Search found 17485 matches

Fri Oct 04, 2019 11:34 am
Forum: General Science Questions
Topic: Kelvin
Replies: 3
Views: 28

Re: Kelvin

Absolute zero is the lowest limit of the thermodynamic temperature scale and its equal to 0 K or -273.15°C.
Fri Oct 04, 2019 11:30 am
Forum: Balancing Chemical Reactions
Topic: balancing charges
Replies: 4
Views: 36

Re: balancing charges

You will practice that more when we start studying redox reactions, Dr. Lavelle hasn't gone over it yet so I wouldn't worry about it too much :)
Fri Oct 04, 2019 11:24 am
Forum: Molarity, Solutions, Dilutions
Topic: Dilution Calculation
Replies: 5
Views: 21

Re: Dilution Calculation

Because the units will cancel out when you divide the Molarity over, you can leave it in mL and you should still get the right answer and then you wouldn't have to convert your final answer.
Fri Oct 04, 2019 11:22 am
Forum: Empirical & Molecular Formulas
Topic: Determining Molecular Formulas
Replies: 1
Views: 22

Re: Determining Molecular Formulas

That should work. It might also be easier to just assume 100g and work your way up from empirical to molecular, like Dr. Lavelle showed in class.
Fri Oct 04, 2019 11:21 am
Forum: Molarity, Solutions, Dilutions
Topic: Homework Question E9 Part A
Replies: 1
Views: 18

Re: Homework Question E9 Part A

Your work looks good, I plugged it in and got the right answer. I would just try plugging it into your calculator again :)
Fri Oct 04, 2019 11:15 am
Forum: Empirical & Molecular Formulas
Topic: Order of elements in formulas
Replies: 5
Views: 28

Re: Order of elements in formulas

Usually you would put Carbon first,Hydrogen second, and then any other elements would go in alphabetical order.
Fri Oct 04, 2019 11:12 am
Forum: Limiting Reactant Calculations
Topic: Mass of AgCl produced?
Replies: 2
Views: 19

Re: Mass of AgCl produced?

After you've found the limiting reactant and you've determined the number of moles of AgCl that would be produced by the reaction, you would multiply the # of moles of AgCl you calculated by the molar mass of AgCl and that should give you the mass of AgCl produced.
Fri Oct 04, 2019 9:47 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Wavelength Plausibility
Replies: 17
Views: 295

Re: Wavelength Plausibility

The context here is when does a particle cease to have detectable wave-like properties. In other words only particle-like behavior will be observed. Typically a particle with a de Broglie wavelength less than 10 -15 m does not have detectable wave-like properties. Obviously the higher the mass, the ...
Fri Oct 04, 2019 9:27 am
Forum: Administrative Questions and Class Announcements
Topic: Discussion 3C, 3F, and 3J Question G.27 Correction and formula units
Replies: 1
Views: 66

Re: Discussion 3C, 3F, and 3J Question G.27 Correction and formula units

This clarified G.27.
Thu Oct 03, 2019 10:10 pm
Forum: SI Units, Unit Conversions
Topic: 1.Homework 1 Problem: G5
Replies: 1
Views: 41

Re: 1.Homework 1 Problem: G5

Once you find the molarity of Na2CO3, you can find the volume needed to produce x amount of Na+, CO3 2-, etc. For part a, you are asked to find the volume to produce 2.15 mmol Na+. There are two mol of Na+ per mol of Na2CO3, as given by the subscript 2. Therefore, you would need to divide by 2, not ...
Thu Oct 03, 2019 9:58 pm
Forum: Balancing Chemical Reactions
Topic: Combustion
Replies: 12
Views: 50

Re: Combustion

That is correct.
Thu Oct 03, 2019 9:58 pm
Forum: Molarity, Solutions, Dilutions
Topic: G. 25
Replies: 3
Views: 32

Re: G. 25

Logarithms are used to solve for unknowns that are the exponent of something (in this case 1/2 to the nth power). Logarithms allow us to easily solve for n. Refreshing on your logarithm rules would be helpful!
Thu Oct 03, 2019 9:54 pm
Forum: Administrative Questions and Class Announcements
Topic: Audio-Visual Modules Update Date
Replies: 2
Views: 11

