Chemistry : C3

What is the formula for percentage mass of an element in a compound

%mass = Atomic mass x number of atoms of that element/Atomic mass of compound x 100

Define one mole

One mole of any substance is the amount of substance that contains an avogrando number of particles

How do you calculate the mole?

Number of moles = mass in g of an element or compound/atomic mass of the element or compound

Define conservation of mass

During a chemical reaction no atoms are destroyed and no atoms are created. This means there are the same number and types of atoms on each side of the reaction.

When does a reaction end?

• The reaction stops when all of one of the reactants is used up. Any other reactants are in excess.

• The reactant that’s used up In a reaction is called the limiting reactant

• The amount of product formed is directly proportional to the amount of limiting reactant

• This is because if you add more reactant there will be more reactant particles to take part in the reaction

Define concentration

The amount of substance in a certain volume of a solution is called its concentration, the more solute there is in a given volume, the more concentrated the solution

What is the formula for concentration?

Concentration = mass of solute/volume of solvent