Have you started studying Unit 3 of QCE Chemistry in class but are a little confused about what you’re meant to be learning? No worries, we’re here to help!
To make things easier for you, we’ve broken down what you’ll be learning in each of the topics for Unit 3 of QCE Chemistry and what assessments you’ll be completing.
So what are you waiting for? Let’s get started!
What is Unit 3 in QCE Chemistry all about?
Topic 1: Chemical Equilibrium Systems
Topic 2: Oxidation and Reduction
QCE Chemistry Unit 3 Assessments
Study Tips
What is Unit 3 in QCE Chemistry all about?
Unit 3 is the first of your two formative senior units for QCE Chemistry. This means thatthe assessments you complete for this unit will count towards your ATAR.
The unit is split into two topics:chemical equilibrium systems, and oxidation and reduction,which cover a variety of subtopics from equilibrium constants to electrolytic cells.
We’ll break down each of these topics so you know exactly what you’ll be studying!
Topic 1: Chemical Equilibrium Systems
Chemical Equilibrium
This subtopic covers:
- open VS closed chemical systems
- forwards VS reverse reactions
- reversibility/irreversibility of physical VS chemical changes
- what it means for a system to have reached a dynamic equilibrium
- observable chemical and physical changes of a chemical system and what they mean at an atomic and molecular level
When studying this area, it may be helpful torevise the following topics:
- Unit 1 Topic 3: Chemical reactions: reactants, products and energy change
- 第二单元主题3:Rates of chemical reactions
Factors that Affect Equilibrium
This subtopic covers:
- the effect that increasing or decreasing temperature, pressure or concentration can have on a particular chemical system at equilibrium
- understanding and applying Le Châtelier’s principle
Equilibrium Constants
This subtopic covers:
- understanding that the equilibrium constant (KC) is a ratio of the product and reactant concentrations at equilibrium
- understanding how to apply theKCformula
Relevant Formulas
Properties of Acids and Bases
This subtopic covers:
- understanding that acids dissociate to produce H+ions
- understanding that bases dissociate to produce OH–ions
- monoprotic VS diprotic VS polyprotic donors
- strong acids/bases: completely dissociate (e.g. hydrochloric acid)
- weak acids/bases: partially dissociate (e.g. ethanoic acid)
- concentrated acids/bases: have many acid/base molecules
- dilute acids/bases: have few acid/base molecules
Learn more about the strength of acid baseshereon QCETogether!
pH Scale
This subtopic covers:
- understanding thatKWcan be used to calculate the concentration of hydrogen ions from the concentration of hydroxide ions in a solution
- understanding that the pH scale is a logarithmic scale
- using appropriate formulas and convention to complete relevant calculations
Relevant Formulas
- self-ionisation of water:KW= [H+][OH–]
- pH= –log10[H+]
Brønsted-Lowry Model
This subtopic covers:
- theBrønsted–Lowry model definition of acids and bases
- conjugate acids vs conjugate bases and how to identify them
- amphiprotic species
- what buffer solutions are and how they respond to the addition of hydrogen and hydroxide ions
Dissociation Constants
This subtopic covers:
- understanding that that the strength of acids is explained by the degree of ionisation at equilibrium in an aqueous solution
- calculating dissociation constants (and) as well as concentrations of reactants and products via the appropriate formulas
- understanding that a highvalue correlates to more product dissociated, stronger acidity, lower pH, higher[H+]
- and lower pKa and vice versa
Relevant Formulas
Acid-Base Indicators
This subtopic covers:
- understanding that an acid-base indicator is a weak acid or a weak base and why the colour change occurs at a certain pH
- understanding that the relationship between the pH range of an acid-base indicator and its pKa value
- understanding that indicators change colour when pH = pKa
- determining appropriate indicators for titrations given the equivalence point and the range of the indicator
Image sourced from Oxford Chemistry Units 3 & 4
Image sourced from Chemistry 2019 Formula and data book
Volumetric Analysis
This subtopic covers:
- equivalence point vs endpoint
- significance of equivalence point and how it is measured
- sketching titration curves and identifying/labelling intercept with pH axis, equivalence point, half-equivalence point, end point and buffer region
- calculating moles, volume and concentration from volumetric data analysis
Image sourced from Lumen Learning
Topic 2: Oxidation and Reduction
Redox Reactions
This subtopic covers:
- understanding that redox reactions involve oxidation of one substance and reduction of another substance
- types of redox reactions e.g. combustion, displacement of metals, corrosion
- understanding how an atom’s position in the periodic table relates to its ability to gain or lose electrons
- identify oxidised and reduced species in redox reactions
- applying Oxidation Number Rules to deduce oxidation states of atoms in an ion or compound
Electrochemical Cells
This subtopic covers:
