Activity 1. Volumetric analysis

The sour taste of vinegar is due to the presence of ethanoic acid (CH₃COOH). Ethanoic acid is a weak acid that is only partially ionised in water.

The concentration of ethanoic acid in a particular sample of vinegar can be determined by neutralising the vinegar with a base such as sodium hydroxide of known concentration. 4 The more sodium hydroxide that is required for the

reaction, the more ethanoic acid is present in the vinegar.

 60 minutes

 Chemistry_QLD12_19_1.spklab

Activity 2. Simple displacement reactions

By definition, reduction is a gain of electrons and oxidation is a loss of electrons. In single displacement reactions in aqueous solutions, the metal loses its electrons to the metal ion in solution. This is a redox reaction. The metal losing its electrons is the reductant and the metal gaining electrons is the oxidant.

Single displacement reactions only occur if the metal is more reactive than the metal ions in solution and as such will give away its electrons. A reactivity series can be developed based on this, with the more reactive metals, those more easily oxidised, sitting higher in the series than those less easily oxidised.

 50 minutes

 Chemistry_QLD12_19_2.spklab

During the operation of a galvanic cell, the relative abilities of the chemical species in the half-cells to donate and accept electrons determine which electrode is positive and which is negative. The half-cell containing the stronger reducing agent will undergo an oxidation reaction; the electrode in this half-cell is the anode and will be negative. The other half-cell will contain the stronger oxidising agent and undergo a reduction reaction. The electrode in this half-cell is the cathode.

Activity 4. Modelling the structure of organic compounds

Physical representation of the bonding and structure of organic molecules enables scientists to identify:

• similarities and differences in the classes of organic compounds

• the various isomerisms that can occur—structural and geometrical isomers

Through this modelling practical, you should recognise the limitations within the models scientists use to describe the various structures seen in the classes of organic compounds.

Up to 90 minutes, depending on number of models constructed

 Chemistry_QLD12_19_4.spklab