Physical and Chemical Changes in Matter

The video tutorial explores the differences between physical and chemical changes, emphasizing the conservation of mass. It explains how physical changes involve changes in state or phase without forming new substances, while chemical changes result in new compounds through reactions. The tutorial includes examples, such as the sublimation of dry ice and the combustion of hydrogen, and demonstrates balancing chemical equations. It concludes with a discussion on the importance of understanding these concepts for solving past paper questions.

Which of the following is an example of a physical change?

• Baking a cake

• Melting ice

• Rusting iron

• Burning wood

What happens to the atoms during a chemical change?

• They disappear

• They remain unchanged

• They rearrange to form new substances

• They are destroyed

In a physical change, what is conserved?

• Only the number of atoms

• Mass, number of atoms, and number of molecules

• Only the number of molecules

• Only mass

What type of bonding occurs between magnesium and oxygen?

• Hydrogen bonding

• Covalent bonding

• Metallic bonding

• Ionic bonding

How is the law of conservation of mass demonstrated in a chemical reaction?

• By creating new atoms

• By destroying old atoms

• By ensuring the mass of reactants equals the mass of products

• By changing the number of molecules

What is the charge of magnesium in magnesium oxide?

• -2

• -1

• +2

• +1

What is sublimation?

• A phase change from gas to liquid

• A phase change from solid to gas

• A phase change from liquid to gas

• A phase change from solid to liquid

Which phase change skips the liquid phase?

• Condensation

• Melting

• Freezing

• Sublimation

What does the 's' in CO2(s) represent?

• Sublimation

• Solution

• Solid

• Suspension

What is the main difference between physical and chemical changes?

• Physical changes create new substances

• Chemical changes do not involve energy

• Physical changes do not form new substances

• Chemical changes are reversible