Chemical Changes in Everyday Life

Chemical changes are an essential part of our daily lives, occurring all around us, often without us even realising it. From the reactions happening in our bodies to those in our homes, kitchens, and even laboratories, chemical changes are constantly at work transforming substances into new forms. These changes are marked by the formation of new substances with different properties and compositions. 

Natural chemical changes are chemical reactions or processes that occur in nature without human intervention. These changes are crucial for maintaining the balance of ecosystems, supporting life on Earth, and driving the natural cycles of matter and energy. Unlike man-made chemical changes, natural chemical changes occur spontaneously due to environmental conditions or biological activity.

1. Respiration

Respiration is a continuous biological process that takes place in the cells of our body. During respiration, we inhale air, which provides our body with oxygen, and we exhale carbon dioxide and water vapour.

• Inside our body, a key chemical reaction occurs where glucose (a type of sugar) reacts with oxygen from the air we breathe.
• This reaction releases energy, which our body uses for various activities, and produces two main by-products: carbon dioxide and water.

Word Equation,

Glucose + Oxygen → Carbon Dioxide + Water

Chemical Equation,

C_6​H_12​O_6​+6O₂​→6CO_2​+6H_2​O

2. Photosynthesis

Photosynthesis is a natural process performed by green plants in the presence of sunlight. During this process, plants use sunlight to convert carbon dioxide and water into glucose (a type of sugar) and oxygen. 

Working,

• Carbon dioxide (CO₂) from the air enters the leaves of plants.
• Water (H₂O) is absorbed by the plant’s roots from the soil.
• Sunlight provides the energy needed for the chemical reaction.
• Chlorophyll, a green pigment in plants, captures sunlight to facilitate the reaction.

Word Equation,

Carbon dioxide + Water + Sunlight → Glucose + Oxygen

Chemical Equation,

6CO_2​+6H₂​O + sunlight→C₆​H₁₂​O₆​+6O₂​

Man-made chemical changes are chemical reactions or processes intentionally initiated by humans to fulfil specific needs in everyday life. These changes often result in the formation of new substances with useful properties, making them an essential part of modern living. From producing energy to cleaning, preserving food, and creating refreshing drinks, man-made chemical changes have a wide range of applications.

• For example, a simple and widely enjoyed example is the creation of the cold drink called "soda lemon."
• This drink involves a chemical reaction between baking soda (sodium bicarbonate) and lemon juice (citric acid), which produces carbon dioxide gas (CO₂).
• The bubbling fizz that forms not only makes the drink refreshing but also exemplifies how chemical reactions can be used for enjoyment and practicality.

1. Combustion of Fuels

Combustion is a chemical change where a substance reacts with oxygen to produce energy in the form of heat and light. It is an irreversible and fast reaction that is commonly used in our daily lives, such as for cooking, heating, and running vehicles.

Working,

• Fuels such as wood, coal, petrol, or cooking gas contain carbon as a primary component.
• During combustion, these fuels react with oxygen (O₂) from the air.
• The reaction produces carbon dioxide (CO₂) as the main product and releases energy in the form of heat and light.
• Byproducts like water vapour, soot, or other gases may also form, depending on the type of fuel.
• Combustion is controlled by humans for energy use, making it a man-made chemical change.

Word Equation,

Carbon + Oxygen → Carbon dioxide

Chemical Equation,

C + O₂ → CO₂

2. Cleaning Shahabad Tile with Hydrochloric Acid

Shahabad tiles are primarily made of calcium carbonate (CaCO₃). When you clean these tiles using dilute hydrochloric acid (HCl), a chemical reaction occurs between the calcium carbonate in the tiles and the hydrochloric acid. This reaction causes the upper layer of the tile to dissolve slightly, producing three distinct products:

• Calcium chloride (CaCl₂) is a water-soluble salt that gets washed away during cleaning.
• Carbon dioxide (CO₂) is a gas that escapes into the air, visible as bubbles during the reaction.
• Water (H₂O) mixes with the water used for cleaning.

Word Equation,

Calcium carbonate + Hydrochloric acid → Calcium chloride + Carbon dioxide + Water

Chemical Equation,

$$\text{CaCO₃ (s)}+2\text{HCl (aq)}\to \text{CaCl₂ (aq)}+\text{CO₂ (g)}+\text{H₂O (l)}$$

3. Softening of Hard Water

Hard water contains dissolved salts of calcium and magnesium, such as magnesium chloride (MgCl₂) and magnesium sulphate (MgSO₄). These salts make water hard because they prevent soap from forming a lather. To soften hard water, a solution of washing soda (sodium carbonate, Na₂CO₃) is added, which reacts with the magnesium salts to form insoluble magnesium carbonate (MgCO₃) and a soluble by-product, sodium chloride (NaCl) or sodium sulphate (Na₂SO₄).

Word Equation for Magnesium Salts,

Magnesium chloride + Sodium carbonate → Magnesium carbonate + Sodium chloride

Magnesium sulfate + Sodium carbonate → Magnesium carbonate + Sodium sulfate

Chemical Equations for Magnesium Salts,

$$\text{MgCl₂ + Na₂CO₃ → MgCO₃ + 2NaCl}$$

$$\text{MgSO₄ + Na₂CO₃ → MgCO₃ + Na₂SO₄}$$

1. Aim: To observe the reaction between carbon dioxide and lime water, forming calcium carbonate as a precipitate.

2. Requirements: freshly prepared lime water (calcium hydroxide solution), test tube, and blow tube.

3. Procedure

• Pour some freshly prepared lime water into a clean test tube.
• Use a blow tube to blow air into the lime water continuously.
• Observe the changes that occur.

4. Observations

• Initially, the colourless lime water turns milky after blowing air into it for some time.
• A white, insoluble solid (calcium carbonate) forms and settles at the bottom of the test tube.

5. Explanation: The milky appearance indicates that the gas being blown in is carbon dioxide.

Chemical Reaction:

Word Equation,

Carbon dioxide + Calcium hydroxide → Calcium carbonate + Water

Chemical Equation,

CO₂ + Ca(OH)₂ → CaCO₃ + H₂O