C5/6 Flashcards
what does pure mean?
a substance is made up of one substance
- it can be an elemnt or compound
what is a compound
made of more than one type of atom bonded together
what is an element
substances with only one type of atom
how can we distinguish between pure and impure substances
melting and boiling points
how do we know if a substance is impure
if it melts over a range of temperatures
what is a formulation
a mixture that has been designed as a useful product
examples of formulations
medicines, paints, washing up liquids, fuels, fertilisers
what is a mixture?
groups of atoms, elements and compounds that are mixed but not bonded
what is a solute?
solid that can dissolve in a solvent
what is a solution?
mixture formed when a solvent dissolves a solute
what is a solvent?
substance that dissolves a solute
what is filtration used to separate?
an insoluble solid from a liquid
what is crystallisation used to separate?
a soluble solid from a solution
what is simple distillation used to separate?
separates a solvent from a solution
what is fractional distillation used for?
used to separate different liquids from a mixture of liquids
how does filtration work?
the insoluble solid is left behind on the filter paper as residue and the liquid passes through the filter paper
how does crystallisation work?
liquid evaporates as the solution is heated, leaving behind the solid
how does simple distillation work?
- liquid evaporates from the solution, it then cools and condenses in a condenser
- liquid is then collected based on boiling points
how does fractional distillation work?
- heat the mixture so it boils at the bottom to form vapours
- vapour rises at column
- the column is hot at the top and cool at the bottom
- vapours condense at different temperatures, depending on their boiling points
what is the atomic mass made up of?
protons and neutrons
what is relative formula mass?
adding up all of the relative atomic masses in the compound
how is relative formula mass presented
Mr
what is the conservation of mass?
no atoms are lost or made in a chemical reaction
what is avogadro’s number?
6.02 x 10(23)
how do you work out mass?
moles x Mr
how do you work out moles?
mass/Mr
how do you work out Mr?
mass/moles
what is a solvent
liquid that the solute dissolves in
what is the mobile phase
phase in chromatography that moves, usually a solvent or a mixture of solvents
stationary phase
phase in chromatography that does not move, for example the paper
why must the start line be in pencil
pen is an ink and could affect the results and pencil is insoluble
what is Rf
distance moved by substance/distance moved by solvent
what does a larger Rf mean
the solute is more soluble
what is a chemical reaction?
change that involves rearranging atoms within reactant molecules and the formation of a new product
how can we tell a chemical reaction has taken place
- colour change
- temperature change
- bubbles
- precipitate formation
- odours and sounds
what is the rate of reaction
the speed at which a reaction occurs
examples of reactions
- rusting
- baking
- explosions
how can you measure the rate of reaction
change in mass, volume, colour or time taken to tur cloudy or precipitate formation
rate of reaction equation
quantity of reactant used or product formed/time taken
for a chemical reaction to happen…
(collision theory)
- reactant particles must collide with each other
- particles must have enough energy to react
whats a successful collision
a collision that produces a reaction
what is activation energy
minimum amount of energy needed to start a reaction
what happens if a particle doesnt have enough energy
they just bounce off each other
what factors affect rate of reaction
concentration, temperature, catalysts, surface area, pressure
how does temp affect ror
as temp increases, the particles move faster so collide more frequently
how does catalysts affect ror
they lower activation energy by providing alternate reaction pathways so increases successful collisions
how does SA affect ror
increased collision frequency as theres more contact points in the surface of particles
how does pressure/concentration affect ror
theres more particles/unit volume making collisions more frequent
what does concentration measure
solutions
what does pressure measure
gases
what is a catalyst
- substance that speeds up reaction without being used up in the reaction
- they provide alternate pathway for reaction
examples of catalysts
nickel, iron, platinum
advantages of using catalysts
- products can be made more quickly so save enrgy and money
- expensive byt reuseable
- reduce the need to increase temperature so save fuel and pollution
biological catalysts
- enzymes - work best in a naerrow range of temp and pH
- used in everyday products like washing powders, breaking down food stains
biological catalysts
- enzymes - work best in a narrow range of temp and pH
- used in everyday products like washing powders, breaking down food stains
