Question

what are three sources of errors that could occur in a calorimetry experiment? is it askingme to just start naming off random flukes?

Answer 1

human error instumental error and inheritant error

Answer 2

No, it's asking you to think of reasonably plausible things that might interfere with the accuracy of your measurements. For example, you probably need to make sure no heat enters or leaves your measurement system. That is, you need to insulate your reacting system. But no insulation is perfect, and what you have available to you that is reasonably cheap -- like a Styrofoam cup -- isn't even very good. Most definitely some heat will enter or leave the system, and since your math will be based on the assumption that it is NOT -- you will experience error. Furthermore, since you don't actually know how much heat is leaking in or out, you aren't going to know how much error you have. Hopefully not much, but...that's why it's called "error" -- it's the UNKNOWN difference between your answer and the right answer. (If you knew it, you could correct for it.)

What else? Well, you probably need to measure the quantities of reactants going into the system. How are you going to do that? To get precise answers, you'd need to count out the atoms and molecules, one by one, to be sure precisely 1 mole (or whatever) of reactant A got into the mix. Well, that's not possible. You're going to weigh it out. But that means you might have some errors there, too, right. The scale might not be perfectly calibrated (meaning it shows "1.00 g" when the actual weight is 1.01 g). Some solid might stick to the weighing pan, or some liquid to the graduated cylinder, when you pour it from where you measure it to the system. There's another error.

Then there may be some important assumptions you make. Perhaps you'll assume you're doing this at 1 atm pressure, and that's important, but the pressure on any given day, at any given location, is never EXACTLY 1 atm -- it will differ slightly, depending on the weather, altitude, et cetera. Maybe you'll assume your reaction mixture has come to equilibrium in 10 minutes, but actually it takes 20 or 30, so it will only be nearly at equilibrium, not all the way there. Maybe you'll assume it was very well mixed, but it wasn't, quite, so there were some unreacted pockets here and there.

You're not generally going to be asked to add in the possibility of random craziness, like maybe your lab partner will hand you a beaker of 18 M stock HCl solution insted of the 0.005 M solution he was supposed to make up, or maybe an asteroid will hit the classroom while you're working and the vaporization of your teacher and half the class will distract you while you're writing down your results, so you transpose a 2 and 6, leading to the wrong calculated result.

Just think of what might reasonably cause the numbers you write down to differ slightly from what they should be. This is actually a profoundly important part of science -- thinking critically, trying to think how your results might be the result of mistakes, inaccuracies, imprecisions, or assumptions that are not perfectly valid. Indeed, this is arguably the single most important part of the process, trying to identify error. Science is, in the end, just a way to reduce errors in your ideas about how things work.

One thing that might be helpful is to think of yourself as a defense attorney trying to defend your client, who has been "accused" of doing the experiment right (and let's say the experiment is forbidden or something). The "prosecutor" (the lab manual) is trying to use the "evidence" of your lab notebook to convict your client. See? He measured out the 0.0056 g of solid, it says so right here! Your job, as the defense attorney, is to cast doubt on that fact. How do you KNOW it was 0.0056 g? Maybe it was 0.0057 g, and, if it was, that changes the whole outcome of the lab, doesn't it?

But you can't just throw crazy stuff out there, because the jury won't swallow it. Maybe he had a mini stroke and wrote down the wrong number? Give me a break. But the jury might accept your argument and vote to acquit if you come up with a reasonably plausible way in which your client might have muffed the lab.