Search found 91 matches

by Alvin Lai 3J
Fri Mar 05, 2021 8:01 pm
Forum: First Order Reactions
Topic: Slope
Replies: 13
Views: 50

Re: Slope

For the zero and first-order reactions, the slope = -k. For the second-order reaction, slope = +k
by Alvin Lai 3J
Sat Feb 27, 2021 8:55 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Textbook Problem 6O.1
Replies: 1
Views: 9

Textbook Problem 6O.1

6O.1 A 1.0 M NiSO4(aq) solution was electrolyzed by using inert electrodes. Write (a) the cathode reaction; (b) the anode reaction. (c) With no overpotential at the electrodes, what is the minimum potential that must be supplied to the cell for the onset of electrolysis? How do determine whether Ni ...
by Alvin Lai 3J
Fri Feb 26, 2021 10:08 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Textbook Problem 6L.3
Replies: 1
Views: 30

Textbook Problem 6L.3

6L.3 Write the half-reactions and the balanced equation for the cell reaction for each of the following galvanic cells:
(d) Pt(s)|O2(g)|H+(aq)∥OH−(aq)|O2(g)|Pt(s)
Can someone show me how to do the half reaction for the anode of (d)? I do not understand how the answer key got 2H2O -> O2 + 4H+ + 4e-
by Alvin Lai 3J
Fri Feb 26, 2021 9:58 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Textbook Problems 6L #3
Replies: 2
Views: 8

Textbook Problems 6L #3

For topic 6L #3, where do we find the Ecell information that the answer key has? Are we supposed to look them up?
by Alvin Lai 3J
Fri Feb 26, 2021 9:35 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Gibbs Free Energy Equation and n
Replies: 13
Views: 26

Re: Gibbs Free Energy Equation and n

I think it is the moles of electrons transferred, which you can find my looking at the redox reaction?
by Alvin Lai 3J
Sat Feb 20, 2021 5:44 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: R gas constant and kPa or Pa
Replies: 9
Views: 21

Re: R gas constant and kPa or Pa

When give kPa, convert it to atm using 1 atm = 101.325 kPa. Then you can use the gas constant of R = 8.206 * 10^-2 L·atm·K-1·mol-1 to cancel out the atm and the other units. Hope this helps!
by Alvin Lai 3J
Sat Feb 20, 2021 5:40 pm
Forum: Van't Hoff Equation
Topic: Application of Van't Hoff Equation
Replies: 11
Views: 44

Re: Application of Van't Hoff Equation

The Van't Hoff Equation can be used to find the K2 value at a different temperature, assuming that you know the temperatures of K1 and K2, and the deltaH. Then you could solve for the right side of the equation, put that result as an exponent of e, then multiply it by K1 to get K2. Hope this helps!
by Alvin Lai 3J
Sat Feb 20, 2021 5:36 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 4J.13 Textbook
Replies: 3
Views: 23

Re: 4J.13 Textbook

You would not calculate the gibbs free energy of formation, but you can calculate deltaG rxn by doing the gibbs free energy of formation of the products - the gibbs free energy of formation of the reactants. I believe that the deltaG has to be negative for stability, not positive, since a negative d...
by Alvin Lai 3J
Sat Feb 20, 2021 5:30 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta H and Delta S both positive
Replies: 26
Views: 72

Re: Delta H and Delta S both positive

The reaction will be spontaneous above a certain temperature, since you would need a greater TdeltaS to subtract from deltaH to make deltaG negative!
by Alvin Lai 3J
Fri Feb 12, 2021 8:47 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Textbook Problem 4.37
Replies: 1
Views: 13

Textbook Problem 4.37

Under what conditions, if any, does the sign of each of the following quantities provide a criterion for assessing the spontaneity of a reaction? (a) ΔG°; (b) ΔH°; (c) ΔS°; (d) ΔStot.

