C2 - Elements, Compounds and Mixtures

What is a solution?

mixture of solute and solvent

What is a solvent?

substance in which the solute dissolves

What does soluble mean?

dissolves in water

What does insoluble mean?

does not dissolve in water

What method would be used to separate sand from water?

filtration

Why must the filter paper be fluted?

increased surface area

What is relative atomic mass?

mass of an atom

What is relative formula mass?

the sum of the relative atomic masses of the atoms in a molecule

What is relative formula mass also known as?

relative molecular mass

What does it mean if a substance is 'pure'?

contains only only one element or compound

How can you determine if a substance is pure or impure?

melting point of a pure substance is at a fixed temperature, so if a substance melts over multiple temperatures it is impure

What method would you use to obtain salt from a salt solution?

crystallisation

What is a saturated solution?

solution in which no more solute can dissolve

What increases the slower the evaporation rate?

size of crystals

What is the main difference between simple distillation and fractional distillation?

simple distillation can only deal with two solvents whereas fractional distillation deals with multiple

What does distillation rely on to work?

different solvents have different boiling points

Which separation technique would you use to separate the dyes in water soluble pens?

paper chromatography

What equipment is needed for paper chromatography?

absorbent paper/water or solvent/pencil

What is the stationaty phase in paper chromatography?

paper

What is the mobile phase in paper chromatography?

solvent

What does the Rf valure tell you?

distance moved by solvent

Why must the line be drawn in pencil?

it is insoluble and will not travel with the solvent

What pH would a soluble metal oxide be?

alkali

What charge of ion do non-metals always make?

negative

Do simple molecular structures have high or low melting points?

low melting points

What state are simple molecular structures?

fluids(gas/liquid)

Can simple molecules conduct electricity?

no because they do not have an overall charge

What do you call the structure that diamond, graphite or silica make?

giant covalent

Whcih giant covalent structure conducts electricity?

graphite

What holds thermosetting polymers together?

strong covalent bonds

What holds thermosoftening polymers together?

weak intermolecular forces

What are the allotropes of carbon?

diamond/graphite/graphene/fullerenes

What do you call the bonds that metals make?

metallic bonds

What did Mendeleev leave spaces for?

undiscovered elements

How many covalent bonds does carbon make in each diamond?

4

What can buckminsterfullerene be used for?

drug delivery

Why can graphite be used as a lubricant?

layers can slide over one another