CHEM 20B
Chemical Energetics and Change
Description: Lecture, three hours; discussion, one hour. Enforced requisites: course 20A or 20AH, and Mathematics 31A, with grades of C- or better. Enforced corequisite: Mathematics 31B. Second term of general chemistry. Intermolecular forces and organization, phase behavior, chemical thermodynamics, solutions, equilibria, reaction rates and laws. P/NP or letter grading.
Units: 4.0
Units: 4.0
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Most Helpful Review
First off, I learnt so much chemistry from her lectures comparing to the horrible 20A class I took. She makes Chemistry interesting. Even though her tests are difficult they are not impossible. The first midterm was manageable the second one was a lot harder and the final, true to a lot of reviews, was downright difficult. Each midterm composes of 4 cumulative questions with smaller parts. They pretty much put all the knowledge together into one big problem solving question. DO NOT let yourself get stuck on ONE problem and try to be careful of the one that you can do. Whoever grades the test like to take off points on ridiculous details. The cheatsheet helps but the key to study well in her class is pay attention to the OWL type of homework and don't do them mindlessly. Also, study in a group and do the back of the book problems. They are really similar to what she gives on the test. Last and not least, find exams online with the same format and try to do them. For me, those exams help a lot.
First off, I learnt so much chemistry from her lectures comparing to the horrible 20A class I took. She makes Chemistry interesting. Even though her tests are difficult they are not impossible. The first midterm was manageable the second one was a lot harder and the final, true to a lot of reviews, was downright difficult. Each midterm composes of 4 cumulative questions with smaller parts. They pretty much put all the knowledge together into one big problem solving question. DO NOT let yourself get stuck on ONE problem and try to be careful of the one that you can do. Whoever grades the test like to take off points on ridiculous details. The cheatsheet helps but the key to study well in her class is pay attention to the OWL type of homework and don't do them mindlessly. Also, study in a group and do the back of the book problems. They are really similar to what she gives on the test. Last and not least, find exams online with the same format and try to do them. For me, those exams help a lot.
Most Helpful Review
Walsh is a decent professor. Her class isn't very hard at all. She gives out handouts in each lecture which provide a good summary of what you need to know for exams, but it's very helpful to go to lecture and listen anyway since she only lectures for about 20-30 minutes anyway. She also gives you practice exams before the two midterms (one during 5th week and one during 10th week). If you read the notes and do the practice tests you should do well on the tests. In addition to getting at least 50% on the tests, you have to turn in all the lab reports to get at least a C-. The lab reports consist of a pre-lab and post-lab due every week and are pretty easy (most post-labs are done with your lab partner). If you have questions, ask one of the T.A.'s because Walsh doesn't seem very approachable or helpful.
Walsh is a decent professor. Her class isn't very hard at all. She gives out handouts in each lecture which provide a good summary of what you need to know for exams, but it's very helpful to go to lecture and listen anyway since she only lectures for about 20-30 minutes anyway. She also gives you practice exams before the two midterms (one during 5th week and one during 10th week). If you read the notes and do the practice tests you should do well on the tests. In addition to getting at least 50% on the tests, you have to turn in all the lab reports to get at least a C-. The lab reports consist of a pre-lab and post-lab due every week and are pretty easy (most post-labs are done with your lab partner). If you have questions, ask one of the T.A.'s because Walsh doesn't seem very approachable or helpful.
