compounds and mixtures Flashcards
what are word equations?
Eg - sodium + water —> sodium hydroxide + hydrogen
what is a reactant?
the starting materials of a reaction
what is a product?
what is made in a reaction
what are symbol equations?
Eg - Na + Cl- —>NaCl
what are pace filler diagrams?
drawing of what happens during a reaction
what happens to atoms during a reaction?
no atoms are created or destroyed just rearranged
new substances are formed
what is an exothermic reaction?
when heat is released and temperature increases during a reaction
what is an endothermic reaction?
when heat is absorbed and temperature decreases during a reaction
what is a compound?
a substance made up of different atoms that are chemically joined together
what is a mixture?
a mixture of substances not joined together
how do you balance an equation?
have the same number of atoms on each side of the arrow
remember: you cannot change the formula only add numbers in front of it
what can be observed in a chemical reaction
effervescence
colour change
temperature change
what are the state symbols?
(S) - solid
(L) - liquid
(G) - gas
(AQ) - aqueous
what is an aqueous?
dissolved in water
describe filtration
example: sand and water
sand particles are larger than water particles.
Therefore, the holes in the filter paper are big enough to let water particles through but not sand particles
describe evaporation
example: salt from salty water
water boils at 100* and leaves the salt behind
evaporate half with Bunsen burner and leave the other half to evaporate itself
describe distillation
example: alcohol from alcohol/water solution
water boils at 100* and alcohol boils at 78*. Alcohol boils first, it cools and condenses back to liquid and is collected over the other side and the water boils eventually
describe chromatography
example: separating coloured dyes in an ink
spot of dye is placed on a pencil line drawn at the bottom of chromatography paper.
paper is placed in water
as solvent soaks up paper and colour separates out
this is because the more soluble the substance is the further it will travel up the paper
note that…
if the ink is insoluble the spot will not move up the paper
in this case a different solvent must be used
if the amount of water is above the spot it will not rise it will dissolve in the water
to find the spots original colour you must submerge the whole chromatogram into the solvent so that the different inks dissolve back into the liquid and mix back together
how do you work out the Rf in value?
distance travelled by the spot
_______________________
distance travelled by solvent from the starting line
