## Search found 69 matches

Sat Jan 23, 2021 9:01 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Sapling week 2 #9
Replies: 8
Views: 54

### Re: Sapling week 2 #9

Fiona Huang 3C wrote:Thank you guys! So is it the opposite for bases? When pH>pka, the neutral species would be predominant?

Yes! When pH>pka, neutral species would dominate and when pH<pka charged species dominate.
Sat Jan 23, 2021 8:57 am
Forum: Student Social/Study Group
Topic: Logistics for the Midterm
Replies: 11
Views: 45

### Re: Logistics for the Midterm

The first midterm is during our class on Friday so I think that it will be proctored like our final in Chem 14A.
Sat Jan 23, 2021 8:55 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE Tables
Replies: 31
Views: 64

### Re: ICE Tables

The C row or the change row is determined by the stoichiometric coefficients in the reaction equation.

For ex: H2 + Cl2 ---> 2HCl

In the forward reaction the change for H2 will be -x, for Cl2 will be -x, and HCl will be +2x(because of its coefficients).
Sat Jan 23, 2021 8:51 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Studying for Midterm #1
Replies: 63
Views: 145

### Re: Studying for Midterm #1

Some things that helped me while doing Chem 14A with Dr. Lavelle last quarter:
1. Attending UA sessions
3. Doing the textbook problems
4. Revisiting the sapling HW problems

Hope this helps!
Sat Jan 23, 2021 8:48 am
Forum: Student Social/Study Group
Topic: Midterm Study Tips
Replies: 41
Views: 86

### Re: Midterm Study Tips

I think the some things that really helped me on the midterm in Chem 14A last quarter were attending the UA sessions and doing the textbook reading along with doing the textbook problems.
Sat Jan 16, 2021 10:31 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: q vs k
Replies: 62
Views: 163

### Re: q vs k

Q and K are calculated in the same way but Q is the calculation that is not done at equilibrium.
Sat Jan 16, 2021 10:29 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: H2O as a Gas
Replies: 68
Views: 403

### Re: H2O as a Gas

If H2O is a gas, you should include it in the ICE table!
Sat Jan 16, 2021 10:28 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling #5
Replies: 5
Views: 53

### Re: Sapling #5

This problem can be solved in the way we solve simultaneous linear equations in algebra. So in this particular question, you will have to add the first reaction equation and the REVERSE of the third reaction equation. Also you might have multiply one of the equations by a constant and don't forget t...
Sat Jan 16, 2021 10:24 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier's Principle
Replies: 19
Views: 102

### Re: Le Chatelier's Principle

Basically Le Chatelier's principle states that when a system experiences a disturbance (such as concentration, temperature, or pressure changes), it will respond to restore a new equilibrium state. For instance, if there is an increase in the concentration of products, the equilibrium will shift tow...
Sat Jan 16, 2021 9:56 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling #3
Replies: 5
Views: 37

### Re: Sapling #3

I did the same mistake! The numerator should be 4x^2 and not 2x^2
Sun Jan 10, 2021 5:35 pm
Forum: Student Social/Study Group
Topic: Study Habits
Replies: 94
Views: 258

### Re: Study Habits

I think the textbook questions helped me a lot. Also, the step-up sessions and workshops really help too! Being regular and keeping up with the lectures also help.
Sun Jan 10, 2021 5:33 pm
Forum: Student Social/Study Group
Topic: Participation
Replies: 45
Views: 347

### Re: Participation

The points for participation can bee seen on your gradebook on ccle. But I don't think that they are updated regularly. Last quarter when I took chem 14A, it took about 3 weeks for the first set of participation points to be uploaded.
Sun Jan 10, 2021 5:30 pm
Forum: Student Social/Study Group
Topic: Chemistry Community
Replies: 29
Views: 85

### Re: Chemistry Community

Jada3K wrote:Hopefully, someone sees this I was wondering if our chem community post carries over if we went over 50 from last quarter.

