Search found 68 matches

by Katie Lam 2J
Thu Jan 21, 2021 10:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook 5I.29
Replies: 2
Views: 14

Re: Textbook 5I.29

The equilibrium partial pressure for HCl is 0.22 because the Kp is < 10^-4. But you would still need to find for x, which is also the molar concentration for H2 and Cl2, by setting the Kp expression and plugging in for each reactant and product. It would be 3.2\times 10^{-34}=\frac{x^{2}}{(0.22...
by Katie Lam 2J
Thu Jan 21, 2021 10:08 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm 1: Lecture cutoff
Replies: 7
Views: 42

Re: Midterm 1: Lecture cutoff

If Chem 14B is similar to Chem 14A, the week of our midterm will not cover any material on that midterm. I would say the cutoff is tomorrow's lecture, but it can always be different. Maybe Dr. Lavelle will send out an email about that!
by Katie Lam 2J
Thu Jan 21, 2021 10:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Studying for Midterm #1
Replies: 36
Views: 82

Re: Studying for Midterm #1

I find that doing the textbook problems and making sure you know everything that is listed on his outlines is the best way to prepare for the midterm!
by Katie Lam 2J
Thu Jan 21, 2021 10:04 pm
Forum: Administrative Questions and Class Announcements
Topic: Homework
Replies: 9
Views: 45

Re: Homework

Even though it is Week 3, our homework assignment due this Sunday at 11:59 p.m. (at the end of Week 3) is the homework assignment titled Week 2. It confused me too!
by Katie Lam 2J
Thu Jan 21, 2021 10:01 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Week 2 Sapling #5
Replies: 9
Views: 59

Re: Week 2 Sapling #5

Jaden Haskins 2E wrote:How would you set up this equation? I tried both times once disregarding x and once without and did not get the correct answer either time. Do you need to switch Kb to Ka?

You do not need to switch Kb to Ka. Just make sure you use the pH to find the pOH and therefore the [OH-]!
by Katie Lam 2J
Thu Jan 21, 2021 9:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook 5I.29
Replies: 2
Views: 14

Textbook 5I.29

Screen Shot 2021-01-21 at 9.51.52 PM.png For this question, I am getting the correct answer for the equilibrium partial pressure of HCl, which is 0.22 bar. However, for the equilibrium partial pressures of H2 and Cl2, I keep getting 8.4x10^-18 bar instead of 3.9x10^-18 bar. How do you get the corre...
by Katie Lam 2J
Sat Jan 16, 2021 11:42 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier's with Solids
Replies: 5
Views: 17

Re: Le Chatelier's with Solids

Increasing the amount of solid or liquid will have no effect on the equilibrium reaction, so you can neglect those two when solving parts of an equilibrium reaction.
by Katie Lam 2J
Sat Jan 16, 2021 11:19 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Week 1 #9
Replies: 7
Views: 59

Re: Sapling Week 1 #9

Sometimes for me, I put down my answer with the correct number of sig figs, and Sapling says it's incorrect. However, if I write down the entire answer that's on my calculator without using scientific notation or the correct number of sig figs, Sapling says it's correct. It's frustrating, but someti...
by Katie Lam 2J
Sat Jan 16, 2021 10:28 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: When x is negligible in Equilibrium constant
Replies: 34
Views: 98

Re: When x is negligible in Equilibrium constant

Catherine Bubser 2C wrote:If K is greater than 10^-3 would we just use the quadratic formula and not assume x is negligible?

Yes! We cannot assume x is negligible in this case, so we would have to use all of the x values in the quadratic formula.
by Katie Lam 2J
Sat Jan 16, 2021 10:25 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Weak versus Strong Acid and Base
Replies: 10
Views: 26

Re: Weak versus Strong Acid and Base

I believe in Chem 14A, we had to memorize the strong acids and bases, and there aren't a lot of them. Anything else would be considered a weak acid or base.
by Katie Lam 2J
Sat Jan 16, 2021 10:20 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling #5
Replies: 5
Views: 51

Sapling #5

How do you approach this problem? I'm just a little unsure about how to manipulate the different equilibrium constants.
by Katie Lam 2J
Fri Jan 08, 2021 6:10 pm
Forum: Administrative Questions and Class Announcements
Topic: Audio-Visual Topics
Replies: 13
Views: 57

Re: Audio-Visual Topics

Unfortunately, we probably won't have Audio-Visual topics for every section :( The textbook is the best way to get practice problems after you have completed all of the Audio-Visual topics in my opinion. UA's also have worksheets with problems, and those are helpful too.
by Katie Lam 2J
Fri Jan 08, 2021 6:07 pm
Forum: Ideal Gases
Topic: Non-Ideal gases?
Replies: 26
Views: 113

Re: Non-Ideal gases?

