Principles Of Chemistry - Chemical Formulae, Equations And Calculations

Question 1

How do you calculate the relative formula mass?

Answer 1

Sum of Mr of reactants in quantities shown = sum of Mr of products in quantities shown

Question 2

What are chemical amounts measured in?

Answer 2

Moles (mol)

Question 3

How do you convert between grams and moles?

Answer 3

Mass = moles x relative atomic mass

Moles = mass / relative atomic mass

Question 4

How to find the moles of a substance?

Answer 4

Moles = mass/ molar mass

Question 5

How do you calculate percentage yield?

Answer 5

Percentage yield = amount of product produced/ maximum amount of product possible x 100

Question 6

What are the 3 reasons that it is not always possible to obtain the calculated amount of a product?

Answer 6

1. The reaction may not be completed because it is reversible
2. Some of the product may be lost when it is separated from there reaction mixture
3. Some of the reactants may react in different ways to the expected reaction