Not every chemical reaction takes place in a laboratory. Some happen while making breakfast, storing food or watering plants. Even the energy our body uses comes from chemical reactions. Many of these processes go unnoticed because they are part of our regular routine. The following are the examples of common chemical reactions in everyday life explain why these changes happen and what causes them.
What Is a Chemical Reaction?
A chemical reaction is a process in which one or more substances change into new substances with different properties. During this process, the original substances, called reactants, rearrange their atoms to form new substances known as products. For example, when iron comes into contact with oxygen and moisture, it forms rust. This is one of the simplest chemical reactions we can observe around us.
15 Important Chemical Reactions We See in Everyday Life
Many things we do every day involve chemical reactions, even when we don’t notice them. The following examples show how these reactions take place in food, nature, household activities and our bodies.
1. Rusting of Iron
Rusting is a chemical process in which iron reacts with oxygen and water to form hydrated iron oxides. It usually occurs when iron objects remain exposed to damp conditions for extended periods. Unlike the original metal, rust is flaky and does not protect the surface, allowing corrosion to continue.
- This reaction commonly affects iron bridges, gates, vehicles, pipes and household tools.
- Oxygen and water are essential for ordinary rusting.
- The reddish-brown rust gradually damages the iron surface.
- Chemical equation (simplified): 4Fe + 3O₂ + 6H₂O → 4Fe(OH)₃.
2. Burning of a Candle
When a candle is lit, the heat from the flame melts the wax near the wick. The liquid wax moves up the wick and turns into vapour, which reacts with oxygen in the air and produces a flame. This process is called combustion. It releases heat and light, which is why a burning candle can be used as a source of light.
- Burning candles during power cuts, birthday celebrations and religious occasions are common examples.
- Wax vapour reacts with oxygen in the surrounding air.
- The main products of complete combustion are carbon dioxide and water vapour.
- Chemical equation (for paraffin wax, approximated as C₂₅H₅₂): 2C₂₅H₅₂ + 77O₂ → 50CO₂ + 52H₂O.
3. Photosynthesis in Plants
Plants prepare their own food through a process called photosynthesis. Green leaves absorb sunlight with the help of chlorophyll and use it to convert water and carbon dioxide into glucose. Oxygen is released during this process. This reaction helps plants grow and also supplies oxygen to the atmosphere.
- Green plants, trees, grass and garden plants carry out photosynthesis.
- Sunlight, water, carbon dioxide and chlorophyll are needed for this process.
- Glucose is produced as food, and oxygen is released.
- Chemical equation: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (in the presence of light and chlorophyll).
4. Cellular Respiration
Every time we walk, run, work or even sleep, our body needs energy to function. Cells obtain this energy by breaking down glucose with the help of oxygen. This process is called cellular respiration. It produces carbon dioxide, water and energy that the body uses for its daily activities.
- It takes place in the cells of humans, animals and many other living organisms.
- Glucose from digested food and oxygen from breathing are used in the process.
- Carbon dioxide and water are formed, along with energy in the form of ATP.
- Chemical equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy (ATP).
5. Fermentation of Bread Dough
Have you noticed how bread dough becomes bigger and softer after being left to rest? This happens because of yeast, a tiny living organism added to the dough. Yeast feeds on the sugars present in the flour and converts them into carbon dioxide and alcohol. The carbon dioxide gets trapped in the dough, making it rise before baking.
- Yeast is commonly used in making bread, buns, pizza bases and other baked foods.
- Yeast breaks down sugars in the absence of oxygen during fermentation.
- Carbon dioxide makes the dough expand, while alcohol evaporates during baking.
- Chemical equation: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂.
6. Formation of Curd from Milk
Milk left in a warm place for several hours can turn into curd. This happens because lactic acid bacteria convert the natural sugar in milk, called lactose, into lactic acid. The acid changes the milk proteins, making the milk thicker and giving curd its slightly sour taste.
- This process is commonly used to prepare curd and yoghurt at home.
- Lactobacillus bacteria help convert lactose into lactic acid.
- Lactic acid causes milk proteins to coagulate and form curd.
- Chemical reaction: Lactose + water → glucose + galactose, followed by fermentation of these sugars into lactic acid.
7. Cooking an Egg
A raw egg has a transparent, runny egg white and a soft yolk. When the egg is heated during cooking, the proteins inside it change their structure and form a solid network. This process is called protein denaturation and coagulation. Once cooked, the egg does not return to its original raw form even after cooling.
- Boiling, frying and scrambling eggs are common examples of this chemical change.
- Heat causes the proteins in egg white and yolk to unfold and join together.
- The transparent egg white becomes white and firm during cooking.
- This is a chemical change involving protein denaturation rather than a single simple chemical equation.
8. Caramelization of Sugar
When sugar is heated in a pan, it gradually melts and changes from white crystals into a golden or dark brown liquid. This change is called caramelization. During heating, sugar molecules break down and form new compounds that give caramel its characteristic colour, smell and taste. It is commonly used in preparing sweets and desserts.
- Caramel is used in cakes, puddings, sweets and dessert toppings.
- Heating sugar to a sufficiently high temperature triggers caramelization.
- New compounds formed during the process produce its brown colour and distinctive flavour.
- Caramelization involves several chemical reactions, so it does not have one simple balanced chemical equation.
