Amount of Substance
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What is a total ionic equation?
A chemical equation that shows all the ions in a reaction
What are spectator ions?
Ions that don’t get involved in the reaction. They don’t change charge
Give the ionic equation for NaOH + HCl –> NaCl + H2O
OH- + H+ –> H2O
State what is meant by the term ‘relative atomic mass’
The average mass of an atom of an element compared to 1/12th the mass of a 12C atom
State what is meant by the term ‘relative molecular mass’
The average mass of an molecule compared to 1/12th the mass of a 12C atom
What is Avogadro’s number and what is meant by this term?
6.023x (10 to the power 23) It is the number of atoms found to be in 12g o 12C
How can you work out mass using Mr and moles?
Mass = Mr x moles
How do you work out the number of molecules in a certain amount of a substance?
Find the moles and then times that by Avogadro’s number
What is empirical formula?
The simplest ratio of atoms of each element in a compound
What is the ideal gas equation?
pV=nRT
What do the letters represent in the ideal gas equation, and what are the units for each?
pV=nRT p=pressure in Pascals V=volume in metres cubed n=moles R=gas constant (8.31 Jk-1mol-1) T=temperature in Kelvin
O*C is how many Kelvin?
273K
What do you have to do to convert from cm3 to dm3?
divide by 1000
What do you have to do to convert from cm3 to m3?
divide by 1,000,000
Give three reasons why 100% yield may not be obtained
-the reaction is reversible -some of the product is lost when it is separated from the reaction mixture -some of the reactants may react in other reactions
How do you calculate % yield?
Actual/theoretical x100
State what is meant by atom economy
The measure of what proportion of the products of a reaction are desired and how much is waste
What can a company do to maximise profits when a reaction has a low atom economy, without changing the reaction conditions or production costs?
Sell unwanted products
How can you calculate moles from concentration and volume?
moles = concentration x volume