Hydrogen peroxide and baking soda are common household ingredients with many uses. Individually, hydrogen peroxide acts as a disinfectant and whitener, while baking soda neutralizes acids and bases. When combined, these two ingredients create an impressive reaction that produces oxygen gas. The chemical reaction between hydrogen peroxide and baking soda has practical applications, but also comes with safety concerns if not handled properly.
The Chemical Reaction
The reaction between hydrogen peroxide (H2O2) and sodium bicarbonate (baking soda, NaHCO3) is an exothermic decomposition reaction. This means that the reaction gives off heat as new substances are formed from the original ingredients. Specifically, when hydrogen peroxide and baking soda mix, oxygen gas (O2) and sodium carbonate (Na2CO3) are produced according to the following reaction:
2 H2O2 + NaHCO3 -> O2 + H2O + Na2CO3
In this reaction, the hydrogen peroxide breaks down into oxygen and water. The sodium bicarbonate (baking soda) gives up a sodium ion and its bicarbonate ion to form sodium carbonate, commonly known as washing soda. The breakdown of the hydrogen peroxide molecule also releases energy, causing the oxygen to rapidly come out of solution as a gas, which is why you see bubbling when the reaction takes place.
The Role of Catalase
While hydrogen peroxide and baking soda will react slowly on their own, the reaction can be sped up dramatically by introducing a catalyst. Catalysts accelerate chemical reactions without being consumed in the process. One of the most effective catalysts for decomposing hydrogen peroxide is the enzyme catalase. Catalase catalyzes the breakdown of hydrogen peroxide into oxygen and water. This reaction is useful for protecting cells from oxidative damage by removing hydrogen peroxide, which can be toxic at high concentrations.
When a small amount of catalase is added to a mixture of hydrogen peroxide and baking soda, the reaction speeds up rapidly, producing fast bubbling and foam. The catalase catalyzes the breakdown of the hydrogen peroxide, while the baking soda helps to neutralize the solution as the reaction proceeds. Some common sources of catalase include potato extract, liver extract, or bottled catalase enzyme.
Practical Uses
The vigorous reaction between hydrogen peroxide, baking soda, and catalase has some interesting and practical applications:
Cleaning and Stain Removal
The oxygen bubbles produced can help lift stains and dirt from surfaces and fabrics. The mixture of hydrogen peroxide and baking soda can be used as a pre-treatment for laundry stains. It can also be used to scrub surfaces in bathrooms and kitchens.
Root Growth Stimulation
Hydrogen peroxide and baking soda can be diluted and applied to plant roots to increase root growth and development. The oxygen released helps provide more oxygen to the root zone.
Aquarium Cleaning
The reaction can be used to scrub algae from aquarium glass and decorations. The bubbles help to lift algae away.
Bath Bombs
The bubbling reaction can be encapsulated in bath bombs to provide a fizzing effect when dissolved in bath water. This provides a fun reaction and sensation.
Rockets
The rapid release of oxygen gas provides thrust for model rocket engines when the reaction takes place in an enclosed chamber.
Step-By-Step Instructions
If you want to experiment with this reaction yourself, here are step-by-step instructions:
- Gather your hydrogen peroxide and baking soda. For best results, use a 3% concentration of hydrogen peroxide. Concentrations above 10% can be dangerous and are not recommended.
- Optional: Obtain a source of the enzyme catalase. This can be from potato extract, liver extract or purchased catalase powder.
- Mix 1 teaspoon of baking soda with 1/4 cup of 3% hydrogen peroxide in a small bowl or cup.
- If using catalase, add just a small pinch of catalase powder or a few drops of potato or liver extract to the mixture.
- Stir with a spoon or small whisk to combine. The mixture will immediately start bubbling and fizzing as oxygen gas is released.
- Let the reaction proceed for 1-2 minutes. It will eventually slow down as the hydrogen peroxide is consumed.
- To speed up again, add another 1/4 tsp of baking soda.
Note that this recipe can be adjusted up or down depending on the volume of foam desired. Always perform this reaction in a well-ventilated area and avoid breathing in the fumes directly. The reaction works best at room temperature.
The Chemistry Behind It
Now that we’ve covered the reaction itself, let’s take a closer look at the chemistry behind this interesting combination of household ingredients:
Hydrogen Peroxide
– Chemical formula: H2O2
– Colorless liquid made up of water with an extra oxygen atom
– Often used as a 3% solution for disinfecting and bleaching
– Decomposes slowly over time into oxygen and water
– Breakdown accelerates rapidly in the presence of catalysts
Baking Soda
– Chemical name: Sodium bicarbonate
– Chemical formula: NaHCO3
– White powder used in cooking and as a mild abrasive
– Dissociates in water to produce sodium and bicarbonate ions
– Bicarbonate neutralizes acids and produces carbon dioxide
Catalase Enzyme
– Protein enzyme found in nearly all living organisms
– Serves to catalyze the decomposition of hydrogen peroxide into oxygen and water
– Protects cells from oxidative damage by removing hydrogen peroxide
– Very effective at speeding up hydrogen peroxide breakdown
Sodium Carbonate
– Chemical formula: Na2CO3
– Formed in the reaction when sodium bicarbonate gives up sodium and bicarbonate ions
– Also known as washing soda, used for cleaning and removing stains
The Role of Oxygen Gas
The key outcome of combining hydrogen peroxide and baking soda is the rapid release of oxygen gas. By itself, hydrogen peroxide decomposes very slowly, releasing a tiny amount of oxygen gas. The baking soda helps to destabilize the hydrogen peroxide molecule. When catalase is added, the reaction accelerates dramatically, generating a rush of oxygen bubbles.
