Reversible and Irreversible Changes
Use bunsen burners to heat samples of exciting chemicals and see how they change. An introduction to chemistry.
Risk Assessment
| Activity | Hazard | Precaution | Risk |
|---|---|---|---|
| Chocolate | Contamination | Use sealed, wrapped bars | Very low |
| Egg | Burns | Ensure egg has sufficient time to cool in advance of workshop | Very low |
| Bunsens | Burns | Clear demonstrationat start of activity covering • Air & gas controls • Lighting • Safety flame • Roaring flame •Half flame | Low |
| Heating chemicals | Burns | Clear demonstrationof how to heat chemicals • Safety goggles • Close supervision during heating •Special instructions before heating wax, ice and copper •Wooden “clothes peg” test-tube holders used •Test-tubes in racks •Heat-proof mats on desks | |
| •zinc oxide | Non-hazardous | Very low | |
| • copper sulphate | Harmful if swallowed. Can irritate sensitive skin | Safety warning at start. Pre-dispensed in test-tube so no direct contact | Low |
| •ammonium chloride | Possible reaction with potassium manganate (VII) | Pre-dispensed in separate test-tubes | Low |
| •copper carbonate | • Harmful if swallowed •Irritant if inhaled | Pre-dispensed in test-tubes stopper with ceramic wool | Low |
| •copper metal | Non-hazardous | Very low | |
| •wax | Flammable if over heated | Clear instructions Ensure students stop heating when melted Stoper with ceramic wool | Low |
| •potassium manganate VII (potassium permanganate) | Oxidising agent Harmful if swallowed | Avoid contact with wax and ammonium chloride Pre-dispensed in separate test-tubes | Low |
| • Ice | Scald hazard from steam | • Use boiling tubes •Clear instructions on. •Close supervision during experiment | Low |
| Ice Cream (if made) | Contamination Over freezing | •Food grade materials stored in food grade conditions only to be used •Ice cream made indirectly in metal bowl over liquid nitrogen • Ice cream beaten thoroughly whilst freezing and removed from coolant when sufficiently stiff. • Ice cream portions i | Very low Low |