I don't think so Jada though I might be wrong!
Sun Jan 10, 2021 5:30 pm
Forum: Student Social/Study Group
Topic: Chemistry Community
Replies: 29
Views: 85

### Re: Chemistry Community

The deadline for completing your 5 posts of the week is Sunday midnight!
Sun Jan 10, 2021 5:26 pm
Forum: General Science Questions
Topic: midterm/final
Replies: 12
Views: 60

### Re: midterm/final

I think it will. If you look at the syllabus on the chemistry 14B website, it says that midterms will be 50 minute long while the final will be 1 hour and 30 minutes long. It also says that both will be proctored, which is sounds exactly like chem 14A!
Tue Jan 05, 2021 8:49 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8544
Views: 1474026

### Re: Post All Chemistry Jokes Here

i really liked this one!
Thu Dec 10, 2020 6:22 pm
Forum: Student Social/Study Group
Topic: Anxiety
Replies: 42
Views: 238

### Re: Anxiety

Anxiety is normal. All of us want to do well and push ourselves to new limits. But I find that while trying to do well, I often forget the importance of taking breaks. It is crucial to step away from what you have been doing. As mentioned above a change of scenery really helps a lot! All the best! Y...
Wed Dec 09, 2020 7:55 am
Forum: Bronsted Acids & Bases
Topic: HF
Replies: 15
Views: 105

### Re: HF

HF is a weak acid as F is highly electronegative and does not readily give up proton.
Wed Dec 09, 2020 7:25 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Sapling Q #1
Replies: 7
Views: 69

### Re: Sapling Q #1

The above answer has included almost all the common strong acids. I think that strong bases include the oxides and hydroxides of both Group 1 and group 2 metals.
Wed Dec 09, 2020 7:22 am
Forum: Naming
Topic: [Co(NH3)5 Cl] Cl 2H2O
Replies: 5
Views: 50

### Re: [Co(NH3)5 Cl] Cl 2H2O

2H2O is named as dihydrate and not diaqua as it is not included in the coordination sphere.
Wed Dec 09, 2020 7:20 am
Forum: Bronsted Acids & Bases
Topic: Amphoteric compounds
Replies: 8
Views: 69

### Re: Amphoteric compounds

An amphoteric compound is one that can act as both an acid and a base. Basically, it can accept and lose protons.
Thu Dec 03, 2020 5:29 am
Forum: Administrative Questions and Class Announcements
Topic: Midterm 1 and 2 Review
Replies: 8
Views: 86

### Re: Midterm 1 and 2 Review

I think that you can go to your TA's office hours for the review!
Thu Dec 03, 2020 5:28 am
Forum: Student Social/Study Group
Topic: How are you?
Replies: 117
Views: 772

### Re: How are you?

I am just waiting for our finals to get over! The last couple of weeks have been really tiring though.
Thu Dec 03, 2020 5:26 am
Forum: Naming
Topic: what does (en) mean?
Replies: 23
Views: 166

### Re: what does (en) mean?

en stands for ethylenediamine, which is a bidendate ligand.
Thu Dec 03, 2020 5:23 am
Forum: Hybridization
Topic: Pi Bonds Cannot Rotate
Replies: 23
Views: 167

### Re: Pi Bonds Cannot Rotate

Pi-bonds overlap side-by-side. If they rotate, they will break. Hence, pi bonds do not rotate.
Thu Dec 03, 2020 5:21 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Finding Coordination Number
Replies: 14
Views: 99

### Re: Finding Coordination Number

The coordination number can be easily found by calculating the number of bonds formed by the central transition atom
Fri Nov 27, 2020 3:39 am
Forum: Hybridization
Topic: Sp3d or dsp3
Replies: 22
Views: 865

### Re: Sp3d or dsp3

It's the same thing. I personally like to use the first one because it follows the order we are used to!
Fri Nov 27, 2020 3:38 am
Forum: Determining Molecular Shape (VSEPR)
Topic: carbon hydrogen bonds
Replies: 6
Views: 36

### Re: carbon hydrogen bonds

From what I understand, if the central atom has lone pairs only then we will see lone pairs affecting molecular geometry.
Fri Nov 27, 2020 3:36 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape Names
Replies: 50
Views: 299

### Re: Shape Names

Yes, the shape of the water molecule is bent or angular.
Fri Nov 27, 2020 3:35 am
Forum: Hybridization
Topic: Single Bonds and Sigma Bonds
Replies: 23
Views: 113

### Re: Single Bonds and Sigma Bonds

I think all bonds have atleast one sigma bonds and the rest are pi bonds.
Fri Nov 27, 2020 3:33 am
Forum: Student Social/Study Group
Topic: How have your study habits changed?
Replies: 45
Views: 315

### Re: How have your study habits changed?

I like to understand the text as a go through it rather than blindly taking notes. Also, I think doing the textbook problems really helped me in the second midterm.
Fri Nov 20, 2020 7:49 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Determining an orbital
Replies: 10
Views: 90

