Chemical calculations

How do you calculate relative atomic mass of an atom?

Ar= (mass number x abundance)+(mass number x abundance)/ abundance+abundance

OR

Ar= total mass of atoms/total number of atoms

How do you find the relative formula mass?

Add up all of the relative atomic masses

What is Avogadro's constant?

6.02×10²³

What is the calculation for moles (mol)?

Moles= mass/relative formula mass

OR

n=m/Mr

What is meant by a limiting reagent

The reactant that gets consumed first in a chemical reaction and therefore limits how much product is made

What is titration?

A technique used to find the concentration of an uknown solution

What is the equation for percentage yield?

Actual yield/theoretical yield

Why is percentage yield less than 100%?

• Not all reactants react

• Side/unwanted reactions may take place

• Lost during completion e.g. filtering

What is the equation for atom economy?

Mr of desired products/sum of Mr

What is the volume of 1mol of gas?

24dm³ or 24,000cm³

What is the calculation for mass/moles?

Mass/moles = concentration x volume

How do you convert dm³ to cm³?

x 1000

How do you convert cm³ to dm³ ?

÷1000

How do you convert mol/dm³ to g/dm³ ?

x by Mr of the reactant