Reacting Masses

Question 1

The number of moles of a substance can be found by using the following equation:

Answer 1

moles = mass / mr

mr= g/mol-1

mass=g

Question 2

It is important to be clear about the type of particle you are referring to when dealing with moles

E.g. … mole of CaF2 contains ….. mole of CaF2 formula units, but … mole of Ca2+ and moles of F- ions

Answer 2

1

1

2

Question 3

The masses of reactants are useful to determine how much

Answer 3

of the reactants exactly react with each other to prevent waste

Question 4

To calculate the reacting masses, the chemical equation is required

This equation shows the ratio of moles of all the reactants and products, also called the …………, of the equation

Answer 4

stoichiometry

Question 5

To find the mass of products formed in a reaction the following pieces of information are needed:

Answer 5

The mass of the reactants
The molar mass of the reactants
The balanced equation

Question 6

The gas volumes can be used to deduce the stoichiometry of a reaction
E.g. in the combustion of 50 cm3 of propane reacting with 250 cm3 of oxygen, 150 cm3 of carbon dioxide is formed suggesting that the ratio of propane:oxygen:carbon dioxide is 1:5:3
C3H8 (g) + 5O2 (g) → 3CO2 (g) + 4H2O (l)

Question 7

PRACTICE