Re: Audio-Visual Modules Update Date

The modules are not posted weekly. All the modules are posted already and are all relevant to Week 0 and 1 material to provide extra review of high school concepts.
Thu Oct 03, 2019 9:10 pm
Forum: Limiting Reactant Calculations
Topic: M.11
Replies: 3
Views: 69

Re: M.11

I worked the problem step-by-step, hope this is helpful. Please come to office hours with any questions/concerns! :) https://imgur.com/a/9wXOgg0
Thu Oct 03, 2019 8:31 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

Thank you so much for sharing your experience! I know getting letters of recommendation is a part of the application process, and I was wondering if you had any advice on how to get close and comfortable enough with professors to ask for a letter? I am also not 100% sure I want to follow this path ...
Thu Oct 03, 2019 8:26 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

Thank you for sharing your personal experience. Do you have any advice for those of us unsure about our majors as first-years? If you don't know what major you want to be in, take classes from all different majors. The classes that you take that don't end up in the major you decide can help fulfill...
Thu Oct 03, 2019 8:23 pm
Forum: Properties of Light
Topic: homework problem
Replies: 1
Views: 30

Re: homework problem

You are given the frequency 99.3 MHz and 1420. MHz. Convert those to Hz and solve using the relevant equation, c = wavelength x frequency. If you are still having trouble, please attend a Step-Up session!
Thu Oct 03, 2019 8:20 pm
Forum: Properties of Light
Topic: HW 1A 19
Replies: 1
Views: 86

Re: HW 1A 19

The key word is ultraviolet, which is involved in the Lyman series (associated with n=1). The question also says emission, so the electron must drop from a higher to lower energy level (here n=1). You can solve for your initial n value since only one unknown is left.
Thu Oct 03, 2019 4:48 pm
Forum: Administrative Questions and Class Announcements
Replies: 3
Views: 45

You are required to make 5 posts. They can be comments or questions. The TA's can view your posts, so you do not need to show them during discussion.
Thu Oct 03, 2019 4:47 pm
Forum: SI Units, Unit Conversions
Topic: E.7 Chemical Principle 7th edition
Replies: 4
Views: 33

Re: E.7 Chemical Principle 7th edition

Recall Avogradro's number is 6.022 x 10^23. In this problem, you're given 2.1 x 10^9 atoms of carbon, so divide by Avogadro's to find the number of moles.

If you're still having trouble understanding the above step, then I would recommend attending Step-Up sessions.
Thu Oct 03, 2019 4:44 pm
Forum: Empirical & Molecular Formulas
Topic: Calculating Empirical Formula with Given Amounts of Each Element
Replies: 7
Views: 32

Re: Calculating Empirical Formula with Given Amounts of Each Element

Your method is acceptable. Keep in mind that when using mass %, you can easily double check that all of the mass of the sample is accounted for. When you convert mass straight to moles, just make sure that all masses given add up to the total sample mass.
Thu Oct 03, 2019 3:08 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student [ENDORSED]
Replies: 133
Views: 83159

Re: Advice from a Medical Student[ENDORSED]

Thank you so much for sharing these. I am a 2nd year right now and was so stressed about being a premed student. I felt like I have so much to do, to get prepared but don’t even know how to start. Your advices are so helpful! I should really make a plan for myself. Don't stress! You have so much ti...
Thu Oct 03, 2019 2:09 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

First off, thanks so much for sharing your story and experience! It's always so nice to hear alumni talk about their past and present experiences. I'm not sure if any of the other students already asked this, but I was wondering what other extracurriculars did you do at UCLA other than being a UA f...
Thu Oct 03, 2019 2:04 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

Hey! Thank you so much for sharing your experience! Were you interested in research at all? If so, what are your opinions on clinical research versus lab research? Was one more interesting to you than another? Or do you think one is more valuable than another? Either one is fine. Medical schools do...
Thu Oct 03, 2019 2:01 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

Wow. Thank you so much for your advice. What major were you as an undergraduate? I was an MCDB major. I loved the upper division bio courses for that major and highly recommend them. However, I will state that after being a UA for so many quarters, I decided to take a few upper division biochemistr...
Thu Oct 03, 2019 1:59 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

