Search found 98 matches

by DesireBrown1J
Sun Mar 15, 2020 7:46 am
Forum: Administrative Questions and Class Announcements
Topic: Recommended Pathway for Chem Series
Replies: 13
Views: 245

Re: Recommended Pathway for Chem Series

For those who already took 14 BL, what advice would you have for the labs? Unfortunately, I will have to do the virtual lab next quarter but I would like to know what was the most useful information from 14A and B that helped you in BL.
by DesireBrown1J
Sun Mar 15, 2020 7:44 am
Forum: Administrative Questions and Class Announcements
Topic: Athena
Replies: 34
Views: 1825

Re: Athena

Thank you Dr. Lavelle, I really appreciated all the resources you created for this class, such as the workshops and step up sessions. Not many professors take the extra time to provide more resources for students.
by DesireBrown1J
Sun Mar 15, 2020 7:42 am
Forum: Administrative Questions and Class Announcements
Topic: ENDGAME Review Session
Replies: 71
Views: 2530

Re: ENDGAME Review Session

Thank you for all your help in chemistry 14A and B. I really appreciate all the hard work you put into making the worksheets and review sessions. They were really helpful.
by DesireBrown1J
Sun Mar 08, 2020 10:34 pm
Forum: Administrative Questions and Class Announcements
Topic: 100 or 50 posts?
Replies: 8
Views: 59

Re: 100 or 50 posts?

Deleting the first 50 posts is unnecessary and is tedious. Your TAs will be able to see when the posts were made and will count the 50 that are during this quarter towards your grade. :)
by DesireBrown1J
Sun Mar 08, 2020 10:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Tips for Test
Replies: 23
Views: 211

Re: Tips for Test

The homework problems at the end of every focus section are the most helpful because they combine lots of topics into 1 problem like the test. (i.e. 4.21, 4.43, 6.43) Would you recommend the ones in sections 5 and 6? Just for clarification which sections were the most helpful related to the Test 2?...
by DesireBrown1J
Sun Mar 08, 2020 10:09 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Study Advice
Replies: 73
Views: 3615

Re: Study Advice

chari_maya 3B wrote:Lyndon's reviews!!


Is his worksheet available now?
by DesireBrown1J
Sun Mar 08, 2020 10:06 pm
Forum: General Science Questions
Topic: Worksheets for Final Review Sessions
Replies: 2
Views: 82

Worksheets for Final Review Sessions

I know that Lyndon will have a worksheet for his final review sessions, but are there any other UAs or TAs who do the same? If so, where can I access and print out their worksheets?
by DesireBrown1J
Thu Mar 05, 2020 12:08 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic cells
Replies: 3
Views: 32

Re: Galvanic cells

One easy way that I remember that the oxidation will be at the anode and reduction at the cathode is through Ox-An (for oxidation-anode). That helped me remember it because it reminded me of the Roxanne song since it sounds like the name. Kinda silly but useful.
by DesireBrown1J
Sun Mar 01, 2020 11:32 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Additional resources: Thermodynamics
Replies: 5
Views: 114

Re: Additional resources: Thermodynamics

Do I have to pay to access Sapling Learning?
by DesireBrown1J
Sun Mar 01, 2020 11:25 pm
Forum: Administrative Questions and Class Announcements
Topic: Sapling Learning
Replies: 6
Views: 59

Re: Sapling Learning

How do I access Sapling Learning?
by DesireBrown1J
Sun Mar 01, 2020 11:20 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Tips for Test
Replies: 23
Views: 211

Re: Tips for Test

The homework problems at the end of every focus section are the most helpful because they combine lots of topics into 1 problem like the test. (i.e. 4.21, 4.43, 6.43)
by DesireBrown1J
Sun Mar 01, 2020 11:02 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 5G.13
Replies: 8
Views: 133

Re: 5G.13

Thank you! I didn't realize I made that small mistake!
by DesireBrown1J
Fri Feb 28, 2020 8:40 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: 6K3
Replies: 3
Views: 77

Re: 6K3

Why is Cl2 the oxidizing agent when it actually gains electrons? Shouldn't it be the reducing agent in that case?
by DesireBrown1J
Sun Feb 23, 2020 10:21 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst
Replies: 7
Views: 64

