Year 8 Chemistry - Reactions

Question 1

What is combustion?

Answer 1

Combustions the process where fuel burns in the presence of oxygen to produce heat or light.

Question 2

What is energy tranfersfers are involved in combustion?

Answer 2

Chemicals to heat energy, heat to light energy

Question 3

What is thermal decomposition?

Answer 3

Thermal decomposition is a single compound breaking down into simpler compound or elements

Question 4

If you heat Lead carbonate what is the product?

Answer 4

LEAD OXIDE + LEAD DIOXIDE

Question 4

If you heat copper carbonate what is the product?

Answer 4

COPPER OXIDE + COPPER DIOXIDE

Question 5

If you heat Zinc carbonate what is the product?

Answer 5

ZINC OXIDE + ZINC DIOXIDE

Question 6

What happens to atoms and particles in chemical reactions?

Answer 6

The particles rearrange and the number of atoms is conserved.

Question 7

Bond breaking is what?

Answer 7

Endothermic

Question 8

Bond making is what?

Answer 8

Exothermic

Question 9

Find the number of mole in 29 grams of water?(H20) RAM of Oxygen=16, RAM of hydrogen=1

Answer 9

1.61 MOLES

Question 10

Name some exothermic changes?

Answer 10

chemical reactions (combustion), freezing and condensing

Question 11

What is the formula to figure out moles?

Answer 11

number of moles = mass (g) over relative formula mass

Question 12

What is an exothermic change

Answer 12

exothermic change releases heat/energy into the surroundings

Question 13

What is an endothermic change?

Answer 13

endothermic change absorbs energy from the surroundings

Question 14

Name some endothermic changes?

Answer 14

Melting & boiling, some chemical reactions

Question 15

Mass is also conserved in physical changes. Name some

Answer 15

Ice-cream melting & water boiling

Question 16

,ass is also conserved in chemical changes. Name some

Answer 16

cooking an egg, burning wood

Question 17

what is it meant by the conservation of mass?

Answer 17

energy can’t be created or destroyed but only transferred/transformed

Question 18

In chemical reactions the total number of (BLANK) does not change. This means that the total mass of reactants (BLANK) the total of mass products. This is called (BLANK) of mass.

Answer 18

Atoms, equal, conservation

Question 19

How do you balance equations? use carbon

Answer 19

Write out the word equation (carbon+ 2 oxygen+ Carbon Dioxide)write the chemical symbols (c+02=c02) balance equation (this equation is balab=nced)

Question 20

How do you calculate masses?

Answer 20

Find mass of element (mg=0.14), burn element (mass of product = 0.40), write word equation ()mg+oxygen=magnesium oxide, magnesium rezvted wih oxygen and oxygen has its ownmass.
Total mass of Oxygen + o.24(mg) = 0.4
mass of Oxygen = 0.4-0.24=0.16
Oxygen mass = 0.16