I don't think we will have to use these in the 14 series.
by Katie Lam 2J
Wed Jan 06, 2021 5:16 pm
Forum: Administrative Questions and Class Announcements
Topic: Sapling Purchase Has not arrived
Replies: 3
Views: 27

Re: Sapling Purchase Has not arrived

The first Sapling homework assignment is due on January 17. I think your textbook should arrive in time for you to do the first assignment.
by Katie Lam 2J
Wed Jan 06, 2021 5:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Q, K and Direction
Replies: 4
Views: 17

Re: Q, K and Direction

The reaction goes towards the production of products to balance out the higher concentration of reactants relative to equilibrium. If there is a high concentration of reactants, then the concentration of products must increase to achieve equilibrium.
by Katie Lam 2J
Fri Dec 11, 2020 11:30 am
Forum: Lewis Acids & Bases
Topic: Acid vs. Base
Replies: 3
Views: 57

Re: Acid vs. Base

I believe NH3 is a weak base and would rather accept a proton because NH4+ is a polyatomic ion. Because NH4+ is a polyatomic ion, I think it is a more favorable structure than NH2-. Please correct me if I am wrong!
by Katie Lam 2J
Fri Dec 11, 2020 11:27 am
Forum: Amphoteric Compounds
Topic: Amphoteric
Replies: 8
Views: 90

Re: Amphoteric

I think one of the TA's said this will be covered in 14B, so we don't have to worry about this right now.
by Katie Lam 2J
Fri Dec 11, 2020 11:20 am
Forum: Administrative Questions and Class Announcements
Topic: Are all questions on the final multiple choices?
Replies: 29
Views: 145

Re: Are all questions on the final multiple choices?

All questions are multiple choice, and there is no partial credit this time :(
by Katie Lam 2J
Wed Dec 09, 2020 4:24 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Last Bullet Point of Outline 4
Replies: 1
Views: 24

Last Bullet Point of Outline 4

I am looking at the last bullet point of Outline 4 which states, "Describe the structure of a molecule, cation, or anion in terms of hybrid orbitals and sigma and
pi bonds." How do sigma and pi bonds affect the structure of a molecule, cation, or anion?
by Katie Lam 2J
Mon Dec 07, 2020 7:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Textbook Question 2.27
Replies: 1
Views: 11

Textbook Question 2.27

The question asks to rank the following species in order of increasing HCH bond angles. The species are CH3+, CH4, CH3-, CH2, CH22+, and CH22-. How come CH22- has the smallest bond angle? I know that the angle is between 90 and 120 degrees because the shape is bent, but how do you determine what the...
by Katie Lam 2J
Fri Dec 04, 2020 5:04 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: H2O Notation
Replies: 5
Views: 47

Re: H2O Notation

I believe H2O is always labeled liquid (l)
by Katie Lam 2J
Fri Dec 04, 2020 4:55 pm
Forum: Administrative Questions and Class Announcements
Topic: Chem 14A Final
Replies: 21
Views: 181

Re: Chem 14A Final

I read the final exam information on Dr. Lavelle's website, and he said it will be approximately weighted to the amount of time covered in the syllabus. He wrote that quantum was the biggest section, so we should expect more questions from that section. Hope this helps!
by Katie Lam 2J
Fri Dec 04, 2020 4:49 pm
Forum: Naming
Topic: sapling 9c.3
Replies: 4
Views: 41

Re: sapling 9c.3

The prefixes don't override the alphabetical order of the names. We just write the name in alphabetical order not including the prefixes :)
by Katie Lam 2J
Fri Dec 04, 2020 4:47 pm
Forum: Hybridization
Topic: Sigma/pi bonds
Replies: 6
Views: 47

Re: Sigma/pi bonds

Hey Claire! I don't think the order matters as long as there is 1 sigma bond and 2 pi bonds total :)
by Katie Lam 2J
Fri Dec 04, 2020 4:44 pm
Forum: General Science Questions
Topic: study methods/recs
Replies: 37
Views: 279

