SC1, SC2: States of Matter, Methods of Separating and Purifying Substances
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What are the three states of matter?
solids, liquids and gas
What is the arrangement of particles in gas?
• random • apart
What is the arrangement of particles in liquids?
• random • close together
What is the arrangement of particles in solids?
• regular • close together
What is the movement of particles in gas?
• fast • in all directions
What is the movement of particles in liquids?
• move around each other
What is the movement of particles in solids?
• vibrate • fixed positions
What are physical changes?
Changes that can be reversed and don’t alter the chemical properties of the substance and can be reversed. Only their movement, arrangement, and amount of stored energy is affected
What type of change is a change in state?
Physical
What are attractive forces?
Forces in which one object attracts the other
In which state do particles have the most energy (at the same temperature)?
Gas
Describe the properties of a solid
• fixed volume • fixed shape • cannot flow, because particles can’t move • can’t be compressed because particles are close together and have no space to move into
Describe the properties of a liquid
• fixed volume • no fixed shape • can flow and take the shape of the container because their particles can move around each other • cannot be compressed easily because particles are close together and barely any space to move into
Describe the properties of a gas
• no fixed shape or volume • can flow and completely fill their container because their particles can move quickly in all directions • can be compressed because particles are far apart and have space to move into
What is sublimination?
When a solid turns straight into a gas on heating without becoming a liquid first, or vice versa
What is a pure substance?
Has the same fixed composition in all its parts so we can’t separate it into other substances using physical methods
What must we do to a substance to witness a change in state?
Heat it or cool it down
What is the energy gained during a change of state used to do?
• break or overcome some bonds between particles during melting • break or overcome all remaining bonds during evaporation
During condensation and freezing, do particles gain or lose energy?
Particles lose energy as bonds form between them
What is a mixture?
Contains elements and/ or compounds that are not chemically joined together
Why is the melting point of a mixture different to that of a pure substance?
• a pure substance has fixed boiling and melting points because it has the same composition everywhere, therefore the physical properties are consistent throughout the substance • a mixture has a range of melting and boiling points because they have a different composition everywhere
What are filters used for?
To separate an insoluble solid from a liquid. It lets smaller pieces or liquids through but traps larger/ insoluble substances
Define insoluble
Unable to dissolve in a certain solvent
What is crystallisation used for?
To produce solid crystals from a solution. Used to separate the solvent from its solutes