Unit 1 - Section 2

Question 1

What is Avogadro’s constant?

Answer 1

6.02 x 10^23

Question 2

How do calculate the number of moles using concentration?

Answer 2

Concentration x volume (in dm^3)

dm^3 = cm^3 / 1000

Question 3

What is the ideal gas equation?

Answer 3

pV = nRT

p = pressure (in Pa)
V = volume (in m^3)
n = moles
R = gas constant = 8.31
T = temperature (in kelvin)

Question 4

How do you write an ionic equation?

Answer 4

1. First balance the equation
2. Write the dissolvable ions out separately
3. Cancel out the repeated ions on both sides of the equation

Question 5

How do you calculate masses?

Answer 5

1. Balance the equation
2. Work out how many moles of the reactant you have
3. Use the molar ratio from the balanced equations to work out the moles of products made
4. Calculate the mass from the mole found

Question 6

How do you preform titration?

Answer 6

Add a known volume of an unknown concentration of alkali solution to a beaker and add an indicator

Then add a known concentration acid to the beaker in till the alkaline neutralises and the indicator changes colour. Use the volume of acid added to work out the mole of the acid added by, concentration x volume.

Use this mole to calculate the concentration of the alkaline as the mole will be the same as the acids

Question 7

What is the empirical formula?

Answer 7

The smallest whole number ratio of atoms in a compound

Question 8

What is the molecular formula?

Answer 8

The actual number of atoms in a molecule

Question 9

How to calculate the theoretical yield?

Answer 9

1. Work out how many moles of the reactant you have
2. Use this to work out how many moles of the product you would expect to get
3. Calculate the mass from the mole and this is the theoretical yield

Question 10

How to calculate the percentage yield

Answer 10

Actual yield
———————— x 100
Theoretical yield

Question 11

What is the atom economy equation?

Answer 11

Molecular mass of desired product
Decided by
Sum of molecular mass of all reactants
x 100