ALEKS: Calculating heat of reaction from bomb calorimetry data

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@BigRed383 Жыл бұрын

The sig figs stuff for ALEKS seem arbitrary. Sometimes it wants sig figs from the data in the problem and then sometimes it wants the original value of sig figs for the same problem, but disguised as "rounded to the correct number of sig figs." So a problem might be 4 sig figs actual but then only be 3 that it wants for the answer which can be frustrating if you don't understand that.

@RoxiHulet Жыл бұрын

Yes, I sympathize with this 100%! Instructors can set up ALEKS to tell the students exactly how many sig figs it wants, which is the setting I use for my students. The problems are hard enough as is. Hang in there.

@sofascomfy Жыл бұрын

this was so helpful, ur so lovely

@kirkabap9095 2 ай бұрын

I got mines wrong and I had the question where it asked for one of the other products. It said I had to put C2H4 (C2H2 for yours) on the bottom when setting up. This question in general is just super weird and I doubt I'll be able to get it correct on the exam. I mean, even chatgpt gets it wrong.

@SteadyDog55 2 ай бұрын

Because she got the last part wrong. There are too many units in her conversion you can’t do that calculation with Kj still in it.

@SteadyDog55 2 ай бұрын

13:15 Basically all you do differently is take the number of moles of C2H2 in this case which is 0.2223mol (you can find this number in red just left of the conversion you are concerned with) and use THAT (0.2223mol C2H2) for the conversion to mols of H2O instead the “-1342” number. Write it on paper and you will see why mols of C2H2 are on bottom. It’s those we wish to cancel.

@RoxiHulet 2 ай бұрын

@@SteadyDog55 I just opened up this ALEKS problem and found one that was asking for the enthalpy of the product. I followed my own instructions in the video and got the answer correct. I usually don't look at ALEKS's explanations because they can be confusing, but I have verified that the method in this video is correct.

@SteadyDog55 2 ай бұрын

@@RoxiHulet That is very interesting. I had to do it my way, and that is how to was written in the explanation. Just like the commenter said, where the mols of the reactant are on the bottom

@RoxiHulet 2 ай бұрын

@@SteadyDog55 Hi! I'm looking at the ALEKS explanation right now for a version of the problem where you are being asked to report the enthalpy of water, which is a product. The explanation shows that the calculation is "kJ / moles of H2O". It does not show the moles of reactant on the bottom of the equation. However... if your problem has the same equation as the one in this video, the moles of C2H2 and moles of H2O are equal, which means that you would have been able to use "kJ / moles of C2H2" and still get the answer correct. Also, I have noticed that the ALEKS explanation I'm looking at has a typo (it references CO2 multiple times, but shows work for calculating H2O). So it is possible that you were looking at an explanation with a typo but you ended up getting the answer correct anyways because of the fact that moles C2H2 = moles H2O. I'd love to be able to attach a screenshot but unfortunately that technology doesn't exist in KZbin :)