In this I/GCSE Chemistry blog post, we will be looking at the formulas used to calculate the chemical equation of moles.
Relative Molecular Mass
NOTE: The same method is used to find relative molecular mass and relative formula mass
To find the relative molecular mass of a substance, add together the atomic masses of all the atoms in the molecule.
E.g.
CH4 contains 1 carbon atom and 4 hydrogen atoms.
The relative atomic mass of carbon is 12 and of hydrogen is 1
The relative molecular mass is therefore 12 + 1 + 1 + 1 + 1 = 16
Number of Moles in a Substance
To find the number of moles in a substance:
Number of moles = mass(g) / mass of 1 mole
E.g. Find the number of moles in 2g of H2O
1. find the mass of 1 mole: 1 + 1 + 16 = 18g
2. divide the mass you have (2g) by the mass of one mole (18g): 2/18 = 0.1111
so there are 0.1111 moles of H20 in 2g
Percentage Yield
To calculate the percentage yield from an experiment:
% yield = actual yield / theoretical yield * 100
That is all!
References:
https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.ncl.ac.uk%2Fwebtemplate%2Fask-assets%2Fexternal%2Fmaths-resources%2Fmolar-calculations.html&psig=AOvVaw0Q_4N_l51i8AOlDUTUxize&ust=1628001185618000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCPCPk5XHkvICFQAAAAAdAAAAABAD