Amount of Substance Flashcards
What is Avogadro’s constant? What does it mean?
6.02 x 10^23- the number of particles in each mole of carbon 12
What is the mass of one mole of any substance equal to?
Relative atomic mass in grams
What equation links moles, mass, mr?
Mass= Mr x Mol
What is the empirical formulae?
The simplest whole number ration of atoms of each element in a compound
Define relative molecular mass
The mass of a molecule compared with the mass of an atom of carbon-12
Define relative formula mass
The mass of a formula unit compared with the mass of an atom of carbon-12
What is ‘analysis’?
Investigation of the chemical composition of a substance
Define ‘water of crystallisation’
Water molecules are part of their crystalline structure
What are the two assumptions made when calculating formula of a dehydrated salt?
All of the water has been lost
No further decomposition
What is 1dm^3 in cm^3?
1000cm^3
What equation links moles, volume and concentration?
moles= concentration x volume
What is a standard solution?
A solution of a known concentration
What is the molar gas volume?
The volume per mole of gas molecules at a stated temperature and pressure
What is RTP?
20 C, 101kPa
What is molar gas volume at RTP?
24.0 dm3 mol-1
What are the assumptions made in an ideal gas equation?
Random Motion
Elastic collisions
Negligible size
No intermolecular forces
What is the ideal gas equation?
pV=nRT
Pressure x volume = moles x ideal gas constant x temperature
What are the units used in ideal gas equation?
Pressure= Pa Volume= m^3 Moles= mol Ideal Gas Constant= mol-1 k-1 Temperature= K
What is the value of the ‘ideal gas constant’?
8.31
Why can the theoretical yield not always be reached?
Reaction may not have gone to completion
Other reactions may have taken alongside reaction
Purification may result in some lost product
What is the equation for percentage yield?
actual yield/ theoretical yield x 100
What is the limiting reagent?
The reactant that will be completely used up first in a reaction and that will cause the reaction to stop
What is atom economy a measure of?
Measure of how well atoms have been utilised
Why are high atom economies important?
Sustainability
Produce little waste products
Preserves raw materials
