Revision Chemistry

Question 1

Explain the properties of a physical change.

Answer 1

A change in state/ arrangement of particles and can be turned back to its original form. It can be a change in texture, shape, temperature, and a change in the state of matter.

Question 2

What is boiling/evaporation?

Answer 2

To change state from a liquid to a gas.

Question 3

What is a Catalyst?

Answer 3

Substances that increase the rate of a reaction
without becoming used up.

Question 4

Chemical Reaction

Answer 4

Procedure that produces new chemicals; same as chemical change

Question 5

Collison Theory

Answer 5

In collision theory, the more collisions that
happen between the particles, the more likely
it is that they will react.

Question 6

Concentration

Answer 6

The number of particles trapped
in a small area

Question 6

Condensation

Answer 6

When a gas becomes a liquid

Question 7

Corrosion

Answer 7

The damage caused to metal in it’s environment

Question 8

Enzyme

Answer 8

A chemical that helps chemical reactions happen; a type of catalyst.

Question 9

Fume

Answer 9

A gas or vapour that has a strong sense of spell or is dangerous to breathe in.

Question 10

Lattice

Answer 10

Three-dimensional arrangement of particles in a regular pattern.

Question 11

Melting

Answer 11

To change state from solid to liquid.

Question 12

Product

Answer 12

Substance obtained at the end of a chemical reaction.

Question 13

Reactant

Answer 13

Substance that reacts or changes to produce
new substances.

Question 14

Sublimation

Answer 14

Change of state straight from a solid to a gas. (Dry Ice).

Question 15

Vaporise/Evaporation

Answer 15

To change from a liquid to gas; same as evaporate.

Question 16

Vapour

Answer 16

A gaseuous form of a substance when it is usually solid in room temperature.

Question 17

Volatile

Answer 17

A substance that easily becomes a gas.

Question 18

Deposition

Answer 18

Change of state straight from gas to solid (Dry Ice).

Question 19

Example of chemical change (Rusting)

Answer 19

Rusting of metal also known as oxidisation is a chemical change as it is irreversable.

Question 20

Example of chemical change (burning toast)

Answer 20

When the toast is burnt it is irreversible. Its reactant is toast and heat and the product is burnt toast.

Question 21

Example of physical change (Nitrogen).

Answer 21

It is a gas but it can still be frozen at a very low temperature to create dry ice. it can be reheated to become nitrogen gas again making it a physical change.

Question 22

Explain how temperature may affect reaction rate.

Answer 22

When the reactants particles are heated, they move faster and faster resulting in larger collisons.

Question 23

Explain how concentration may affect reaction rate.

Answer 23

More concentrated substances will
react more easily, again due to the collision
theory. A more concentrated substance
has more particles available to collide with
particles from another substance.

Question 24

Explain how dyes used to be made and how they are made now.

Answer 24

Use to be made from welks which are snails which created a puple dye that could change the colour of wool or cotton… as usually they would be their natural colour but thousands of snails would be needed just to coulour one piece of clotheing as to why the snails nearly went extinct. They the used crusted insects to dye a piece of clothing red. Then William perkins created the first type of artificial dye in 1878.

Question 25

The effect of particle size with reaction rates.

Answer 25

The smaller the size of the particles, the faster the rate of the reaction. Smaller particles have a greater total surface area, which means that the particles have a greater chance of interacting with each other

Question 26

Combustion

Answer 26

Burning- a substance reacts rapidly with oxygen and gives off heat.