Preliminary Chemistry Concepts You Need to Know for the HSC

You might already know that your marks from Year 11 Chemistry won’t count towards your HSC mark, but don’t throw out all your Year 11 notes just yet. The Preliminary Course is assumed knowledge for the HSC course, where you’ll be exploring the concepts you learned previously in greater depth.

Preliminary Chemistry Concepts You Need to Know for the HSC

We’ve put together a list of some of the most important concepts you need to know inside out to ensure you have a solid foundation for success in Year 12 Chemistry.

Mole Calculations

Moles are the central currency of chemistry. All throughout Year 12 (and later, if you decide to do science-related studies at university), you’ll be performing calculations where you’ll convert from moles to:

• mass
• concentration
• gas volume

and vice versa. You should have committed these equations to memory:

$$n = \frac{m}{MM}$$

$$n = \frac{PV}{RT}$$

$$c = \frac{n}{V}$$

You’ll also need to be able to solve straightfoward mole calculations as well as limiting reactant questions, where one or more reactants are left over after the reaction is complete.

Intermolecular Forces

In Year 11 chemistry, you learned about the three types of intermolecular forces that govern interactions between molecules:

• Dispersion forces
• Dipole-dipole interactions
• Hydrogen bonding

Questions will often need you to remember when each intermolecular force arises, what their strength depends on, and how they relate to physical properties like boiling point, volatility and solubility.

Ionic Formulae and Common Compounds

Can you quickly work out the formula of an ionic compound from its name? Then congratulations – you’re well on your way to acing Year 12 chemistry! If you’re a bit rusty, try to get in some revision before you get bogged down in assignments.

Polyatomic ions will frequently show up in questions too, as well as the formulae for common compounds like water, ammonia, hydrochloric acid and sulfuric acid.

Rate of Reaction and Enthalpy

The physical chemistry concepts you studied in the Preliminary Course will show up again in Year 12. This includes:

• factors that affect the rate of reaction
• reaction profile diagrams
• the difference between exothermic and endothermic reactions
• how to use the equation ∆H = mC∆T