You have inspired me immensely! I know this is a bit unrelated to Chemistry and its topics, but how was the transition when it came to applying to medical school? what were some of the big necessities that made applying to medical school make you stand out? It was a bit difficult. Medical school is...
Thu Oct 03, 2019 12:31 am
Forum: Properties of Light
Topic: Properties of light in class
Replies: 3
Views: 34

Re: Properties of light in class

Hz are units of frequency in inverse seconds, s^{-1} This indicates how many times a wave of light peaks, troughs, and then peaks again if measured in one location over one second. Amplitude is the distance between the peak and trough of each wave, and is separate from frequency. A higher amplitude ...
Thu Oct 03, 2019 12:26 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: E.29 b and c
Replies: 3
Views: 41

Re: E.29 b and c

Consider the molar ratio of Cl- ions and H2O molecules in the compound
Thu Oct 03, 2019 12:24 am
Forum: SI Units, Unit Conversions
Topic: E1
Replies: 3
Views: 26

Re: E1

Unless the problem specifies which units to give the answer in, you can leave it in whichever units you deem reasonable.
Thu Oct 03, 2019 12:23 am
Forum: Balancing Chemical Reactions
Topic: Unequal coefficients
Replies: 7
Views: 44

Re: Unequal coefficients

Unless there is a typo, every reaction given in the book should be able to be balanced using whole number coefficients.
Thu Oct 03, 2019 12:21 am
Forum: Limiting Reactant Calculations
Topic: M 15
Replies: 4
Views: 30

Re: M 15

First, identify the limiting reactant based off the starting amounts of each reactant. Then, calculate the maximum theoretical yield of the product based off the amount of the reactant that you have identified as limiting. Finally, use the actual yield given in the problem and the formula for percen...
Thu Oct 03, 2019 12:17 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Problem E2
Replies: 1
Views: 49

Re: Problem E2

You can calculate the total money spent in 90 years by knowing that there are roughly 365 days in year, 24 hours in a day, 60 minutes in an hour, and 60 seconds in a minute. The prize money remaining will be one mole of dollars minus the total money spent. You should find that the total money spent ...
Thu Oct 03, 2019 12:15 am
Forum: Administrative Questions and Class Announcements
Topic: Week 1 Peer Learning Sessions in Young Hall [ENDORSED]
Replies: 1
Views: 44

Week 1 Peer Learning Sessions in Young Hall[ENDORSED]

Hi everybody, Peer Learning Sessions in Young Hall begin today (Thursday 10/3)! I will be hosting a Step-Up session in YH 1032(3) from 2-3pm, so if you have time please feel free to come!
-Matthew
Wed Oct 02, 2019 8:06 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Problem E3
Replies: 2
Views: 26

Re: Problem E3

For showing work, as long as you don't skip steps and the grader can easily follow your work and how you got to the answer, you should be fine. I'd recommend labelling calculations, I imagine that one is the ratio of a molecular molar mass to the empirical molar mass, so perhaps write (molecular MW)...
Wed Oct 02, 2019 8:04 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: E.7 calculate atoms in moles
Replies: 4
Views: 30

Re: E.7 calculate atoms in moles

This question is essentially asking you to convert some amount of carbon atoms to moles of carbon. The whole DNA part is extra, it is just to give some real world context. To solve this problem, you would convert atoms to moles by dividing the atoms by avogadro's number.
Wed Oct 02, 2019 6:06 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student [ENDORSED]
Replies: 133
Views: 83159

Re: Advice from a Medical Student[ENDORSED]

Thanks so much for your advice! I will definitely keep my notes handy as I go through my UCLA journey. Can you tell us a little bit more about your gap year? What types of clubs/ internships/ research opportunities/ etc. you were involved in that helped strengthen your medical school application? M...
Wed Oct 02, 2019 3:38 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

Thank you for sharing your story and offering to help us premeds out! If I may ask, did you use a counselor to help guide you through UCLA? It's unfortunate that we don't have enough pre-health counselors, and I was wondering if you or anyone you know has sought out a private counselor. If they did...
Wed Oct 02, 2019 3:36 pm
Forum: Balancing Chemical Reactions
Topic: Question L.35
Replies: 4
Views: 20

