Search found 88 matches
- Sat Dec 08, 2018 10:16 pm
- Forum: Bronsted Acids & Bases
- Topic: Base Strength
- Replies: 4
- Views: 1828
Re: Base Strength
Morphine will accept a proton on the N atom. This is a very weak base. The conjugate acid of BrO- is BrOH which is a weak acid. This suggests that BrO- is a relatively strong base, stronger than morphine
- Sat Dec 08, 2018 10:14 pm
- Forum: Bronsted Acids & Bases
- Topic: Base Strength
- Replies: 4
- Views: 1828
Re: Base Strength
You mean BrO-
- Sat Dec 08, 2018 10:14 pm
- Forum: Bronsted Acids & Bases
- Topic: Lewis vs Bronsted
- Replies: 10
- Views: 1504
Re: Lewis vs Bronsted
Lewis Acids and Bases are electron pair acceptors and donors respectively.
Bronsted Acids and Bases are proton donors and acceptors respectively.
Bronsted Acids and Bases are proton donors and acceptors respectively.
- Sat Dec 08, 2018 3:49 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: SO THERE ARE SPECIAL RULES FOR SIG FIGS IN pH THEN
- Replies: 5
- Views: 765
Re: SO THERE ARE SPECIAL RULES FOR SIG FIGS IN pH THEN
Thank you everyone! Good luck on the final
- Fri Dec 07, 2018 1:34 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: SO THERE ARE SPECIAL RULES FOR SIG FIGS IN pH THEN
- Replies: 5
- Views: 765
Re: SO THERE ARE SPECIAL RULES FOR SIG FIGS IN pH THEN
Did Dr. Lavelle mention this in class?
- Fri Dec 07, 2018 1:30 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Sig Figs for pH
- Replies: 3
- Views: 379
- Fri Dec 07, 2018 1:28 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: SO THERE ARE SPECIAL RULES FOR SIG FIGS IN pH THEN
- Replies: 5
- Views: 765
SO THERE ARE SPECIAL RULES FOR SIG FIGS IN pH THEN
Does anyone know if Dr. Lavelle gave instructions on doing sig figs in pH calculations? Apparently there is a special rule in chemistry. Each decimal place AFTER the decimal pointcounts as one sig fig. Everything to the LEFT of the decimal point does not count as a sig fig. For example: 7.3 has one ...
- Fri Dec 07, 2018 1:23 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Are all pH calculations done to 2 decimal places or do we use sig figs in pH calculations? [ENDORSED]
- Replies: 2
- Views: 1353
Are all pH calculations done to 2 decimal places or do we use sig figs in pH calculations? [ENDORSED]
For example 6B.5c in the 7th edition textbook asks us to calculate the pH for 0.0092 M Ba(OH)2. This is 2 sig figs but the answer in the back gives 12.96. Should the answer instead be 13?
- Fri Dec 07, 2018 12:40 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: 6B. 3 [ENDORSED]
- Replies: 3
- Views: 392
Re: 6B. 3 [ENDORSED]
This is how I did it and I got the correct answers. The phrasing of the question is terrible. You have to assume that the solution of 250 ml is DILUTED with water
- Fri Dec 07, 2018 12:31 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: 6B. 3 [ENDORSED]
- Replies: 3
- Views: 392
Re: 6B. 3 [ENDORSED]
I'm stuck on this too. I can get the right answer for part A but part B doesn't make any sense. Wouldn't the pH of either volume be the same??
- Fri Dec 07, 2018 12:08 am
- Forum: Amphoteric Compounds
- Topic: What makes As2O3 Amphoteric?
- Replies: 2
- Views: 498
Re: What makes As2O3 Amphoteric?
Aha, I might be getting Amphoteric and Amphiprotic mixed up. As2O3 is NOT Amphiprotic, as it can not donate an H+ ion. It IS Amphoteric because it can react with an acid (such as HCL) or with a base (such as NaOH) Am I correct in this logic? All amphiprotic substances are amphoteric but not all amph...
