Originally authored by Dr Hal Sosabowski University of Brighton.

Transcription

1 Opening a glowstick, removing the contents and showing the chemiluminescent reaction Supplementary Risk Assessment (to meet the COSHH and/or Management Regulations) Originally authored by Dr Hal Sosabowski University of Brighton. CLEAPSS would like to acknowledge the work of Dr Hal Sosabowski of University of Brighton in writing this SOP/RA and bringing this activity to our attention. He has demonstrated the procedure to numerous children and it was first broadcast on Rocket Science, BBC2 6 th March Details of operation: The demonstrator opens up a Glowstick, removes the chemicals and then either mixes them or allows the pupils to do the mixing Schools are advised not to deviate from the details described in this risk assessment. If any variation is required, members should contact CLEAPSS for a Special Risk Assessment. Obtaining Glowsticks: Illumiglow provide discounted 10-packs of each of the standard colours and the ultra-orange. They also provide a further discounted classroom pack of 40 glowsticks (10 of each of the colours and 10 of the orange ultra). sales@illumiglow.com or call Introduction: This procedure outlines a spectacular visible demonstration which shows that some reactions give out light rather than heat. Fireflies, glowworms and certain jellyfish glow using bioluminescence which involves the same type of mechanism as is Page 1 of 11

2 demonstrated in this manner. The two liquids in the test tubes are derived from commercially available glowsticks. Glowsticks consist of a tough, (normally) transparent polypropylene sleeve which contains a suspension of oxalate ester sensitizer (an organic dye which glows when oxidized by hydrogen peroxide) and a glass phial containing the hydrogen peroxide. The glowstick is activated by bending the tube until the phial is heard and felt to break, then shaking the stick. Whilst this approach is moderately interesting it doesn t appear particularly scientific to the pupils, and separating the reagents into test tubes which are then used to mix the raw reagents provides a more scientific learning outcome. After the experiment it may be an added item to then demonstrate the application of the science by breaking a real glowstick. Glowsticks are used for leisure activities but also have various commercial applications, they are used by divers, in environments where use of conventional light sources may be dangerous and by the military as a non-lethal method of destroying the opponents light vision (an adapted slow stick called a light-grenade). This procedure is valid for Illumiglow products only, from whom a teachers pack of 40 sticks (4 of each colour, red, yellow, green and ultra orange) can be purchased at a discount. This pack is sufficient for 3 complete demonstrations (4 colours x 3 sticks per colour) per experiment. Chemistry involved The reaction sequence shows that diphenyl ethanedioate is oxidisied with hydrogen peroxide the intermediate carbon dioxide dimer breaks apart to form carbon dioxide and activate the dye to a higher energy state. As this dye molecule relaxes to its ground state, energy is emitted as light. There is a good explanation of the chemistry on Page 2 of 11

3 Health & Safety: Chemicals Hazard Who may be harmed? Risks Control measures Hydrogen peroxide gel Whoever disassembles the glowstick, teacher/pupils mixing the liquids during the demonstration. Hydrogen peroxide gel: found inside the glowstick surrounding the internal glass phial. Causes irritation to skin and eyes. Residues in test tubes may affect glass-washing staff if unaware of their contents. The slightly viscous gel will increase its stickiness to the skin. PPE including nitrile gloves, safety glasses and lab coats to be worn at all times during preparation, execution and disposal of the demonstration. All surfaces to be wiped after the demonstration to remove any spilt peroxide. Peroxide-contaminated glassware to be rinsed with water and marked as may contain peroxide and/or phenol residues (see phenol table below) for the glass-washing staff. Hazard Who may be harmed? Risks Control measures Sensitiser dye (oxalate ester, stains clothing/skin). Whoever disassembles the glowstick, teacher/pupils mixing the liquids during the demonstration. The concentration of dye is so low that it presents no risk. Full PPE including lab coat. Well considered disposal of plastic sleeves. Benches to be wiped diligently after the demonstration. Hazard Who may be harmed? Risks Control measures Phenol, a by-product of the reaction. Whoever is in the vicinity of the tubes after mixing of the solution (teachers, pupils, and technical staff). The low concentrations of phenol coupled with the control measures mean that there is low risk. PPE including nitrile gloves, safety glasses and lab coats to be worn at all times during preparation, execution and disposal of the demonstration. Page 3 of 11

4 All surfaces to be wiped after the demonstration to remove any spilt phenol residue. Potentially phenol-contaminated glassware to be rinsed with water and marked as may contain peroxide and/or phenol residues for the glass-washing staff. Hazards of equipment Hazard Who may be harmed? Risks Control Measures Blade/knife used to open polypropylene glowstick sleeve. Whoever disassembles the glowstick. Potential to cut operator. Do not use a scalpel blade. Carry out glowstick dissection as per Image 3. Ensure thumb is not directly behind blade when cutting the glowstick sleeve. Do not cut all the way through the sleeve. Hazard Who may be harmed? Risks Control Measures Glass shards/ fallout/shrapnel. Whoever disassembles the glowstick. Potential for glass debris to cause harm to others later if it is left at the site of the demonstration. Cuts, eye trauma. Tube opening to be carried out over/partially inside a large sharps bin which will catch glass debris. This to be done at arm s length by operative (see Image 6). Wear goggles or consider face shield to supplement eye protection. Requirements: PPE (nitrile gloves, safety glasses and labcoat); Glowsticks (3 yellow, 3 red, 3 green and 3 orange ultra); Cutting knife (e.g. stout kitchen knife but NOT a scalpel which can break if used on polypropylene glowstick sleeve); Pliers; Sharps bin; Non-sharps bin; Laboratory absorbent roll; Wash bottle; 8 boiling tubes in a rack. Page 4 of 11

