Reactions

Question 1

How do you tell if something is a chemical reaction?

Answer 1

Bubbles, rusting, colour change, baking and burning are types of chemical change. Chemical changes make new substances whereas physical changes usually involve a change of state.

Question 2

How do you tell if something is a physical change?

Answer 2

Dissolving, freezing, cutting, melting and boiling are physical changes.

Question 3

What happens to the particles in a chemical reaction?

Answer 3

The particles are rearranged to produce a new substance.

Question 4

What are catalysts?

Answer 4

Catalysts are substances that speed up a chemical reaction but aren’t used in them. An example is mentos in coke.

Question 5

What are the reactants and products in the equation:

Magnesium + Oxygen —> Magnesium Oxide

Answer 5

Magnesium and oxygen are the reactants. Magnesium oxide is the product.

Question 6

What is a fuel?

Answer 6

A material that releases energy in the form of heat such as coal, oil and gas.

Question 7

What is combustion?

Answer 7

Combustion is another word for burning.

Question 8

What is the equation for burning?

Answer 8

Fuel + Oxygen —> Carbon Dioxide + Water

Question 9

What is thermal decomposition?

Answer 9

When a chemical substance breaks down (decomposes) due to heat into at least 2 chemical substances.

Question 10

What are the products of the decomposition of calcium carbonate?

Answer 10

Calcium oxide and carbon dioxide.

Question 11

What is the law for the conservation of mass?

Answer 11

Mass of Reactants = Mass of Products

Question 12

What do exothermic reactions show?

Answer 12

An increase in temperature, for example burning fuels. It makes the surroundings warmer by taking heat from the object and transferring it to the surroundings.

Question 13

What do endothermic reactions show?

Answer 13

A decrease in temperature for example sports ice packs. They make the surrounding colder by taking heat from the surroundings and transferring it to the object.

Question 14

What is the law of conservation of mass?

Answer 14

• Mass is never gained or lost in a chemical reaction.
• When a reaction happens, the atoms in the chemicals are rearranged into different compounds. No new atoms are created and no atoms can disappear.

Question 15

What are the 3 things in the fire triangle?

Answer 15

Oxygen, fuel, heat (ignition).

Question 16

What do fuels react with to produce energy in an exothermic reaction?

Answer 16

Oxygen.

Question 17

What is reduction?

Answer 17

When oxygen is removed from a chemical in a reaction.

Question 18

What is oxidation?

Answer 18

When oxygen is added to a chemical in a reaction.

Question 19

Which 3 metals do not react with oxygen and why?

Answer 19

Silver, gold and platinum because they are lower down in the reactivity series.

Question 20

What is the word equation for the combustion of methane?

Answer 20

Methane + Oxygen –> Water + Carbon Dioxide

Question 21

What is metal carbonate?

Answer 21

A compound which contains metal (Ca, Cu, Mg), carbon and oxygen. Eg: CuCO3, CaCO3.

Question 22

What is a foam extinguisher used for?

Answer 22

It is to be used on class A and class b fires and it removes the parts heat and oxygen from the fire triangle.

Question 23

What is a water extinguisher used for?

Answer 23

It is to be used on class A fires and it removes the part heat from the fire triangle.

Question 24

What is a CO2 extinguisher used for?

Answer 24

It is to be used on class B fires and it removes the part oxygen from the fire triangle.

Question 25

What is a powder extinguisher used for?

Answer 25

It is to be used on class A, class B and class C fires and it removes the part oxygen from the fire triangle.

Question 26

What are class A fires?

Answer 26

Fires involving freely burning materials like wood, paper, textiles and other carbon-based materials.

Question 27

What are class B fires?

Answer 27

Fires involving flammable liquids such as oil, alcohol, gasoline, ether and grease which are best extinguished by smothering.

Question 28

What are class C fires?

Answer 28

Fires involving flammable gases such as butane, propane, ethane and hydrogen. They can be highly explosive if ignited.

Question 29

What are class D fires?

Answer 29

Fires involving combustible materials such as titanium, lithium, magnesium and potassium.

Question 30

What does the exclamation mark symbol mean?

Answer 30

Irritant.

Question 31

What does the fire on line symbol mean?

Answer 31

Flammable substances.

Question 32

What does the symbol with stuff sizzling away objects mean?

Answer 32

Corrosive.

Question 33

What does the body with lines coming out of circle in it symbol mean?

Answer 33

Health hazard, could cause cancer.

Question 34

What does the exploding circle symbol mean?

Answer 34

Explosives.

Question 35

What does the stick on fire with a circle in symbol mean?

Answer 35

Flammable oxidisers.

Question 36

What does the skull and crossbones symbol mean?

Answer 36

Poisonous/danger to life.

Question 37

What does the symbol with the tree and dead fish mean?

Answer 37

Toxic to aquatic life and wildlife.

Question 38

What does decomposition mean?

Answer 38

It means break down, and an example of this is a compost heap.

Question 39

What is thermal decomposition?

Answer 39

When a chemical substance breaks down into two or more chemical substances due to heat.

Question 40

What happens when a metal carbonate thermally decomposes?

Answer 40

It goes to metal oxide and carbon dioxide.

Question 41

Why are metals not reacting with the oxygen in the room?

Answer 41

The metals aren't reacting because they are already bound to something else.

Question 42

What are metals that are bound to something called?

Answer 42

Alloys.

Question 43

What is oxidation?

Answer 43

Loss of electrons and gain of oxygen in a chemical reaction.

Question 44

What is reduction?

Answer 44

Gain of electrons and loss of oxygen in a chemical reaction.

Question 45

What happens when hydrocarbons react with oxygen?

Answer 45

They turn into water and carbon dioxide.

Question 46

What are some examples of hydrocarbons?

Answer 46

Methane, ethene and benzene.

Question 47

What kind of reaction is combustion?

Answer 47

Combustion is exothermic.

Question 48

What is in the fire triangle?

Answer 48

Fuel, heat and oxygen.

Question 49

What types of paper can test for water?

Answer 49

Cobalt chloride and anhydrous copper sulphate.

Question 50

How can you test for carbon dioxide?

Answer 50

If you bubble carbon dioxide through limewater it will go cloudy.

Question 51

What happens in combustion?

Answer 51

Fuel reacts with oxygen to release energy and requires fuel, oxygen and heat to start the reaction.

Question 52

What is oxidation?

Answer 52

A type of reaction where oxygen bonds to elements of the reactants.

Question 53

What is burning?

Answer 53

A type of combustion where substances react with oxygen to produce a visible flame.

Question 54

What is a fuel?

Answer 54

Substance that releases stored energy when combusted.

Question 55

What is a molecule?

Answer 55

Two or more chemically bonded atoms.