### Re: Determining an orbital

'l' will determine which subshell it is: s, p, d, or f.

l=0 --> s
l=1 --> p
l=2 --> d
l=3 --> f
Fri Nov 20, 2020 7:47 am
Forum: Bond Lengths & Energies
Topic: Boiling/Melting Point
Replies: 20
Views: 144

### Re: Boiling/Melting Point

You would look at the intermolecular forces. As the intramolecular forces don't contribute towards the melting/boiling points.
Fri Nov 20, 2020 7:41 am
Forum: Bond Lengths & Energies
Topic: Bond Strength in DNA
Replies: 12
Views: 121

### Re: Bond Strength in DNA

G-C bonds are stronger as they are triple bonds while A-T bonds are only double bonds. Due to larger bond strength, G-C bonds are more stable too.
Fri Nov 20, 2020 7:38 am
Forum: Dipole Moments
Topic: Midterm 2 Results
Replies: 7
Views: 112

### Re: Midterm 2 Results

I think they will be released sometime next week. As a couple of people mentioned above, they could be released sooner as there are no partial points this time.
Fri Nov 20, 2020 7:37 am
Forum: Student Social/Study Group
Replies: 110
Views: 1173

You are not alone! I am sure a lot of us(including me) are super stressed about grades. But just know that if you stress too much or put pressure on yourself, you won't be able to perform your best. So just chill!
Thu Nov 12, 2020 8:29 am
Forum: Sigma & Pi Bonds
Topic: Triple bond?
Replies: 21
Views: 165

### Re: Triple bond?

A triple bond has one sigma and one pi bond

Basically, multiple bonds have both sigma and pi bonds.
Thu Nov 12, 2020 8:25 am
Forum: Formal Charge and Oxidation Numbers
Topic: Oxidization Numbers
Replies: 10
Views: 77

### Re: Oxidization Numbers

I don't think that we went over this in lectures, but as there is a homework question I assume that we need to know the basics. The link below really helped me!

https://www.thoughtco.com/rules-for-ass ... ers-607567
Thu Nov 12, 2020 8:07 am
Forum: Bond Lengths & Energies
Topic: Sapling HW Bond Length
Replies: 7
Views: 60

### Re: Sapling HW Bond Length

I think you have interpreted the relationship between the atomic radius of O and S incorrectly. S has a larger atomic radius as atomic radii increases down the group.
Thu Nov 12, 2020 8:01 am
Forum: General Science Questions
Topic: Which would have lower ionization energy?
Replies: 13
Views: 118

### Re: Which would have lower ionization energy?

Chlorine will have lower ionization energy. This is so as it is one period below oxygen and so its electrons will be less tightly held.
Thu Nov 12, 2020 7:58 am
Forum: Lewis Structures
Topic: Formal Charge
Replies: 5
Views: 37

### Re: Formal Charge

I don't think that it is necessary to find the formal charge every time, but it certainly helps in checking your work. It could also help in calculating the formal charge of the central atom without many calculations. Like in the last week's lecture, Lavelle used the formal charges along with the ov...
Fri Nov 06, 2020 8:24 pm
Forum: Resonance Structures
Topic: Bond lengths
Replies: 20
Views: 143

### Re: Bond lengths

I don't think that we actually have to draw the double bonds shorter. Knowing that double bonds are shorter is enough!
Fri Nov 06, 2020 8:22 pm
Forum: *Shrodinger Equation
Topic: Electron Density
Replies: 3
Views: 57

### Re: Electron Density

Electron density is just the probability of an electron being present.

The electron density or the probability of finding electrons in a nodal plane is zero.
Fri Nov 06, 2020 8:19 pm
Forum: Student Social/Study Group
Topic: Blind sided by Midterm 1 memorization questions, How to study for memorization questions
Replies: 11
Views: 118

### Re: Blind sided by Midterm 1 memorization questions, How to study for memorization questions

I personally did not expect memorization problems on the midterm, but my previous knowledge helped me there. I think what you did in terms of preparing for the first midterm is perfect. Instead of skimming over the memorization based topics, make notes on them. Usually, memorization topics include t...
Fri Nov 06, 2020 8:12 pm
Forum: Octet Exceptions
Topic: Phosphorus and d-Orbital
Replies: 7
Views: 66

### Re: Phosphorus and d-Orbital

I think I need to first understand the octet rule, can anyone help with that? The octet rule refers to the tendency of atoms preferring to have eight electrons in the valence shell. Basically, the tendency of elements to have the electronic configuration of the nearest noble gas(which has fully fil...
Fri Nov 06, 2020 8:07 pm
Forum: Properties of Light
Topic: Photoelectric Effect
Replies: 14
Views: 138

### Re: Photoelectric Effect

Yes, it is the same thing.