Re: Nernst

Why is n moles of electrons transferred instead of the number of electrons transferred? How do we convert it into moles if they are electrons?
by DesireBrown1J
Sun Feb 23, 2020 10:11 pm
Forum: Student Social/Study Group
Topic: Friday lecture 02/21
Replies: 3
Views: 61

Re: Friday lecture 02/21

Where in the textbook does it talk about the Nernst Equation? I can't seem to find it.
by DesireBrown1J
Sun Feb 23, 2020 10:09 pm
Forum: Administrative Questions and Class Announcements
Topic: Pizza Rolls REVIEW Session DOWNLOAD HERE
Replies: 67
Views: 2646

Re: Pizza Rolls REVIEW Session DOWNLOAD HERE

Does Lyndon have a practice worksheet for Test 2?
by DesireBrown1J
Wed Feb 19, 2020 11:38 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 5G.13
Replies: 8
Views: 133

Re: 5G.13

This is what I plugged into the equation G = -RTlnK + RTlnQ

delta G=(-(8.314 J*K-1*mol-1)(1200K)(ln(6.8))-((8.314J*K-1*mol-1)(1200K)(ln(7.38)))

However, my answer was completely off and was not close to the solutions manual.
by DesireBrown1J
Wed Feb 19, 2020 6:39 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 5G.3 Reading in Outline 4
Replies: 1
Views: 26

5G.3 Reading in Outline 4

I am doing the reading for 5G.3: "The Origin of Equilibrium Constants" in Outline 4. It states that the two approaches are kinetics and thermodynamics. We discussed the thermodynamics approach on Friday after the midterm but we did not talk about the kinetics approach. Do we need to know t...
by DesireBrown1J
Wed Feb 12, 2020 12:49 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test 1 #5
Replies: 3
Views: 66

Re: Test 1 #5

My final answer was pOH=12.5. Is that correct (for those who got full points)?
by DesireBrown1J
Wed Feb 12, 2020 11:36 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4A.7
Replies: 4
Views: 51

Re: 4A.7

(a) Calculate the heat that must be supplied to a copper kettle of mass 400.0 g containing 300.0 g of water to raise its temperature from 20.0 C to the boiling point of water, 100.0 C. (b) What percentage of the heat is used to raise the temperature of the water? (See Table 4A.2.) How do I solve th...
by DesireBrown1J
Mon Feb 10, 2020 10:11 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: R constants
Replies: 21
Views: 600

Re: R constants

For which problems on the equation sheet will we ever use R=8.314*10-2 L*bar*K-1*mol-1?
by DesireBrown1J
Mon Feb 10, 2020 9:09 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Heat capacity
Replies: 6
Views: 49

Re: Heat capacity

On page 251, the textbook says "The heat capacity of a sample of a substance is calculated from its mass and its specific heat capacity by using C=m*C s ". I'm confused on what exactly the book is trying to say with this because mass cancels out anyways in this equation since C s =C/m. C=m...
by DesireBrown1J
Mon Feb 10, 2020 8:27 pm
Forum: Phase Changes & Related Calculations
Topic: Work (w)
Replies: 8
Views: 65

Re: Work (w)

There are other types of work but we only need to worry about expansion work for the midterm. Here is a table of other types of work that was in the textbook on page 245.

types of work.JPG
by DesireBrown1J
Sun Feb 09, 2020 8:51 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: State Function
Replies: 7
Views: 40

Re: State Function

Cavalli_1H wrote:hess's law can also be applicable to gibbs free energy for the reason of it being a state property


How is it explained and applied to Gibbs free energy?
by DesireBrown1J
Sun Feb 09, 2020 8:28 pm
Forum: Administrative Questions and Class Announcements
Topic: Pizza Rolls REVIEW Session DOWNLOAD HERE
Replies: 67
Views: 2646

Re: Pizza Rolls REVIEW Session DOWNLOAD HERE

Why is delta H always q but q is not always delta H? What exactly does he mean by that?
by DesireBrown1J
Sun Feb 09, 2020 7:45 pm
Forum: Administrative Questions and Class Announcements
Topic: Pizza Rolls REVIEW Session DOWNLOAD HERE
Replies: 67
Views: 2646