For (d), can someone explain to me why if ΔStot. > 0, that the reaction would be spontaneous? Thank you!
by Alvin Lai 3J
Wed Feb 10, 2021 5:56 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: deltaS and deltaU
Replies: 2
Views: 15

deltaS and deltaU

In Dr. Lavelle's lecture, why does he draw a curve facing upwards for deltaU and a downward facing curve for deltaS?
by Alvin Lai 3J
Tue Feb 09, 2021 10:10 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Textbook Problem 4G.3
Replies: 1
Views: 11

Textbook Problem 4G.3

Which would you expect to have a higher molar entropy at T=0, single crystals of BF3 or of COF2? Why?
So the answer is COF2 and not BF3 because the oxygen and fluorine can change places while the fluorine in BF3 will just occupy the same place? So there's more disorder in COF2?
by Alvin Lai 3J
Tue Feb 09, 2021 8:34 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Self-test 4F.5A
Replies: 2
Views: 7

Self-test 4F.5A

Calculate the change in entropy when the volume of 2.00molAr(g) is decreased from 10.00 L to 5.00 L, while the temperature decreases from 300. K to 100. K. Assume ideal behavior.
The answer is −38.9J⋅K−1, but I do not know how to get it. Can someone explain how to do this?
by Alvin Lai 3J
Tue Feb 09, 2021 4:57 pm
Forum: Student Social/Study Group
Topic: When is Midterm 2?
Replies: 4
Views: 20

When is Midterm 2?

When is the next midterm? Just to know so I can prepare myself with workloads. Thank you!
by Alvin Lai 3J
Sun Feb 07, 2021 4:14 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Textbook Problem 4D.11
Replies: 1
Views: 9

Textbook Problem 4D.11

4D.11 The oxidation of nitrogen in the hot exhaust of jet engines and automobiles occurs by the reaction N2(g)+O2(g)→2NO(g)ΔH°=+180.6kJ (c) When the oxidation of N2 to NO was completed in a bomb calorimeter, the heat absorbed was measured as 492 J. What mass of nitrogen gas was oxidized? Can someone...
by Alvin Lai 3J
Sun Feb 07, 2021 2:02 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: deltaU=nCvdeltaT
Replies: 9
Views: 25

Re: deltaU=nCvdeltaT

We know that the volume is constant in the equation because of the subscript V in Cv. Cv means the heat capacity at a constant volume.
by Alvin Lai 3J
Fri Feb 05, 2021 9:17 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Self-test 4B.3A in Topic 4B.3
Replies: 1
Views: 23

Self-test 4B.3A in Topic 4B.3

Estimate the contribution of motion to the molar internal energy of water vapor at 25 °C. [Answer: 7.44 kJ⋅mol−1]
Can someone explain this to me? I tried to understand how to calculate Um, but I do not get it still. Please help, and thank you!
by Alvin Lai 3J
Fri Feb 05, 2021 8:21 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Thermochemistry Equations?
Replies: 7
Views: 32

Thermochemistry Equations?

How are you guys remembering the various equations for Thermochemistry? Since the equations do not seem to be on the constants and equations sheet, are there any tricks to remembering all the equations?
by Alvin Lai 3J
Fri Feb 05, 2021 8:02 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Sapling Week 3 and 4 #8
Replies: 4
Views: 18

Re: Sapling Week 3 and 4 #8

So since you know that for every 358.8 kJ absorbed, you get 4 moles of CS2. With this, you take the energy they give you times that conversion factor to get the # of moles: (379 kJ ) x (4 moles CS2/358.8 kJ) = 4.23 mol Cs2 Now that you have moles of CS2, you multiply the moles by the molar mass of C...
by Alvin Lai 3J
Thu Feb 04, 2021 10:39 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: W
Replies: 14
Views: 66

Re: W

Yep, N means the molecules in the system!
by Alvin Lai 3J
Sun Jan 31, 2021 2:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Factors that affect the equilibrium constant
Replies: 31
Views: 88

Re: Factors that affect the equilibrium constant

The equilibrium constant, K, will only be affected by a change in temperature, not change in volume or pressure.
by Alvin Lai 3J
Sun Jan 31, 2021 12:00 pm
Forum: Ideal Gases
Topic: Reversing Reactions
Replies: 24
Views: 84