9. Baking Soda and Vinegar Reaction
When baking soda is mixed with vinegar, the mixture starts bubbling and producing foam. This happens because baking soda (sodium bicarbonate) reacts with acetic acid present in vinegar and releases carbon dioxide gas. The bubbles we see are the carbon dioxide escaping from the mixture. This reaction is also commonly used in simple science experiments at home and in classrooms.
- Mixing baking soda and vinegar in a glass or bowl is a common example of this reaction.
- Sodium bicarbonate reacts with acetic acid to produce carbon dioxide.
- The visible bubbles and foam are caused by the released gas.
- Chemical equation: NaHCO₃ + CH₃COOH → CH₃COONa + H₂O + CO₂.
10. Digestion of Food
After eating a meal, the food passes through the digestive system, where it is broken down into smaller substances that the body can absorb. Digestive juices and enzymes help break down carbohydrates, proteins and fats into simpler molecules. These nutrients are then absorbed and used by the body for energy, growth and repair.
- Digestion takes place in different parts of the digestive system, including the mouth, stomach and small intestine.
- Amylase breaks down starch, proteases break down proteins, and lipase helps digest fats.
- Carbohydrates are broken down into simple sugars, proteins into amino acids and fats into fatty acids and monoglycerides.
- Digestion involves several enzyme-controlled chemical reactions rather than one single chemical equation.
11. Tarnishing of Silver
Silver jewellery, spoons and other decorative items may gradually develop a dark coating when kept unused for a long time. This change is called tarnishing. It occurs when silver reacts with small amounts of sulfur-containing compounds in the air, forming silver sulfide on its surface. The dark layer can be removed by cleaning or polishing the silver object.
- Silver jewellery, coins, utensils and decorative items often develop tarnish.
- Silver reacts with sulfur compounds, particularly hydrogen sulfide present in the air.
- A black or dark grey layer of silver sulfide forms on the surface.
- Chemical equation: 2Ag + H₂S → Ag₂S + H₂.
12. Neutralization of Stomach Acid
The stomach produces hydrochloric acid to help digest food and protect the body from harmful microorganisms. Sometimes, excess acid can cause heartburn or acidity. Antacids help relieve this discomfort by reacting with the stomach acid and reducing its acidity. This process is known as a neutralization reaction.
- Antacid tablets and liquid antacids are commonly used to relieve excess stomach acid.
- Basic substances such as magnesium hydroxide react with hydrochloric acid.
- The reaction produces a salt and water, reducing the acidity of the stomach contents.
- Chemical equation: Mg(OH)₂ + 2HCl → MgCl₂ + 2H₂O.
13. Browning of Cut Fruits
Have you noticed that a freshly cut apple turns brown when left on a plate for some time? This happens because an enzyme called polyphenol oxidase reacts with certain compounds in the fruit when exposed to oxygen in the air. The reaction produces brown-coloured pigments on the cut surface. The same change can also be seen in fruits such as bananas, pears and avocados.
- Cut apples, bananas, pears and avocados commonly show this change.
- Exposure to oxygen activates an enzyme-driven oxidation process.
- Brown pigments called melanins develop on the fruit surface.
- Lemon juice can slow down browning because its acidity and vitamin C help reduce the reaction.
14. Chemical Reactions in Batteries
A battery powers many everyday devices, including wall clocks, remote controls, toys and mobile phones. It works through chemical reactions that take place between different materials inside the battery. These reactions transfer electrons through an external circuit, producing electrical energy that allows the connected device to operate.
- Remote controls, flashlights, watches, toys and mobile phones use batteries.
- Chemical reactions take place between the electrodes and the electrolyte inside a battery.
- These reactions convert stored chemical energy into electrical energy.
- In a typical alkaline battery, zinc is oxidised and manganese dioxide is reduced during discharge. The exact chemical equation depends on the battery type.
15. Fireworks and Combustion Reactions
Fireworks produce bright colours, flashes of light and loud sounds during celebrations. These effects are created by rapid chemical reactions that take place when fireworks are ignited. The burning of fuel releases heat and light, while different metal compounds produce different colours in the sky. For example, strontium compounds create red colours, while copper compounds produce blue shades.
- Fireworks are commonly seen during festivals, public celebrations and special events.
- Combustion reactions release heat, light and gases.
- Different metal salts produce different colours when heated.
- For example, strontium compounds produce red, barium compounds produce green and copper compounds produce blue colours.
Why Are Chemical Reactions Important in Everyday Life?
Chemical reactions are responsible for many processes that make everyday life possible. From the food we eat to the energy our bodies use, these reactions play an important role in our daily activities. Some of their key uses and benefits include:
- Food preparation: Chemical reactions change the taste, colour, texture and smell of food during cooking and baking.
- Energy production: Cellular respiration breaks down glucose and releases energy that our bodies need to function.
- Plant growth: Photosynthesis helps plants prepare food and release oxygen into the atmosphere.
- Food preservation: Processes such as fermentation help prepare and preserve foods like curd, yoghurt and certain pickles.
- Household cleaning: Chemical reactions in cleaning products help remove stains, grease and other unwanted substances.
- Electricity generation: Chemical reactions inside batteries provide electrical energy to operate many devices.
- Health and digestion: Chemical reactions help break down food, support body functions and allow certain medicines to work.
Conclusion
Chemical reactions are not limited to science laboratories or school experiments. They happen in our kitchens, gardens, homes and bodies every day. From cooking an egg and making curd to rusting iron and producing energy, each reaction has a reason behind it. Learning about these examples helps us understand the science behind ordinary activities and see how closely chemistry is connected to our daily lives.
