Chemistry Physical & Chemical Changes Part 3 (Chemical Change) Class 7 VII

TL;DR

Chemical changes involve a change in the chemical composition of a substance, resulting in the formation of a new substance that is often irreversible.

Transcript

hello friends this video on physical and chemical changes part three is brought to you by exam for your calm no more fear from exam so now that we have discussed about physical change let us look at chemical change so chemical change the name itself suggests to the head we will see some changes in the chemical composition of the substance secure su... Read More

Key Insights

• 💱 Chemical changes involve a change in the chemical composition of a substance and are often irreversible.
• ♻️ Rusting is an example of a chemical change, where iron reacts with water and oxygen to form iron oxide.
• 🍳 Cooking an egg involves a chemical change, as heat alters the protein structure and the chemical composition of the egg.
• 🍌 Spoiling of fruits and vegetables is a chemical change caused by the growth of microorganisms and the chemical transformation of the substances.
• 💱 Baking a cake involves a chemical change, with the action of baking powder and heat causing the release of carbon dioxide and changes in the protein structure.
• 👶 Chemical changes can result in the formation of new substances with different properties.
• 💱 Chemical changes can be observed through changes in appearance, texture, and chemical properties.

Questions & Answers

Q: What is a chemical change?

A chemical change refers to a process in which the chemical composition of a substance is altered, resulting in the formation of a new substance. It is often irreversible.

Q: Why is rusting considered a chemical change?

Rusting is considered a chemical change because it involves the reaction of iron with water and oxygen, resulting in the formation of a new chemical substance called iron oxide. The rust cannot be reversed back to the original iron.

Q: How does cooking an egg involve a chemical change?

Cooking an egg involves a chemical change because heat alters the chemical composition of the egg, causing the liquid egg white to solidify and the protein molecules to undergo structural changes. This results in the formation of a new substance with different properties.

Q: Why do fruits and vegetables spoil?

Fruits and vegetables spoil due to the action of microorganisms such as bacteria and fungi. When these microorganisms feed on the fruits or vegetables, they chemically transform them, resulting in a change in their composition and appearance. This change is irreversible.

Summary & Key Takeaways

• Chemical changes involve a change in the chemical composition of a substance, not just a change in appearance.

• Examples of chemical changes include the rusting of iron, cooking an egg, and the spoiling of fruits and vegetables.

• During chemical changes, the chemical composition of a substance is altered due to various factors such as heat or the action of microorganisms.