Re: Reversing Reactions

The K for a reverse equation is the reciprocal of K, so 1/K. Hope this helps!
by Alvin Lai 3J
Thu Jan 28, 2021 8:45 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Matthew's Workshop Week 3 #3b
Replies: 2
Views: 44

Re: Matthew's Workshop Week 3 #3b

In step 2, you need to do the -5000 kJ divided by -2878 kJ/mol, not the other way around. Everything else looks good, so try what I said instead.
by Alvin Lai 3J
Thu Jan 28, 2021 5:41 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Sapling #8 Weeks 3&4
Replies: 10
Views: 79

Sapling #8 Weeks 3&4

Carbon disulfide can be prepared from coke (an impure form of carbon) and elemental sulfur. 4C(s)+S8(s)⟶4CS2(l) ΔH∘=+358.8 kJ Calculate the amount of heat absorbed when 1.31 mol S8 is reacted at constant pressure. Can someone run by me all the steps for this problem? I do not know where to start, pl...
by Alvin Lai 3J
Sun Jan 24, 2021 9:40 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Textbook Problem 4E.7
Replies: 1
Views: 26

Textbook Problem 4E.7

Use the data in Tables 4E.2 and 4E.3 to estimate the reaction enthalpy for (a) N2(g)+3F2(g)→2 NF3(g) (b) CH3CHCH2(g)+H2O(g)→CH3CH(OH)CH3(g)
(c) CH4(g)+Cl2(g)→CH3Cl(g)+HCl(g)

For (b), why did the textbook solution say that a C-C bond was formed? Can someone explain this to me? Thank you!
by Alvin Lai 3J
Sat Jan 23, 2021 9:55 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Example 4D.3 and converting heat output into moles of fuel molecules
Replies: 1
Views: 17

Example 4D.3 and converting heat output into moles of fuel molecules

In example 4D.3, they did n(C4H10) = (350.kJ) × (2mol C4H10/5756kJ) = (350. × 2)/5756 mol C4H10 = 0.122 … molC4H10

Do we need to know how to convert heat output into moles of fuel molecules for the midterm? If we do, could someone explain this process to me since it is completely new?
by Alvin Lai 3J
Sat Jan 23, 2021 8:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Do concentrations change at equilibrium?
Replies: 9
Views: 39

Re: Do concentrations change at equilibrium?

At equilibrium, concentrations should not change unless concentration is added or subtracted for the product or reactants. Hope this helps!
by Alvin Lai 3J
Wed Jan 20, 2021 9:27 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook Problem 5G.1
Replies: 3
Views: 38

Re: Textbook Problem 5G.1

You are also correct, you just included how the equilibrium reaction is specifically affected from products, in which the book just states that the equilibrium reaction is affected. You're good!
by Alvin Lai 3J
Wed Jan 20, 2021 8:12 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Textbook Problem 6D.5
Replies: 2
Views: 29

Textbook Problem 6D.5

Calculate the pH, pOH, and percentage protonation of solute in each of the following aqueous solutions: (a) 0.057 M NH3(aq); (b) 0.162 M NH2OH(aq); (c) 0.35 M (CH3)3N(aq); (d) 0.0073 M codeine, given that the pKa of its conjugate acid is 8.21. Can someone run down the steps on how to approach (a)? T...
by Alvin Lai 3J
Tue Jan 19, 2021 9:42 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Calculating the pH and percentage deprotonation of a weak acid
Replies: 8
Views: 31

Calculating the pH and percentage deprotonation of a weak acid

When you are using the ICE box to solve for x, when do you know to approximate for x? Does the Ka or Kb need to be *10^-4 or smaller? Thank you!
by Alvin Lai 3J
Sun Jan 17, 2021 5:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE Box Polynomials
Replies: 10
Views: 58

Re: ICE Box Polynomials

I have not encountered any polynomials larger than x^3, because some equations when putting Products/Reactants can be square rooted to remove the squares on the top and bottom. For x^3, you would assume that x is a very small number, like 10^-10, and can make equations with a number + or - x to just...
by Alvin Lai 3J
Sun Jan 17, 2021 12:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: textbook 5.35
Replies: 2
Views: 8