Re: Question L.35

t is one metric ton, which is 1000 kg. I believe that technically you need to balance each individual reaction and then calculate the answer using stoichiometry. However, you may want to try crossing out intermediates and balancing, then finding the amount from that final reaction (509 kg Fe). It ma...
Wed Oct 02, 2019 2:45 pm
Forum: Limiting Reactant Calculations
Topic: M#11
Replies: 2
Views: 30

Re: M#11

Great explanation, I like how you went through it step by step. Only thing is that oxygen is technically O2 in that reaction, so the molar mass you would use is 32 g/mol, which will certainly change some numbers.
Wed Oct 02, 2019 1:34 pm
Forum: Limiting Reactant Calculations
Topic: Homework for week 2 [ENDORSED]
Replies: 3
Views: 36

Re: Homework for week 2[ENDORSED]

Besides this week, homework will always be due in your discussion section.
Wed Oct 02, 2019 11:41 am
Forum: Empirical & Molecular Formulas
Topic: Homework Problem L.39
Replies: 2
Views: 33

Re: Homework Problem L.39

We can find the moles of tin first by converting the 1.50 g to moles using the molar mass. The moles of oxygen can also be found by the difference of mass between the product (1.90 g) and the tin itself (1.50 g), which gives 0.40 g, which can then be converted to moles using the molar mass. The rati...
Wed Oct 02, 2019 11:23 am
Forum: Molarity, Solutions, Dilutions
Topic: G.5 Concentration Calculation
Replies: 4
Views: 43

Re: G.5 Concentration Calculation

Once you find the molarity, you have a way to convert between moles and liters. So for a), convert mmol of Na+ to mol, then convert from moles of Na+ to moles of Na2CO3, then divide by the molarity to get the volume needed. The same procedure applies for b) and c).
Wed Oct 02, 2019 11:18 am
Forum: Empirical & Molecular Formulas
Topic: Homework problem E1
Replies: 9
Views: 48

Re: Homework problem E1

One tip for that problem is that they give you the radius of one atom, but to find the total length you must use the diameter, so multiply by two. You'll need to convert moles to atoms first, as the radius and diameter are for one atom, not one mole. Then convert pm to m using 1 m = 1 x 10^12 pm.
Wed Oct 02, 2019 11:18 am
Forum: Photoelectric Effect
Topic: photoelectric effect
Replies: 2
Views: 29

Re: photoelectric effect

Is there a specific question about how to solve this problem?
Wed Oct 02, 2019 11:13 am
Forum: Administrative Questions and Class Announcements
Topic: First Test in Discussion
Replies: 13
Views: 109

Re: First Test in Discussion

The First Test is only on fundamentals, no quantum
Wed Oct 02, 2019 10:30 am
Forum: Empirical & Molecular Formulas
Topic: Question E9
Replies: 2
Views: 31

Re: Question E9

Magnesium sulfate heptahydrate is actually MgSO4*(7 H20) because sulfate is (SO4)2-, but right now it is not expected to know the names of these polyatomic ions. But to what is important and required to know... We need to get to "atoms of O" from "g of MgSO4*(7 H20)". Yes, Dr. La...
Wed Oct 02, 2019 10:14 am
Forum: Molarity, Solutions, Dilutions
Topic: G. Mixtures and Solutions
Replies: 3
Views: 20

Re: G. Mixtures and Solutions

Remember that concentration means Molarity, M. M is mol per liter (mol/L).