Re: study methods/recs

Hey Lea! I find that writing out my responses to every bullet point in the outline is very helpful. I am also planning on attending every review session I can go to in Week 10 :)
by Katie Lam 2J
Sat Nov 28, 2020 12:05 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sapling Weeks 7-8 #16
Replies: 6
Views: 56

Re: Sapling Weeks 7-8 #16

A delocalized pi bond occurs when pi orbitals extend over more than two atoms. This occurs in resonance structures with double or triple bonds. For example, in O3, the double bond can occur between the left and center O's or the right and center O's. The pi bond is not fixed to one particular local ...
by Katie Lam 2J
Sat Nov 28, 2020 12:00 pm
Forum: Hybridization
Topic: Sapling #12
Replies: 27
Views: 182

Re: Sapling #12

Because C has 4 regions of electron density (4 single bonds), and O also has 4 regions of electron density (2 single bonds and 2 lone pairs), the hybridization of both C and O is sp3.
by Katie Lam 2J
Sat Nov 28, 2020 11:56 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Sapling Wk8 Q. 18, Determining Molecular Shape
Replies: 10
Views: 70

Re: Sapling Wk8 Q. 18, Determining Molecular Shape

Yes it does. However, in your structure for H2CCCH2, you have 3 H's on the end instead of 2. Isaac is also correct in that there should be a double bond between every C.
by Katie Lam 2J
Sat Nov 28, 2020 11:53 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Double/Triple Bonds and Polarity
Replies: 8
Views: 60

Re: Double/Triple Bonds and Polarity

I'm not entirely sure if my logic is correct, but I think yes because double bonds mean that the distance between the (in the arsenate ion from your example) Oxygen atom (that is double bonded) and the As would be shorter, causing larger electron repulsion, making the molecule more polar (more unev...
by Katie Lam 2J
Sat Nov 28, 2020 11:31 am
Forum: Lewis Structures
Topic: SnCl2 lewis structure
Replies: 2
Views: 23

Re: SnCl2 lewis structure

The lewis structure has Sn in the middle with a lone pair of electrons. Sn is single bonded to each Cl, and each Cl has 3 lone pairs of electrons. I believe this is the most likely structure based on formal charge.
by Katie Lam 2J
Sun Nov 22, 2020 9:26 pm
Forum: Sigma & Pi Bonds
Topic: Pi Bonds with s Orbital
Replies: 4
Views: 23

Re: Pi Bonds with s Orbital

It is not possible for a pi bond to be formed between 2 s orbitals because s orbitals have spherical symmetry, so there is no way to overlap them to form a bond. Hope this helps!
by Katie Lam 2J
Sun Nov 22, 2020 9:23 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw Shape
Replies: 8
Views: 39

Re: Seesaw Shape

The seesaw shape gets created because the more repulsive lone pair interacts with only 2 bonds at 90 degrees, forcing them down a little, and that create the seesaw shape. Hope this helps!
by Katie Lam 2J
Sun Nov 22, 2020 9:18 pm
Forum: Resonance Structures
Topic: Resonance Hyrbid
Replies: 11
Views: 86

Re: Resonance Hyrbid

this is a bit of a dumb question but what exactly do we mean when we say something is delocalized? i've seen it in a couple of posts and im a bit confused as to what that exactly means Tae answered that perfectly! To add on, the reason why you can remove a pair of electrons from an atom and then dr...
by Katie Lam 2J
Sun Nov 22, 2020 9:11 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: polarity of trans-dichlorethene
Replies: 4
Views: 25

Re: polarity of trans-dichlorethene

Yes there will be a dipole on each side of the molecule even though the overall charge of the molecule is 0.
by Katie Lam 2J
Sun Nov 22, 2020 9:03 pm
Forum: Dipole Moments
Topic: Dipole-Dipole
Replies: 10
Views: 42

Re: Dipole-Dipole

You can tell if there is an electronegativity difference between the atoms. This electronegativity difference helps you determine whether a bond is polar, and dipole-dipole interactions can only occur between polar molecules. Hope this helps!
by Katie Lam 2J
Sun Nov 15, 2020 7:06 pm
Forum: Octet Exceptions
Topic: Textbook 2C.1
Replies: 5
Views: 50

Re: Textbook 2C.1

How would you arrange OH in order to make it a total charge 0 and a radical? I figure you just take away one electron from O (7 valence e- instead of 8)? Can you just do that? If anyone could please explain for CH3 as well I would appreciate it so much. For CH3, carbon has 4 valence electrons, and ...
by Katie Lam 2J
Sat Nov 14, 2020 8:09 pm
Forum: Quantum Numbers and The H-Atom
Topic: under which circumstances does 4s have lower energy than 3d?
Replies: 2
Views: 40

Re: under which circumstances does 4s have lower energy than 3d?