Re: textbook 5.35

I think Evelyn means the partial pressure of A from around 27 to 17, not 35 to 25. But her explanation of how the change in partial pressure is around 10 for A and C, while B has only a change of 5.
by Alvin Lai 3J
Sun Jan 10, 2021 10:01 pm
Forum: Student Social/Study Group
Topic: Study Tips
Replies: 32
Views: 113

Re: Study Tips

I think it would be best to read the textbook and do the problems, as they enhance what Dr. Lavelle discusses in lecture. Then, you could try to form a study group or attend UA sessions to review what you've learned. Also, make sure to read the section outlines to check what you know and don't know....
by Alvin Lai 3J
Sun Jan 10, 2021 9:46 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: relationship between reaction, product, and K
Replies: 7
Views: 57

Re: relationship between reaction, product, and K

Yep, you got it! What multiplies to the entire reaction equation is put as an exponent to the K value.
by Alvin Lai 3J
Sun Jan 10, 2021 4:30 pm
Forum: Administrative Questions and Class Announcements
Topic: Sapling homework due date
Replies: 14
Views: 88

Re: Sapling homework due date

While the first Sapling homework is due on the 17th, you should try to wrap up the section soon to start working on the next section, since we will be starting the next section soon.
by Alvin Lai 3J
Thu Jan 07, 2021 8:52 pm
Forum: Ideal Gases
Topic: Chemical Equilibrium Part 1A Post-Module Assessment
Replies: 11
Views: 38

Re: Chemical Equilibrium Part 1A Post-Module Assessment

C is false, because the even at equilibrium, forward and reverse reactions are still occurring.
by Alvin Lai 3J
Thu Jan 07, 2021 8:43 pm
Forum: Administrative Questions and Class Announcements
Topic: Audio-Visual Topics
Replies: 13
Views: 91

Re: Audio-Visual Topics

I do not think there will be Audio-Focused modules on the upcoming topics, at least not for them all. In Chem 14A, there were not any for the last topics of the quarter, so I think the same will happen for this quarter. I do recommend doing the textbook problems, since they offer practice and have a...
by Alvin Lai 3J
Tue Jan 05, 2021 6:42 pm
Forum: Ideal Gases
Topic: Step 1. Chemical Equilibrium Part 1B Pre-Assessment #40
Replies: 2
Views: 38

Step 1. Chemical Equilibrium Part 1B Pre-Assessment #40

Calculate the concentration of CO(g) in mol.m-3 at 423 K and 0.8 atm using R = 8.206 × 10-5 m3.atm.K-1.mol-1 and assuming only CO(g) is present.
Can someone show me the steps to do this problem? I am lost on where to start. Thank you!
by Alvin Lai 3J
Tue Dec 15, 2020 9:27 pm
Forum: Student Social/Study Group
Topic: Study music
Replies: 32
Views: 263

Re: Study music

I just have all my favorite songs in a playlist on YouTube playing at the lowest possible volume. It's perfect for keeping me relaxed without totally distracting me. Hope everyone has an amazing break!
by Alvin Lai 3J
Fri Dec 11, 2020 12:01 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Textbook 6B.1
Replies: 8
Views: 76

Re: Textbook 6B.1

Can someone run down how to do this step by step? This does not make much sense to me.
by Alvin Lai 3J
Thu Dec 10, 2020 9:33 pm
Forum: Identifying Acidic & Basic Salts
Topic: Textbook Problem J.17
Replies: 2
Views: 39

Re: Textbook Problem J.17

That makes sense, thank you!
by Alvin Lai 3J
Thu Dec 10, 2020 8:43 pm
Forum: Identifying Acidic & Basic Salts
Topic: Textbook Problem J.17
Replies: 2
Views: 39

Textbook Problem J.17

In each of the following salts, either the cation or the anion is a weak acid or a weak base in water. Write the chemical equation for the proton transfer reaction of this cation or anion with water: (a) NaC6H5O; (b) KClO; (c) C5H5NHCl; (d) NH4Br. How do you figure out whether to use the cation or t...
by Alvin Lai 3J
Sat Dec 05, 2020 9:51 pm
Forum: Lewis Acids & Bases
Topic: KA and pKA
Replies: 19
Views: 153