We need to somehow get from what we are given, units of grams over units of mL, to units of mols over units of L. We can use conversion factors to convet mL to L and molar masses to go from g to mol.
Tue Oct 01, 2019 7:28 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

Thank you for taking time out of your probably busy schedule to help all of us! I was wondering if you had any specific advice on time management and studying tips that you’ve learned over the years. The important thing is to find what works for you and be efficient when studying. Breaks are super ...
Tue Oct 01, 2019 7:22 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

Thank you so much for sharing your experience as a medical student! It is truly inspiring to hear about all the things you have accomplished over the past three years. I am also pursuing a career in medicine. However, I am a first-generation student and I have no family members or friends who are i...
Tue Oct 01, 2019 6:34 pm
Forum: Administrative Questions and Class Announcements
Topic: Discussion 3C, 3F, and 3J Question G.27 Correction and formula units
Replies: 1
Views: 66

Discussion 3C, 3F, and 3J Question G.27 Correction and formula units

A few students today pointed out a mistake I made on question G.27 on the worksheet. The 37.50% by mass should be applied to the step after conversion to grams and prior to conversion to mL, due to the difference in density. 10.0\, L\, dil\, HCl(aq)(\frac{0.7436\: mol\ HCl}{1L dil\ HCl &...
Tue Oct 01, 2019 9:33 am
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

Thank you so much for taking the time to offer us undergraduates guidance despite of your busy schedule as a medical school student! How do you think UCLA has helped you in your med school pursuits? Specifically, what resources should we be taking advantage of? UCLA core classes (Chemistry, Physics...
Tue Oct 01, 2019 9:30 am
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

I've heard that if you can imagine yourself being anything else besides a doctor, than the medical route may not be the right path for you. Do you think there's any truth to that statement; does medicine really need to be a calling in order to succeed? I'm on the fence about different career option...
Tue Oct 01, 2019 9:27 am
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

Thank you so much for sharing your experience with us! As a pre-med student it's always very encouraging to hear about UCLA graduates pursuing medical school and beyond. That being said, I was wondering if you had any tips regarding the application process? Also, I noticed in one of your replies yo...
Mon Sep 30, 2019 8:46 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

First of all, thank you for sharing your advice! As I was reading through the replies, you specifically said to be involved in clubs or extracurriculars that set you apart from the other pre-med students. Can you give us some examples that you found insightful and unique? Unfortunately I can't give...
Mon Sep 30, 2019 8:42 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

I was wondering what it takes to get into med school. I know the expectations were high to get into UCLA in the 1st place and was wondering how much harder does it get? The one thing you have to think about is the more advanced you get with any graduate program, the tougher it gets. Think of it lik...
Mon Sep 30, 2019 6:17 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

Thank you so much for sharing your experience! We appreciate the time you're taking to answer our questions. When did you first decide you wanted to go to medical school? Was being pre-med something you've always known, or something you decided as the quarters went on in UCLA? I always was interest...
Mon Sep 30, 2019 6:12 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

This was such a great share.. emphasizing the importance of enjoying the present, whatever that may be. I know it's very early, but for the past few weeks, I have been struggling to decide whether I should go to med school, or even stay within a STEM-related major. I feel if I don't decide soon, it...
Mon Sep 30, 2019 6:05 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

What an incredible story! Thank you for sharing. Was your path to achieving your pre-med degree at UCLA difficult? Do you have any advice for a second year like me following a similar path? Thank you!! I was an MCDB major and I really enjoyed the upper division courses I took. It's nice because the...
Mon Sep 30, 2019 5:54 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

Thank you for sharing, it's great to hear your story! I was wondering if you participated in any extracurriculars during your time at UCLA that helped you gain medical experience? Also do you have any advice for chem 14A? Thank you! I spent a lot of my time volunteering in an autism clinic, which I...
Mon Sep 30, 2019 5:47 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

Thank you so much for your inspiring insight and story about your journey. It is really amazing to see someone who was in our shoes just a little while ago doing such amazing things. Do you have any advice for undergraduates potentially interested in medical school on when and how to study for the ...
Mon Sep 30, 2019 5:40 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

This was such a cool story to read about and helped ease some worries of mine. I was wondering what do you think the hardest part of medical school is? For me, the hardest part was my first semester. I want to pinpoint it on one thing, but it seems to just be everything as a whole. Your first semes...
Mon Sep 30, 2019 3:35 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: F3 Naming compunds
Replies: 2
Views: 39

Re: F3 Naming compunds

You do not need to worry about this right now. This will be covered later on in the quarter.
Mon Sep 30, 2019 3:35 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: F3 Naming compunds
Replies: 2
Views: 39

