Observing Chemical Reactions (Can Be Used For Assessment Layout Or For Actual Prac)
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Writing Practical Reports
Aim:
To observe what happens during and after a chemical reaction.
Equipment:
Concentrated nitric acid in a glass dropping bottle
Small pieces of Copper
250ml Beaker
2 M Lead nitrate in a dropping bottle
2 M Potassium iodide in a dropping bottle
2 M Copper sulfate in a dropping bottle
2 M Sodium hydroxide in a dropping bottle
2 M Hydrochloric acid in a dropping bottle
4 Pyrex test tubes
Test tube rack
Spatula
Bunsen burner, gauze mat
Sandpaper
Magnesium Ribbon
Tongs
Safety glasses
Procedure:
This is a teacher-only demonstration.
Place a 250ml Beaker in the fume cupboard. Place the pieces of Copper into the Beaker and add 150ml of concentrated nitric acid to the beaker.
Add Potassium iodide to a test tube to the level of about 1cm. Add approximately the same amount of Lead nitrate to the test tube.
Add a small amount of Copper carbonate powder in a test tube. Strongly heat the test tube in the Bunsen burner.
Clean some Magnesium ribbon with sandpaper and place it in a test tube that is about one-third full with Copper sulfate.
Add a small amount of Hydrochloric acid to some sodium Hydroxide in a test tube. Feel the base of the test tube during the reaction.
Hold a piece of Magnesium ribbon in a pair of tongs and ignite the Magnesium by holding it in a Bunsen burner flame: Caution: Do NOT look at burning Magnesium directly – look at it from off to the side.
Results:
Reactants
Changes observed
Concentrated nitric acid and copper
Froff, bubbles, brown smoke, original transparent liquid went green
Potassium iodide and lead nitrate
Went a yellow, paint resembling liquid
Copper carbonate powder and ?
Went black, the burnt powder raised to the top but as it got close to the tip dropped to the bottom and let of green smoke
Magnesium ribbon and copper sulfate
Fizzed and then dissolved the ribbon itself
Hydrochloric acid and sodium hydroxide
Bubbled