Science Unit B Section 1 Review

Question 1

What does each hazard symbol mean?

Answer 1

Each hazard symbol shows two separate pieces of information. The shape of the symbol indicates how hazardous a substance is. A yellow triangle means “caution,” an orange diamond means “warning,” and a red
octagon means “danger.”

Question 2

What is WHMIS used for?

Answer 2

The Workplace Hazardous Materials Information System—or WHMIS—is
another system of easy-to-see warning symbols on hazardous materials.

Question 3

What does WHMIS stand for?

Answer 3

Workplace Hazardous Material Information System.

Question 4

What are some safety things you have to follow in science class?

Answer 4

• Follow the safety instructions outlined by your teacher and in this textbook.
• Identify possible hazards and report them immediately.
• Show respect and concern for your own safety and the safety of your classmates and teachers.
• Read Toolbox 1: Safety in the Laboratory.

Question 5

What are the physical properties of a substance?

Answer 5

• colour
• lustre
• melting point
• boiling point
• hardness
• malleability
• ductility
• crystal shape
• solubility
• density
• conductivity

Question 6

What happens to a substance that undergoes physical change?

Answer 6

When a substance undergoes a physical change, such as melting, its
appearance or state may be altered, but its composition stays the same.

Question 7

What is a change from solid to a liquid called?

Answer 7

Melting

Question 8

What is a change from liquid to a gas called?

Answer 8

Evaporation

Question 9

What is a change from gas to liquid called?

Answer 9

Condensation

Question 10

What is a change from liquid to a solid called?

Answer 10

Freezing

Question 11

If a gas can change directly into a solid what is this process called?

Answer 11

This process is called deposition.

Question 12

If a solid can change directly into a gas what is this process called?

Answer 12

This is called deposition.

Question 13

What are properties?

Answer 13

Properties are characteristics that can be used to describe a
substance.

Question 14

How many types of properties does matter have?

Answer 14

All matter has two types of properties: physical and chemical.

Question 15

What is solubility? And give an example.

Answer 15

Solubility is the ability of a substance to be dissolved in another. For example, sugar is soluble in water, but cooking oil is not.

Question 16

What is density?And give an example.

Answer 16

Density is the amount of mass in a given volume of a substance. For example; the density of water is 1 g/ml and the density of gold is 19 g/cm3.

Question 17

What is malleability? And what is an example?

Answer 17

A substance that can be pounded or rolled into sheets is said to be malleable. Metals such as gold and tin are malleable. Aluminum foil is an example of a product made from a malleable
substance.

Question 18

What is conductivity?

Answer 18

Conductivity is the ability of a substance to conduct electricity or heat. A substance that conducts electricity or heat is called a conductor. A substance with little or no conductivity is an insulator.

Question 19

What is ductility?

Answer 19

Any solid that can be stretched into a long wire is said to be ductile. The most common example of a ductile material is copper.

Question 20

What is crystal shape?

Answer 20

The shape of a substance’s crystals can help identify it. Silicon crystals, for example, are diamond shaped. Salt crystals form cubes.

Question 21

What is Hardness?

Answer 21

Hardness is a substance’s ability to resist being scratched. Hardness is usually measured on the Mohs’ hardness scale from 1 to 10.

Question 22

What is a mixture?

Answer 22

A mixture is a combination of pure substances.

Question 23

What is an aqueous solution? Give at least 4 examples.

Answer 23

Chemists call a substance dissolved in water an aqueous solution. Examples include fresh water, vinegar, and cleaning solvents

Question 24

What is a mechanical mixture?

Answer 24

A mechanical mixture, the different substances that make up the
mixture are visible.

Question 25

What is a suspension? What is an example of this?

Answer 25

A suspension is a cloudy mixture in which tiny particles of one substance are held within another. Tomato juice is an example of a
suspension.

Question 26

What is a colloid? What are two examples?

Answer 26

A colloid is a cloudy mixture, but the particles of the suspended
substance are so small that they cannot be easily separated out from the other substance. Milk and ketchup are examples of colloids.

Question 27

What are some types of solutions?

Answer 27

1. Solid dissolved in liquid - sugar in hot coffee.
2. Liquid dissolved in liquid - acetic acid in water (to create white vinegar).
3. Gas dissolved in liquid - carbon dioxide gas in water (to create carbonated pop).
4. Gas dissolved in gas - oxygen and smaller amounts of other gases in nitrogen
   (in the atmosphere).
5. Solid dissolved in solid - copper in silver (to create sterling silver)

Question 28

What is the difference between an element and a compound?

Answer 28

An element is a material that cannot be broken down into any simpler
substance. Where as when two or more elements combine chemically—that is, in specific, fixed proportions—they form a compound.

Question 29

What are some examples of evidence of chemical change?

Answer 29

1. Change in colour - When bleach is added to the dye on a denim jacket, a noticeable colour change occurs.
2. Change in odour - When a match is struck, the substances in the match head react and give off a distinctive odour.
3. Formation of a solid or gas - When vinegar (a liquid) is added to baking soda (a solid), carbon dioxide gas is formed.
4. Release or absorption of heat energy - When gasoline burns in a car engine, heat is released.

Question 30

What is freeze drying?

Answer 30

Freeze drying is a way to preserve foods so that they can be eaten months—and
sometimes even years—later. As well, freeze-drying makes foods easy to prepare—all you have to do is add hot water.

Question 31

What is the process of freeze-drying?

Answer 31

In the freeze-drying process, the food is first frozen to convert the water content in the food to ice. The frozen food is then put in a pressure chamber and the pressure is reduced until the ice sublimes (changes from a solid to a gas). The result is that about 98% of the water in the original food item is removed. This leaves a food that is about 10% its original mass and that, once packaged, doesn’t have to be refrigerated.

Question 32

Who uses this technique of freeze-drying?

Answer 32

The technique of freeze-drying is also used by biologists.

Question 33

What does MRE stand for?

Answer 33

Meals Ready to Eat.

Question 34

Are corn based solvents harmful?

Answer 34

Corn-based solvents for removing paint and nail polish are not as harmful to the
environment as other types of solvents.

Question 35

What is the difference between a chemical change and a physical change?

Answer 35

A physical change is one in which a material
changes from one state to another. The material can also physically change
back into its original state. Where as a chemical change occurs when two or more materials react and create new materials. The new materials have completely different properties from the original substances.

Question 36

Is popping popcorn a physical or chemical reaction? Explain your
answer.

Answer 36

It is a physical change because the shape of it is only changing.

Question 37

Define matter.

Answer 37

Matter is anything that has mass and
occupies space.