Topic 2- states of matter and mixtures

Question 1

The three states of matter

Answer 1

• solid, liquid and gas

Question 2

Particles in liquid

Answer 2

• fixed, have more energy in particles than a solid, but less than gas

Question 3

Physical state of substance

Answer 3

• temperatures below melting point, the substance will be solid
• temperatures above melting point but below the boiling point, the substance will be liquid
• temperatures above boiling point, the substance will be a gas

Question 4

What is a mixture?

Answer 4

• 2 or more elements or compounds not chemically combined together
• chemical properties of each substance in the mixture are unchanged

Question 5

What is a pure substance?

Answer 5

-single element or compound, not mixed with any other

substance – nothing added to it

Question 6

Explain simple distillation

Answer 6

• separate pure liquid from mixture of liquids (liquids have different boiling points)
• sequence of events are : heating -> evaporating -> cooling -> condensing

Question 7

Explain fractional distillation

Answer 7

• oil heated & evaporated in fractionating column-
  condenses at a number of different temperatures.
  -hydrocarbons in crude oil can be separated into fractions -contains molecules with similar number of carbon atoms
  -fractionating column works continuously, heated crude oil is piped in at the bottom vaporised oil rises up the column and fractions tapped off at different levels where they condense.
  -fractions processed to produce fuels

Question 8

Explain filtration

Answer 8

• separate salt/precipitate from solution.

- filter solution, leaving behind precipitate on the filter paper

Question 9

Explain crystallisation

Answer 9

warm the solution in an open container, allow
solvent to evaporate, leaving saturated solution
-Allow solution to cool
-solid will come out of solution and crystals start to
grow, can be collected and allowed to dry

Question 10

Rf value equation

Answer 10

Rf value = distance moved by substance / distance moved by solvent

Question 11

How to distinguish pure and impure substances on chromatogram

Answer 11

• pure will have one spot
• If both spots are at same height up the paper at the end then substance you’re testing is the same as the known substance

Question 12

What is potable water?

Answer 12

• low levels of microbes

- low levels of contaminating substances– so safe to drink