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Most Helpful Review
Spring 2025 - Paul Weiss is one of the worst teachers I have ever had in my entire life. This man has no regard for how well his students actually learn. If there are other options for teachers in this class, take them. If you have the flexibility to wait a quarter and take it with a different teacher, do it. DO NOT TAKE HIS CLASS. During the class I heavily relied on my friend who had taken 20B a quarter before with a different professor. About halfway through the quarter we reached a point where she could no longer help me because we were learning stuff that wasn't even apart of regular 20B content. The entirety of that sentence alone should be a red flag enough. But to actually get in to Paul's teaching style, the bottom line is he doesn't actually teach. Each class I would try to pay attention and learn the content, yet each time probably 5 minutes in we reached the inevitable point where he would go on a rant about some medical device that his friend created or about his friend that he's about to go visit that has a noble prize or their own lab or is doing this great research. While normally I can appreciate a little bit of getting sidetracked, as it can make the content more interesting, his getting sidetracked has the exact opposite effect. He would go on for so long about topics that have nothing to do with the class it gave no chance for us to actually learn anything. Additionally, his lectures consisted of a series of slides, each composed of a long bulleted list of topics. He would proceed to "explain" the topics, but most of the explaining was what I described before, bragging about his cool friends and his personal life, or medical things that the majority of the class had no interest in knowing, or need to ever know. Because of that I stopped going to lectures a few weeks in. A week before the midterm I decided to go and see if we would actually learn any content (spoiler alert: we didn't), and I counted how many students were actually present in class. Out of the at least 120 students taking the course, 40 were present. That just goes to show how bad of a lecturer he really is. Now you may be wondering about homework and tests and the rest of the course. Surprise, they're just as bad. Each week he would assign homework that would take an insane amount of time, that also had NOTHING TO DO WITH ANYTHING ELSE. Several times he stated that the lectures, homework, and readings were "complementary." They are anything but that. Put together they made no sense and made it impossible to actually know what content we needed to know for the exams. While both the midterms and the final were all open note, it doesn't matter. The tests would ask the most convoluted questions that he said would test our intuition. Shocker, I don't have the same intuition as someone who has been studying chemistry their entire life, and have only ever taken two other chemistry courses. Also, don't expect your TA to be of any assistance during this class either. In my discussion of at least 20 people, 4 of us regularly attended. This is because any time we asked a question about the test, or about the grading of the test, the reply was "I don't know, you would have to ask Paul." All in all, please do not take his class, it's not worth the extreme headache and time wasted. I wish I had just waited a quarter to take it with a different professor.
Spring 2025 - Paul Weiss is one of the worst teachers I have ever had in my entire life. This man has no regard for how well his students actually learn. If there are other options for teachers in this class, take them. If you have the flexibility to wait a quarter and take it with a different teacher, do it. DO NOT TAKE HIS CLASS. During the class I heavily relied on my friend who had taken 20B a quarter before with a different professor. About halfway through the quarter we reached a point where she could no longer help me because we were learning stuff that wasn't even apart of regular 20B content. The entirety of that sentence alone should be a red flag enough. But to actually get in to Paul's teaching style, the bottom line is he doesn't actually teach. Each class I would try to pay attention and learn the content, yet each time probably 5 minutes in we reached the inevitable point where he would go on a rant about some medical device that his friend created or about his friend that he's about to go visit that has a noble prize or their own lab or is doing this great research. While normally I can appreciate a little bit of getting sidetracked, as it can make the content more interesting, his getting sidetracked has the exact opposite effect. He would go on for so long about topics that have nothing to do with the class it gave no chance for us to actually learn anything. Additionally, his lectures consisted of a series of slides, each composed of a long bulleted list of topics. He would proceed to "explain" the topics, but most of the explaining was what I described before, bragging about his cool friends and his personal life, or medical things that the majority of the class had no interest in knowing, or need to ever know. Because of that I stopped going to lectures a few weeks in. A week before the midterm I decided to go and see if we would actually learn any content (spoiler alert: we didn't), and I counted how many students were actually present in class. Out of the at least 120 students taking the course, 40 were present. That just goes to show how bad of a lecturer he really is. Now you may be wondering about homework and tests and the rest of the course. Surprise, they're just as bad. Each week he would assign homework that would take an insane amount of time, that also had NOTHING TO DO WITH ANYTHING ELSE. Several times he stated that the lectures, homework, and readings were "complementary." They are anything but that. Put together they made no sense and made it impossible to actually know what content we needed to know for the exams. While both the midterms and the final were all open note, it doesn't matter. The tests would ask the most convoluted questions that he said would test our intuition. Shocker, I don't have the same intuition as someone who has been studying chemistry their entire life, and have only ever taken two other chemistry courses. Also, don't expect your TA to be of any assistance during this class either. In my discussion of at least 20 people, 4 of us regularly attended. This is because any time we asked a question about the test, or about the grading of the test, the reply was "I don't know, you would have to ask Paul." All in all, please do not take his class, it's not worth the extreme headache and time wasted. I wish I had just waited a quarter to take it with a different professor.
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