- Fri Dec 07, 2018 12:02 am
- Forum: Amphoteric Compounds
- Topic: What makes As2O3 Amphoteric?
- Replies: 2
- Views: 498
What makes As2O3 Amphoteric?
On one of the homework questions (I believe it was 6A.17 from the 7th edition) we had to classify As2O3 as basic, acidic, or amphoteric. I know the definition of amphoteric is that it reacts with both acids and bases. My question is how? here is the structure of As2O3 imgsrv.png I can see how it wou...
- Thu Dec 06, 2018 8:01 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: pH formula?
- Replies: 69
- Views: 3569
Re: pH formula?
We don't need to know how they're derived although reading through the textbook I feel it is helpful in understanding how they work.
- Thu Dec 06, 2018 3:23 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Will we need to know how to use Ksubw the autoprotilysis constant for the final? [ENDORSED]
- Replies: 1
- Views: 356
Will we need to know how to use Ksubw the autoprotilysis constant for the final? [ENDORSED]
To what extent are we expected to know how to do ph calculations for the final?
- Thu Dec 06, 2018 2:08 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Will any kind soul please let me know what we went over in class yesterday? (Wednesday)
- Replies: 2
- Views: 560
Re: Will any kind soul please let me know what we went over in class yesterday? (Wednesday)
Thank you VERY much! This is perfect!
- Thu Dec 06, 2018 10:22 am
- Forum: Administrative Questions and Class Announcements
- Topic: Will any kind soul please let me know what we went over in class yesterday? (Wednesday)
- Replies: 2
- Views: 560
Will any kind soul please let me know what we went over in class yesterday? (Wednesday)
I missed Wednesday's class 12/5 and I was just wondering if anyone could help out and let me know what Dr. Lavelle went over. He was scheduled to go over "only 3 pages" and was going to finish the syllabus. I'd appreciate any help!
- Thu Dec 06, 2018 10:21 am
- Forum: Conjugate Acids & Bases
- Topic: Will any kind soul please let me know what we went over in class yesterday? (Wednesday)
- Replies: 1
- Views: 304
Will any kind soul please let me know what we went over in class yesterday? (Wednesday)
I missed Wednesday's class 12/5 and I was just wondering if anyone could help out and let me know what Dr. Lavelle went over. He was scheduled to go over "only 3 pages" and was going to finish the syllabus. I'd appreciate any help!
- Thu Nov 29, 2018 8:21 pm
- Forum: Hybridization
- Topic: 2F.15 question 7th edition
- Replies: 3
- Views: 378
Re: 2F.15 question 7th edition
That makes perfect sense thank you!
- Thu Nov 29, 2018 8:21 pm
- Forum: Hybridization
- Topic: 2F.15 question 7th edition
- Replies: 3
- Views: 378
Re: 2F.15 question 7th edition
That makes perfect sense thank you!
- Thu Nov 29, 2018 7:11 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 7th edition 2E.1 mistake ?
- Replies: 6
- Views: 741
Re: 7th edition 2E.1 mistake ?
Got it! AX2E3 is linear with three equatorial lone pairs.
- Thu Nov 29, 2018 7:10 pm
- Forum: Hybridization
- Topic: 2F.15 question 7th edition
- Replies: 3
- Views: 378
2F.15 question 7th edition
So why does the bond angle increase as the s character of a hybrid orbital increase?
- Wed Nov 28, 2018 9:35 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 7th edition 2E.1 mistake ?
- Replies: 6
- Views: 741
7th edition 2E.1 mistake ?
2E.1 part b gives you a bond angle of 180 degrees (linear shape) and asks whether around the central atom there: must be, may be, or cannot be one or more lone pairs. I'm pretty sure the answer is cannot be one or more lone pairs. Isn't the only way you can have a 180 degree bond angle (linear shape...
