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Mike Bullivant's diary: Ice

Updated Monday, 28th January 2008

Mike Bullivant's Feel the Heat diary, from the BBC/OU series Rough Science 2

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Day 1

The challenge for Programme 4 is to make ice. Now, that's not so easy in this weather: 30°C+ and 86% humidity. Making ice in these conditions will be right at the limit of what we can do. For this challenge, my contribution will be to make methanol (methyl alcohol), which shouldn't be too difficult. You can produce it by distilling (heating) wood over a hot fire. However, any methanol I do manage to produce will be so adulterated with other solvents, for example, acetone, acetic acid and water that I don't think it'll do the job of cooling things down as it evaporates. That's my job for this challenge - to produce a cooling effect through the evaporation of a solvent. I know that methanol's readily available from the destructive 'distillation' of wood. Just heat some wood up and collect what distils over. Easy, peasy! But, I think methanol has a very low latent heat of evaporation, which won't help at all. Still, we'll see.

I have to work with the kiln (1000°C+) all day, and the sweat literally drips off me. I must remember to drink lots of water and not get so involved with what I'm doing that I forget and become dehydrated.

Angie (top banana and Rough Science science advisor) is such a great help, and things would be so much more difficult without her. She's a star, and she's always there when you need her. Ellen, the botanist on the team, is proving to be something of a twinkler too. Her enthusiasm is infectious. There seems to be something of a small clique developing which isn't so positive. Sarah, Drew and Paul have been filming all day with Ellen, and they seem to have bonded really well. Perhaps too well in Sarah's case. I hope all her over-competitive talk of 'our team' stops soon. There's only ONE team. We're not in competition (except with Nature) and the development of small 'exclusive' groups will bring a competitive spirit to the enterprise that we could well do without.

Kathy's job for Programme 4 is to make a thermometer, which isn't going to be easy at all. She'll certainly earn her stripes if she succeeds. Jon just gets on quietly with his challenge. In just one day, he's produced something that should do the trick - an electrical thermometer. Jonathan's unfazeable. He just gets his head down and gets on with it. Kate Humble's away with Ellen, Sara, Paul and Drew today, which leaves just one film crew, John (sound) and Derek (camera), to film what Mike, Jon, Kathy and I are doing back at the lime factory. Together with David (Shulman, one of the two Directors), they're running from pillar to post - and in this heat too! How do they do it? Those guys must be fit. And they do their job with such wit and grace. Real professionals and great, great fun to work and relax with.

Having only one crew is beginning to cause a problem. It's 3.30pm before I even get round to distilling some wood because David and the crew have been busy elsewhere, and unable to film me working. This could/should have been done four hours ago! I'm getting behind already. By the time we end the first day's filming, we've managed to produce just a few cubic cm of methanol distillate. We're going to need more, so Angie, Steve, Sandra and I all stay behind for an hour longer, just to catch up on the time we've lost through having only one film crew this afternoon. But, hey, ho! That's science!! Progress can be slow at times.

 

Day 2

Managed to prepare some more methanol today but whether it'll do the trick and help us make ice, remains to be seen. I have serious doubts. I think the methanol's too contaminated. We did rush it last night.

At the end of day two, we're called together for our first attempt at making ice. I'm not at all confident that the various components will all come together. We've only had two days to do such a lot. Nevertheless, I'm so pleased that Kathy's had some success with her thermometer. I know from the first series of Rough Science how a little success can boost your confidence. Ellen seems to be making headway with her challenge, as does Mike L.

In order to get water vapour to cool sufficiently, we're going to have to significantly reduce the pressure inside our apparatus. Mike L's designed a system that generates some drop in pressure but will it be enough? Combined with my worries about the methanol, I doubt we'll succeed at this first attempt. But, as they say, if at first you don't succeed ... don't take up hang-gliding!

Despite our relative individual successes, we collectively fail miserably to produce any appreciable drop in temperature in the methanol. We're invited to suggest ways of improving on what we've done and I think I need to produce a more volatile solvent: something like (diethyl) ether. Compared to (wet) methanol, ether stands a much better chance under reduced pressure of cooling down sufficiently to produce ice crystals. It's not going to be easy. For one, ether is very volatile and boils at 35°C, not far above the ambient temperature in the lime factory. It's also highly flammable, so we shan't be able to have fires or any other sources of ignition nearby - yet to make ether we need to heat a reaction to 140°C. We also need a source of ethyl alcohol and the only way I can think of getting any by tomorrow (the final day of this programme) is to ask Kate H for a bottle of rum from which I can distil the ethyl alcohol that I want. Even if Kate allows this (is it Rough enough Science?), the reaction is a difficult one to carry out and it requires sulfuric acid - but then again, I did see an old car battery lying around somewhere ... now where was it?

We have one more day to complete this programme's challenge and we all leave the lime factory at the end of the day thinking of ways to improve on our efforts of the last two days ... and hoping that Kate will let me have the rum. It is one of Carriacou's 'natural' resources after all.