KA and pKA

In Dr. Lavelle's Friday lecture, he talked about KA and pKA. I do not really understand what these are, can someone explain to me? Also, are we going to be calculating these numbers for the final?
by Alvin Lai 3J
Fri Dec 04, 2020 10:27 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Textbook Problem 9C.5
Replies: 1
Views: 30

Textbook Problem 9C.5

Which of the following ligands can be polydentate? If the ligand can be polydentate, give the maximum number of places on the ligand that can bind simultaneously to a single metal center: a) HN(CH2CH2NH2)2; (b) CO32−; (c) H2O; (d) oxalate. Can someone explain to me how to approach this? I do not und...
by Alvin Lai 3J
Fri Dec 04, 2020 9:51 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Example 9C.1 in Textbook
Replies: 3
Views: 49

Re: Example 9C.1 in Textbook

Thank you! I actually understand that now. So we can find the charge on the TM metal by using the compounds total charge? And we can find the total charge of the compound by adding all the charges of the elements?
by Alvin Lai 3J
Fri Dec 04, 2020 9:37 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Example 9C.1 in Textbook
Replies: 3
Views: 49

Example 9C.1 in Textbook

(b) Write the formula of sodium dichloridobis(oxalato)platinate(IV).
(Book help->) Two Cl− ligands and two C2O42− ions are attached to Pt4+. The charge on the complex is −2.

How did they figure out that Pt has a 4+ charge? Please help.
by Alvin Lai 3J
Fri Dec 04, 2020 8:56 pm
Forum: Naming
Topic: oxidation number
Replies: 3
Views: 35

Re: oxidation number

If you're looking for the oxidation number of Pt, you do -1 times the number of Chlorines there are, which gives you -6. Then the equation is Pt - 6 = -2. The equation equals -2 because that is the charge of the compound. This leaves Pt to equal +4 to make -2. Hope this helps.
by Alvin Lai 3J
Fri Dec 04, 2020 8:53 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: linear same atoms?
Replies: 6
Views: 62

Re: linear same atoms?

Hey! So you are right in that there are three lone pairs on the middle Iodine. This makes five electron densities, and that would be trigonal bipyramidal. The three lone pairs take all the equatorial electron densities, leaving only the axial atoms as Iodine. This makes the linear shape. Hope this h...
by Alvin Lai 3J
Fri Dec 04, 2020 8:48 pm
Forum: Sigma & Pi Bonds
Topic: sigma and pi bonds for benzene molecule
Replies: 3
Views: 51

Re: sigma and pi bonds for benzene molecule

I believe it would be 12 sigma bonds and 3 pi bonds because each carbon is also bonded to a hydrogen. Hope this helps!
by Alvin Lai 3J
Sat Nov 28, 2020 4:40 pm
Forum: Hybridization
Topic: Textbook problem 2F.15
Replies: 4
Views: 53

Re: Textbook problem 2F.15

Thank you, that really helped! I do not think the textbook talked much about it, so thanks for telling me.
by Alvin Lai 3J
Sat Nov 28, 2020 3:51 pm
Forum: Hybridization
Topic: Textbook problem 2F.15
Replies: 4
Views: 53

Textbook problem 2F.15

Noting that the bond angle of an sp3 hybridized atom is 109.5° and that of an sp2 hybridized atom is 120°, do you expect the bond angle between two hybrid orbitals to increase or decrease as the s-character of the hybrids is increased? Can someone explain to me what the question means by s-character...
by Alvin Lai 3J
Fri Nov 27, 2020 9:55 pm
Forum: Hybridization
Topic: 2F.3 Other Common Types of Hybridization
Replies: 1
Views: 59

2F.3 Other Common Types of Hybridization

h1=s+21/2py h2=s+(32)1/2px−(12)1/2py h3=s−(32)1/2px−(12)1/2py

Do we need to know about the hybrid orbitals h1, h2, etc.? Like the equations at the beginning of 2F.3?
by Alvin Lai 3J
Fri Nov 27, 2020 8:41 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Geometry
Replies: 7
Views: 51

