Chemistry yr 7

Question 1

What would a graph documenting the increase of temperature of an impure substance look like?

Answer 1

Where there is a vertical line at some point in the graph to show stabilizing temperature before state change (with a pure substance), there is a curved line instead to due to the mixture of elements within

Question 2

What is the difference between evaporation and boiling?

Answer 2

1. Boiling occurs at a fixed temperature whereas evaporation does not
2. Boiling takes place throughout the liquid whereas evaporation only takes place at the surface
3. In boiling, thermal energy is supplied by an energy source whereas evaporation’s thermal energy is supplied by its surroundings

Question 3

What is diffusion?

Answer 3

Diffusion is the process by which particles of one substance spread out through the particles of another substance from an area of high concentration to an area of low concentration

Question 4

How does diffusion differ with different elements?

Answer 4

Gasses have lower particle density, which is why diffusion is faster within gasses than the other states of matter

Question 5

Why do balloons get bigger as you blow them up?

Answer 5

The gas particles exert a force on the balloon’s rubber, causing it to expand

Question 6

What is gas pressure?

Answer 6

The force per unit area of the container the gas is in

(per square metre)

Question 7

Which gas withstands cold temperature?

Answer 7

Nitrogen

Question 8

How does increasing temperature increase gas pressure?

Answer 8

1. increasing temperature —>
2. increases particle energy –>
3. increases particle speed of movement —>
4. increases particle collisions —>
5. increases gas pressure

Question 9

What is an element?

Answer 9

a substance made up of one kind of atom

Question 10

What is a compound?

Answer 10

A pure substance made up of two or more elements chemically bonded together

Question 11

What is a mixture?

Answer 11

2 or more elements that are not chemically bonded

Question 12

How do you name metal + non-metal compounds?

Answer 12

Metal + non metal ending ide

Question 13

How do you name metal + non-metal + oxygen compounds?

Answer 13

Metal + non metal ending ate

Question 14

Saturated definition

Answer 14

A solvent that can’t dissolve any more solute

Question 15

What is fuel?

Answer 15

A material that burns to transfer energy by heating

Question 16

What is combustion?

Answer 16

Burning

Question 17

Combustion formula

Answer 17

fuel + oxygen –> carbon dioxide + water

Question 18

Conservation of Mass formula

Answer 18

mass of reactants = mass of products

atoms cannot be created or destroyed

Question 19

What is decomposition?

Answer 19

the breaking down of a substance

Question 20

What is thermal decomposition?

Answer 20

The process of breaking down a substance using heat

Question 21

What does a metal carbonate break down into?

Answer 21

metal carbonate —> metal oxide + carbon dioxide

Question 22

What is a reversible reaction?

Answer 22

A reaction in which the products formed can either decompose or react to give the reactants back again

Question 23

What happens to the particles of the solute when dissolved in solvent?

Answer 23

The particles of the solvent surround those of the solute

Question 24

What is distillation?

Answer 24

A method used to separate a soluble solid from a liquid

Question 25

What is chromatography?

Answer 25

Chromatography is a separation technique used to separate mixtures of soluble substances

can be used for both coloured substances (like pen ink) and non coloured substances (like drugs)

Question 26

liquid —> gas

at the surface of seawater

Answer 26

boiling

Question 27

gas —> liquid

Answer 27

condensation

Question 28

molecule

Answer 28

2 or more atoms chemically bonded together