- Wed Nov 28, 2018 6:15 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone pairs and polarity
- Replies: 1
- Views: 255
Re: Lone pairs and polarity
SF6 has a perfectly symmetrical octahedral shape right? The charges therefore "cancel out."
SF4 is AX4E which is a seesaw shape. This is not symmetrical. The F atoms pull in one direction. See the table on page 113 in the 7th edition textbook for a clear diagram on shapes and polarity.
SF4 is AX4E which is a seesaw shape. This is not symmetrical. The F atoms pull in one direction. See the table on page 113 in the 7th edition textbook for a clear diagram on shapes and polarity.
- Wed Nov 28, 2018 6:11 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Why is AX3E2 not trigonal planar?
- Replies: 2
- Views: 736
Why is AX3E2 not trigonal planar?
To me trigonal planar for AX3E2 would make more sense, putting the lone pairs on axial positions. This way they are 180 degrees apart from each other. Since lone pairs have the strongest repulsion wouldn't this be optimal? Why is it T-shaped instead?
- Wed Nov 28, 2018 6:09 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: So does the dipole moment point to the partial positive charge or the partial negative charge?
- Replies: 2
- Views: 427
So does the dipole moment point to the partial positive charge or the partial negative charge?
The book says either. My previous chem class we pointed to the partial negative charge. Does anyone know what Dr. Lavelle said regarding this?
- Sun Nov 25, 2018 6:16 pm
- Forum: Lewis Acids & Bases
- Topic: How do we know something is a lewis acid or base?
- Replies: 4
- Views: 691
How do we know something is a lewis acid or base?
I don't remember!
- Sun Nov 25, 2018 6:15 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 3 material
- Replies: 6
- Views: 698
Test 3 material
Up to which topics will be on test 3, anyone know?
- Sun Nov 25, 2018 6:13 pm
- Forum: Octet Exceptions
- Topic: How do we know if an element can have an expanded octet?
- Replies: 3
- Views: 2766
How do we know if an element can have an expanded octet?
I know it's period 3 elements and on but why? It's something to do with an available d orbital?
- Sun Nov 25, 2018 6:12 pm
- Forum: Hybridization
- Topic: Hybridization
- Replies: 4
- Views: 484
Re: Hybridization
Remember:
# of hybridized orbitals = # of regions of electron density
# of hybridized orbitals = # of regions of electron density
- Sun Nov 25, 2018 6:07 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent/Angular Shape
- Replies: 4
- Views: 514
Re: Bent/Angular Shape
They are the same, I've only heard of "bent" in my previous chem classes, I have never used angular. According to the book, they are the same
- Sun Nov 25, 2018 6:06 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: hydrogen bonding
- Replies: 4
- Views: 851
Re: hydrogen bonding
Just remember that it only occurs between hydrogen, nitrogen, oxygen or fluorine atoms (H N O F). What is it? Take water molecules for example. 2 hydrogen atoms are bonded with one oxygen atom. The oxygen atoms, because of higher electronegativity, pull the electrons closer to it than the hydrogen a...
- Thu Nov 15, 2018 7:29 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Do we not need to know oxidation numbers for this class?
- Replies: 2
- Views: 1950
Do we not need to know oxidation numbers for this class?
It seems like all we need to know is formal charge? Is it worth it to go back and learn oxidation numbers?
- Thu Nov 15, 2018 7:28 pm
- Forum: Electronegativity
- Topic: Is it best to memorize electronegativity?
- Replies: 8
- Views: 1928
Is it best to memorize electronegativity?
If we don't "memorize" atom's electronegativity, is there a way to intuitively know what makes a polar vs nonpolar molecule?
- Thu Nov 15, 2018 7:27 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Discussion posts grading (Anyone have a grade for this yet?)
- Replies: 3
- Views: 485
Discussion posts grading (Anyone have a grade for this yet?)
