Chapter 11 Chemical Changes Flashcards

Flashcards for reviewing chemical changes, reactions, and related concepts.

What is a chemical change?

A change in which one or more new substances are formed.

What is a physical change?

A change in which no new substances are formed.

What are reactants?

Substances that react with each other in a chemical reaction.

What are products?

The new substances formed in a chemical reaction.

What does a word equation represent?

A chemical reaction using the names of the reactants and products.

What happens to atoms during a chemical reaction?

Atoms rearrange themselves and combine chemically to form products; atoms are neither created nor destroyed.

What is combustion?

A chemical reaction in which a substance is heated in the presence of oxygen to form one or more new substances.

What is thermal decomposition?

The process in which a substance breaks down into two or more simpler substances upon heating.

What is oxidation?

A chemical change in which a substance gains oxygen.

What is formed when an acid is mixed with an alkali?

Salt and water (neutralisation reaction).

Give three properties of acids.

Sour taste, turns blue litmus paper red, dissolves in water to form solutions which conduct electricity.

Give three properties of alkalis.

Soapy feel, bitter taste, turns red litmus paper blue, conducts electricity.

What are the products of a reaction between acid and a reactive metal?

Salt and hydrogen gas.

What are the products of a reaction between acid and carbonate?

Salt, carbon dioxide, and water.

How to test for hydrogen gas?

Place a lighted splint at the mouth of the test tube. Hydrogen gas extinguishes the flame with a ‘pop’ sound.

How to test for carbon dioxide gas?

Bubble the gas through limewater. Carbon dioxide forms a white precipitate with limewater.

What is the pH range for acids?

0 to less than 7.

What is the pH range for alkalis?

More than 7 to 14.

What is the pH of a neutral solution?

7

How does litmus paper react to acids?

Blue litmus paper turns red, red litmus paper remains red.

How does litmus paper react to alkalis?

Red litmus paper turns blue, blue litmus paper remains blue.

Give three applications of neutralisation.

Antacids neutralize stomach acid, toothpaste neutralizes acid in the mouth, calcium carbonate controls soil pH.

Name five factors that can cause chemical changes to occur.

Mixing, heating, exposure to light, interaction with oxygen, using an electric current.

Give three benefits of chemical reactions.

Cooking, respiration, photosynthesis.

Give three harmful effects caused by chemical reactions

Rusting, decay, acidification of oceans, combustion of fuels.