States of Matter and Mixtures

Question 1

Are changes of state physical changes or chemical changes?

Answer 1

Physical changes

Question 2

What are the two main differences between physical changes and chemical changes?

Answer 2

Physical changes are reversible and do not change the composition of the reactants.

Question 3

What is an alloy?

Answer 3

A mixture of metals or metal + carbon.

Question 4

What is a mixture?

Answer 4

Substances together that are not chemically joined.

Question 5

What is a pure substance?

Answer 5

A substance with the same composition throughout.

Question 6

What has exact temperatures for state changes, pure or impure substances?

Answer 6

Pure substances

Question 7

What does the heating curve of a pure substance look like?

Answer 7

Diagonal lines when a solid, liquid and gas and horizontal lines when melting and boiling.

Question 8

Name all 6 state changes

Answer 8

melting, freezing, condensing, evaporating, deposition (gas to solid), sublimation (solid to gas)

Question 9

What is the difference between the heating curve of a pure substance and one for an impure substance and why?

Answer 9

A pure substance stops increasing in temperature during a change of state because all the energy is being used to change the state of the substance. An impure substance curves when changing state because the different components of it have different points for changes of state.

Question 10

What is simple distillation?

Answer 10

Extracting one pure substance from a mixture by evaporating it and condensing it in the separate container.

Question 11

What is fractional distillation?

Answer 11

Extracting more than one pure substance from a mixture by creating a heat gradient in a fractional column and distilling like normal.

Question 12

What is filtration?

Answer 12

Passing a liquid through a filter, trapping larger particles and insoluble substances.

Question 13

What is paper chromatography?

Answer 13

The separation of mixtures of soluble substances by running a solvent through the mixtures on a piece of paper, which causes substances to move at different rates.

Question 14

Which substances will travel further and faster?

Answer 14

More soluble substances

Question 15

How can a chromatogram distinguish between pure and impure substances?

Answer 15

Pure substances will have just one dot, impure substances should have more.

Question 16

How do you calculate an Rf value?

Answer 16

distance moved by compound/distance moved by solvent

Question 17

What is the stationary phase in a chromatogram?

Answer 17

The paper

Question 18

What is the mobile phase in a chromatogram?

Answer 18

The solvent

Question 19

What are the three main stages of treating fresh water to make it drinkable?

Answer 19

Sedimentation, filtration, chlorination

Question 20

What is the process of crystallisation when using copper oxide?

Answer 20

The copper oxide is added to an acid until the solution is neutral and saturated. Then the excess base is filtered out and the filtrate is left to evaporate over time.