Re: Pizza Rolls REVIEW Session DOWNLOAD HERE

What was the little saying to remember the state functions other than entropy and enthalpy? The HUGS and TV one?
by DesireBrown1J
Mon Feb 03, 2020 10:09 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isobaric Reversible Expansion
Replies: 4
Views: 38

Re: Isobaric Reversible Expansion

Where exactly in the textbook does it talk about isobaric reversible reactions?
by DesireBrown1J
Mon Feb 03, 2020 9:57 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Lyndon Bui Workshops
Replies: 7
Views: 137

Re: Lyndon Bui Workshops

I know that Lyndon usually posts a practice worksheet for his midterm/final review sessions and he often names it after some type of food (such as marshmallow for his Chem 14a final review session). Has he posted the review worksheet for his review session next week?
by DesireBrown1J
Sun Feb 02, 2020 11:54 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: degeneracy
Replies: 7
Views: 50

Re: degeneracy

Where in the textbook do they talk about degeneracy and which homework problems are related to it?
by DesireBrown1J
Sun Feb 02, 2020 11:46 pm
Forum: Phase Changes & Related Calculations
Topic: 4A. 1 Identifying open and closed system
Replies: 11
Views: 195

Re: 4A. 1 Identifying open and closed system

Just to clarify, all biological systems are closed systems?
by DesireBrown1J
Sun Feb 02, 2020 5:24 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy Changes Due to Temperature
Replies: 2
Views: 24

Re: Entropy Changes Due to Temperature

The equation for change in entropy is delta(S)=q rev /T. As temperature increases, the change in entropy will decrease because temperature is in the denominator. Exothermic and endothermic have to do with changes in temperature but in this case, temperature is remaining constant (from what I underst...
by DesireBrown1J
Fri Jan 31, 2020 1:12 am
Forum: Calculating Work of Expansion
Topic: 4A.3
Replies: 8
Views: 85

Re: 4A.3

Jeremy_Guiman2E wrote:You do use w = P * A * D!

w = 2 atm * (0.015 m)2 * 0.2 m * pi
w = 2.8274 * 10-4 m3 * atm

Then, you can multiply the answer by 101,325 Pa to convert from atm to Pa. Once you have your answer in m3 * Pa, it is equal to that amount in joules (J).


Where did you get 0.015m from and pi from?
by DesireBrown1J
Thu Jan 30, 2020 10:42 pm
Forum: Phase Changes & Related Calculations
Topic: 4A. 1 Identifying open and closed system
Replies: 11
Views: 195

Re: 4A. 1 Identifying open and closed system

I see that everyone is saying C is either a closed or isolated system. For clarification, the textbook solutions states that it is an isolated system. It's an isolated system because nothing is being exchanged with the environment in the bomb calorimeter. In a closed system, energy can be exchanged ...
by DesireBrown1J
Thu Jan 23, 2020 10:16 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6D.5
Replies: 2
Views: 79

Re: 6D.5

You need to make an ice table for the reaction of NH3 reacting with H2O. Once you solve for the equilibrium concentration of OH-, you can find pOH (pOH= -log[OH-]). Then you can convert pOH to pH (pH + pOH = 14). Percentage protonation is calculated by doing ([NH4+]/[NH3]initial) x100% How are we s...
by DesireBrown1J
Thu Jan 23, 2020 9:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chem. Equilibrium Post Assessment 2 #29
Replies: 1
Views: 23

Chem. Equilibrium Post Assessment 2 #29

A researcher fills a 1.00 L reaction vessel with 1.84 x 10 -4 mol of BrCl gas and heats it to 500 K. At equilibrium, only 18.3 % of the BrCl gas remains. Calculate the equilibrium constant, assuming the following reaction is taking place. 2BrCl(g) ⇌ Br2 (g) + Cl2(g) A. 19.5 B. 8.39 x 10-5 C. 4.98 D....
by DesireBrown1J
Thu Jan 23, 2020 1:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chemical Equilibrium 1B Post-Assessment #19.b
Replies: 2
Views: 30

