatremia can occur. 

What does baking soda do to your body?

When consumed, baking soda (a salt) breaks down in the body to form sodium and bicarbonate, an alkaline solution that neutralizes acid in the stomach. That is why so many people opt to mix baking soda and water to ease indigestion. 

Final Words

What happens when you mix baking soda and water? A chemical and exothermic reaction takes place that produces carbon dioxide, which is why the water fizzes ever so slightly. This change raises the temperature of the water, although it is insignificant. 

Did you know what happens when you mix baking soda and water? Readers, did I miss anything? Share with us in the comment section below!

About Michelle
I have been a lover of sweets since day one. This led me on a self-taught baking journey starting at the age of 13. It's been over 10 years since the start of my baking adventures, and I’ve learned a lot along the way. Now, people rave about my delectable treats, whether it’s a chocolate cake or a strawberry crepe.

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  • Dave

    Good article. I have wondered if I add baking soda to water and let’s say put my toothbrush head in the solution, will it go bad? If so, how long?

    Dave Powell

    • Michelle

      Hi Dave! I’m not really sure about that one, to be honest. My apologies.

  • SMC Interior Design

    Great post. keep sharing such a worthy information.

    • Michelle

      Thank you! I’m glad you enjoyed it!

  • Freda

    Hi I live in Australia and purchased baking soda bob mills from USA…when I put with water to make a drink for digestion it does not fizz? I’m confused it is not the right one.

    • Michelle

      Hi Freda,
      Try using baking powder rather than baking soda. Or, add an acid such as vinegar with the baking soda.

  • E. Kaye

    If I put baking powder in my water when I boil eggs it seems to help make the shell crisper and easier to peal??????

    • Michelle

      Hi E. Kaye,
      I have heard of many people using this trick, and I hear it works wonders! Don’t hesitate to keep adding a small amount to your water.

  • Peri

    Have you confused baking soda and baking powder? Baking soda will not fizz in water, and no carbon dioxide is released. It needs an acid to produce that reaction. Baking powder contains an acid, potassium bitartrate, and will produce carbon dioxide and will fizz in water.

    • Michelle

      Hi Peri,
      Thank you for your added info!

  • Jason

    One thing, when you mix baking soda and water and reactions all finish what you are left with is carbonated lye water. Lye is not nearly as dangerous as many think.

    • Michelle

      Hi Jason,
      Thanks for sharing this information!

  • Herman

    If I Mix baking soda and water and spraying it in all corners of the house is that harmful for me and my family??I’m trying to get rid of roachs