- understanding that electrochemical cells consist of oxidation and reduction half-reactions connected via an external circuit that allows electrons to move from the anode (oxidation reaction) to the cathode (reduction reaction)
Galvanic Cells
This subtopic covers:
- understanding that galvanic cells generate an electrical potential difference from a spontaneous redox reaction
- understanding that oxidation occurs at the negative electrode (anode) and reduction occurs at the positive electrode (cathode)
- describing and labelling the components of a galvanic cell on a diagram, including: the oxidation and reduction half-cells, the positive and negative electrodes and their solutions of their ions, the flow of electrons, the movement of ions and the salt bridge
Things to Remember
- anode is negative (-)
- cathode is positive (+)
- spontaneous reaction occurs
- does not require external energy source
- converts chemical energy into electrical energy
- EMF is positive (+)
Image sourced from Oxford Chemistry Units 3 & 4
Standard Electrode Potential
This subtopic covers:
- 理解标准电极潜能l is the electrical potential than an electrode generates under standard conditions
- determining the relative strength of oxidising and reducing agents by comparing standard electrode potentials
- understanding that the limit of standard electrode potentials is that they can only be applied to aqueous equilibrium
- using appropriate formulas and convention to complete relevant calculations
Section of the Electrochemical Series Table
Image sourced from Oxford Chemistry Units 3 & 4
Relevant Formulas
- EMF=E°reduction half-cell—E°oxidation half-cell
Electrolytic Cells
Things to Remember
- anode is negative (-)
- understanding that electrolytic cells use an external electrical potential difference to provide the energy to allow a non-spontaneous redox reaction to occur
- predicting and explaining the products of the electrolysis of a molten salt and aqueous solutions of sodium chloride and copper sulfate
- describing and labelling the components of a galvanic cell on a diagram, including source of electric current and conductors, positive and negative electrodes and the electrolyte
Things to Remember
- cathode is negative (-)
- anode is positive (+)
- non-spontaneous reaction occurs
- requires external voltage source
- converts electrical energy into chemical energy
- EMF is negative (-)
Image sourced from Oxford Chemistry Units 3 & 4
QCE Chemistry Unit 3 Assessments
#1: IA1 – Data Test
It will assess your ability to interpret and analyse data from various data sets and constitutes 10% of your overall grade. For IA1 practice questions, seeQCE Unit 3 Chemistry Data Test IA1 – Practice Questions!
#2: IA2 – Student Experiment
It will assess your ability to create a research report based on an experiment that you conduct. It constitutes 20% of your overall grade. To find out how to write your student experiment, seeThe Definitive Guide to Writing a Student Experiment Report for QCE Chemistry!
#3: EA – External Assessment
It is an exam that consists of both Unit 3 and 4 content and constitutes 50% of your overall grade. To find out how to best prepare for the external assessment, seeHow to Ace Your External Assessment for QCE Chemistry.
For practice questions, see:
- QCE Multiple Choice Practice Questions for Unit 3 & 4 Chemistry External Assessment
- QCE Practice Questions for Unit 3 & 4 Chemistry External Assessment
- Download QCE Chemistry Practice Exam for External Assessment Revision
Tips for Study
#1: Create a revision table like the one below using the syllabus dot points to guide you
#2: Get visual!
Use diagrams, flowcharts and other visual forms of displaying information where you can when making your notes.
#3: Don’t forget examples
Include examples of each concept you learn about. For example, when learning about buffer solutions, make sure to include examples of a few relevant buffer solutions.
#4: Manage your time well
The syllabus has a guide to how much time should be spent on each subtopic. Although this guide is technically for teachers and their lesson planning, you as a student can also use it to help guide your study (i.e. to figure out what topics may be more important and therefore require more study time)
Are you looking for some extra help with revising QCE Chemistry Unit 3?
我们有一个令人难以置信的股价化学教师团队s and mentors!
We can help you master the QCE Chemistry syllabus and ace your upcoming Biology assessments with personalised lessons conducted one-on-one in your home or online!
We’ve supported over8,000 students over the last 11 years, and on average our students score mark improvements of over 20%!
To find out more and get started with an inspirational QCE tutor and mentor,get in touch todayor give us a ring on1300 267 888!
Yalindi Binduhewais an Art of Smart tutor based in Queensland and was part of the very first cohort to go through the ATAR system, so she knows exactly how fun and enjoyable it can be. She is currently studying a Bachelor of Medical Imaging (Honours) at QUT and is loving it. When she’s not doing uni-related stuff or tutoring, she’s hanging out with her friends, rewatching a show for the 100th time, or trying out new crafty projects and discovering that she doesn’t have a talent for everything.