I haven't had any feedback yet on my chem community discussion posts in terms of a grade. How do I know my 3 weekly posts are being counted?
- Thu Nov 15, 2018 7:22 pm
- Forum: Dipole Moments
- Topic: Dipole Moments
- Replies: 6
- Views: 600
Re: Dipole Moments
It's a way to indicate the pull of electrons. It all depends on electronegativity. For example, O will pull electrons towards it in a C-O bond so this creates a dipole moment.
- Thu Nov 15, 2018 7:18 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: AX2E3 shape
- Replies: 2
- Views: 278
Re: AX2E3 shape
lone pair-lone pair > lone pair-atom > atom-atom
- Thu Nov 15, 2018 7:15 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Thanksgiving Wednesday Class
- Replies: 19
- Views: 1371
Re: Thanksgiving Wednesday Class
He hasn't officially announced either way but if we are ahead we will not have class. Basically to be determined.
- Thu Nov 15, 2018 7:14 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular shapes
- Replies: 3
- Views: 400
Re: Molecular shapes
Here's my tip: DON'T memorize anything! Start by getting very familiar with Lewis Structures. Once you can do them in your sleep, get familiar with finding the VSEPR models (AXE formula) for these Lewis structures. This should be fairly easy if you're comfortable with doing Lewis structures. Once yo...
- Thu Nov 15, 2018 7:12 pm
- Forum: SI Units, Unit Conversions
- Topic: VSEPR model
- Replies: 5
- Views: 3186
Re: VSEPR model
To me the model is very intuitive but the definition can be overwhelming. Basically VSEPR models follow the basic formula of AXE with a number subscript on the X and E. We regard A as the central atom. X is the number of bonds of with other atoms (VSEPR doesn't care if they're single, double, or tri...
- Thu Nov 15, 2018 7:04 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Writing VSEPR for (CH3)2Be
- Replies: 1
- Views: 214
Re: Writing VSEPR for (CH3)2Be
Hi Katelin, I believe you can use the VSEPR model in 2 instances here: One regarding the Be atom as the central atom (which would give you AX2, linear structure) and one for either of the carbon atoms as the central atom (this case giving you AX4, tetrahedral structure). The overall structure is lin...
- Mon Nov 05, 2018 2:00 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Is my bruin card a valid form of "photo ID?" [ENDORSED]
- Replies: 1
- Views: 1638
Is my bruin card a valid form of "photo ID?" [ENDORSED]
For the midterm we have a to bring a photo ID, will my bruin card work?
- Mon Nov 05, 2018 1:59 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Is my bruin card a valid form of "photo ID?"
- Replies: 1
- Views: 218
Is my bruin card a valid form of "photo ID?"
For the midterm we have to bring a photo ID. Will my bruin card work?
- Mon Nov 05, 2018 1:41 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chemistry Community
- Replies: 2
- Views: 318
Re: Chemistry Community
I think the calculations are done automatically by the system so I think if you miss one week it automatically gives you a 0. If you had a valid excuse or reason talk to Dr. Lavelle or your TA
- Mon Nov 05, 2018 1:31 pm
- Forum: Lewis Structures
- Topic: SO2 Lewis Structure
- Replies: 4
- Views: 1352
Re: SO2 Lewis Structure
I spoke to Dr. Lavelle after class today as I had drawn resonance structures to answer this question. I drew O-S=O <-> O=S-O with a lone pair of electrons on S.
O=S=O is BETTER because this gives every atom a 0 formal charge and S can use it's d orbitals to hold extra electrons in bonding.
O=S=O is BETTER because this gives every atom a 0 formal charge and S can use it's d orbitals to hold extra electrons in bonding.
