Chemical And Physical Reactions

Question 1

What do chemical reactions always do?

Answer 1

They always make new substances.

Question 2

Are they easily reversible?

Answer 2

No, they are not easily reversible.

Question 3

Do they involve energy transfers?

Answer 3

Yes

Question 4

Are physical reactions reversible?

Answer 4

Yes

Question 5

What are physical reactions?

Answer 5

Physical changes of state.

Question 6

Name an example of a chemical change.

Answer 6

Burning diesel to make carbon dioxide and water.

Question 7

Name an example of a physical change.

Answer 7

Dissolving sugar in tea to make it taste sweet.

Question 8

Another chemical change…

Answer 8

Baking raw cake to make a cooked cake.

Question 9

Another physical change…

Answer 9

Boiling water to make steam!

Question 10

Can you name some improvements to make an experiment a fair test?

Answer 10

Use the same starting mass.
Use the same starting temp.
Same length of burning time.
Raise temperature same amount.

Question 11

What are hydro carbons?

Answer 11

Fossil fuels.

Candle

Question 12

Are hydro carbons non renewable?

Answer 12

Yes.

Question 13

Will hydro carbons eventually run out, and if so, when?

Answer 13

They will eventually run out because they take millions of years to form.

Question 14

Name examples of non renewables.

Answer 14

Coal, oil, natural gas.

Question 15

What is an alternative fuel?

Answer 15

Hydrogen

Question 16

What reacts with oxygen to form water?

Answer 16

Hydrogen.

Question 17

Hydrogen+oxygen > water.

A) Is harmful carbon dioxide released?

B) Is hydrogen obtained from methane?

Answer 17

A) No

B) Yes

Question 18

Is hydrogen flammable?

Answer 18

Yes, it can explode.

Question 19

What does does thermal decomposition mean?

Answer 19

Breaking a substance down, using heat, into 2 or more products.

Question 20

Reaction of copper carbonate in limewater?

Answer 20

Turns black and gives out the carbon dioxide to turn the limewater cloudy the fastest.

Question 21

Reaction of zinc carbonate in limewater?

Answer 21

Turns yellow/green hot and gives out the carbon dioxide to turn the limewater cloudy, not so fast.

Question 22

Reaction of calcium carbonate in limewater.

Answer 22

Produced bubbles of gas in the limewater, but it dosen’t turn really cloudy in 5 mins.

Question 23

Conclusion of calcium,zinc and copper carbonate in limewater?

Answer 23

So calcium is more reactive than zinc+copper.

Zinc is less reactive than calcium but more reactive than copper.

Question 24

What is the most reactive of the carbonates?

Answer 24

Calcium + zinc carbonate

Question 25

Least reactive of the carbonates?

Answer 25

Copper carbonate

Question 26

Chemical equations for zinc carbonate.

Answer 26

ZnC03 --- Zn0+C02

Question 27

Word equation for zinc carbonate.

Answer 27

Zinc carbonate ---- Zinc Oxide + carbon dioxide

Question 28

What is endothermic?

Answer 28

Decreasing...

Question 29

What is Exothermic?

Answer 29

Increasing...

Question 30

Copper carbonate is placed in a test tube and heater. The products are copper oxide and carbon dioxide. The temperature of the reaction falls.

Answer 30

Endothermic change.

Question 31

Suggest the name for this type of reaction.

Answer 31

Physical reaction.

Question 32

In an endothermic change, where is the energy transferred from?

Answer 32

It comes from the surroundings.

Question 33

Explain Exothermic. Facts.

Answer 33

Feels hot Heat energy given Out to the surroundings Temperature rises

Question 34

Explain endothermic. Facts.

Answer 34

Feels cold Heat energy taken in from surroundings. Temperature falls.

Question 35

What do chemical reactions involve?

Answer 35

It re-arranges atoms.