 

Day 3

Kate has allowed me the rum but it's still a hard day ahead of us. Mike L's decided to improve his pump so as to get it to produce a lower pressure. I'm too involved with preparing the ether from the ethyl (drinking) alcohol (or ethanol) to know exactly what he's up to but I have every confidence he'll succeed. As for me, well, making ether from ethanol is a difficult enough process in a well equipped laboratory. Here in the lime factory, with makeshift apparatus and no fume cupboard to reduce the risk of the ether going up in flames, it is even more difficult and hazardous. Nevertheless, I've every confidence that ether will give us a positive result with this ice-making challenge, even if Mike L can't beat the drop in pressure he achieved yesterday. The methanol-to-ether improvement should be enough in itself. It's down to me, the chemist, to do my bit.

The apparatus we use looks a bit Heath-Robinson but it'll do the trick. As we carry out the synthesis of the ether, we must be careful to replace the ethanol reagent (from the rum), as it reacts at roughly the same rate at which the ether product distils over. We must also be careful to see that the temperature of the reagents (sulfuric acid, from the car battery, and ethanol) is kept within the temperature range 140-160°C. If we let the reaction temperature fall below 140°C, no ether will form and above 160°C we'll produce ethene gas rather than ether. And we don't yet have a working thermometer. We also have to use a hot sand bath to heat the reaction vessel - using naked flames when ether is about is very risky. It's highly flammable and heavier than air - the thought of us inadvertently generating a knee-high sea of highly flammable gas is more than a little worrying. We therefore have to use a very efficient condensing system that will ensure that, once formed, no ether escapes into the atmosphere - we must condense every drop of the ether we produce.

Despite these concerns, this is Rough Science at its best. I just love playing about like this. Being inventive, thinking around the difficulties and just doing the best you can in the less-than-perfect circumstances. This is what all five of us are doing and, like me, they seem as happy as pigs in muck. The fact that we're actually being paid to do it makes it even more enjoyable.

I've often said that an organic synthesis, like making ether from drinking (ethyl) alcohol, is just like cooking. Add a bit of this, a bit of that, and heat for 30 mins at 140°C. Trouble is that some of the things you want to make are like soufflés. One false step and you fail miserably. This is one such synthesis. Angie (the series science advisor) and I sit watching the distillation apparatus for signs of reaction (drops of ether condensing on the inside wall of the plastic tubing leading from the reaction flask to our Heath-Robinson apparatus). Five minutes pass and nothing. Ten minutes and still no ether. Then, to our relief, we see tiny drops of a colourless liquid condensing out on the plastic tubing. The reaction's underway but it still has to be nursed. Replace the reacted ethanol at too fast a rate and the reaction will stop. The reaction generates heat as it takes place and we have to ensure that this doesn't take the temperature of the reagents beyond the 160°C limit.

Five minutes later and the first drops of ether are falling into the bottle at the other end of our primitive condenser. I can't wait to check what it smells like. The colourless liquid that's collecting might, after all, be something other than diethyl ether. We have no way of telling as we don't have a thermometer to measure the boiling temperature of the vapour that's condensing. If it isn't ether, we're in trouble because we have very little sulfuric acid (from the car battery) left and without it there's no way we'll be able to have a second go at the reaction.

To our relief it's ether that's distilling over alright. I've worked with this solvent enough to be able to identify it by its smell. Not very scientific, I know, but it'll do. By the time we've collected enough diethyl ether to have another go at the ice-making challenge, it's mid afternoon. Mike L is still fine-tuning his pump, which, according to him, is a vast improvement on yesterday's version. Surely we can't fail this time. We've made all the improvements we recommended following yesterday's failure.

It's now the end of day three and we gather to have our second, and final, attempt at making the ice. If we succeed it'll be great. If we fail, well ... We gather round Mike L's pump, which is connected to the small, green insulated bottle into which we've placed my ether. The film crews are ready and primed to record what happens and our reactions to it. Mike L turns on his pump and we await the outcome. This is the culmination of three days' work. Five minutes pass and we remove the small green bottle containing the ether from the insulated bucket. Although some of the ether has evaporated, and thereby cooled the bottle, there's no ice. B*gger!!

It's difficult not to be disappointed by our failure but we must remember that along the way we've had our small successes. I've actually made methanol from wood. I've also made ether from rum and battery acid. Mike has improved his pump to such an extent that he's actually crushed a can - at least the viewers will be able to see the evidence for this and won't just have to take our word for it. As for Ellen's sunscreens and sun-blocks, well they're a great success too. I'm always telling people that science is more about failure than it is about success ... now I have to convince myself that this is the case. Not so easy.

Tenacity is perhaps one of the most useful things a practising scientist can possess. One mustn't be daunted by failure. We weren't.

Endnote

Having re-visited the ice-making challenge (many times) in my mind and thought about why it failed, I can only think that there must have been a kink or a leak somewhere in the air line between Mike's collapsing tin can and the bottle containing the ether. Ether boils at 35°C, which is only 5 degrees above ambient temperature on Carriacou. If we'd just left the bottled ether out on the bench in these conditions at atmospheric pressure, it would have all evaporated in ten minutes. Mike had produced a significant pressure reduction and the ether should have boiled under this reduced pressure, thereby cooling the bottle down and producing ice crystals on its outer surface. I suspect that Mike's low pressure just wasn't transmitted to the bottle. That's the only reason I can think of for our failure to produce ice. I'd very much like to re-visit this challenge. I know it can be done (so does Angie, much to her annoyance). We were so close. Maybe Steve will let us try again, not necessarily for inclusion as a post-script to the programme but just to satisfy ourselves that it can be done. As I said, tenacity is a useful thing to have. If at first you don't succeed...

 

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