I believe that is correct. In one of the lectures, Dr. Lavelle mentioned that, for multi-electron atoms after atomic number 20 (Ca), the 4s state is higher in energy than 3d. Hope this helps!
by Katie Lam 2J
Sat Nov 14, 2020 8:05 pm
Forum: Quantum Numbers and The H-Atom
Topic: Exceptions for electron configuration
Replies: 3
Views: 38

Re: Exceptions for electron configuration

Chromium is an exception because, if you were to do the electron configuration normally, you would get [Ar]3d^4 4s^2. However, a half full d orbital is more stable. Therefore, the electron configuration will be [Ar]3d^5 4s^1. Copper is an exception because, if you were to do the electron configurati...
by Katie Lam 2J
Sat Nov 14, 2020 7:41 pm
Forum: Administrative Questions and Class Announcements
Topic: Saving 14B for second enrollement
Replies: 4
Views: 75

Re: Saving 14B for second enrollement

I am also saving 14B for second enrollment because Dr. Lavelle says he always admits students off his waitlist.
by Katie Lam 2J
Sat Nov 14, 2020 7:39 pm
Forum: Ionic & Covalent Bonds
Topic: Sapling #13
Replies: 8
Views: 36

Re: Sapling #13

Hey Anna! Hydrogen bonds occur between an H atom and either an N, O, or F atom. Therefore, the oxygen can bond with 2 H2O molecules. The 4 hydrogens each bond with one H20 molecule. Each nitrogen can also bond with one molecule. If you add up all of those bonds, you get 8 bonds total. Hope this helps!
by Katie Lam 2J
Sat Nov 14, 2020 2:42 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Textbook Problem 1.E.25
Replies: 7
Views: 73

Re: Textbook Problem 1.E.25

I got the same answers as you did but for C the answer from the test book is (n−1)d5 ns2 Can someone explain why this is the answer and not (n-1)d3 ns2? Thank you! Hi! The solutions manual on sapling says that the answer to C) is (n-1)d3ns2 for group 5 transition metals, which is correct because gr...
by Katie Lam 2J
Thu Nov 05, 2020 3:51 pm
Forum: Administrative Questions and Class Announcements
Topic: Points to Grades Breakdown
Replies: 5
Views: 77

Re: Points to Grades Breakdown

Unfortunately, I don't think there's a grade breakdown posted anywhere. His syllabus does say a 50% or higher is required to pass with a C- or higher.
by Katie Lam 2J
Thu Nov 05, 2020 3:47 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: energy in electron configurations
Replies: 7
Views: 57

Re: energy in electron configurations

Hey Kaylee! I think we will always have to write 3d before 4s. However, if there are 9 electrons in 3d, and 2 electrons in 4s, then we can move the one electron from 4s to 3d. Having a 3d shell with only 9 electrons is very unstable, so adding that one electron to make a full shell will make it more...
by Katie Lam 2J
Thu Nov 05, 2020 3:43 pm
Forum: General Science Questions
Topic: Grade Breakdown
Replies: 32
Views: 351

Re: Grade Breakdown

Unfortunately, the syllabus does not say anything about the specific grade breakdowns.
by Katie Lam 2J
Thu Nov 05, 2020 3:39 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm 1
Replies: 2
Views: 45

Re: Midterm 1

In Dr. Lavelle's email, he said, "Also, for my final exam review sessions in Week 10, I will go through problems that some students had difficultly with in MT1 and MT2." Unfortunately, we will not know how to do the problems we missed anytime soon.
by Katie Lam 2J
Thu Nov 05, 2020 3:37 pm
Forum: Administrative Questions and Class Announcements
Topic: Reviewing Answers for Midterm 1
Replies: 13
Views: 133

Re: Reviewing Answers for Midterm 1

Hey Amanda! Unfortunately, we cannot review our midterm questions and answers. I wish we could see which ones we got incorrect, but I am hoping we will be able to see them soon.
by Katie Lam 2J
Thu Oct 29, 2020 10:55 pm
Forum: *Particle in a Box
Topic: Midterm 1
Replies: 16
Views: 258

Re: Midterm 1

David Jen 3I wrote:So we don't need to study 1.D?


