Calculations using reacting masses

Question 1

a balanced equation not only shows the same number of each species on both sides, but is also balanced

Answer 1

for the masses of each species

Question 2

we can use balanced equations to work out

Answer 2

amounts of substances

Question 3

we can use the……….in balanced equations to work out the amounts of substances

Answer 3

ratios of the species

Question 4

the 4 steps for working out amounts of substances are: (generically)

Answer 4

1) work out the molar masses of the substances you are told about and asked about
2) calculate the amount (moles) of the substance you are told about (i.e. have been given the mass)
3) use the reaction ratio in the equation to work out the amount (moles) of the substance you ‘want’
4) Now use n=m/M to calculate the mass of the substance you are asked for

Question 5

sometimes, there are two or more possible

Answer 5

reactions for the same reactants, so the reacting masses can be used to identify which of the reactions is occurring

Question 6

hydrates are

Answer 6

compounds containing water of crystallisation, represented by formulae such as CuSO4.5H2O