Grade 6
  1. Introduction to Chemistry  1.1. What is Chemistry?  1.2. Importance of chemistry in daily life  1.3. Branches of chemistry  1.4. Safety rules in chemistry laboratory  1.5. Common Laboratory Equipment and Their Uses
  2. Matter and its states  2.1. Definition of Matter  2.2. Properties of matter  2.3. States of matter  2.4. Solid state  2.5. Fluid state  2.6. Gaseous state  2.7. Plasma state  2.8. Changes in the states of matter  2.9. Melting and freezing  2.10. Evaporation and Condensation  2.11. Sublimation  2.12. Deposit
  3. Physical and chemical changes  3.1. Definition of Physical Change  3.2. Examples of physical change  3.3. Definition of Chemical Change  3.4. Examples of chemical change  3.5. Difference Between Physical and Chemical Changes  3.6. Indicators of Chemical Change
  4. Elements, Compounds, and Mixtures  4.1. Definition of the element  4.2. Classification of elements  4.3. Metals  4.4. Non metallic  4.5. Metalloids  4.6. Noble gases  4.7. Definition of compound  4.8. Properties of Compounds  4.9. Definition of Mixture  4.10. Types of mixtures  4.11. Homogeneous mixture  4.12. Heterogeneous mixtures
  5. Separation of mixtures  5.1. The need for isolation  5.2. Separation methods  5.3. Handpicking and winnowing  5.4. Filtration  5.5. Sedimentation and decantation  5.6. Evaporation  5.7. Crystallization  5.8. Distillation  5.9. Magnetic Separation  5.10. Chromatography
  6. Air and its composition  6.1. Components of air  6.2. Importance of Oxygen  6.3. The importance of nitrogen in the air and its composition  6.4. Carbon dioxide in the atmosphere  6.5. The role of water vapor and other gases in air and its composition  6.6. Properties of Air  6.7. Uses of air  6.8. Air pollution and its effects
  7. Water and its properties  7.1. Importance of Water  7.2. Sources of water  7.3. Properties of water  7.4. Water as the universal solvent  7.5. Water Purification  7.6. Water purification methods (boiling, filtration, chlorination)  7.7. Water cycle  7.8. Water conservation  7.9. Water pollution and its effects
  8. Acids, Bases and Salts  8.1. Definition of Acid  8.2. Properties of Acids  8.3. Examples of Acids  8.4. Definition of Bases  8.5. Properties of bases  8.6. Examples of Bases  8.7. Definition of Salt  8.8. Neutralization reaction  8.9. pH Scale and Indicators  8.10. Uses of Acids, Bases and Salts
  9. Introduction to the Periodic Table  9.1. History of the Periodic Table  9.2. Arrangement of elements in the periodic table  9.3. Groups and periods  9.4. Importance of periodic table  9.5. First 10 elements and their symbols
  10. Metals and Nonmetals  10.1. Properties of Metals  10.2. Properties of Non-Metals  10.3. Difference Between Metals and Nonmetals  10.4. Uses of metals and nonmetals  10.5. Corrosion of metals and its prevention
  11. chemical reactions  11.1. Introduction to Chemical Reactions  11.2. Types of Chemical Reactions  11.3. combustion reaction  11.4. Oxidation and Reduction  11.5. Simple chemical equations  11.6. Rusting of iron
  12. Fuel and energy  12.1. Types of fuel  12.2. Fossil fuels  12.3. Renewable and non-renewable sources of energy  12.4. Energy Conservation  12.5. Alternative sources of energy (solar, wind, hydropower)
  13. Plastic and fiber  13.1. Natural and synthetic fibers  13.2. Properties of plastics  13.3. Advantages and disadvantages of plastic  13.4. Recycling of plastic  13.5. Biodegradable and non-biodegradable materials

Grade 6 → Physical and chemical changes ↓


Indicators of Chemical Change


Chemistry is all around us, even if we don't notice it. From cooking to lighting a match, chemical changes are happening every day. In grade 6 chemistry, we learn about physical and chemical changes, and more specifically, how to detect when a chemical change has occurred. In this lesson, we will explore the different indicators of chemical change, using examples and simple explanations to help us better understand these concepts.

What is a chemical change?

A chemical change occurs when substances combine or break down to form new substances. This means that the original substances, called reactants, change into new substances, called products. This change involves the formation or breaking of bonds between atoms and results in a new substance with different properties.

Difference between physical and chemical change

Before we discuss the indicators of chemical change, it is important to know the difference between physical and chemical changes:

  • Physical changes are changes in the state or appearance of a substance that do not change its chemical composition. Examples include ice melting, paper tearing into pieces, and sugar dissolving in water.
  • On the other hand, chemical changes result in the formation of new substances. It involves changes at the molecular level. Examples include burning wood, rusting of iron, and baking a cake.

Indicators of chemical change

There are a number of indicators that can help us identify whether a chemical change has occurred:

1. Color change

One of the most obvious signs of a chemical change is a change in color. This indicates that a new substance with a different color has formed.

Example: If you cut an apple and leave it in the air, its flesh will turn brown. This happens because the substances present in the apple react with the oxygen present in the air to form new compounds that change the color of the apple.

Brown applefresh apples

2. Production of gas

Another sign of a chemical change is the production of gas. This can often be seen as bubbles forming in the liquid.

Example: When you mix baking soda ( NaHCO 3 ) with vinegar ( CH 3 COOH ), it creates carbon dioxide gas ( CO 2 ). The gas forms bubbles, which is a clear sign that a chemical change has occurred.

BubbleVinegar + Baking Soda

3. Formation of precipitate

Chemical changes can also be identified by the formation of a solid substance from a liquid solution. This solid substance is called a precipitate.

Example: Mixing a solution of sodium chloride ( NaCl ) with silver nitrate ( AgNO 3 ) forms a solid called silver chloride ( AgCl ), which is a precipitate.

Sediment2. NaCl + 2.5 MgO3

4. Changes in temperature

A change in temperature can also indicate a chemical change. Some reactions release heat (exothermic), while others absorb heat (endothermic).

Example: When you mix cement with water to make concrete, the reaction releases heat, which is an exothermic change.

The heat continuesCement + water

5. Change in smell

The appearance of a new odor or the disappearance of an odor can be a sign of a chemical change. This shows that new substances with different odors have been formed.

Example: Spoiled milk smells sour because bacteria convert lactose into lactic acid. This change in smell is an indication of a chemical change.

spoiled milk

Conclusion

In short, chemical changes are the changes that result in the formation of new substances. These changes can be identified through several indicators such as colour change, production of gas, formation of precipitate, change in temperature and change in odour. Understanding these indicators not only helps in identifying chemical changes around us but also strengthens the foundation for further studies in chemistry.


Grade 6 → 3.6


U
username
0%
completed in Grade 6

← Prev (3.5)
Difference Between Physical and Chemical Changes
Next (4) →
Elements, Compounds, and Mixtures

Comments 



Indicators of Chemical Change

https://www.chemistryelite.com/g6/3.6?ceal=en