- Mon Nov 05, 2018 1:13 pm
- Forum: DeBroglie Equation
- Topic: work function and frequency
- Replies: 4
- Views: 878
Re: work function and frequency
You would have to find the energy of the incoming photons. You would convert the wavelength of the elected electron into kinetic energy then add that to the work function. This gives you the energy of an incoming photon. Then you simply convert energy into frequency using E=hv
- Mon Nov 05, 2018 1:09 pm
- Forum: Resonance Structures
- Topic: Radicals
- Replies: 11
- Views: 1374
Re: Radicals
A radical typically has an unpaired valence electron. A good example is the chlorine atom which has 7 valence electrons. You would draw this as Cl with 7 dots around it
- Mon Nov 05, 2018 1:06 pm
- Forum: Ionic & Covalent Bonds
- Topic: Midterm Material
- Replies: 3
- Views: 450
Re: Midterm Material
We will not be going over polarity or electronegativity
- Fri Nov 02, 2018 6:52 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Scantron
- Replies: 6
- Views: 551
Re: Scantron
I THINK it'll be similar in format to the first 2 tests. 8 questions, just bring a pencil and non programmable calculator
- Fri Nov 02, 2018 6:51 pm
- Forum: Trends in The Periodic Table
- Topic: Will we need to calculate the effective nuclear charge for the midterm?
- Replies: 1
- Views: 235
Will we need to calculate the effective nuclear charge for the midterm?
Does anyone know?
- Fri Nov 02, 2018 6:46 pm
- Forum: Lewis Structures
- Topic: Do brackets go over cations or anions or either or both?
- Replies: 3
- Views: 556
Do brackets go over cations or anions or either or both?
Is there even a specific guideline or it doesn't really matter?
I am referring to [ ] these brackets. For example which is more correct?
[Na] Cl or Na [Cl] or [Na] [Cl] ? (Add charges and dots for electrons)
I am referring to [ ] these brackets. For example which is more correct?
[Na] Cl or Na [Cl] or [Na] [Cl] ? (Add charges and dots for electrons)
- Fri Nov 02, 2018 6:43 pm
- Forum: Ionic & Covalent Bonds
- Topic: 2A.5 7th edition
- Replies: 5
- Views: 419
Re: 2A.5 7th edition
You're welcome! I just learned in discussion today that it is the same case for Ag+ ion which sits right below it on the periodic table. Happy studying!
- Tue Oct 30, 2018 2:22 pm
- Forum: Ionic & Covalent Bonds
- Topic: 2A.5 7th edition
- Replies: 5
- Views: 419
Re: 2A.5 7th edition
Copper has a "half-filled" 4s subshell. It is a special case. Only 1 electron sits in it's 4s subshell while 10 electrons sit in it's 3d subshell. This is a special case. Therefore, Cu+ is [Ar] 3d^10
- Tue Oct 30, 2018 2:19 pm
- Forum: Significant Figures
- Topic: Exam
- Replies: 6
- Views: 1151
Re: Exam
Dr. Lavelle has a great resource for sig figs on the class website. Here it is: https://lavelle.chem.ucla.edu/wp-conten ... OUT_SF.pdf
- Tue Oct 30, 2018 2:17 pm
- Forum: General Science Questions
- Topic: Midterm studying
- Replies: 10
- Views: 1408
Re: Midterm studying
I think for any Chemistry test, practice practice practice and then practice some more. Practice until the material becomes so easy that you can do it in your sleep. Try as many different problems as you can. Do all the problems in your textbook, try Khan Academy, there are practice problems here ht...
- Tue Oct 30, 2018 2:15 pm
- Forum: General Science Questions
- Topic: Khan Academy
- Replies: 10
- Views: 1485
Re: Khan Academy
Khan Academy is great. I also find this website to be somewhat helpful and there are a few practice problems on here: https://chem.libretexts.org/
- Thu Oct 25, 2018 2:16 pm
- Forum: Administrative Questions and Class Announcements
- Topic: 0/70 homework grade on myucla
- Replies: 2
- Views: 345
0/70 homework grade on myucla
Our grades for exam 1 and homework were posted to my ucla. My homework grade is 0/70. I have turned in completed homework for all 3 weeks so far so I'm wondering if this is in error. Does anyone else have this as well? I'm very OCD so I'm wondering what's going on here haha.