5 Procedure: (refer to the numbered images) Step 1: Illumiglow provide teacher s packs of yellow, green, red 12 hour glowsticks and also orange ultra (5 minute) in transparent form. Procedure: (refer to the numbered images) Step 1: Illumiglow provide teacher s packs of yellow, green, red 12 hour glowsticks and also orange ultra (5 minute) in transparent form. Image 1: The current range of Illumiglow glowsticks Step 2: There are also orange sticks in coloured polypropylene. The old version of the red were similarly coloured by the sleeve rather than the sensitizer. These should be avoided since the colour is derived from the plastic rather than the oxalate ester sensitizer, and when the reagents are removed from the stick the glow is uniformly off-white. Page 5 of 11

6 Image 2: On the left hand side the non-transparent glowstick version which should not be used for this demonstration and on the right the transparent version which should. Step 3: From this point on, PPE in the form of nitrile gloves, safety glasses and labcoat should be worn with sleeves rolled down. Each colour (pair of boiling tubes) requires 3 glowsticks and a worthwhile demonstration involves 3 standard colours plus the ultra finale. Therefore a total of 12 glowsticks are required. To open the glowstick and separate the reagents carry out the following procedure for each colour you wish to demonstrate: Step 4: Remove all three of the glowsticks from their foil wrappers. Take the first in your non-dominant hand and with the knife cut just below the raised top of the stick. It is better to cut in the manner shown in the Image 3, i.e. your thumb providing the traction to the blade through the stick toward you rather than sawing downward on the glowstick which may result in splash or loss of the phial. You will feel the polypropylene top cleaving and when it is cut about ¾ the way through stop and just push back the nearly-severed top. You will see the phial inside the sleeve with the oxalate ester sensitizer around it. Page 6 of 11

7 Image 3: Recommended Method of Opening Glowstick Step 5: Carefully tip the clear hydrogen peroxide into a boiling tube (Image 4). The phial (which contains the oxalate ester sensitizer) may slide partially out, and it may be prevented from falling out by using the inside edge of the boiling tube. Image 4: Decanting the hydrogen peroxide. Step 6: When the hydrogen peroxide has been decanted, put the boiling tube into the rack and carefully tip out the phial (containing the oxalate ester sensitizer) onto a piece of laboratory roll. Discard the polypropylene sleeve with the other sleeves Page 7 of 11

8 when all the glowsticks have been processed in the non-sharps bin after wrapping in several layers of newspaper which are then taped. Wipe the peroxide off the outside of the phial. Repeat the above steps until you have 3 glowstick s worth of reagents. Image 5: Three glowstick s worth of reagents Once you have 3 glowstick s worth of reagents (3 glass phials containing oxalate ester sensitizer plus 3 glowstick s worth of peroxide in a boiling tube) you must open the glass phials and decant the oxalate ester sensitizer into a separate boiling tube. For each phial in turn, pick it up, and hold it upright inside a large sharps bin. With the pliers, crush the top of the phial above the level of the liquid until it shatters. The top should break quite easily with minimal loss of oxalate ester sensitizer. Glass fragments may be propelled during this process so this must be done at arm s length, holding the phial well down inside the sharps bin and with full PPE as previously described. Consider using a face shield at this point (Image 6). Page 8 of 11

9 Image 6: Using pliers to open the top of the oxalate-containing inner glass phial Step 7: Decant the oxalate ester sensitizer into another boiling tube and place this into the rack next to the peroxide-containing tube. Repeat twice more, adding the same reagents to these two tubes so that a total of three glowstick s worth of reagent is in each tube. Step 8: Repeat for other colours as required. You should then have several pairs of boiling tubes containing reagents, two for the demonstration of each colour. Step 9: To perform the demonstration, for each pair (i.e. a tube of peroxide and tube of oxalate ester sensitizer ) simply pour the contents one of the pair of tubes into the other (Image 7). Page 9 of 11

10 Image 7: The demonstration It is recommended that the orange ultra demonstration is done as a finalé. The end result is shown in Image 8. Image 8: The resultant demonstration Page 10 of 11

11 Step 10: After the demonstration the liquids can be washed down the sink with plenty of water. The boiling tubes should be rinsed to remove the peroxide before being left in the washing-up area having been clearly marked with may contain peroxide and/or phenol residue. Ordering glowsticks: Illumiglow provide discounted 10-packs of each of the standard colours and the ultraorange. They also provide a further discounted classroom pack of 40 glowsticks (10 of each of the colours and 10 of the orange ultra). sales@illumiglow.com or call Prices are outlined below: Price excl. VAT/ 10 x red 12 hour glowsticks x yellow 12 hour glowsticks x green 12 hour glowsticks x orange ultra 5 minute glowsticks pack: 10 each of red, yellow, green 12 hour glowsticks and 10 orange ultra Shipping (flat rate independent of size) 6.95 This risk assessment was produced on 28 th January You are advised to check for any update on the CLEAPSS web site. Page 11 of 11