Chemical Equilibrium 1B Post-Assessment #19.b

18. You are studying the following unbalanced reaction at high temperatures: NH3 (g) ⇌ N2 (g) + H2 (g) In one of your experiments at 500K the measured partial pressures are: NH3 0.887 bar H2 0.168 bar N2 0.0561 bar a) Determine the equilibrium constant for this reaction at 500 K. A. K = 3.38 x 10-4 ...
by DesireBrown1J
Sat Jan 18, 2020 2:48 pm
Forum: Administrative Questions and Class Announcements
Topic: Study Guide Test One
Replies: 17
Views: 155

Re: Study Guide Test One

Although there is no practice test or study review for Test 1, I highly recommend completing all of the homework problems to make sure you can answer and understand all of them and make sure you can explain all the concepts in the outlines. I also recommend going to UA sessions because they provide ...
by DesireBrown1J
Sat Jan 18, 2020 2:44 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6A19 part c
Replies: 5
Views: 54

Re: 6A19 part c

I was wondering about this too. The book gives 3.2 x 10^-12 as the answer because it multiplies 3.1 by 10^-3, which I think implies that it has something to do with units. However, the units of 3.1 are mol*L^-1, which are the same units the values in the other parts had and those values weren't mul...
by DesireBrown1J
Wed Jan 15, 2020 6:03 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6A19 part c
Replies: 5
Views: 54

Re: 6A19 part c

I used (1.0 x 10^-14)/3.1 but my answer was also 3.2 x 10^-15. Also, when I multiplied 3.1 with 3.2 x 10^-15 to see if my calculations are correct, I get 1.0 x 10^-14.
by DesireBrown1J
Wed Jan 15, 2020 5:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: HW 5I.3
Replies: 2
Views: 29

Re: HW 5I.3

You do not have to convert them to partial pressure. You can use Kc=[R]/[P] to solve for this problem by plugging in Kc from the Table 5G.2 and [HI] is 2.21 x 10^-3 mol/L and [I2] is 1.46 x 10^-3 mol/L to solve for the equilibrium molar concentration of H2. If you completed 5I.1, it follows the same...
by DesireBrown1J
Wed Jan 15, 2020 5:22 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.1
Replies: 3
Views: 46

Re: 5I.1

Do sig figs matter in this one? I did 3 sig figs for the equilibrium molar concentration because Kc had 3 sig figs, yet the solutions manual answer was in 2 sig figs.
by DesireBrown1J
Sat Jan 11, 2020 6:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc vs. Kp [ENDORSED]
Replies: 4
Views: 49

Re: Kc vs. Kp [ENDORSED]

Yes, KP applies to gases with partial pressures and KC is for aqueous solutions or gases with molar concentration.
by DesireBrown1J
Fri Jan 10, 2020 9:43 am
Forum: Administrative Questions and Class Announcements
Topic: Discussion 1J with TA Kevin?
Replies: 2
Views: 35

Discussion 1J with TA Kevin?

I am confused because today I was supposed to have my discussion at 9am with TA Kevin Chandler in Rolfe 3134 because that's on the study list and on the office hours sheet I printed out in the beginning of this week. Yet, when I walked in the classroom, it was a different TA, a woman, and I assumed ...
by DesireBrown1J
Thu Jan 09, 2020 4:32 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.9
Replies: 4
Views: 55

Re: 5G.9

PO2/PO3 will be different because the ratio of the reactant to the product is different at equilibrium point for different amounts of starting reactant. Only (PO2)^3/(PO3)^2 or (PO3)^2/(PO2)^3 are guaranteed to be the same because they are the equilibrium constant and the inverse of it. For c, woul...
by DesireBrown1J
Wed Jan 08, 2020 6:04 pm
Forum: Ideal Gases
Topic: R constant in PV=nRT
Replies: 9
Views: 64

R constant in PV=nRT

What exactly is the ideal gas constant in R? When I looked it up, I realized that there are two different ones to use. How do we determine which one to use based on what information is given to us in a problem?
by DesireBrown1J
Mon Jan 06, 2020 11:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.3
Replies: 8
Views: 86

Re: 5G.3

I wrote my answer for part a as K=[C 2 H 4 Cl 2 ] 2 [H 2 O] 2 /[C 2 H 4 ] 2 [O 2 ][HCl] 4 but the textbook has it in terms of partial pressures because they are gases. This is also how we had to write it when doing the modules. If I do not write it in terms of partial pressures on the exams or homew...
by DesireBrown1J
Sat Dec 07, 2019 3:25 pm
Forum: Administrative Questions and Class Announcements
Topic: TAs for next quarter, Chem 14B
Replies: 1
Views: 52