Re: Molecular Geometry

For me, I just try to memorize it. I try to remember the geometry with no lone pairs on the center atom, and then think of the geometry and it's name when there are lone pairs.
by Alvin Lai 3J
Fri Nov 27, 2020 8:39 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Bracket Notation
Replies: 4
Views: 43

Re: Bracket Notation

Yeah, you would put the charge on the outside, top right of the brackets. You are right!
by Alvin Lai 3J
Sun Nov 22, 2020 8:13 pm
Forum: Administrative Questions and Class Announcements
Topic: 14B Enrollment [ENDORSED]
Replies: 31
Views: 1472

Re: 14B Enrollment [ENDORSED]

They are also recorded, so you should be able to take your fiat lux as well!
by Alvin Lai 3J
Sun Nov 22, 2020 8:12 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Textbook Problem 2E. 19
Replies: 3
Views: 27

Textbook Problem 2E. 19

Predict the shapes and estimate the bond angles of (a) the thiosulfate ion, S2O32−; (b) (CH3)2Be; (c) BH2−; (d) SnCl2.

For (b), do you predict the shapes with the carbons as the central atoms?
by Alvin Lai 3J
Sun Nov 22, 2020 5:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Textbook Problem 2E. 5
Replies: 3
Views: 48

Textbook Problem 2E. 5

2E.5 (a) What is the shape of a ClO2+ ion? (b) What is the expected OClO bond angle?

Is the lewis structure for ClO2+ drawn with one double bond or two? Can someone explain to me why? Thank you!
by Alvin Lai 3J
Mon Nov 16, 2020 3:34 pm
Forum: Student Social/Study Group
Topic: Winter 2021 Classes
Replies: 20
Views: 247

Re: Winter 2021 Classes

Thank you! Also, would it be okay to take the Chem 14BL Lab section from 11am-1:30pm on Friday even though it goes into Chem 14B's friday lecture at 1pm, since the lecture is recorded?
by Alvin Lai 3J
Mon Nov 16, 2020 3:19 pm
Forum: Student Social/Study Group
Topic: Winter 2021 Classes
Replies: 20
Views: 247

Winter 2021 Classes

Hello, I am thinking of taking Chem 14B and Chem 14BL next quarter along with LS30B. Is the minimum units per quarter 12 or 13? If it is 13, then I would have to take another class, probably a GE since Chem 14B is 4 units, Chem 14BL is 3 units, and LS30B is 5 units which equals 12 units. Please help!
by Alvin Lai 3J
Fri Nov 13, 2020 5:09 pm
Forum: Lewis Structures
Topic: Textbook Problem 2C.1
Replies: 3
Views: 36

Re: Textbook Problem 2C.1

My book gives me the wrong answers then. Is there a place that I could get the correct answers for the odd numbers?
by Alvin Lai 3J
Thu Nov 12, 2020 8:50 pm
Forum: Lewis Structures
Topic: Textbook Problem 2C.1
Replies: 3
Views: 36

Re: Textbook Problem 2C.1

Also, the book says just (a) and (b) are radicals. Is (c) also a radical since the O has one electron by itself?
by Alvin Lai 3J
Thu Nov 12, 2020 8:45 pm
Forum: Lewis Structures
Topic: Textbook Problem 2C.1
Replies: 3
Views: 36

Textbook Problem 2C.1

Which of the following species are radicals? (a) NO2−; (b) CH3; (c) OH; (d) CH2O.

Can someone explain to me how (a) is a radical? Thank you!
by Alvin Lai 3J
Thu Nov 12, 2020 7:26 pm
Forum: Lewis Structures
Topic: Textbook Problem 2B.21
Replies: 2
Views: 40

Textbook Problem 2B.21

Hypochlorous acid, HClO, is found in white blood cells, where it helps to destroy bacteria. Draw two Lewis structures with different atom arrangements for HClO and select the most likely structure by identifying the structure with formal charges closest to zero. Consider only structures with single ...
by Alvin Lai 3J
Wed Nov 11, 2020 9:35 pm
Forum: Lewis Structures
Topic: homework 2B.3
Replies: 5
Views: 46