We know, kinetic energy = energy of incident light - threshold energy. Thus, it is evident from the equation that the excess energy corresponds to kinetic energy
Fri Nov 06, 2020 8:03 pm
Forum: Ionic & Covalent Bonds
Replies: 38
Views: 224

All the elements in a period have the same number of shells(just the number of valence electrons vary). But, the number of protons across a period increases, and so the effective nuclear charge increases which causes the size to decrease across a period.
Sun Nov 01, 2020 3:13 am
Forum: Student Social/Study Group
Topic: Halloween!!!
Replies: 54
Views: 332

### Re: Halloween!!!

Happy Halloween!

I watched my missed chemistry lectures and The Mandalorian simultaneously while gorging on the pumpkin choco-chip cookies I baked!
Sun Nov 01, 2020 3:07 am
Forum: Trends in The Periodic Table
Replies: 30
Views: 411

The atomic radius depends upon the effective nuclear charge and number of shells. Across a period, the nuclear charge increases, and the number of shells remain the same, so the size decreases. However down the group, though both the effective nuclear charge and the number of shells increases, the m...
Sun Nov 01, 2020 3:02 am
Forum: Properties of Light
Topic: Is c always the speed of light?
Replies: 88
Views: 457

### Re: Is c always the speed of light?

This class requires us to know c as the speed light which is 3 X 10^8 m/s
Wed Oct 28, 2020 10:39 pm
Forum: Student Social/Study Group
Topic: Lavelle's Jokes
Replies: 18
Views: 213

### Re: Lavelle's Jokes

I really liked this one!
Wed Oct 28, 2020 10:30 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 3d and 4s orbitals
Replies: 9
Views: 82

### Re: 3d and 4s orbitals

I personally like to use the Aufbau principle that states that in the ground state of an atom or ion, electrons fill atomic orbitals of the lowest available energy levels before occupying higher levels. The arrows in the figure really help to determine which comes first.
Wed Oct 28, 2020 10:27 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 4s and 3d
Replies: 14
Views: 104

### Re: 4s and 3d

I think that's because of the Aufbau principle which states that in the ground state of an atom or ion, electrons fill atomic orbitals of the lowest available energy levels before occupying higher levels.
Tue Oct 20, 2020 11:04 pm
Forum: Properties of Electrons
Topic: 1A.1
Replies: 1
Views: 39

### Re: 1A.1

All light(EM radiations) travel at the same speed, i.e approx 3 X 10^8 m/s. But as the observed speed is LESS THAN the speed of light, it supports the particle model. Hope it helps!
Tue Oct 20, 2020 10:52 pm
Forum: Photoelectric Effect
Topic: Photoelectric Experiment
Replies: 6
Views: 51

### Re: Photoelectric Experiment

The photoelectric experiment can only give accurate results under vacuum. If not conducted in a vacuum, the ejected electrons can collide with the particles present in the air and interfere with the data.
Tue Oct 20, 2020 10:46 pm
Forum: Properties of Light
Topic: Difference between E=hv and E=hc/v?
Replies: 9
Views: 91

### Re: Difference between E=hv and E=hc/v?

I think you meant to ask the difference between E = hv and E= hc/λ. They are essentially the same thing.

We know, c = λv
=> v = c/λ --- equation 1

So, E = hv
=> E = hc/λ (from equation 1)

Hope it helps!
Tue Oct 20, 2020 10:42 pm
Forum: Properties of Light
Topic: Planck's Constant
Replies: 7
Views: 51

### Re: Planck's Constant

As stated in the previous responses, Planck's constant(h) = 6.626 X 10^(-34). I had trouble remembering its value earlier, but as I started doing the textbook questions in the syllabus, I realized that it was being used regularly. So, the repeated usage has permanently etched the value in my head! B...
Tue Oct 20, 2020 10:37 pm
Forum: Student Social/Study Group
Topic: How are you studying?
Replies: 203
Views: 1295

### Re: How are you studying?

I first go through all the pre-modules. Even though they are a bit lengthy and take up a lot of time, they are really useful. Then I watch the lectures and take notes on the topics that I might have not understood in the pre-modules. Then I do the textbook questions given in the syllabus - THEY ARE ...
Tue Oct 13, 2020 10:27 pm
Forum: Balancing Chemical Reactions
Topic: Naming compounds
Replies: 21
Views: 194

### Re: Naming compounds

The majority of the compound names will be given on the test. But, it is always helpful to know the compounds that occur repeatedly like CO2, H20 (as someone already mentioned above).