Re: F3 Naming compunds

HNO3 is a strong acid, so it is a good compound to memorize the chemical formula for. However, if you did not have it memorized, you could determine the chemical formula by knowing that HNO3 is a protonated compound of NO3-, which has a charge of -1. HNO3 is neutrally charged and H+, a proton, has a...
Mon Sep 30, 2019 3:33 pm
Forum: Molarity, Solutions, Dilutions
Topic: Homework Problem G.23
Replies: 3
Views: 71

Re: Homework Problem G.23

Use the chemical formulas given in the problem, KCl and NaCl. This tells you that in each ionic compound of KCl, there is a 1:1 ratio of K+ to Cl-, and same goes for NaCl. Therefore, dissolving one mole of KCl will yield one mole of Cl-, and same for NaCl. You would thus find the concentration of Cl...
Mon Sep 30, 2019 3:28 pm
Forum: Empirical & Molecular Formulas
Topic: Fundamentals L.39
Replies: 2
Views: 41

Re: Fundamentals L.39

You would be correct in using 32.00 g/mol if you were giving your answer in terms of moles of O2. However, if you want to determine moles of O as the element, then 16.00 g/mol would be the correct number to use, as the molar mass of O as listed on the periodic table is 16.00 g/mol. Had they asked fo...
Mon Sep 30, 2019 3:19 pm
Forum: Empirical & Molecular Formulas
Topic: Homework Problem F.17
Replies: 2
Views: 39

Re: Homework Problem F.17

Yes, that looks right. To get from the molecular to empirical formula you can just divide by the greatest common factor.
Mon Sep 30, 2019 3:14 pm
Forum: Molarity, Solutions, Dilutions
Topic: Homework problem E23
Replies: 5
Views: 42

Re: Homework problem E23

The ratio of Cu(2+) to Br- in CuBr2 is 1:2; 1 mol of Cu(2+) combines with 2 moles of Br- to form CuBr2. This is because the copper cation has a charge of +2 and bromide has a charge of -1. Therefore, to form a neutral compound in a reaction, we would need 2 moles of bromide for a total charge of 2x-...
Mon Sep 30, 2019 3:10 pm
Forum: Molarity, Solutions, Dilutions
Topic: HW1 F3 Help
Replies: 4
Views: 57

Re: HW1 F3 Help

For now, knowing the polyatomic ions and other names will be provided. As you go through problems, you will become familiar with the common names that we use.
Mon Sep 30, 2019 3:07 pm
Forum: Administrative Questions and Class Announcements
Replies: 7
Views: 60

It is definitely helpful to do all of the questions given by Dr. Lavelle as it is good practice. However, you only have to submit 5 questions per week to your TA for grading.
Mon Sep 30, 2019 3:07 pm
Forum: Molarity, Solutions, Dilutions
Topic: Homework problem E23
Replies: 5
Views: 42

Re: Homework problem E23

Please provide the problem so other students can understand the context of your question as well as the topic. Thank you!
Sun Sep 29, 2019 8:07 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

Your journey sounds like it has been amazing! As someone that also wants to go into the medical field, this is very inspiring. And you certainly made me more excited for Dr. Lavelle's class. Do you currently have other interests outside the medical field, and do you still have time to engage in the...
Sun Sep 29, 2019 7:24 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

Thank you for sharing your experiences--it was amazing to hear about what to expect from med school and beyond! Highly looking forward to Dr. Lavelle's classes! Did you have your mind set on a medical occupation from the start, or would there be an alternate universe where you would pursue somethin...
Sun Sep 29, 2019 7:12 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

Really enjoyed reading about your academic experience and journey so far. Sounds like this path is very rewarding and opportunistic. Do you think you could have started a challenging and rewarding career without medical school or did you always feel medical school was necessary for any job you migh...
Sun Sep 29, 2019 6:58 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

Thank you for sharing your experience and journey! I really appreciate your advice. I'm not really sure what I want to do with my major (microbio/mimg), but the medical route seems like a viable (and interesting) option. I actually found myself relieved that even someone as accomplished as yourself...
Sun Sep 29, 2019 3:36 pm
Forum: Molarity, Solutions, Dilutions
Topic: Homework Problem G.25
Replies: 1
Views: 38

