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Author: Subject: Design of experiments

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[*] posted on 22-7-2016 at 18:31
Design of experiments

How do you do it? In my own amature musings in chemistry, once I feel I have put sufficient study into the theory behind the experiment, on paper I go step by step through whatever processes I intend to do. Once I am satisfied with my planning the materials are gathered. Generally I will weigh out the majority of materials and make preliminary solutions before I begin any experiment. Once all of this work has been done I double check that all of my weighed and prepared chemicals are accurate with my writeup. Once everything has been verified as correct I proceed with the actual experiment.

Are there any flaws or holes in my planning and execution process?

I would be very interested in finding software that helps design chemistry experiments or methods that make putting theory into practice easier.
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[*] posted on 22-7-2016 at 18:38

depends on the experiment. i.e. for analytical work you only weigh once("approximately accurately") and always use the exact same balance/scales for any subsequent weighing.
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National Hazard

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[*] posted on 22-7-2016 at 18:58

Personally, I tend to casually do some research on general chemistry(i.e. Watching Nile Red's or chemplayer's YouTube videos) until I find an idea that piques my interest. Then, I usually follow one of two routes:

A) I follow an experiment I've researched on recently, on an impulse.


B)I intensely read up on a subject(either my own idea or a possible known reaction).

In either choice, I tend to extensively plan the experiment in my head first, which can sometimes be over days, then which I may or may not write it down. I prefer to write my ideas out, as I then see possible outcomes(i.e. Possible dangers, failures, ect.) that I would not likely have seen if I hadn't written it down. Unfortunately, I usually don't write my ideas down, but I'm beginning to.

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Hazard to Others

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[*] posted on 23-7-2016 at 08:46

We were 'noobies' 18 months ago and our number 1 golden rule has to be this: "have an equation!"

It's an exciting subject and it's easy to try to jump in and do something. But you HAVE to do your research, you really have to read everything you can find out about the reaction and related reactions, and then based on all of that come up with a plan. But if at the end of all that, you don't have a stoichiometric theory about what's going to happen, and a balanced equation to go with it, then you're NOT ready and you're about to waste time and resources proceeding.

Not just the equation itself, but often you find that writing it all down in a structured way makes you think about it a bit more. Suddenly you start to question, "will the solvent react with anything?", "what byproducts could there be?", "what side reactions could occur?" etc.

And then you start to get it (a little bit).

Watch some vintage ChemPlayer:
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International Hazard

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[*] posted on 23-7-2016 at 09:03

Quote: Originally posted by pepe  

Are there any flaws or holes in my planning and execution process?

If you're anticipating exothermic reactions you might want to try and predict the expected rises in temperature. Thermal runaways can ruin the best laid plans and be very dangerous to boot.

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lab constructor

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[*] posted on 23-7-2016 at 09:21

I second everything in chemplayer's post. Garage chemist said that he would not attempt an experiment for which he could not write the equation.

If hydraulics and gas pressures are involved these must be planned for. Suck backs and gas leaks are not fun and can be dangerous.

The single most important condition for a successful synthesis is good mixing - Nicodem
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