# How to lose as little heat as possible to the surroundings from an endothermic reaction?

For an experiment, I'm adding several substances (as powders) to hydrogen chloride, and measuring the temperature changes to calculate enthalpy. What is a container I could perform it in (other than a styrofoam cup) that would minimise the heat lost to the surroundings?

I looked up using a vacuum flask of some sort, but would that be appropriate for this sort of reaction? The temperature is being measured via a temperature probe.

• In endothermic reaction, if you start it at room temp., you'd have heat gain from the surroundings. – Mithoron Mar 25 '15 at 11:03
• Yeah, some are endothermic and some are exo. I'm trying to minimise the effect of heat losses/gains on the change temperature. – deusy Mar 26 '15 at 6:47

1. What is the scale?
2. What is the budget?

Reactors are available from 250 mL up.

It might be cheaper to place a flask in a cut-off bottom of a suitable PE bottle and insulate it with PU foam from a DIY market.

UPDATE

A small Dewar cylinder might be an option too. The model 00C has a volume of 100 mL and lids are available too. Usually, these Dewars are used to store liquid nitrogen and cooling mixtures (2-propanol + dry ice, etc.) so I don't know how resistant the lid is towards $\ce{HCl}$ over time. In addition, this setup isn't as tight as a flask with hollow stoppers and/or a silicone seal if that's an issue.

• The scale is pretty small, only $50cm^3$ of HCl. Would a vacuum flask, the sort shown here, reduce heat loss? – deusy Mar 25 '15 at 8:15
• @deusy The Dewars might work too. I've updated my answer. – Klaus-Dieter Warzecha Mar 25 '15 at 10:00
• Thanks! One last thing that you might have a suggestion for: What is the best way to stir the reaction once I add the powder? I'm measuring temperature with a temperature probe, but stirring with that is probably not a good idea because it may affect the temperature recordings. – deusy Mar 26 '15 at 7:19
• Does the powder dissolve immediately? Are measurements on an inhomogenenous sample useful? Can you measure the temperature before, then add the powders to a stirred solution, stop stirring and start the real measurements? Maybe this is good enough for a separate question on experimental-chemistry. – Klaus-Dieter Warzecha Mar 26 '15 at 7:28
• The new question is here. – deusy Mar 26 '15 at 8:46