C4 Chemical Calcuations Flashcards
How do you calcuate the relative formular mass?
You add the atomic mass of all of the atoms in the formular
Which number is the relative atomic mass?
The top number
The bigger number
How do you calcuate the % mass of an element in a compound?
%mass = (relative atomic mass (of those element) /Relative atomic mass of compound)X100
What is a mole?
A substance with 6.02X10^23 particles in it
What is avogadro’s number?
6.02X10^23
1 mole of a substance is equal to?
The mass of that substance eg 1 mole of Carbon weights 12 grams and the Mr of Carbon is 12
How can you calucate moles?
Moles = mass (g)/Mr
What method wpuld you use to answer this?
How many moles are there in 66g of carbon dioxide?
Mr of Carbon dioxide = 44
Moles = mass / Mr
Moles = 66/44=1.5
1.5 moles
How would you answer this?
What mass of Carbon is there in 4 moles of carbon dioxide?
Mr of Carbon = 12
Mr of Oxygen = 16
Moles = mass/Mr
Mass = Moles X Mr
Mass = 4 X 12 =48
48g
What does the conservation of mass state?
No mass (atoms) can be created or destroyed
What hapens to mass to mass in a reaction?
It stays the same
It is CONSERVED
What has happened if you do an experiment and there is a change in mass?
There is usually a gas involved. If you are doing an experiment in a unsealed container you can’t accunt for the mass of the gas eg Oxygen.
However the amount of the mass of the reactant + gas will be the same as the product
What does the big number tell you infront of the elements in an equasion?
The amount of moles
What has happened when the reactant stoppes?
The limiting reactant has been used up
What is the other reactant in an reaction called?
(Not the limiting reactant?
It is IN EXCESS
