CHEMISTRY COMMUNITY

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How do I know if my respondus is updated? I have a macbook and I already did the 2 question quiz and everything worked fine, does that mean that it is up to date?

105736938 AADL

Hi! So I was told earlier by a TA that any gas that is added that is not a part of the reactants/products will not affect equilibrium because it does not change the concentrations of the reactants and products. But yes, inert gases/noble gases do not affect the equilibrium. I hope this helps!!

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Hi! So one thing to note is that weak acids/bases do dissociate, just not fully. Strong acids/bases fully dissociates. I think it is important to note this when calculating for ph or K. So for example, if you have 1.0M of HCl, it will fully dissociate to 1M of H+ and 1M of Cl-. With weak acids/bases...

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Hi! So the reason we use the 5% rule goes hand-in-hand with the idea that you can ignore x in the denominator. So when K is below 1x10^-3, you can exclude x from the denominator. So the reason you can do this is that the change in x is so small compared to the overall reaction. The way to explain th...

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Hi! So for the phase change itself we use the equation q=n*deltaH. The delta H you use depends on the phase change. So from solid to liquid, you use deltaH fusion, for liquid to gas you use deltaH vaporization. We use this equation because there is no change in temperature during the phase change si...

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Hi! To add one the above answers, a catalyst is an enzyme that is added to the slowest elementary step to speed up the overall reaction.

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There's a difference between being used and being consumed. So basically, you can think of it as a not a part of the reaction, A catalyst is simply an enzyme that helps the reaction go faster by lowering the EA. It does this by being added to the slowest elementary step. So catalysts are being used ...

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I would tell another chemistry joke…

…but all the good ones Argon.

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I dare you to lower your body temperature to absolute zero.

I promise you’ll be 0K.

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Is work of expansion always negative and work of compression always positive in respect of the system?

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I went to pretty much all of Vivek's UA sessions and he helped me so much understand all the topic and was very kind and understanding when I asked questions. All his worksheets were very relevant to what we were learning and helped a lot when reviewing for exams. Thank you Vivek!

105736938 AADL

When studying and doing homework, I listen to classical music, so for example I listen to Einstein Study Music Academy.

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I was at that review session and the answer is both A and D. For starters increasing the pH means more basic solution. Both OH- and NaCH3COO- are basic so adding it to the solution would make the overall solution more basic. An important thing to note is that we are looking at the problem with the n...

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Do all the posts have to be related to chem to receive points, or as long as it is 30, were fine?

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I looked at the UA worksheets, going to as many review sessions as possible, and rewatching lectures for more conceptual review!

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My comfort movie is definitely mean girls. I have more comfort shows which include, grey's anatomy, criminal minds, and modern family.

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It is 25 multiple choice questions, including all topics. A TA told me that the amount of time we spent on the topic in class equals the percentage of the test. For example, we covered acids and bases for 1 week, so it will be 10% of the final.

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my favorite food is definitely suhsi and pasta. I'm going to be having one of those after finals as a prize.

105736938 AADL

When finding k for elementary steps, you just look at the stoichiometric coefficient, and for overall reactions, you calculate it right?

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I was at a step up and the UA gave me a very helpful way to determine K units, it is: 1/(M^(overall order -1)S). I hope this helps!

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What is the difference between something being Kinetically stable vs. Thermodynamically stable

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What does it mean when the questions asks about the rate-determining step?

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Is Enaught considered a state function?

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The cut off value is 10^-3. If the value of K is smaller, such as 10^-10, the you can remove the x that was part of the equilibrium concentration for the reactant. For example, if you had, x^2/0.025-x, it would become x^2/0.025. I hope this helps!

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In order to determine whether a step has a high Ea or not do we just look at whether it is slow or fast, or are there other factors that determine whether it can have a high Ea

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So to make a reaction go faster, you would add the catalyst to the slowest elementary step right?

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This rule applies because it means that the change in x is so small to the point where you can ignore it. Don't forget, this does not mean that x=0. A real life example of this is if someone is a millionaire, and they give 1,000 dollars to someone, people would say that they are still a millionaire ...

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What has helped me a lot is to make sure I get a good night sleep. Although very tempting, it is not good for you to stay up all night studying. Also make sure you eat a good breakfast before the exam and take some deep breaths before entering. Remember that your life does not depend only on this ex...

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How do you know if a solid is conducting? Or are all metals conducting?

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Someone threw sodium chloride at me.

I yelled, “That’s a salt!”

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Did you hear the one about cobalt, radon, and yttrium?

It was CoRnY

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Two chemists walk into a bar.
One says, “I’ll have an ‎H2O.” The other says, “I’ll have an ‎H2O too.” The second chemist dies.
Hydrogen peroxide is very dangerous!

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I did not have the best experience in Chem 14A so I was very nervous coming into this class. Dr. Lavelle has completely changed my perspective on chemistry and I just want to say thank you. I really learned a lot in the class and although pretty challenging, overall I enjoyed this class so much more...

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I am getting an error page when I am trying to login into the webiste. How can I fix this?

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Can you please post the answer key after the session because I cannot attend at 2pm

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Old chemists never die, they just stop reacting.

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I feel the midterm was very content heavy, what is the best way to study this way?

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What were the extracurriculars you did to be a competitive applicant?

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I feel some very intense imposter syndrome right now? What is the best way to get over it?

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I'd give you some more chemistry jokes, but all the good ones argon.

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Where can I find more questions that test my knowledge conceptually, last midterm was concept heavy and not much math, so I want more questions that test my knowledge of the concept. Thanks!

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I think there can be a decrease in disorder because it depends on the change of entropy, so if entropy is negative, then disorder decreases.

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Lose an electron?

Gotta keep an ion it.

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Gold is the best element because it's AU-some.

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Hi! Weak acids and weak bases do not completely disassociate and strong acids and strong bases do.

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Based on the units of P, you decide which R to use. The units must cancel out, so R and P must be in the same unit

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Hi! So K can be used to describe Kc and Kp but Kc is talking about molar concentrations in moles per liter ^-1 and Kp is talking about partial pressure for gases.

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Homogeneous equilibrium is when all products and reactions are in the same phase. For example all reactants and products would be in the gas phase and have a (g) next to it. Heterogeneous equilibrium is when at least one product or reaction is in a different phase. For example, some can be liquid an...

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