The fast release of gas leads to foaming and bubbling as the oxygen quickly comes out of solution. This is what produces the fun foaming effects that make hydrogen peroxide and baking soda useful for demonstrations and cleaning applications.
Driving the Decomposition Reaction
While hydrogen peroxide breaks down into oxygen and water on its own, the reaction is extremely slow without a catalyst. Baking soda helps drive the decomposition by destabilizing the hydrogen peroxide molecule. The sodium ions likely interfere with the hydrogen bonding network keeping the hydrogen peroxide stable. This makes the oxygen atoms more likely to break off and be released as a gas.
Rapid Foaming with Catalase
While baking soda helps the reaction along, the addition of catalase is what really accelerates the rate of oxygen production. Catalase is an enzyme that is highly specific for breaking down hydrogen peroxide molecules as its main function. It does this extremely rapidly, causing the oxygen to be release faster than it can diffuse smoothly out of the liquid. This leads to rapid bubbling and foaming as the oxygen forms gas pockets in solution.
Uses of the Oxygen Gas
The oxygen released by the reaction has several handy uses:
- Cleaning – The bubbles help lift stains from surfaces and fabrics
- Plant growth – The extra oxygen helps stimulate root development
- Aquariums – Bubbles scrub algae off glass and decorations
- Bath bombs – Provides the fizzing effect
- Rockets – Oxygen gas provides thrust
Is the Reaction Exothermic or Endothermic?
The chemical reaction between hydrogen peroxide and baking soda is exothermic. This means it releases energy to the surroundings in the form of heat. As the hydrogen peroxide decomposes into water and oxygen, energy is liberated.
You can test whether a reaction is exothermic or endothermic based on whether the temperature increases or decreases. An exothermic reaction results in an increase in temperature. An endothermic reaction decreases in temperature.
To demonstrate the exothermic nature of the hydrogen peroxide plus baking soda reaction, you can measure the temperature of the solution before and after mixing. The temperature after mixing will be slightly higher as the ingredients interact to generate heat. This release of energy is what categorizes it as an exothermic reaction.
Signs of an Exothermic Reaction
Here are some signs that a chemical reaction is exothermic:
- Increase in temperature
- Release of heat energy
- Rapid bubbling or gas release
- Light production in some cases
The heat released by an exothermic reaction can be harnessed to do useful work like cooking, heating, or producing electricity.
Examples of Exothermic Reactions
Some other examples of exothermic reactions include:
- Vinegar + baking soda
- Water + calcium chloride
- Steel wool burning in air
- Mixing fuel and oxidizer in rockets or explosives
In contrast, examples of endothermic reactions that absorb heat include photosynthesis, evaporating water, and dissolving ammonium nitrate in water.
Safety Tips
While mixing household hydrogen peroxide and baking soda is generally safe with the right precautions, here are some tips for staying safe:
Use Dilute Hydrogen Peroxide
Avoid using hydrogen peroxide at concentrations over 10%. The 3% solution found in pharmacies is recommended. Higher concentrations can irritate skin and lungs.
Work in a Well-Ventilated Area
Perform the reaction in a well-ventilated room or outdoors. Avoid leaning directly over the mixture when combining the ingredients.
No Ingestion
Do not ingest hydrogen peroxide or the foam/bubbles produced from the reaction. Ingesting can cause irritation to the gastrointestinal tract.
Avoid Eyes
Keep the ingredients and foam away from your eyes, as it can potentially cause irritation. Wash eyes with water if exposure occurs.
Clean Up Spills
Wipe up any spilled hydrogen peroxide or wet reaction mixture promptly to prevent slips or stains.
Monitor Children
Do not allow young children to handle or work with hydrogen peroxide, as ingestion could be harmful. Supervise older children closely.
Check for Catalase Allergies
Avoid catalase from liver or potato extracts if you have related food allergies. Opt for purchased catalase enzyme instead.
Frequently Asked Questions
Why does hydrogen peroxide foam up when you add baking soda?
The foaming results from the rapid release of oxygen gas. The baking soda helps destabilize the hydrogen peroxide, while catalase speeds up the decomposition. The fast bubbling of oxygen coming out of solution causes foaming.
Is mixing hydrogen peroxide and baking soda dangerous?
The reaction between hydrogen peroxide and baking soda is not particularly dangerous with appropriate safety precautions. However, ingesting hydrogen peroxide can be harmful, so keep it away from small children. It’s also important to avoid high concentrations of hydrogen peroxide.
Does baking soda remove hydrogen peroxide from hair?
Yes, baking soda can help remove residual hydrogen peroxide from hair after bleaching. The reaction between the ingredients helps break down the peroxide into oxygen and water, eliminating it from the hair shaft.
What is the chemical reaction for hydrogen peroxide and baking soda?
The balanced chemical equation is:
2 H2O2 + NaHCO3 → O2 + H2O + Na2CO3
The hydrogen peroxide decomposes into oxygen gas and water. The sodium bicarbonate forms sodium carbonate.
Can you brush your teeth with hydrogen peroxide and baking soda?
It’s not generally recommended to brush with hydrogen peroxide, as it can damage tooth enamel with prolonged use. A small amount of baking soda mixed with water can be used occasionally to help clean and whiten teeth.
Conclusion
The combination of hydrogen peroxide and baking soda produces an impressive chemical reaction that rapidly releases oxygen gas. This exothermic reaction has many practical uses, from cleaning to stimulating plant growth. With proper safety precautions, this classic chemical reaction provides an entertaining demonstration of chemistry at work. Just be sure to carry out the experiment in a well-ventilated space and keep the foamy results away from your eyes and skin.