The water from copper(II) sulfate solution is evaporated and some of it is condensed using simple apparatus.
This is a simple introduction to aqueous solutions. Water is the solvent and it is only water that distils off when a solution is boiled. Other coloured solutions can be used – ink was the traditional one, but few students will still use ink pens and fewer will be aware of ‘bottles of ink’.
This is quite a complicated apparatus to set up at what might be an early stage of the students’ chemical careers. It is recommended that the flasks are set up with delivery tubes for the students. The clamped apparatus should also be set up in advance for the students if there are any doubts about their ability to do this correctly.
Pupils must be standing up while practical work is being carried out.
More water can be condensed if a beaker of water is held round the collecting tube. This leads to the idea of a water condenser as a more efficient way of collecting the water. See experiment Recovering pure water from a solution using a water condenser.
The experiment will take about 20 minutes.
Each group of students will need:
Conical flask, 100 cm3
Cork or bung with hole for delivery tube, to fit flask (see diagram)
Lengths of glass tubing, bent as shown in the diagram
Rubber connection tubing
Stand and two clamps
Tripod and gauze
Heat resistant mat
Measuring cylinder, 25 cm3
Copper(II) sulfate(VI) solution, about 0.5 M, 20 cm3 per group
Refer to Health & Safety and Technical notes section below for additional information.
Health & Safety and Technical notes
Wear eye protection throughout.
Copper(II) sulfate(VI) solution, CuSO4(aq) - see CLEAPSS Hazcard and Recipe Book.
The solution left in the flask should be recycled by diluting after the experiment (the exact concentration is not important, but note that solutions of greater concentration than 1 mol dm–3should be labelled HARMFUL)
a Set up a Bunsen burner on the base of a stand placed on a heat resistant mat.
b Place a tripod and gauze above the burner.
c Clamp a flask and a test tube as shown in the diagram.
d Collect 20 cm3 of copper sulfate solution and place it in the flask.
e Fix the tubing in position as in the diagram.
f Light the Bunsen and heat the flask gently with a small flame. Do not heat to dryness.
g Water should distil over into the collecting tube.
The colourless liquid collected can be assumed to be water at this stage. The main point is that it is not blue. It may be possible to detect a darkening of the original solution, showing that it is becoming more concentrated.
Health & Safety checked, 2016
This Practical Chemistry resource was developed by the Nuffield Foundation and the Royal Society of Chemistry.
© Nuffield Foundation and the Royal Society of Chemistry
Page last updated October 2015
This is a resource from the Practical Chemistry project, developed by the Nuffield Foundation and the Royal Society of Chemistry. This collection of over 200 practical activities demonstrates a wide range of chemical concepts and processes. Each activity contains comprehensive information for teachers and technicians, including full technical notes and step-by-step procedures. Practical Chemistry activities accompany Practical Physics and Practical Biology.