Physical and Chemical Changes: Chemistry for Kids - FreeSchool

Summary

In this educational video, viewers learn about the two main types of changes in chemistry: physical and chemical changes. Physical changes, such as cutting cloth or dissolving sugar in water, alter the appearance or state of a substance without creating a new one. Chemical changes, like baking or burning wood, result in new substances and are irreversible. The video provides clear examples, such as the melting of ice, rusting metal, and food digestion, and explains how to distinguish between physical and chemical changes by observing clues like color change, odor, gas release, and heat absorption or release.

Takeaways

• 😀 Physical changes alter the size, shape, or form of a substance but do not create a new substance.
• 😀 A classic example of a physical change is cutting a piece of cloth, which changes its shape but remains the same material.
• 😀 Changing the state of matter is a physical change. For example, ice melting into water or water evaporating into steam.
• 😀 Physical changes can often be undone. For instance, liquid water can be frozen back into ice.
• 😀 Dissolving sugar in water is a physical change because it doesn’t create a new substance, and the sugar can be separated from the water.
• 😀 Mixing ingredients like butter, sugar, flour, and eggs is a physical change because no new substances are created until heat is added.
• 😀 Chemical changes occur when particles of substances are rearranged to form new substances.
• 😀 Baking is an example of a chemical change, as heat causes a mixture to change color, produce gases, and become a new substance (like a cake).
• 😀 Burning wood is a chemical change because it transforms into ash, releasing gases, heat, and light in the process.
• 😀 Chemical changes are often irreversible, meaning you cannot undo the change, like unbaking a cake or unburning wood.

Q & A

What are the two main types of changes in chemistry?

The two main types of changes in chemistry are physical changes and chemical changes.

What is a physical change?

A physical change is a change in the physical properties of a substance, such as size, shape, or state, without creating a new substance.

Can you give an example of a physical change?

An example of a physical change is cutting a piece of cloth. It changes shape and size, but it’s still cloth, which is the same substance.

How do we know a change in matter is physical?

We know a change is physical if the substance remains the same, even though it may look different or have a different form. For instance, water changing from ice to liquid and back is a physical change.

What happens to water when it changes states, and is this a physical change?

When water changes states, like from ice to water or water to steam, it is still water. These changes are physical because they do not create a new substance and are reversible.

What is a chemical change?

A chemical change occurs when substances combine or break apart, forming a new substance with different properties, and these changes are usually irreversible.

What is an example of a chemical change?

An example of a chemical change is baking a cake. The ingredients change into a new substance (cake), and the change cannot be undone.

What are some signs that a chemical change has occurred?

Signs of a chemical change include a change in color, the release of gases (like smoke), the production of light or heat, and sometimes the formation of a new odor.

Why can’t you unbake a cake?

You can’t unbake a cake because the chemical reaction that occurs during baking forms new substances, making it an irreversible chemical change.

What is the difference between physical and chemical changes in terms of reversibility?

Physical changes are often reversible, such as freezing and melting water, while chemical changes are usually irreversible, like burning wood or baking a cake.