Re: Homework Problem G.25

First we want to determine the beginning amount of molecules, so think about the information given, and conversion factors that can get us to amount of molecules. Second, we want to set up an equation to figure out how many times we can double the volume, effectively halving the concentration, until...
Sun Sep 29, 2019 3:21 pm
Forum: Limiting Reactant Calculations
Topic: Homework Problem M.11
Replies: 3
Views: 44

Re: Homework Problem M.11

Try using the method you used to determine the limiting reactant from the first equation, but this time include the molar ratios between P4O6 and O2 in the second equation to determine the limiting reagent. Begin with mass of P4 and using dimensional analysis to get to mass of O2.
Sun Sep 29, 2019 11:26 am
Forum: Significant Figures
Topic: How does Significant Figures work? [ENDORSED]
Replies: 12
Views: 99

Re: How does Significant Figures work?[ENDORSED]

Dr. Lavelle's website has a great resource on sig figs that covers most of the great responses on this post: https://lavelle.chem.ucla.edu/wp-content/supporting-files/Chem14A/EVERYTHING_YOU_WANTED_TO_KNOW_ABOUT_SF.pdf
Sat Sep 28, 2019 5:52 pm
Forum: Molarity, Solutions, Dilutions
Topic: G.13
Replies: 3
Views: 37

Re: G.13

Looking at the molecular formula for NH4NO3, there contain 2 nitrogens in the compound. Therefore you would multiply the moles of NH4O3 by 2.
Sat Sep 28, 2019 5:41 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

Thank you for that advice! I will definitely try to adopt that approach, as it seems to be working very well for you. Have you encountered any fields you may want to specialize in? I have enjoyed all three rotations I have been on so far, and I can see myself doing any of those three. Pathology is ...
Sat Sep 28, 2019 5:33 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

Thanks for sharing your story with us! What made you decide to go to medical school? Some people have these incredible stories about some defining "ah-ha" moment where they realized they wanted to do medical school. For me, I just always had an interest in science. I love how rapidly the ...
Sat Sep 28, 2019 5:19 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Re: Advice from a Medical Student - Part II[ENDORSED]

This is so inspiring and gives me hope. Can I ask what extracurriculars you took part in? I did a lot of tutoring and volunteered in an autism clinic. I personally wasn't too involved with the extracurriculars at UCLA, not by choice but because I commuted and just wasn't always around on campus dur...
Fri Sep 27, 2019 8:55 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 111
Views: 1158

Advice from a Medical Student - Part II[ENDORSED]

Hey Chem 14A and 14B Students! This is a two year update from my last post...although both posts are still active, and you're welcome to post questions/comments in either one. I read through all of them and promise to reply. Just a quick update. For those of you who didn't read my first post, my nam...
Wed Jul 31, 2019 12:22 pm
Forum: Administrative Questions and Class Announcements
Topic: Saying Thank You to Dr. Lavelle
Replies: 207
Views: 97058

Re: Saying Thank You to Dr. Lavelle

Hi Bella,

Thank you for sharing.

I do put much effort into encouragement and organize extensive additional support for students in my classes.

More importantly, excellent to hear you did not give up!
:-)

A lesson I hope will stay with you for life.
Wed Jul 31, 2019 12:07 pm
Forum: Administrative Questions and Class Announcements
Topic: 14A Summer 19 Final Review
Replies: 3
Views: 457

Re: 14A Summer 19 Final Review

Wed Jul 31, 2019 12:07 pm
Forum: Administrative Questions and Class Announcements
Topic: Butter Chicken Week 5 Worksheet Answers
Replies: 1
Views: 175

Re: Butter Chicken Week 5 Worksheet Answers

Wed Jul 31, 2019 12:07 pm
Forum: Administrative Questions and Class Announcements
Topic: Butter Chicken-Week 5 Worksheet
Replies: 1
Views: 196

Re: Butter Chicken-Week 5 Worksheet

Wed Jul 31, 2019 12:06 pm
Forum: Administrative Questions and Class Announcements
Replies: 1
Views: 177

Wed Jul 31, 2019 12:06 pm
Forum: Administrative Questions and Class Announcements
Topic: Week 4 Worksheet
Replies: 1
Views: 236

