Ultimate Toolkit for HSC Chemistry Module 8 [Cheatsheet]

Need help studying for HSC Chemistry Module 8? Read this guide to equip yourself with all the tools you need to ace Module 8 Applying Chemical Ideas.

What do you need to know to ace HSC Chemistry Module 8 Applying Chemical Ideas?

As the module name suggests, a majority of HSC Chemistry Module 8 exam questions are application questions. This means that students must draw from their knowledge of various key chemical ideas to solve a problem. 

In this article, you will find all the useful tables and chemical equations you need to analyse both inorganic and organic substances along with practice exam-style questions.

We discuss:


Key chemical reactions for HSC Chemistry Module 8

Acid-carbonate reaction

Acids react with metal carbonates to form water, carbon dioxide and a salt.

acid + carbonate → water + salt + carbon dioxide

eg. 2HCl(aq) + Na2CO3(aq) → H2O(l) + 2NaCl(aq) + CO2(g) 

Since carbon dioxide is produced during this reaction, gas bubbles will be observed. This appearance of bubbles is referred to as effervescence and allows for carbonate anions (CO32-) to be easily identified through the addition of an acid.


Complexation reactions

Complexation reactions are often used to identify cations. The two complexation reactions you should memorise are: 

  1. The reaction of iron (III) ions with thiocyanate ions to form a dark red complex. 
  2. The reaction copper(II) ions with ammonia (NH3) to form a deep blue [Cu(NH3)4]2+ complex.


Solubility rules

Memorising the solubility rules is crucial to your success in HSC Chemistry. 

Nitrate , ammonium and Group 1 salts (except ) are always soluble. You can recall most exceptions using the Ksp data in HSC Data Sheet.

Typically, the solubility of compounds is defined as follows:

  • A soluble substance will dissolve more than 10 g/L.
  • A slightly soluble substance will dissolve at 1-10 g/L.
  • An insoluble substance will dissolve less than 1 g/L.

You are not expected to know the solubility of Hg2+ or Sr2+ salts for the HSC


Knowing the solubility rules will not only help you answer questions in HSC Chemistry Module 8, but will help you assign states when writing out chemical reactions. 


Failing to memorise the solubility rules is one of the biggest mistakes students make going into their HSC Chemistry exam.


Compound colours

The colour of aqueous solutions and precipitates can indicate the presence of certain ions in an unknown sample.

The table below shows the colours of some common ionic compounds.

The colours of some precipitates are due to additional reactions (indicated by *), and these exceptions are summarised below.

  • Copper(II) iodide: unstable, forming copper(I) iodide (off-white).
  • Iron(II) phosphate/carbonate/hydroxide: the pure form is white, but in solution, they form basic iron(II)-iron(III) (green) and iron(III) hydroxide (orange-brown).
  • Iron(III) carbonate: unstable, forming iron(III) hydroxide (orange-brown).
  • Silver(I) hydroxide: unstable, decomposing to form silver(I) oxide (dark brown).

Ag+ halide precipitates decompose with exposure to light to form Ag(s). This is observed as darkening of the solid.


Question 1   (6 marks)

Write the net ionic equations for any precipitation reactions that may occur between the following compounds. If a precipitate is formed, identify its colour.

a) Ammonium nitrate + sodium phosphate

b) Lithium carbonate + iron(II) chloride

c) Potassium hydroxide + iron(III) chloride

See Question 1 Solution



Characteristic flame test colours

The following table outlines the flame test colours you are expected to know for HSC Chemistry Module 8.

Metal IonColour
Ba2+Pale green (apple green)
Ca2+Brick red (orange-red)
Cu2+Green (copper(I) or halide = blue-green)
Mg2+No characteristic flame colour*
Ag+No characteristic flame colour

*Magnesium metal will give intense white colour as it reacts with oxygen.

Question 2   (6 marks)

A student performed some diagnostic tests to identify the cations of three nitrate solutions. Her observations are described below:

XPrecipitate formed with sodium sulfate solution. An apple green colour resulted when solution X was sprayed into the Bunsen flame.
YYellow precipitate formed with potassium iodide solution. The precipitate darkens with exposure to light.
ZPrecipitate formed with sodium hydroxide solution. An emerald green colour was observed when solution Z was sprayed into the Bunsen flame.


The possible cations are Cu2+, Na+, Pb2+, Ba2+, Ca2+ and Ag+. Identify the cation in solution X, Y and Z. Explain your answer and include relevant equations.

See Question 2 Solution


Basic and neutral ions

For anion identification, testing the pH of a solution can be used to narrow down the possible anions in a solution.

  • Anions which are the conjugate bases of weak acids will produce a basic solution when dissolved in water.
  • Anions which are the conjugate bases of strong acids will dissolve to produce a solution with a neutral pH.

This is summarised in the table below.

Basic IonsNeutral Ions
Hydroxide (OH)

Acetate (CH3COO)

Carbonate (CO32-)

Phosphate (PO43-)

Chloride (Cl)

Bromide (Br)

Iodide (I)

Sulfate (SO42-)


Question 3   (4 marks)

Identify a test that can be used to distinguish between the following pairs of ions and give the expected results.

a) Cl and OH

b) CO32- and PO43-

See Question 3 Solution


Chemical tests for organic compounds

To determine the presence of different functional groups, various chemical tests can be performed. These tests include the

  • bromine water test,
  • sodium metal test,
  • reaction with acidified permanganate,
  • litmus test and
  • reaction with sodium carbonate.