Re: homework 2B.3

In the textbook solutions, it shows one of the F with only two pairs of electrons and one bond with Br. This is a book mistake right?
by Alvin Lai 3J
Fri Nov 06, 2020 4:44 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm 2 [ENDORSED]
Replies: 11
Views: 139

Re: Midterm 2 [ENDORSED]

When is Midterm 2 going to be? Thanks in advance.
by Alvin Lai 3J
Fri Nov 06, 2020 4:41 pm
Forum: Photoelectric Effect
Topic: Units for energy
Replies: 11
Views: 145

Re: Units for energy

HI! It's 1 Hz = 1/second
I hope this helps!
by Alvin Lai 3J
Fri Nov 06, 2020 4:34 pm
Forum: Ionic & Covalent Bonds
Topic: Textbook Problem 2A.11
Replies: 4
Views: 27

Re: Textbook Problem 2A.11

That really helps, thank you!
by Alvin Lai 3J
Thu Nov 05, 2020 9:04 pm
Forum: Ionic & Covalent Bonds
Topic: Textbook Problem 2A.19
Replies: 2
Views: 26

Textbook Problem 2A.19

Give the ground-state electron configuration and number of unpaired electrons expected for each of the following ions: (a) Sb3+; (b) Sn4+; (d) Br−; (e) Ni2+. For (e) Ni2+, the textbook says the answer is [Ar]3d8 and two unpaired electrons. I thought the answer would have been [Ar]3d6 4s2 and four un...
by Alvin Lai 3J
Thu Nov 05, 2020 8:39 pm
Forum: Ionic & Covalent Bonds
Topic: Textbook Problem 2A.11
Replies: 4
Views: 27

Textbook Problem 2A.11

Which M3+ ions (where M is a metal) are predicted to have the following ground-state electron configurations:
(a) [Ar]3d6; (b) [Ar]3d5

I'm confused on how to solve this correctly, can someone clarify the exceptions when it comes to the d orbitals? Thank you!
by Alvin Lai 3J
Fri Oct 30, 2020 8:45 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Exam Scores
Replies: 15
Views: 116

Re: Midterm Exam Scores

Oh I see, thank you for figuring that out. Maybe I'm just bad at figuring things out, but that was a bit obscure. Thanks again though!
by Alvin Lai 3J
Fri Oct 30, 2020 8:39 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal Plane Importance
Replies: 9
Views: 52

Re: Nodal Plane Importance

Did Dr. Lavelle say that we do not have to think about nodal planes too much in his lecture? Maybe I'm wrong?
by Alvin Lai 3J
Fri Oct 30, 2020 8:37 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Exam Scores
Replies: 15
Views: 116

Re: Midterm Exam Scores

Same, I can't find it anywhere. I tried searching google, but still didn't figure it out. Please help!
by Alvin Lai 3J
Fri Oct 30, 2020 8:30 pm
Forum: *Shrodinger Equation
Topic: New Audio-Visual Modules
Replies: 9
Views: 104

Re: New Audio-Visual Modules

I also really enjoyed the modules, since they taught me quick and easy, and that I could view them before a quiz or midterm. Too bad he's not making any more.
by Alvin Lai 3J
Fri Oct 30, 2020 8:17 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Exam Scores
Replies: 15
Views: 116

Re: Midterm Exam Scores

Hi, apparently there was an error with one of the questions and each individual midterm is being looked at. This means it will probably be next week when we can see our scores.
by Alvin Lai 3J
Fri Oct 23, 2020 8:53 pm
Forum: General Science Questions
Topic: Midterm
Replies: 5
Views: 55

Re: Midterm

Like the midterm is still proctored by our TA with our discussion group, but every student takes it on Friday at like 4pm PST? Realistically, we should just prep for our discussion section for the midterm.
by Alvin Lai 3J
Fri Oct 23, 2020 8:22 pm
Forum: Balancing Chemical Reactions
Topic: Balancing Equation Post Module Assessment
Replies: 2
Views: 46

Re: Balancing Equation Post Module Assessment

So the coefficients in front of each compound is a mole. All you have to do is add up the total moles on the left and compare them to the total moles on the right. This should be 30->36, so the net moles is 6.
by Alvin Lai 3J
Fri Oct 23, 2020 8:17 pm
Forum: Student Social/Study Group
Topic: How are you studying?
Replies: 203
Views: 1402

Re: How are you studying?

