Iron, 5 ˚C (slow to start, then fairly brisk reaction).The rise in temperature and vigour of the reactions will obviously depend mainly on the surface area of the metals and the actual concentration of the acid. Then repeat the experiment using each of the other metals in turn. Do not pour the metal and acid mixture into the sink. Discard the residues into the plastic bowl provided.Observe the temperature over the next few minutes until a maximum temperature is reached.Add the first of the powdered metals and stir the mixture with the thermometer.Measure and record the starting temperature of the acid.Measure 20 cm 3 of hydrochloric acid into the polystyrene cup.Put the cup into the empty 250 cm 3 beaker so that the cup is more stable.After neutralisation, the residue can then be poured down the foul water drain with a bucket of water. Any unreacted metal can be dissolved in dilute acid (in a fume cupboard). Do not let students discard residues into sinks. For disposal, provide a number of bowls (eg washing-up bowls) for the metal residues.Two spatula measures of each metal should be more than sufficient for each group. The metal samples can be provided in labelled plastic weighing boats, small beakers or watch glasses to prevent cross-contamination or wastage.A lid can be made by cutting a suitably-sized piece from a polystyrene ceiling tile and making a hole for the thermometer. It also prevents spillage if the student accidentally pokes the thermometer through the bottom of the polystyrene cup. A desirable, but not essential, addition is the provision of lids for the polystyrene cups. This provides a more stable reaction vessel. Typical expanded polystyrene cups fit snugly into 250 cm 3 squat form beakers.Hydrogen gas, H 2(g), (EXTREMELY FLAMMABLE) – see CLEAPSS Hazcard HC048.‘Powder’ refers to metal which is obviously ‘gritty’. Iron filings tend to be greasy and may need to be degreased with propanone (HIGHLY FLAMMABLE, IRRITANT – refer to CLEAPSS Hazcard HC085A) and dried before being provided to students. Powdered metals: aluminium, Al(s), copper, Cu(s), iron, Fe(s), magnesium, Mg(s) and zinc, Zn(s), (all HIGHLY FLAMMABLE) – see CLEAPSS Hazcards HC001A, HC026, HC055A, HC059A and HC107. The metals should be provided as powders or fine filings, or fine turnings, rather than fine powders or ‘dust’ (which are likely to be significantly oxidised).Dilute hydrochloric acid, HCl(aq), (IRRITANT) – see CLEAPSS Hazcard HC047a and CLEAPSS Recipe Book RB043. Each group of students can be provided with a 250 cm 3 beaker containing about 100 cm 3 of 2 M hydrochloric acid.Read our standard health and safety guidance.Aluminium powder (HIGHLY FLAMMABLE) (see note 4).Set of apparatus and chemicals as above.Large bowl for collecting the waste residues from the experiments (see note 8)įor the additional teacher-only demonstration.Powdered or finely-divided metals: magnesium, zinc, iron, copper (ALL HIGHLY FLAMMABLE) (see notes 4 and 7).Hydrochloric acid, approximately 2 M (IRRITANT) (see note 3 below).Beaker, 250 cm 3, to stand the polystyrene cup in for support.
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