Learner resource 1 – Gas tests
Equipment:
New undamaged test tubes, 4 per group
Test tube rack
4x solid rubber bungs
2x 10 cm3 measuring cylinders
Plastic dropping pipette (disposable)
For hydrogen:
Small coil magnesium ribbon
10cm3 1.0 mol/dm3 HCl
For oxygen:
Spatula tip (tiny) MnO2 powder
5cm3 6% H2O2
For carbon dioxide:
1 medium marble chip
10cm3 1.0 mol/dm3 HCl
For chlorine (teacher demonstration):
Large spatula tip KMnO4
2cm3 concentrated HCl (using a dropping pipette)
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Method
Take 4 test tubes and carefully place in a test tube rack; replace any with damage to the
mouth, as this will allow gas to escape.
For each gas in turn place the solid in the bottom of the test tube. One by one add the
relevant liquid and immediately place the bung upside down on top of the tube. After a few
seconds test as appropriate and record your findings.
Tests
Hydrogen:
Bring a lit splint to the mouth of the tube, lift the bung and quickly pass the splint into the
mouth.
Oxygen:
Bring a glowing splint to the mouth of the tube, lift the bung and quickly plunge the splint into
the tube.
Carbon dioxide:
Bring a lit splint to the mouth of the tube, lift the bung and quickly plunge the splint into the
mouth of the tube.
Chlorine:
Bring a piece of damp blue litmus to the mouth of the tube, lift the bung and place the paper
in the mouth of the tube. Care here! Two observations should be made.
All residues should be collected and returned to the laboratory technician for disposal.
Health and safety
Refer to CLEAPPs student safety pages for details.
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Version 1
Predicting chemical reactions
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© OCR 2016