I just watch the lectures, take notes on the modules/do the assessments, and do the problems in the textbook. If I get stuck on a problem, I look at Chemistry Community to get help. Hope this helps!
by Alvin Lai 3J
Fri Oct 16, 2020 4:01 pm
Forum: Photoelectric Effect
Topic: photoelectric experiment post assessment
Replies: 2
Views: 37

Re: photoelectric experiment post assessment

I believe it is ultraviolet light. Hope this helps. And if you need it, you can paste your question into google and find a quizlet for the post-assessment.
by Alvin Lai 3J
Fri Oct 16, 2020 3:59 pm
Forum: Photoelectric Effect
Topic: photoelectric effect
Replies: 17
Views: 145

Re: photoelectric effect

Yes work function is the same as the threshold energy.
by Alvin Lai 3J
Fri Oct 16, 2020 3:55 pm
Forum: Empirical & Molecular Formulas
Topic: Question from a Workshop problem
Replies: 4
Views: 58

Re: Question from a Workshop problem

Hi! Basically when we calculate the empirical formula, we only want to use individual elements. In other words, instead of O2 you would simply use only O. Your calculations should look like this: 69.9 g Fe (1 mol Fe/55.85 g Fe)= 1.25 mol Fe 30.1 g O (1 mol O/16.00 g O) = 1.88 mol O Dividing by the ...
by Alvin Lai 3J
Fri Oct 16, 2020 3:47 pm
Forum: Significant Figures
Topic: rounding during equations
Replies: 14
Views: 111

Re: rounding during equations

I try not to round during the equations, and round the final answer with sig figs. That way, I get the most accurate answer. Hope this helps!
by Alvin Lai 3J
Thu Oct 15, 2020 10:34 pm
Forum: Photoelectric Effect
Topic: Mass of an object
Replies: 5
Views: 66

Re: Mass of an object

Hey! On a different post, somebody said this acronym to help remember the prefixes:

Great Mr. Knight Doesn't Cook Me Macaroni Until Nine Pm
(giga, mega, kilo, deci, cent, milli, micro, µ, nano, pico)
(credit: Shreya Patel- 2D)

Hope this helps
by Alvin Lai 3J
Sun Oct 11, 2020 9:24 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Test Accuracy
Replies: 13
Views: 156

Re: Test Accuracy

I read on a different post that the midterms and quizzes will be multiple choice, so I don't think we have to worry about sig figs and rounding.
by Alvin Lai 3J
Thu Oct 08, 2020 9:56 pm
Forum: Molarity, Solutions, Dilutions
Topic: Concentration Calculations
Replies: 11
Views: 3144

Re: Concentration Calculations

How did you find the molarity of Na2CO3?
by Alvin Lai 3J
Thu Oct 08, 2020 9:35 pm
Forum: SI Units, Unit Conversions
Topic: Acronym for prefixes
Replies: 7
Views: 86

Re: Acronym for prefixes

Prefix Name Meaning G giga 10^9 M mega 10^6 k kilo 10^3 d deci 10^-1 c centi 10^-2 m milli 10^-3 u micro 10^-6 n nano 10^-9 p pico 10^-12 I'll just leave this here :)
by Alvin Lai 3J
Thu Oct 08, 2020 9:29 pm
Forum: Balancing Chemical Reactions
Topic: Fundamental Question E.17
Replies: 3
Views: 44

Re: Fundamental Question E.17

You would convert the grams for each element into moles using the element's molar mass. So take the mass of Phosphorus and divide it by the molar mass to convert it to moles, and do the same with Te. Then you would compare the moles of P to Te and see which moles is bigger.
by Alvin Lai 3J
Tue Oct 06, 2020 8:53 pm
Forum: General Science Questions
Topic: Office Hours
Replies: 5
Views: 43

Re: Office Hours

Should we be attending as many office hours for Dr. Lavelle? I understand it's not required but am I missing out from not attending them?

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