I think we have to know up to 1D1 for the midterm.
by Katie Lam 2J
Thu Oct 29, 2020 10:49 pm
Forum: Administrative Questions and Class Announcements
Topic: Chem 14A Website
Replies: 5
Views: 65

Re: Chem 14A Website

I have the email from Dr. Lavelle starred just in case I have to find the password again! The email is from noreply@chem.ucla.edu and it was sent on Friday, September 25.
by Katie Lam 2J
Thu Oct 29, 2020 10:46 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configurations
Replies: 15
Views: 93

Re: Electron Configurations

I think Dr. Lavelle said the longer, more detailed way is better. It is clearer and will help you draw the electron configurations better. However, either way is correct, and I don't think you will lose any points for doing it the shorter way unless he specifically asks for the longer form.
by Katie Lam 2J
Thu Oct 29, 2020 10:41 pm
Forum: Student Social/Study Group
Topic: How to relax
Replies: 113
Views: 595

Re: How to relax

I like to cook, go to stores, watch television shows, and play with my dogs!
by Katie Lam 2J
Thu Oct 29, 2020 10:37 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Sapling hw "wavelength range"
Replies: 3
Views: 50

Re: Sapling hw "wavelength range"

Hey Kate! Since you know the number of spectral lines is 5, you have to use the equation En= -hr/n^2 where n = 5. You should get an energy of -8.7195x10^-20J. Then you should use the equation Ef-Ei, where Ef = the energy of n=6, and Ei = the energy of n=5. You should get 2.6643 x 10^-20J. Afterwards...
by Katie Lam 2J
Thu Oct 22, 2020 12:40 pm
Forum: Student Social/Study Group
Topic: How are you studying?
Replies: 203
Views: 1290

Re: How are you studying?

I find the audio-visual modules super helpful. I take very detailed notes when I watch the videos in the modules. The post-video assessments are also super useful. When I watch the recorded lectures, since I already have a general idea of what the topics are based on the audio-visual module videos, ...
by Katie Lam 2J
Thu Oct 22, 2020 12:36 pm
Forum: Properties of Light
Topic: Wavelengths in Light Spectrum
Replies: 9
Views: 78

Re: Wavelengths in Light Spectrum

After attending my discussion section today, my TA told us to take a quick look at the reference sheet he will be giving us. If the electromagnetic spectrum is not on the reference sheet, it will be a good idea to go ahead and memorize it. Hope this helps!
by Katie Lam 2J
Thu Oct 22, 2020 12:34 pm
Forum: Properties of Electrons
Topic: intensity vs energy
Replies: 29
Views: 251

Re: intensity vs energy

I believe this is false. An increase in intensity would increase the number of particles at a time. An increase in energy has to do with an increase in frequency.
by Katie Lam 2J
Thu Oct 22, 2020 12:32 pm
Forum: Photoelectric Effect
Topic: Sapling HW 2 Question 4
Replies: 6
Views: 94

Re: Sapling HW 2 Question 4

Hi! The find the maximum number of electrons, you need to divide the total energy (6.84x10^-7 J) by the work function (which is in J/photon). When dividing, Joules should cancel out, so you should be left with photons as your units. Since the ratio of photons to electrons is 1:1, the number of photo...
by Katie Lam 2J
Thu Oct 22, 2020 12:24 pm
Forum: DeBroglie Equation
Topic: De Brogile Wavelength Car Ex. from Lecture 8
Replies: 7
Views: 72

Re: De Brogile Wavelength Car Ex. from Lecture 8

Hi! I was watching Dr. Lavelle's lecture and he said anything with a De Broglie wavelength less than 10^-15 m does not have detectable wavelike properties. Hope this helps!
by Katie Lam 2J
Fri Oct 16, 2020 10:41 am
Forum: Properties of Electrons
Topic: Sapling HW question 4
Replies: 6
Views: 80

Re: Sapling HW question 4

Hi! I am still a little confused on this question. It mentions that the burst of photons (in part 2) is coming from a light with a different frequency. Wouldn't that impact the work function because we used the frequency in part one to calculate it? Or is the work function specific to the kind of m...
by Katie Lam 2J
Thu Oct 15, 2020 11:06 am
Forum: Einstein Equation
Topic: m vs nm
Replies: 66
Views: 444

Re: m vs nm

In the lecture, Dr. Lavelle said you can leave your answer in meters. However, in my discussion, my TA converted all those values to nanometers because the electromagnetic spectrum has wavelengths measured in nanometers. Sometimes it is helpful to make this conversion. Unless it is directly specifie...
by Katie Lam 2J
Thu Oct 15, 2020 11:00 am
Forum: Properties of Light
Topic: Problem 1A.15
Replies: 3
Views: 59

