Science 3: Changes in Matter

Question 1

Most gases do not have color. So how do you detect these gases?

Answer 1

By their effect on other objects.

For example blowing into a straw in a drink creates bubbles - that’s the effect of gas on the liquid.

Or, wind (a gas) can movie solid objects.

Question 2

Does gas have weight?

Answer 2

Gasses have mass and thus they have weight

Question 3

Why does ice melt?

Answer 3

Ice melts when it absorbs heat energy, which cases its molecules to move faster, which turns solid ice into a liquid state

Question 4

Fill the blank with the correct word:

Gasses undergo (deposition / sublimation) to turn into solids.

Answer 4

Deposition.

Solids undergo sublimation to turn into gasses.

Question 5

What properties are impacted by temperature?

Answer 5

Materials might expand (get bigger) at higher temperatures or contract (get smaller) at lower temperatures.

Materials might be more stretchable at higher temperatures or become brittle at lower temperatures.

Some materials might change color, depending on the temperature.

Temperature could cause some materials to change states.

Question 6

What are ways that matter might undergo physical change?

Answer 6

It might change size and shape.

Question 7

Does physical change result in a new substance?

Answer 7

No. When materials undergo physical change, they do not react with other substances and remain the same matter.

For example, when a piece of glass breaks, it turns into many pieces (change in size and shape) but the pieces are still glass.

Question 8

Fill the blank with the correct word:

Liquids undergo (evaporation / condensation) to turn into gas.

Answer 8

Evaporation.

Gas undergoes condensation to turn into water.

Question 9

True or false: all matter have the same melting and freezing points.

Answer 9

False. Different matter have different melting and freezing points.

Question 10

When matter changes states, does its mass also change?

Answer 10

No, its mass stays the same because the number of molecules change the speed of movement but the number of molecules does not change.

Question 11

How is chemical change different from physical change?

Answer 11

Chemical changes result in one or more new substances.

Question 12

List 3 examples of chemical change

Answer 12

Burning
Rusting
Baking/cooking
Explosion
Digestion
Photosynthesis

Question 13

What might be evidence of a chemical change?

Answer 13

Change of color

Change in temperature

Release of heat or light

Release of gas bubbles

Change in smell

Precipitation (a solid forms and falls out of a liquid)

Change in state of matter without changes in temperature or pressure

Question 14

Iron (Fe) is solid, shiny, malleable, magnetic and conducts electricity.

Oxygen (O) is a gas, it’s transparent, odorless and highly reactive.

What happens when Iron (Fe) combines with oxygen (O)?

Answer 14

A new substance called Iron Oxide is formed due to chemical change.

The properties of the new substance are different from the original substances. Iron Oxide is solid, but brittle and powdery, it’s reddish brown, it is an electrical insulator and is only weakly magnetic.

Question 15

What happens to the particles of a substance during chemical change?

Answer 15

Particles of a substance re-arrange during chemical change to form a new substance.

Question 16

Does mass change after chemical change?

Answer 16

No, total mass remans the same. Particles of the original substance will all become particles of the new substance(s).

This is called conservation of matter.

Question 17

If you mix 100 grams of Substance A and 20 grams of Substance B, and this results in 2 new substances C and D.
If there are 30 grams of a new Substance C, what is the mass of new Substance D?

Answer 17

90 grams.

Question 18

How is a mixture different from a solution?

Answer 18

Both involve combining different substances, but they are different.

In a mixture, the combined substances retain their individual properties and can often be separated by simple physical means. Chemical change does not occur.

But in a solution, one substance is completely dissolved in another substance and is spread out evenly throughout that substance. In a solution, substances can be separated by complex methods but cannot be separated by simple physical means. That means there is also no chemical change.

Question 19

What are some ways to speed up dissolving one substance in another?

Answer 19

Stirring or heating

Grinding a solid into smaller pieces

Question 20

Can a solution be made between different states of matter?

Answer 20

Yes, a solution can be made by combining solids and liquids, or by 2 liquids, or by gases and liquids

Question 21

Could a mixture also be a solution?

Answer 21

Yes.

All solutions are mixtures because both are combining different substances, but not all mixtures are solutions because in some mixtures, a substance is not completely dissolved and spread out evenly in the other mixture.

Question 22

Take 2 cups of juice:

A. It is all yellow color and there are no chunks of fruit observable in the cup.

B. It is all orange color but there are chunks of fruit observable in the cup.

Which is a solution, and which is a mixture?

Answer 22

Cup A is a solution because the fruit juice looks to be completely and evenly dissolved in water.

Cup B is a mixture because the fruit juice is only partly dissolved in the water, as you can tell by the chunks of fruit.

Question 23

What are some ways of separating substances in a mixture?

Answer 23

Using a filter or sieve

Using a magnet to remove magnetic material

Allowing the mixture to settle, and then simply picking one out from the other

Question 24

What are some ways of separating substances in a solution?

Answer 24

Evaporation

Distillation

Reverse osmosis

Question 25

True or false: some substances are soluable only in certain liquids while others are not.

Answer 25

True.

Some substances can only be dissolved in certain types of liquids such as acid.

Question 26

How is dissolving different from suspension?

Answer 26

When something is dissolved, it is completely combined and spread evenly in the other substance. You can not see separate substances.

When something is suspended, you can see different substances, which means one substance is not dissolved in the other.