Sciencemadness Discussion Board

The crudest anti bumping + increase heating efficiency

Antiswat - 9-12-2021 at 11:27

so ive always been a fan of tall beakers, and they oftenly do bump a lot when boiling something
ive used aluminium foil for many things, especially insulating distillation equipment and even pressed a foot for round bottom flasks, turns out it helps massively with transferring hotplate heat as you can just make it as wide as the hotplate and you lose very little heat and you can have it climb really far up the bottle itself

thinking back, i dont remember any bumping when distilling using my aluminium disc?

anyhow so i had to boil 100mL water in a tall 250mL beaker and i just took a piece of aluminium foil, folded in half, wrapped around beaker and pressed down along the beaker to the bottom as pictured

i came back to see the whole deal bubbling and boiling vigorously, but zero bumping? none at all
and you cant even argue the aluminium foil absorbs the bumping because its in direct contact with the hotplate

as for making a round bottom flask disc you wanna take maybe equal to 6 A4 sheets of foil, fold it like 6 sheets of A4, crumble it a bit, then crush it down to the size of a dish, put the round bottom flask on top, press it down into it a bit andthen press inwards towards the round bottom flask, once aluminium foil is well compressed it doesnt shield from heat, it rather acts as a conductor, the disc i have made originally for 500mL flask works well even for 50mL flask and ive had the same disc for 3 years

macckone - 9-12-2021 at 11:40

It is probably slowing the heating just enough to get good convection and if it is up the sides it is helping heat the sides which improves convection as well. More even slower heating reduces bumping.

Antiswat - 16-12-2021 at 00:49

no it doesnt slow the heating but i believe what happens is that it ensures the sides of the beaker stays warm so that the solution is heated from all sides rather than just the bottom, causing some odd physical phenomena when the bubbles interacts with a colder upper layer, or maybe the bubbling happening on all sides of the beaker stabilizes the bubbling
but it certainly doesnt halt the heating process, it directs the heat into the beaker rather

Re:The crudest anti bumping + increase heating efficiency

Colleen Ortiz - 11-2-2022 at 04:19

When boiling water, aluminum appears to be an excellent anti-bumping agent; it makes the water boil hard and minimizes its bumping. When the water was boiled without any aluminum foil, it bumped before boiling, wasting almost half of the beaker filled with it. The results improved significantly with aluminum, removing virtually all the bumping. It might be due to the effect of aluminum that it allows the appropriate heating to the water and eliminates the bumping enabling the water to boil without any bumping, allowing good convection of the heat to the water. It could also be that the foil keeps all the sides of the beaker warm, allowing equal heat transfer to the water from all sides, making the water boil without any bumping, thus working as an anti-bumping agent during water boil minimizing the wastage.
Bumping occurs when the upper colder layer comes in contact with the hot water bubbles, bumping starts; what aluminum does here is allow the equal heat transfer to all areas of the water and minimizes the bumping effect.

Rainwater - 11-2-2022 at 04:29

Quote: Originally posted by Colleen Ortiz  

Bumping occurs when the upper colder layer comes in contact with the hot water bubbles, bumping starts;

I think its more of the difference in densty than temp, but i am nit picking at this. Even heating is still the best way to work a solution. Thanks for the tip. Ill be giving this a try

Antiswat - 24-6-2022 at 05:09

i ran into bumping due to Na2SO4 formation- usually bumping isnt a problem as i always wrap my flasks in aluminium
adding about 20 pieces of silica gel balls completely solved it