Physical and Chemical Changes
Grade 7 Science Worksheets
Every substance has a certain property like –
Physical Properties:Â A physical property of a substance means its shape, size and physical state of a substance. For example: when water boils it turns to vapor but its still water in gaseous form. Although its state changes.
Schedule a Free session to clear worksheet doubts
No credit card required, no obligation to purchase.
Just schedule a FREE Sessions to meet a tutor and get help on any topic you want!
Chemical Properties:Â The basic inherent nature of a substance is known as chemical properties. For example mold on a piece of bread. Once yeast is formed, we would never get the original bread form.
All such changes can be separated into two types – Physical and Chemical.
What are the physical changes?
- Physical changes are the changes in physical properties which does not involve new produce of substances.  Changes are very much reversible like – melting of ice.
Nature of a Physical change –
- Physical changes are mostly reversible
- Physical properties of a substance only changes not its chemical properties
- New substance is not created in this process
Chemical Changes
Chemical changes are permanent changes which happen to the original substances making it lose its inherent properties. Changes like these are irreversible like – rusting of iron, burning of wood.
Credit:Â https://pixabay.com/en/chain-rust-iron-metal-macro-rusty-566778/
Nature of a Chemical change :
- A chemical change cannot be brought to original by physical methods. Chemical properties of substance change
- In a chemical change, new substances are formed
- Chemical changes are not reversible
- The chemical composition and properties of a substance changes during a chemical chnage
- Gas evolves
Results of Chemical Change :
- Change in smell.
- Gas evolves.
- Heat is produced.
- Sound is produced.
- Change in color.Â
What is an example of a physical change?
Heating of water:Â When water is heated no new substance is formed. No change in color or smell.
Paper folding:Â Â A paper can be folded or refolded and unfolded again hence it is an example of physical change. Here, no new substance is formed in this. So, it is a physical change.Â
Molding of clay:Â Clay when molded. Shape changes, its size changes but no gas evolves, or no new substance is formed and no smell is produced.Â
Cutting of wood:Â When we cut a piece of wood we get more number of wood pieces but there is no new substance produced, no gas evolution and no change in the property of wood.
Crushing paper:Â Here, again no new substance is formed. Can be brought back to its original form. No gas is released.
Mixing salt in water:Â Water and salt can be easily separated. This is a physical change because no new substance is formed and the chemical properties of substances involved are completely intact.Â
Chemical Changes
When properties of substance change and new substances are formed is called chemical changes. Sometimes chemical changes are irreversible. In chemical change  where it can be reversed chemical properties of substance alter and a new substance is formed.Â
What is an example of a chemical change?
Burning of anything like paper, wood, fuel etc. When a substance burns, many new substances are formed like ash and carbon dioxide is formed. Â A burnt substance cannot be turned to the original form by any chance since ash is what remains.
Hence, burning of a substance is an irreversible chemical change.
Wax melting:Â This is a reversible change because wax solidifies in room temperature. There is no new substance formed. No gas emissions and chemical property of wax does not change.
Cooking vegetables: This involves baking or frying of food which then cannot be brought back to the original self. Smell is produced. It’s a new substance altogether.
Digestion is an example of chemical change. New substances are produced. Food is broken down. Energy is released, cannot be converted to food again.
Weathering of rocks:Â Rock formation involves immense heat and pressure. Running water on them, intense wind and expansion as a result of heat. These changes are irreversible.
Learn more about Physical and Chemical Changes and other important topics with 7th Grade Science Tutoring at eTutorWorld. Our expert science tutors break down the topics through interactive one-to-one sessions. We also offer the advantage of customized lesson plans, flexible schedules and convenience of learning from home.
Personalized Online Tutoring from eTutorWorld
eTutorWorld offers affordable one-on-one live tutoring over the web for Grades K-12, Test Prep help for Standardized tests like SCAT, CogAT, MAP, SSAT, SAT, ACT, ISEE and AP. You may schedule online tutoring lessons at your personal scheduled times, all with a Money-Back Guarantee. The first one-on-one online tutoring lesson is always FREE, no purchase obligation, no credit card required.
For answers/solutions to any question or to learn concepts, take a FREE TRIAL Session.
No credit card required, no obligation to purchase.
Just schedule a FREE Sessions to meet a tutor and get help on any topic you want!
Check Point
I. State True or False –
- Melting of wax is a chemical change.
- A physical change involves formation of new products.
- A chemical change is irreversible.
- Burning of paper is a chemical change.
- Chemical change cannot be reversed by simple physical means.
Answer Key
- False
- False
- True
- True
- True
Learn more about Scientific Method and other important topics with 7th Grade Science Tutoring at eTutorWorld. Our expert science tutors break down the topics through interactive one-to-one sessions. We also offer the advantage of customized lesson plans, flexible schedules and convenience of learning from home.
Pricing for Online Tutoring
Tutoring Package | Validity | Grade (1-12), College |
---|---|---|
5 sessions | 1 Month | $124 |
1 session | 1 Month | $25 |
10 sessions | 3 months | $239 |
15 sessions | 3 months | $354 |
20 sessions | 4 months | $449 |
50 sessions | 6 months | $1049 |
100 sessions | 12 months | $2049 |
6th Grade Free Worksheets
- Elements & Compounds
- Solar Energy
- Photosynthesis
- Digestive System
- Electricity and Magnetism
- Law of conservation of energy
- Law of Conservation of Mass
- Periodic table
- Properties of Matter
- Waves
- Energy Resources
- Weather and Climate
- Immune, Circulatory and Digestive Systems
- Organs in Multi-cellular Organisms
- Sedimentary, Igneous, and Metamorphic Rocks
- Structure of the Earth
- Physical and Chemical Changes
- Scientific Method
- Cycles in Nature
- Environmental Science
- Renewable and Non-renewable energy Resources
- Characteristics of Living Organisms
- Life Science
- Earth and Space Science
- Solar Eclipse
- Heat Technology
- Newton’s Laws of Motions
- Physical Science
- Tools, Measurement and SI Units
- Earth Atmosphere
- Interactions of Living things
- The Earth Ecosystem
- Organelles in Plant and Animal cells
- Layers of the Earth