Tue Oct 13, 2020 10:22 pm
Forum: Empirical & Molecular Formulas
Topic: Sapling Week 1 #8
Replies: 23
Views: 234

### Re: Sapling Week 1 #8

The molecular formula can be determined from the figure simply by counting the number of atoms of each element in the compound. For instance, you can figure out that the compound has three elements: C, O, and H. Now just count the number of C, H, and O. That will be your molecular formula: C6H8O6. T...
Tue Oct 13, 2020 10:13 pm
Forum: Balancing Chemical Reactions
Topic: Balancing Chemical Equations
Replies: 11
Views: 107

### Re: Balancing Chemical Equations

CO4 will mean that C=1 and O=4. However, if the compound had been (CO)4, it would have meant that C=4 and O=4. Usually, the parentheses(if present) around the atoms of the compound will help you to determine the number of those atoms.
Tue Oct 13, 2020 10:07 pm
Forum: Molarity, Solutions, Dilutions
Topic: mmol
Replies: 14
Views: 170

### Re: mmol

Whenever you see 'm', it implies 'milli'. So, the unit mmol means millimolar. Also, milli corresponds to 10^(-3).
Tue Oct 13, 2020 10:04 pm
Forum: Significant Figures
Topic: Sapling HW #4
Replies: 31
Views: 324

### Re: Sapling HW #4

950000 has only two significant figures as all the trailing zeroes to the non-zero numbers are NOT SIGNIFICANT

80060 has 4 significant figures as the zeroes between two non zero numbers are significant. The last zero won't be significant as trailing zeroes to any non-zero number isn't significant.
Tue Oct 06, 2020 9:40 pm
Forum: Molarity, Solutions, Dilutions
Topic: concentration of the solution
Replies: 6
Views: 67

### Re: concentration of the solution

Hi!

I just wrote down the solution. Hope it helps! Also, I used slightly different masses than the question but the answer is the same!
Tue Oct 06, 2020 9:28 pm
Forum: Molarity, Solutions, Dilutions
Topic: G5 Molarity of Na
Replies: 6
Views: 95

### Re: G5 Molarity of Na

From the formula of sodium carbonate, Na2CO3, you can see that 1 mole of Na2CO3 has 2 moles of Na+ ions. So, 2 moles Na+ ---> 1 mole Na2CO3 2.15 mmol Na+ ---> (1/2) * 2.15 * 10^(-3) moles Na2CO3 ---> 1.075 * 10^(-3) moles Na2CO3 Molarity =number of moles of solute/ volume of solution => Volume of so...
Tue Oct 06, 2020 9:21 pm
Forum: Empirical & Molecular Formulas
Topic: Fundamentals F 13
Replies: 8
Views: 86

### Re: Fundamentals F 13

As asked by the question, I first calculated the empirical formula. In the second part, since the question says that the empirical and the molecular formula are the same the compound is PCl5. Since we know that '5' in chemistry corresponds to 'penta'. So, the compound is Phosphorous Pentachloride
Tue Oct 06, 2020 9:14 pm
Forum: Balancing Chemical Reactions
Topic: Periodic Table
Replies: 50
Views: 484

### Re: Periodic Table

The memorization of the periodic table is not necessary. But, I like to remember the first 20 elements as I find that those are the ones that are often repeated. However, you don't have to remember the masses. I have realized that the more questions I do, I remember the atomic masses of the commonly...
Tue Oct 06, 2020 9:09 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Moles produced
Replies: 3
Views: 41

### Re: Moles produced

From what I have understood, you don't have to use the limiting reagent steps as you know the amount of just one of the two reactants. So, you cannot figure out the limiting reagent. As for the concept of moles, it is just the relation between the stoichiometric coefficients. For instance, in the eq...
Sat Oct 03, 2020 9:17 pm
Forum: Administrative Questions and Class Announcements
Topic: Students in different time zones [ENDORSED]
Replies: 27
Views: 1398

4 in India