- Thu Oct 25, 2018 2:06 pm
- Forum: *Particle in a Box
- Topic: Particle in a box (textbook) [ENDORSED]
- Replies: 4
- Views: 1338
Re: Particle in a box (textbook) [ENDORSED]
Basically think of what a wavelength is. It is the distance from one "peak" to another "peak." Think of a wavelength in a "box." It is bounded on 2 sides right? Therefore only a certain wavelength can "fit" into this box. A bigger or smaller wavelength will be...
- Wed Oct 24, 2018 11:01 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Answers to module questions?
- Replies: 2
- Views: 265
Answers to module questions?
Is there a way to access these so we can know if we're getting the right answers or not?
- Wed Oct 24, 2018 10:18 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: 7th edition 1B.27 [ENDORSED]
- Replies: 3
- Views: 420
Re: 7th edition 1B.27 [ENDORSED]
I was right all along then! Haha thank you so much
- Wed Oct 24, 2018 10:05 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Extra Practice Problems
- Replies: 2
- Views: 1328
- Wed Oct 24, 2018 9:58 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Extra Practice Problems
- Replies: 2
- Views: 1328
Extra Practice Problems
This is for anyone looking for extra practice. There are good 5 problems on this site that I think cover this topic thoroughly and make you think about its practical use. https://chem.libretexts.org/Textbook_Maps/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_The...
- Wed Oct 24, 2018 6:31 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: 7th edition 1B.27 [ENDORSED]
- Replies: 3
- Views: 420
7th edition 1B.27 [ENDORSED]
This question gives the velocity of the bowling ball to be 5.00 +/- (plus or minus) 5.0 m/s. I plugged 5.0 m/s into the uncertainty formula and got the right answer. My question is why? The total uncertainty would be 10.0 m/s correct? This doesn't give me the correct answer though.
- Tue Oct 23, 2018 4:34 pm
- Forum: Properties of Light
- Topic: Atomic Spectra
- Replies: 2
- Views: 219
Re: Atomic Spectra
Yes this will be on the exam! To add on what has been replied to, this relates to hydrogen ONLY.
- Tue Oct 23, 2018 4:31 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Significance of XYZ to PDF orbitals
- Replies: 6
- Views: 526
Re: Significance of XYZ to PDF orbitals
I think it's just one way to distinguish between different locations in a given shell. It's like filling _ _ _ with electrons except we use X, Y, and Z
- Tue Oct 23, 2018 4:29 pm
- Forum: Properties of Light
- Topic: Is light in waves or photons?
- Replies: 10
- Views: 906
Re: Is light in waves or photons?
Think about it, we don't know the mass of a photon right? Also, use landa x v =c
- Tue Oct 23, 2018 4:28 pm
- Forum: Properties of Light
- Topic: Is light in waves or photons?
- Replies: 10
- Views: 906
Re: Is light in waves or photons?
For calculation purposes, use light as a wave (do not use De Broglie formula). Use E=hv when doing light calculations. However it DOES has light-wave duality. Hope that helps!
- Thu Oct 18, 2018 12:23 am
- Forum: Photoelectric Effect
- Topic: Pre Assessment Module Question #13
- Replies: 2
- Views: 316
Pre Assessment Module Question #13
The question asks: Does the photoelectric experiment need to be done under a vacuum? I'm reading the text and I can't seem to find it here and I don't think Dr. Lavelle explicitly mentioned it in class. My instinct is to say yes.
- Sun Oct 14, 2018 1:53 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Is homework graded for correctness or completeness?
- Replies: 5
- Views: 852
Is homework graded for correctness or completeness?
