JSSS
Teacher Support Material
Carbon Dioxide
OC27, OC28, OC29
The apparatus being used for the preparation of carbon dioxide is the same as that used for
oxygen. Carbon dioxide can be collected over water as it is only slightly soluble.
The apparatus used is of the traditional nature. A plastic 50 cm3 syringe, rather than a thistle
funnel, allows the release of the hydrochloric acid
i,
and hence that of the carbon dioxide, to
be controlled. A dropping funnel could be used instead of the 50 cm3 plastic syringe. The gas can
be produced in a side-arm flask or side-arm test tube. A side-arm test tube can be placed in a test
tube rack and so there is no need for a retort stand.
The water ‘trough’ used is a plastic food / ice cream container. The delivery tube is pushed
through a hole melted in the side of the plastic container. Test tubes are used for collecting the
carbon dioxide. This method works well as the volumes of gas required for any tests are small
and the gas samples are collected very quickly. The test tube can be hand held over the delivery
tube, doing away with the need for a beehive shelf. A weight or washer near the end of the
delivery tube helps to keep it in place under the water. Test tubes can be filled with water in the
trough and left lying in the trough until needed.
The syringe, side-arm test tube, delivery tube, 6 test tubes and stoppers can be stored in the
plastic container. This then is a gas preparation kit. A number of them could be made up and
kept together. The same kit can be used for the preparation of other gases.
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