Re: Problem 1A.15

Hi Astha! In the Atomic Spectrum audio-visual module video, Dr. Lavelle drew out the hydrogen atom spectrum, and the UV spectrum is named the Lyman series. The visible light spectrum is also named the Balmer series. Hope this helps!
by Katie Lam 2J
Wed Oct 14, 2020 10:58 am
Forum: Properties of Electrons
Topic: Atomic Spectra
Replies: 5
Views: 56

Re: Atomic Spectra

When an electron is energized, the electron does move away from the nucleus to a energy level further from the nucleus. The hydrogen spectral lines do correspond to this. The hydrogen spectral lines show how energized atoms only give off photons of a particular energy or frequency. Infrared, visible...
by Katie Lam 2J
Wed Oct 14, 2020 10:49 am
Forum: Properties of Light
Topic: Photoelectric spectrum
Replies: 24
Views: 163

Re: Photoelectric spectrum

Adding on to memorizing the wavelengths, are we also supposed to know things like the frequencies or energy of each one, or can we just understand that higher frequency correlates with longer wavelength and more energy? I don't think we have to memorize the frequencies and energies of each one. Kno...
by Katie Lam 2J
Thu Oct 08, 2020 4:55 pm
Forum: SI Units, Unit Conversions
Topic: Sig figs and molar mass
Replies: 18
Views: 101

Re: Sig figs and molar mass

Hi! The periodic table I use has 4 digits after the decimal point. What I do is I use the entire number in my calculations. I try not to round while I am working through the problem. I usually keep 4 digits after the decimal point for every value in my calculation. Only at the end do I round my numb...
by Katie Lam 2J
Wed Oct 07, 2020 2:38 pm
Forum: Empirical & Molecular Formulas
Topic: Limiting Reactant Post-Module Q.18
Replies: 3
Views: 67

Re: Limiting Reactant Post-Module Q.18

Hi Kayla! I thought about it this way: First I converted the grams of NH3 and O2 to moles, 21.4g NH3 x (1 mol/17g NH3) = 1.258 mol NH3 42.5g O2 x (1 mol/32g O2) = 1.328 mol O2 Then, I divided each mol value by the smallest mol value, 1.328 mol O2/1.258 mol = 1.055 1.258 mol NH3/1.258 mol = 1 The rat...
by Katie Lam 2J
Wed Oct 07, 2020 2:18 pm
Forum: Molarity, Solutions, Dilutions
Topic: #25 on Molarity and Dilution of a Solution Post Assessment
Replies: 6
Views: 72

Re: #25 on Molarity and Dilution of a Solution Post Assessment

Step 1. Covert 5.00g KMnO4 to moles: 5.00g *(1mol/158.04g) = 0.0316 mol KMnO4 Step 2. Covert 150.00 mL to L: 0.150 L Step 3. Using the M1V1=M2V2 formula, the 20.00 ml (0.02L) will be your V1, the 250.00 ml (0.250 L) is V2 Step 4. M1 will be calculated from step 1 and 2: (0.0316 mol/0.150L) = 0.211M...
by Katie Lam 2J
Wed Oct 07, 2020 2:16 pm
Forum: Molarity, Solutions, Dilutions
Topic: #25 on Molarity and Dilution of a Solution Post Assessment
Replies: 6
Views: 72

Re: #25 on Molarity and Dilution of a Solution Post Assessment

I did this post assessment module a few days ago but if I remember correctly I got it right using these steps: Convert the 5.00 g KMnO4 to mols using its molar mass (158.04g/mol) and you'll get 0.0316 mol. Then using the volume you're given, find the molarity of the solution. Make sure to change th...
by Katie Lam 2J
Tue Oct 06, 2020 11:20 pm
Forum: Molarity, Solutions, Dilutions
Topic: #25 on Molarity and Dilution of a Solution Post Assessment
Replies: 6
Views: 72

#25 on Molarity and Dilution of a Solution Post Assessment

I have tried to work out this question multiple ways, but I never seem to get the correct value. The question is: 5.00 g of KMnO4 is dissolved in a 150.00 mL flask of water. If 20.00 mL of this solution is removed and placed in a new 2nd 250.00 mL flask and filled with water, what is the concentrati...

Go to advanced search