I don't know if correctness is a word but my question is will the homeworks be graded if the answers are correct or do we just full credit if we did 7 problems, right or wrong?
- Sun Oct 14, 2018 1:52 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Grades??
- Replies: 4
- Views: 278
Grades??
Has anyone received any grades yet for homeworks or the test? I have not.
- Thu Oct 11, 2018 8:49 pm
- Forum: Properties of Light
- Topic: Problem 1A.9 (7th edition)
- Replies: 5
- Views: 257
Re: Problem 1A.9 (7th edition)
Isn't it dumb how we need E=hv to solve this problem, yet that isn't given until 1B? Am I tripping?
- Thu Oct 11, 2018 8:45 pm
- Forum: Properties of Light
- Topic: HW 1A.9 [ENDORSED]
- Replies: 4
- Views: 273
HW 1A.9 [ENDORSED]
For this problem, if I know the frequency and the wavelength, how do I find the energy of the photon? Is there a specific formula?
- Thu Oct 11, 2018 8:43 pm
- Forum: Properties of Light
- Topic: HW 1A.7
- Replies: 2
- Views: 148
Re: HW 1A.7
Yes I realized that! Problem solved, thank you!
- Thu Oct 11, 2018 2:08 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Where to find assignments
- Replies: 5
- Views: 411
Re: Where to find assignments
They're due every week during your discussion
- Thu Oct 11, 2018 2:06 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Homework and discussion grading?
- Replies: 2
- Views: 209
Homework and discussion grading?
I'm curious if anyone has gotten grades for the week 1 homework or discussion yet. Does anyone know when these will be up if not?
- Thu Oct 11, 2018 2:02 pm
- Forum: Properties of Light
- Topic: HW 1A.7
- Replies: 2
- Views: 148
HW 1A.7
For part b, I got 0.15 nm and the back of the book says 150. I'm confused??
- Thu Oct 11, 2018 1:41 pm
- Forum: Administrative Questions and Class Announcements
- Topic: So can we do problems from Review of Chemistry for week 2 homework?
- Replies: 4
- Views: 277
Re: So can we do problems from Review of Chemistry for week 2 homework?
So which is it?? lol
- Thu Oct 11, 2018 11:49 am
- Forum: Administrative Questions and Class Announcements
- Topic: So can we do problems from Review of Chemistry for week 2 homework?
- Replies: 4
- Views: 277
So can we do problems from Review of Chemistry for week 2 homework?
I am turning in my homework tomorrow (Friday) and I saw a couple posts related to doing problems from Review of Chemistry for week 2 homework. Can anyone confirm this?
- Tue Oct 09, 2018 1:54 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: writing the formula of a molecule
- Replies: 5
- Views: 5809
Re: writing the formula of a molecule
While Dr. Lavelle didn't explicitly state to do so, I think it would generally be a good idea in chem to know these anyway. They're not hard! I pasted them below, they're pretty intuitive:
1: mono-
2: di-
3: tri-
4: tetra-
5: penta-
6: hexa-
7: hepta-
8: octa-
9: nona-
10: deca-
1: mono-
2: di-
3: tri-
4: tetra-
5: penta-
6: hexa-
7: hepta-
8: octa-
9: nona-
10: deca-
- Tue Oct 09, 2018 1:50 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: (Typo??) HW L.35 - 7th edition
- Replies: 3
- Views: 401
Re: (Typo??) HW L.35 - 7th edition
Thank you, I figured it's a total typo because otherwise it's impossible. I recommend to those with the same problem to just use Fe3Br8 as Ashish said.
- Thu Oct 04, 2018 11:35 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: writing the formula of a molecule
- Replies: 5
- Views: 5809
Re: writing the formula of a molecule
A magnesium ion is Mg2+
Sulfate is SO4 2-
Together that makes MgSO4
The heptahydrate basically just adds H2O at the end. Hepta- is a prefix for 7.
