Calculations from equations

Question 1

5 steps to approach a calculation involving mass?

Answer 1

1. Write a balanced equation
2. Identify the 2 chemicals referred to in the question and write the mole ratio
3. Calculate the moles of the substance you have been given a mass for
4. Use the mole ratio to calculate the number of moles of the others substance
5. Calculate the mass

Question 2

6 steps to tackle calculations involving volumes and concentrations of solutions?

Answer 2

1. Write a balanced equation
2. Identify the 2 chemicals referred to in the question and write the mole ratio
3. Write down volumes (in litres) and the concentrations under the reactants
4. Calculate the number of moles of the chemical with the most information
5. Use the mole ratio to work out the moles of the other reactant
6. Calculate volume, concentrations or mass of the chemical you’re asked about

Question 3

How would you go about solving calculations involving excess reactant?

Answer 3

1. Show by calculation which reactant is in excess (calculate the number of moles and check the ratio)
2. Calculate the value you need using the reactant that is NOT in excess

Question 4

What is molar volume?

Answer 4

The concept that the volume of 1 mole of any gas is the same, provided the temperature and pressure are constant

Question 5

Molar volumes equation:

Answer 5

V = n MV

Question 6

What is the atom economy of a reaction with one product?

Answer 6

100%

Question 7

What is the equation that combines heat energy and enthalpy change?

Answer 7

DeltaH= - Eh/n