Good News, Bad News, and Questions - Comments

@ I'm.Haunted
I really think I failed. I didn't understand more than two questions and most of them were equations. And I'm sorry to hear that. If you wanna talk about anything, Im here to listen or anything.
But yeah I did try and maybe I at least got a D but I doubt it..

@ nefarious
I'm sure you did okay. If it's any consolation I just failed an organic chem. exam because I didn't study after being dumped yesterday. So. No matter what happens at least you tried. Unlike me.

@ I'm.Haunted
I definitely failed. I think I did well on my anatomy though.

@ nefarious
That's so bizarre. I really wish I could've thought of a solution. How did the exam go?

@ I'm.Haunted
The thing is, it doesn't always happens. And I have noticed it happens a lot when it's a bigger number raised to power. When the number is like 23 or something it's usually fine.

@ nefarious
That's so strange. I saw this when I was leaving school and I spent most of my drive home trying to figure it out. All I can think of is that maybe a setting is off in your calculator, or your syntax is off. I have students who get completely wrong answers because they forget to close their parentheses.

@ I'm.Haunted
The yield part kind of does but the scientific notation problems that you mentioned isn't what is happening. What happens in my calculator will say like
5.60 E23 and I'll type it in the computer for my online homework and it'll say incorrect and the answer is something like 5.60 • 10 ^-2. That's not an actual example and it may not be accurate but the number in my calculator will be really big and my homework will say it's like -2.

@ nefarious
Do mean like if your calculator gives you 0.0000567 mol, or something absurd like that? If that's the case, then it's all about scientific notation, and depending on the calculator you have you can change your mode to scientific notation and you'll get an answer that looks something like "5.67E-5" for the above example. That would mean 5.67 * 10^-5 mol.

As far as actual and theoretical yield, I don't have an example accessible, but what you calculate based on your stating materials would be your theoretical yield. Actual yield and comparisons are what usually gets dealt with in lab. It basically says given the starting materials you started with, you should have gotten "x" but you got "y." How different is x from y. That's a really bad way of putting it.

Right now I'm looking at an equation in orgo that says I should have ended up with about 165mg of caffeine residue at the end of the experiment. I started with 170mg. When I do all of the math it tells me I should, if everything went perfect and to 100% completion, have 165mg and I should only lose 5mg. But we don't live in a perfect world. Our scales can be miscalibrated, we can add an extra drop of solution, we might drop a crystal of whatever solute we're working with. So I wound up with 154mg. My theoretical yield was 165mg, but my actual yield was 154mg. We usually talk about actual yield as a percent. So, 154 is 93.3% of 165. Therefore my actual yield was 93.3% of my theoretical yield.
Does that make any sense?

@ I'm.Haunted
Well right now we are learning so much at once and I'm laying bed now far away from my book but there are a few things that I remember struggling with. I think I can find number of mols and atoms from mols just fine but I always struggle with writing the answer out right because it's hardly the same as what my calculator gives me. And surprisingly enough I don't mean the significant figures part either. It's usually the part raised to power. Also I'm having a really really hard time with theoretical and actual yeild. My car broke down on the day we went over it and the exam over it is tomorrow so I'm trying to teach myself and it's not working.

What in chem are you having a hard time with? I took gen. chem. last year and am always willing to pass on what I remember.