So the official formula is MgSO4 . 7H2O
In chemistry, it's standard to add a little dot between the compound and the hydrate
Sulfate is SO4 2-
Together that makes MgSO4
The heptahydrate basically just adds H2O at the end. Hepta- is a prefix for 7.
So the official formula is MgSO4 . 7H2O
In chemistry, it's standard to add a little dot between the compound and the hydrate
- Thu Oct 04, 2018 11:29 pm
- Forum: Limiting Reactant Calculations
- Topic: Volume of Solution
- Replies: 2
- Views: 261
Re: Volume of Solution
So I'm assuming you converted grams of Na2CO3 to 39.84 mmoles of Na+. So now you have mmoles of Na+ in a volume of 250.0 ml and you want 2.15 mmol Na+. The mmoles of Na+ that you converted from the grams of Na2CO3 and the 250.0 ml are your "initial" mols and volume, respectively. Think of ...
- Thu Oct 04, 2018 11:21 pm
- Forum: SI Units, Unit Conversions
- Topic: Hecto as SI Unit [ENDORSED]
- Replies: 4
- Views: 246
Re: Hecto as SI Unit [ENDORSED]
By "never saw it," I mean it didn't pop up in the homework problems or examples but they did display it on the section reading covering SI units.
- Thu Oct 04, 2018 11:20 pm
- Forum: SI Units, Unit Conversions
- Topic: Hecto as SI Unit [ENDORSED]
- Replies: 4
- Views: 246
Re: Hecto as SI Unit [ENDORSED]
Hi Stephen, I think it would be safe to assume that the units Dr. Lavelle gave us were the only ones we'd be using for the class. Since he did not give us hecto-, I would assume that we would not need to use it for this class. However this does not mean that this is not an SI unit. As you mentioned ...
- Thu Oct 04, 2018 11:17 pm
- Forum: SI Units, Unit Conversions
- Topic: Reaction Stoichiometry Unit Conversion
- Replies: 2
- Views: 280
Re: Reaction Stoichiometry Unit Conversion
Hi Andrew, if you are referring to question L.5.a, it is totally ok to give the answer in either grams or kilograms. Prof. Lavelle even mentioned in class that both would be correct. The reason the textbook gives the answer in grams is think about it, 507.1 g Al versus 0.5071 kg Al. I think and the ...
- Thu Oct 04, 2018 11:10 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: (Typo??) HW L.35 - 7th edition
- Replies: 3
- Views: 401
(Typo??) HW L.35 - 7th edition
Hi, so I was very stuck on the balancing part of this equation. I googled the answer and found links from Prof. Lavelle's chemistry community and I think there might be typo in my book. So my book asks the following question for L.35 "Sodium bromide, NaBr, which is used to produce AgBr for use ...
- Sun Sep 30, 2018 1:28 pm
- Forum: Balancing Chemical Reactions
- Topic: Question H21 (6th Edition)
- Replies: 2
- Views: 299
Re: Question H21 (6th Edition)
For the unbalanced equation we have: C10H15N + O2 --> CO2 + H2O + CH4N20 I started with balancing N first: 2C10H15N + O2 --> CO2 + H2O + CH4N20 Then H: 2C10H15N + O2 --> CO2 + 13H2O + CH4N20 Then C: 2C10H15N + O2 --> 19CO2 + 13H2O + CH4N20 Finally O: 2C10H15N + 26O2 --> 19CO2 + 13H2O + CH4N20
- Sat Sep 29, 2018 9:50 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Do we have to write out the question for homework?
- Replies: 4
- Views: 477
Do we have to write out the question for homework?
Like the subject asks. This is for Chem 14A Dr. Lavelle
- Fri Sep 28, 2018 1:02 pm
- Forum: SI Units, Unit Conversions
- Topic: How does grading for discussion posts work?
- Replies: 80
- Views: 8161
How does grading for discussion posts work?
Is there a minimum number of posts/replies to get full points?