Chemical formulae, equations and calculations

Question 1

What is the formula for moles?

Answer 1

Moles = mass / molar mass

Question 2

What is the formula for mass?

Answer 2

Mass = moles x molar mass

Question 3

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

Answer 3

% mass of an element = Ar x number of atoms of the element/ Mr of the compound x 100%

Question 4

How many particles are there in one mole?

Answer 4

6.02 x 10^23

Question 5

What is the formula for percentage yield?

Answer 5

Percentage yield = actual yield/theoretrical yield x 100%

Question 6

What is meant by the term ‘molecular formula’?

Answer 6

The formula that shows the number and type of each atom in a molecule

Question 7

What is meant by the term ‘empirical formula’?

Answer 7

Gives the simplest whole-number ratio of atoms of each element in the compound

Question 8

What is the formula for concentration (mol dm^-3)?

Answer 8

Concentration (mol dm^-3) = number of moles of solute(mol)/volume of solution (dm^3)

Question 9

What is the formula for volume(cm^3)?

Answer 9

Volume (cm^3) = amount of gas (moles) x 24,000(cm^3 mol^-1)