Unit B Section 4.1

Question 1

What is a chemical reaction?

Answer 1

• A chemical reaction takes place when two or more substances combine to form new substances.
• A chemical change in a substance results from a chemical reaction.

-occur because some substances react with each other
when they come into contact

Question 2

What are the explosive chemical airbags contain>

Answer 2

sodium azide (NaN3(s))

When the vehicle is in a collision, the sodium azide reacts and forms large volumes of nitrogen gas
and sodium

Question 3

What are reactants?

Answer 3

The materials at the start of a reaction are called reactants.

Question 4

What are products?

Answer 4

The new materials produced by the reaction are called

products.

Question 5

Give an example of reactants >product

Answer 5

The burning wood undergoes a combustion reaction. In this case, the reactants, or substances being combined in the reaction, are wood and oxygen.

the products are carbon dioxide and water, formed while energy is released.

Question 6

What should a chemical equation look like?

Answer 6

in such equations, the reactants always appear to
the left of the arrow and the products to the right.

wood + oxygen → carbon dioxide + water + energy released

Question 7

What is evidence for a chemical reaction?

4

Answer 7

• a color change
• the formation of an odour
• the formation of a solid or a gas
• the release or absorption of heat
-(Formation of bubbles)

Question 8

Do the evidence for chemical reaction always indicate the occurrence of a chemical reaction.

Answer 8

• color change and formation of an odour are usually good indicators that a chemical reaction has taken place
• the formation of bubbles in a solution doesn’t always mean that new gas is being produced in a chemical reaction. The bubbles may simply mean that the solution has begun to boil.

-Evidence of heat being released or absorbed
may also indicate a physical change rather than a chemical change.
Some solids, for example, release heat when they are dissolved.

Question 9

What is an “Exothermic reaction”

Answer 9

A chemical reaction that releases heat energy is called an exothermic reaction.

Ex. When you burn an object in the presence of oxygen, energy in the form of heat is given off

Question 10

What is an endothermic reaction?

Answer 10

A chemical reaction that absorbs heat energy is an endothermic reaction

Ex. The reactants in the cold-packs must be crushed together to start the reaction. The reactants in the cold-packs must be crushed together to start the reaction

MELTING ICECuBES

Question 11

What do the most common types of chemical reactions involve?

Answer 11

Oxygen

Question 12

What are the three reactions that involve oxygen?

Answer 12

• Combustion
• Corrosion
• Cellular Respiration

Question 13

What is combustion?

Answer 13

Combustion is a chemical reaction that occurs when oxygen reacts with a substance to form a new substance and give off energy.

Combustion could be considered the first chemical reaction used by humans

One of the most important chemical reactions we use.

Question 14

What is a common kind of combustion?

Answer 14

Fire

In burning, wood reacts with oxygen to give off heat and light and produce carbon dioxide and water.

Question 15

What is corrosion?

Answer 15

Corrosion is the slow chemical change that occurs when oxygen in the air reacts with a metal

Question 16

What is a common example of corrosion?

Answer 16

Rusting

Rusting occurs when iron reacts with oxygen to form iron oxide.

Question 17

What are the three factors to keep a fire going?

Fire triangle

Answer 17

Air, heat, and fuel

Question 18

What is cellular respiration?

Answer 18

is a chemical reaction that takes place in the cells

in your body

Question 19

Example of cellular respiration?

Answer 19

Food (glucose) reacts with oxygen to produce energy, water, and carbon dioxide.