TAs for next quarter, Chem 14B

Will we have the same TAs for next quarter for the most part? If so, is there a list of which TAs are teaching the discussion sections?
by DesireBrown1J
Thu Dec 05, 2019 12:42 pm
Forum: Bronsted Acids & Bases
Topic: Correct equation for 6A.3?
Replies: 4
Views: 61

Re: Correct equation for 6A.3?

I got the correct answers for all the parts in 6A.3, yet I wanted to double check to make sure my chemical equations for the proton transfer equilibria were correct because that wasn't in the solutions manual. a) H 2 SO 4 + H 2 O <-> H 3 O + + HSO 4 - b) C 6 H 5 NH 3 + + H 2 O <-> H 3 O + + C 6 H 5...
by DesireBrown1J
Wed Dec 04, 2019 4:45 pm
Forum: Bronsted Acids & Bases
Topic: Strong vs Weak Acids (6C.19)
Replies: 2
Views: 49

Re: Strong vs Weak Acids (6C.19)

Look at which ones have the higher electronegativity difference on a central atom and which ones have more oxygens attached to the central atom.
by DesireBrown1J
Wed Dec 04, 2019 12:01 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Strong vs Weak Acids and H atoms
Replies: 2
Views: 46

Strong vs Weak Acids and H atoms

If a molecule has more H atoms compared to another molecule with fewer H atoms, would the one with more H atoms be considered a weaker acid because it is less likely that it will be completely deprotonated?
by DesireBrown1J
Tue Dec 03, 2019 11:19 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Electronegativity and Acid Strength
Replies: 3
Views: 53

Electronegativity and Acid Strength

So, a greater electronegativity means that the acid is stronger?
by DesireBrown1J
Mon Dec 02, 2019 7:50 pm
Forum: Identifying Acidic & Basic Salts
Topic: Electron withdrawing to identify acids
Replies: 2
Views: 41

Electron withdrawing to identify acids

So, electron-withdrawing leads to the release of H+ ions because cations has high electron-withdrawing and pull the electrons towards it, which then results in the release of H+ to form H3O+? And all this makes it an acid?
by DesireBrown1J
Mon Dec 02, 2019 11:17 am
Forum: Bronsted Acids & Bases
Topic: 6A. 9
Replies: 2
Views: 38

Re: 6A. 9

For this problem, how do we write the net ionic equations for I- to cancel out?
by DesireBrown1J
Sun Dec 01, 2019 10:38 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6B.3
Replies: 2
Views: 47

Re: 6B.3

Can someone explain to me what I did wrong for this problem?

a) M=0.025 mol HCl/0.200 L =0.125 mol*L-1
pH=-log(0.125)=0.903?
But the solutions manual says 1.6
by DesireBrown1J
Sun Dec 01, 2019 10:24 pm
Forum: Bronsted Acids & Bases
Topic: 6A.9 a
Replies: 3
Views: 64

Re: 6A.9 a

The chemical equation is not balanced(The I2 should be just I^-(aq)). After correcting this, writing the net ionic equation, the I^- ions will cancel out and the species left are NH4+,H2O,H3O^+,NH3. Since the proton donator is NH4+, NH4+ is the bronsted acid. Why would it be NH 4 + as the acid inst...
by DesireBrown1J
Sun Dec 01, 2019 9:28 pm
Forum: Lewis Acids & Bases
Topic: lewis vs. bronsted
Replies: 10
Views: 94

Re: lewis vs. bronsted

Do we need to know about the Arrhenius acids and bases? I saw it in the textbook but I do not remember him mentioning it in class.
by DesireBrown1J
Sun Dec 01, 2019 9:04 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Final Exam
Replies: 10
Views: 148

Re: Final Exam

Does anyone have any good tips and tricks for memorizing certain things for the exam? Such as the naming for coordination compounds
by DesireBrown1J
Sun Dec 01, 2019 9:02 pm
Forum: Bronsted Acids & Bases
Topic: Correct equation for 6A.3?
Replies: 4
Views: 61

Correct equation for 6A.3?

