Amount of substance

Question 1

What is Avogadro’s constant?

Answer 1

6.02 x10^23

Question 2

What does each letter stand for in the ideal gas equation?

Answer 2

-pV=nRT
-p=pressure (Pa)
-V=volume (m^3)
-n=number of moles
-R=gas constant (8.31J/K/mol)
-T=temperature (K)

Question 3

What are the main two indicators used in titrations?

Answer 3

-Methyl orange
-Phenolphthalein

Question 4

How do you calculate empirical formulas?

Answer 4

1. Assume you have 100g of the compound, turn the percentages into masses.
2. Calculate the moles of each element.
3. Divide each number of moles by the smallest to find the ratio.
4. Apply the numbers from the ratio to the formula.

Question 5

How do you calculate molecular formula?

Answer 5

1. Fine empirical mass (Mr of empirical formula).
2. Divide relative molecular mass by empirical mass.
3. Multiply empirical formula by that number to find molecular formula.

Question 6

How do you calculate theoretical yield?

Answer 6

1. Work out moles of the reactant.
2. Use equation to work out moles of product you would expect.
3. Calculate mass.

Question 7

What is the equation for percentage yield?

Answer 7

Actual yield/Theoretical yield x100

Question 8

What are the advantages of a high atom economy?

Answer 8

-Economic–> more efficient use of raw materials
-Environmental–> more sustainable, less waste

Question 9

What is the equation for atom economy?

Answer 9

Molecular mass of desired product/sum of molecular masses of reactants x100