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ExposeExciteIgniteMay2012

What you will need

What you will need Chemicals • Fine aluminium powder, 325 mesh or finer • Powdered sulfur • Dry white sand - beach sand or washed white builder’s sand • Hydrochloric acid, 4M (add 180 mL conc. HCl to 500 mL water) Initiator chemicals: • Fine magnesium powder & magnesium ribbon (5 cm) or Potassium permanganate (KMnO4) and glycerine • Extension chemicals: Sodium hydroxide solution, 5M (dissolve 50 g NaOH in 250 mL water) Other • Mortar & pestle • Small clay flower pot, ! 6.5 cm (2.5”) inside top diameter • 100 mL glass beaker & plastic container • Electronic balance, 100 g ± 0.1 g • Heat resistant pad (1 m x 1m) • Transparent safety shield or fume cupboard • Heat-protective gloves eg. welding gloves • Spatula & metal tongs • Fire lighter with long stem For Extension activities • Test tube, clamp & burner • Wires with croc clips (2) • Ammeter & battery pack • 3.2 V lamp in holder • Hammer & Nail Figure 6.2 Here’s how 1. Dry about 50 g of sand in an oven for 2 hours (! 180", 350!) and then grind the sand to a powdered form in a mortar and pestle. 2. Weigh and mix the following to form a homogenous mix: 8 g of dry aluminium powder 10 g of powdered sulfur 7 g of dry powdered sand 67

Figure 6.3 Figure 6.4 3. The best mix is obtained by shaking the mixture for a minute in a sealed plastic container (Figure 6.4). Do NOT grind them together in a mortar and pestle. Figure 6.5 4. Use the small clay flower pot. If it has a hole in the bottom - cover the hole with paper. Transfer all of the mix to the pot (Figure 6.5). 5. Make a small cone-shaped indentation at the top (2 cm deep and 2 cm wide) and fill this with magnesium powder to facilitate ignition. (For an alternative method see Note 1 below). Fray a 5 cm (2”) magnesium ribbon’s end with scissors. This will enlarge its surface area and aid ignition. Push this fuse into the magnesium powder pile. Safety: Position the pot on a heat resistant pad in a fume cupboard or outdoors away from any combustible material. Use a safety shield. Wear protective eye wear, gloves and a lab coat. 6. Light the frayed end of the magnesium ribbon using a long stemmed fire lighter (Figure 6.6). It may take a few seconds before the ribbon starts burning. Once this happens – step back immediately. Ignition of 68 Figure 6.6