The following table summarises the expected results of each test.

TestC=C double bondAlcoholCarboxylic acid
Bromine waterDecolourisesNo immediate colour change (may change with heating but this can be ignored)No colour change
Sodium metal testNo reactionEffervescesEffervesces
Reaction with acidified MnO4DecolourisesDecolourisesNo colour change
Blue litmusStays blueStays blueTurns red
Reaction with sodium carbonateNo reactionNo reactionEffervesces


The following flow chart illustrates a possible analysis sequence to distinguish between a carboxylic acid, alcohol, alkene and alkane using the tests outlined above.

HSC Chemistry Module 8 - Functional Group Analysis


Question 4   (3 marks)

Describe a sequence of tests that could be performed to distinguish between pure samples of hex-2-ene, acetic acid and propan-1-ol. 

See Question 4 Solution


Common mass fragments

The table below shows some commonly observed fragments in mass spectra.

15HSC Chemistry Module 8 - Common Mass Fragments
17HSC Chemistry Module 8 - Common Mass Fragments
29HSC Chemistry Module 8 - Common Mass Fragments
31HSC Chemistry Module 8 - Common Mass Fragments
43HSC Chemistry Module 8 - Common Mass Fragments
45HSC Chemistry Module 8 - Common Mass Fragments



Infrared absorption data

BondWavenumber / cm-1
3300 – 3500
3230 – 3550
C—H2850 – 3300
2500 – 3000
(very broad)
C\equivN2220 – 2260
C=O1680 – 1750
C=C1620 – 1680
C—O1000 – 1300
C—C750 – 1100


Question 5   (3 marks)

A sample of solvent was analysed by mass spectrometry and infrared spectroscopy. The following data were collected:

  • Mass spectrum: peaks at m/z = 15, 17, 29, 46
  • Infrared spectrum: broad peak at 3316 cm-1

Explain how the spectral data is evidence that the solvent is ethanol.

See Question 5 Solution


13C NMR chemical data shift

Type of carbon\delta/ppm
HSC Chemistry Module 8 CNMR Data5 – 40
HSC Chemistry Module 8 CNMR Data10 – 70
HSC Chemistry Module 8 CNMR Data20 – 50
25 – 60

alcohols, ethers or esters
50 – 90
90 – 150
110 – 125
110 – 160

esters or acids
160 – 185

aldehydes or ketones
190 – 220


UV absorption

(This is not a definitive list and is approximate.)

Chromophore\lambda_{max} (nm)
C\equivC173            178
196            222


The last three tables can be found on the NESA HSC Chemistry Formula and Data Sheet or on Learnable’s online, mobile friendly version.


Solutions to HSC Chemistry Module 8 practice questions

1a) No reaction

b) Fe2+(aq) + CO32-(aq) → FeCO3(s)      grey precipitate

c)Fe3+(aq) +3OH(aq) → Fe(OH)3(s)       brown precipitate

Back to question 1 

2X is Ba2+. Barium forms a white precipitate with sulfate ions:

Ba2+(aq) + SO42-(aq) → BaSO4(s)

Barium also gives off an apple-green colour during a flame test.

Y is Ag+. Silver forms a yellow precipitate with iodide ions:

Ag+(aq) + I(aq) → AgI(s)

Silver iodide precipitates darkens in light.

Z is Cu2+. Copper forms a precipitate with hydroxide ions:

Cu2+(aq) +2OH(aq)→ Cu(OH)2(s)

An emerald green coloured flame is characteristic of Cu2+.

Back to question 2

3a) Check pH of solution: OH solution is basic, Cl solution is neutral.

Add Ag+ (e.g. AgNO3): AgOH precipitate decomposes to brown Ag2O, AgCl precipitate is white and darkens in light.

Add Cu2+, Fe2+ or Fe3+: OH forms precipitates, Cl does not.


b) Add acid (e.g. HCl): CO3 forms bubbles, PO43- does not.


Note: Multiple answers are possible

Back to question 3

4Place 1 mL of each sample into separate test tubes. Add 5 drops of bromine to each. The sample that decolourises the bromine is hex-2-ene.

Place 1 mL of the remaining samples into separate test tubes. Add 0.5 mL sodium carbonate solution to each. The sample which produces bubbles is acetic acid. The remaining sample is propan-1-ol.

Back to question 4

5The peaks in the mass spectrum match molecular fragments derived from ethanol:

m/z = 15: [CH3]+

m/z = 17: [OH]+

m/z  = 29: [CH3CH2]+

m/z = 46: [CH3CH2OH]+ (molecular ion)

The broad IR absorbance at 3316 cm-1 is consistent with a vibration of the O–H bond in an alcohol.

Back to question 5 



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Written by Varisara Laosuksri

Varisara is a 2019 St George Girls High School graduate who achieved Band 6 in her HSC Chemistry and Physics.

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