Re: Week 4 Worksheet

Wed Jul 31, 2019 12:05 pm
Forum: Administrative Questions and Class Announcements
Replies: 1
Views: 258

Wed Jul 31, 2019 12:04 pm
Forum: Administrative Questions and Class Announcements
Topic: Week 2 Butter Chicken Answers
Replies: 1
Views: 226

Re: Week 2 Butter Chicken Answers

Wed Jul 31, 2019 12:04 pm
Forum: Administrative Questions and Class Announcements
Topic: Practice Midterm
Replies: 1
Views: 263

Re: Practice Midterm

Wed Jul 31, 2019 12:03 pm
Forum: Properties of Light
Topic: Butter Chicken-Part 2
Replies: 1
Views: 562

Re: Butter Chicken-Part 2

Wed Jul 31, 2019 9:10 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty Principal
Replies: 1
Views: 308

Re: Uncertainty Principal

Wavelength = h/momentum, here we see that wavelength is inversely proportional to momentum. So any change in momentum would affect the wavelength.
Wed Jul 31, 2019 8:30 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg Equation
Replies: 3
Views: 306

Re: Rydberg Equation

Rydberg Equation: 1/λ=R(1/n(1)^2−1/n(2)^2) You can change n(1) and n(2), which refer to different energy levels in the Hydrogen atom. For example, you can use n(1)= 1 and n(2)=2 to find the wavelength of light emitted when an electron drops from the n=2 to the n=1 energy level (or the wavelength of ...
Wed Jul 31, 2019 8:28 am
Forum: Lewis Structures
Topic: Octet
Replies: 1
Views: 410

Re: Octet

The octet rule is violated in compounds with more than eight electrons assigned to their valence shell. These are called expanded valence shell molecules. Such compounds are formed only by central atoms in the third row of the periodic table and beyond that have empty d orbitals in their valence she...
Tue Jul 30, 2019 11:21 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Induced dipole?
Replies: 3
Views: 223

Re: Induced dipole?

Induced dipoles, like London forces, are not considered dipoles. They are short term, induced dipoles. They are important when dealing with shape, such as rod shape is more affected by induced dipoles than spherical shapes. Dipoles result from electronegative pulling and are present in polar molecul...
Tue Jul 30, 2019 11:13 pm
Forum: Hybridization
Topic: Unhybridized orbitals
Replies: 6
Views: 11601

Re: Unhybridized orbitals

Unhybridized p orbitals allow for pi bonding, not empty hybridized orbitals. Take for example an sp2, you would have the 3 hybridized sp2 orbitals, and then remember you would still have a leftover p orbital (you had 4 total- 1 s and 3 p's), so that leftover p orbital can make the pi bond, resulting...
Tue Jul 30, 2019 11:02 pm
Forum: Lewis Acids & Bases
Topic: Na+
Replies: 3
Views: 352

Re: Na+

Salts that contain the conjugate base (anion) of a weak acid will raise the pH by removing protons from H2O thus generating OH- 's. Na+ doesn't react with the hydrolysis of water. Remember in lecture when Dr. Lavelle said if the tomato sauce tasted really acidic, adding table salt wouldn't do anythi...
Tue Jul 30, 2019 10:54 pm
Forum: Lewis Acids & Bases
Topic: Acids & Bases
Replies: 4
Views: 186

Re: Acids & Bases

Bronsted Acids-Bases are all about proton transfer, H+. Bronsted Acid donates a proton/H+. Bronsted Base accepts a proton/H+. Lewis is all about electron transfer. Lewis Acid is an electron pair acceptor. Tip: Lewis Acid initials, LA, can be said as (e)Lectron Acceptor to help you remember. Lewis ba...
Tue Jul 30, 2019 10:44 pm
Forum: Lewis Acids & Bases
Topic: Neutralization reaction
Replies: 1
Views: 155

Re: Neutralization reaction

A neutralization reaction is when an acid and base react with each other to form a salt and water. Think of an acid and base as two antagonistic things, one as acidic and one as basic, so when they react, they neutralize the acidity and basicity of each other, which results in water because the acid...