Chemical Calculations

for Year X

n 22.4

m

n Mnum

n 6x1023

You need to become familiar with the following types of calculations

1. mole > mole2. mole > gas volumes (STP + NTP)3 mole > mass4 mass > mole5 mass > mass easiest

hardest, most steps

Some hand written examples1. mole > mole

Some hand written examples1. mole > mole

Some hand written examples2. mole > gas volumes (STP + NTP)

Hydrogen gas is produced when magnesium is added to dilute hydrochloric acid.

Mg + 2HCl ---------à MgCl2 + H2

What volume of gas is produced when 0.6 moles of the acid is used completely?

Mg + 2HCl ---------à MgCl2 + H2

Hydrogen gas is produced when magnesium is added to dilute hydrochloric acid.

Mg + 2HCl ---------à MgCl2 + H2

What volume of gas is produced when 0.6 moles of the acid is used completely?

Some hand written examples2. mole > gas volumes (STP + NTP)

The lab prep for oxygen requires hydrogen peroxide and the catalyst manganese dioxide

2H2O2 ------------à 2H2O + O2

25mL of oxygen gas is produced during an experiment. How many moles of hydrogen peroxide has decomposed?

The lab prep for oxygen requires hydrogen peroxide and the catalyst manganese dioxide

2H2O2 ------------à 2H2O + O2

25mL of oxygen gas is produced during an experiment. How many moles of hydrogen peroxide has decomposed?

2H2O2 ------------à 2H2O + O2

Some hand written examples2. mole > gas volumes (STP + NTP)

Carbon dioxide is made by adding hydrochloric acid to calcium carbonate. A teacher requires 150mL at NTP. How g of calcium carbonate should he use?

CaCO3 + 2HCl --------à CaCl2 + H2O + CO2

Carbon dioxide is made by adding hydrochloric acid to calcium carbonate. A teacher requires 150mL at NTP. How g of calcium carbonate should he use?

CaCO3 + 2HCl --------à CaCl2 + H2O + CO2

Q1 Hydrogen sulphide H2S gas can be made by adding sulphuric acid to iron sulphide. (FeS) Iron sulphate is also produced during this reaction.

If 4 moles of iron sulphide is used what volume of gas will be produced at STP?

Q2 A technician requires 500mL of laughing gas (N2O). How many moles of ammonium nitrate should be decomposed to produce this?

NH4NO3 --------à N2O + 2H2O

Q3 500Kg of old car panels need to be dissolved in sulphuric acid. Assuming that the car panels are steel (mainly iron) How many moles of sulphuric acid is required for this job?

Fe + H2SO4 --------à FeSO4 + H2

Q4 Copper metal can be extracted from copper oxide CuO by simply heating it with carbon powder C. If 750g of copper is required, how many g of copper oxide should be treated with carbon. What volume of carbon dioxide will be produced during this process? (NTP conditions)

Questions

Some hand written examples2. mole > gas volumes (STP + NTP)

Some hand written examples3 mole > mass

Some hand written examples3 mole > mass