C02 Amount of Substance

Define ‘relative atomic mass’:

the mean mass of an atom of an element divided by 1/12 of the mean mass of an atom of carbon-12

What is defined as ‘the mean mass of an atom of an element divided by 1/12 of the mean mass of an atom of carbon-12’?

relative atomic mass

Define ‘relative molecular mass’:

the mean mass of a molecule of a compound, divided by 1/12 the mean mass of an atom of carbon-12

What is defined as ‘the mean mass of a molecule of a compound, divided by 1/12 the mean mass of an atom of carbon-12’?

relative molecular mass

What is the relative molecular mass of an ionic compound called?

relative formula mass

What does Avogadro’s constant represent?

number of particles in one mole

What is Avogadro’s constant?

6.022×10²³

What equation links number of moles, mass and relative molecular mass?

moles = mass / Mr

What equation links number of particles, number of moles, and Avogadro’s constant?

particles = moles * 6.022×10²³

What equation links number of moles, concentration and volume?

concentration = moles / volume

State the ideal gas equation:

pV=nRT

What is p in pV=nRT?

pressure in Pa

What is V in pV=nRT?

volume in m³

What is n in pV=nRT?

number of moles

What is R in pV=nRT?

ideal gas constant in JK⁻¹mol⁻¹

What is T in pV=nRT?

temperature in K

Define ‘empirical formula’:

simplest whole number ratio of atoms of each element in a compound

What is defined as ‘simplest whole number ratio of atoms of each element in a compound’?

empirical formula

Define ‘molecular formula’:

actual number of atoms of each element in a compound

What is defined as ‘actual number of atoms of each element in a compound’?

molecular formula

Describe the process of working out empirical formula from given elements:

find % mass, find atomic mass, divide % mass by atomic mass, divide by the smallest value, multiply up to get integers

What must equations be to be used in calculations?

balanced

What is the formula to calculate percentage atom economy?

(mass of useful product / total mass of reactants)*100

What are the advantages of using reactions with a high percentage atom economy?

less waste, more efficient use of raw materials, more cost-effective