This section is not limited to any particular year but covers general skills that you should know by CE. If you are in year 7 and have not covered some of this work do not worry.  If you are unsure come and ask us or drop us an email.  ABT / CLP

Collection of gas over water

When a gas is generated as a product of a reaction and does not dissolve readily in water, it can be “collected over water” This method is shown in the diagram below. The tap funnel contains the liquid reagent (A) and the conical flask the solid reagent. The liquid reagent is slowly dripped onto the solid reagent and the gaseous product has only one place to go - through the delivery tube and bubbled through the water into the gas jar (B)

The first gas jar of gas will contain predominantly air that has been displaced from the apparatus, therefore several jars of gas will need to be collected.

This apparatus can be used to collect oxygen when hydrogen peroxide (liquid) is broken down using the manganese dioxide catalyst (solid)

It can also be used to react acid with metals.

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