How much? Flashcards
What is an isotope
An atom with the same number of protons and electrons but a different number of neutron to make a new type of element without an overall charge
What is a mole
The relative atomic mass of an atom or the relative formula mass of a compound
How to work out Ar?
Ar is the relative atomic mass
It’s the average value of all of the isotopes in an element
How to work out Mr?
Mr is the relative formula mass
It’s the weight of all the Ar’s in compound
How do we find the percentage of carbon in CO2
Divide the Ar of Carbon by the Mr of the whole element
Ar of carbon = 12
Mr of CO2 = 12 + (2 x 16 (oxygen2)) = 44
12/44 x 100 = 27.3%
What is the empirical formula
The ratio of elements in a compound, different from the formula usually
What’s the empirical formula of the hydrocarbon that contains 80% carbon?
Mass : Carbon: 80 Hydrogen: 20
Mass/Ar: Carbon: 80/12=6.67 Hydrogen: 20/1=20
Divide by smallest: Carbon: 6.67/6.67= 1 H: 20/6.67= 3
Empirical formula: CH3
How to calculate percentage yield
Amount of product collected / maximum amount of product possible x 100
Why can’t you always get 100% of a percentage yield or why isn’t the yield always accurate
Lost when collected or separated
Why should manufacturers use reactions with high yields
High yields help to conserve resources and to reduce waste. Little energy is wasted and less pollution is made so it’s more sustainable
What is paper chromatography
Used to analyse food additives
A colour is put onto paper, a solvent runs through the liquid and the colours move different distances based upon their solubility
What is gas chromatography
Particles of a solid are passed through a column with a gas. the individual compounds travel at different speeds and leave the column at different speeds. Their retention time (time they leave the column) can be compared with other compounds to see what it is.