I got the correct answers for all the parts in 6A.3, yet I wanted to double check to make sure my chemical equations for the proton transfer equilibria were correct because that wasn't in the solutions manual. a) H 2 SO 4 + H 2 O <-> H 3 O + + HSO 4 - b) C 6 H 5 NH 3 + + H 2 O <-> H 3 O + + C 6 H 5 ...
by DesireBrown1J
Sun Nov 24, 2019 11:26 pm
Forum: Student Social/Study Group
Topic: test 2
Replies: 2
Views: 59

Re: test 2

I do not think the TAs will have enough time to grade them and give them back to us before Thanksgiving break. So, we should get them back during our week 10 discussions. I would email your TA and see what they will be doing.
by DesireBrown1J
Fri Nov 22, 2019 12:49 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape
Replies: 6
Views: 74

Re: Shape

The VSEPR formula for pentagonal bipyramidal is AX7.
by DesireBrown1J
Thu Nov 21, 2019 9:41 pm
Forum: Sigma & Pi Bonds
Topic: More complex practice problems
Replies: 2
Views: 79

More complex practice problems

I know that for the exam, the problems will probably be more advanced than those on the homework. Does anyone have any more additional practice problems for sigma and pi bonds?
by DesireBrown1J
Thu Nov 21, 2019 9:10 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: in need of test 2 practice problems
Replies: 5
Views: 89

Re: in need of test 2 practice problems

I would also recommend doing homework problems from 3F because intermolecular forces will also be on the exam.
by DesireBrown1J
Sun Nov 17, 2019 10:47 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.19A
Replies: 2
Views: 35

Re: 2E.19A

2E.19, Part B

So if we do get a molecule like (CH3)2Be on the test or final, would we have to say it is tetrahedral about the carbon atoms, since there is not an exact shape we learned to accurately represent the whole molecule?
by DesireBrown1J
Sun Nov 17, 2019 8:20 pm
Forum: Administrative Questions and Class Announcements
Topic: test 2
Replies: 7
Views: 100

Re: test 2

I would recommend making flashcards on the 12 different shapes and also adding the bond angles, VSEPR formula, name, examples, and a drawing. That has been helping me remember them and also color-coding everything in the drawings.
by DesireBrown1J
Sat Nov 16, 2019 5:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape
Replies: 6
Views: 74

Re: Shape

This photo is from the textbook of all the shapes we should know for test 2.

[img]
Screenshot%202019-11-16%2017.24.28.png
[/img]
by DesireBrown1J
Sat Nov 16, 2019 4:30 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent or Angular
Replies: 13
Views: 192

Re: Bent or Angular

So, the bond angle in H2O is 104.5 degrees (from the textbook). On test 2, should we state that the bond angle for all angular molecules is 104.5 degrees or should we just say less than 120 degrees?
by DesireBrown1J
Sat Nov 16, 2019 3:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: test 2
Replies: 13
Views: 116

Re: test 2

Kaitlyn Jang 1F wrote:Only if hybridization is also on the one page of notes he has left to teach us on Monday


I thought I heard Lavelle state in lecture that there will not be any hybridization on Test 2. Did anyone else hear the same or did I hear it wrong?
by DesireBrown1J
Fri Nov 15, 2019 2:48 pm
Forum: Bond Lengths & Energies
Topic: Bond lengths and lone pairs
Replies: 3
Views: 55

Bond lengths and lone pairs

If a central atom has more lone pairs, would that affect its bond lengths with the surrounding atoms?
by DesireBrown1J
Wed Nov 13, 2019 6:38 pm
Forum: Bond Lengths & Energies
Topic: Interaction Potential Energy equation
Replies: 7
Views: 78

Re: Interaction Potential Energy equation

What is an example of a question where we would use the interaction potential energy equation? Are you talking about this one introduced in the beginning of 3F.1? I was not sure about that one because there are no homework problems related to that question and it is not on the constants and equatio...
by DesireBrown1J
Wed Nov 13, 2019 6:00 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone pairs of other atoms in molecule
Replies: 3
Views: 44

Lone pairs of other atoms in molecule

Do the lone pairs of the noncentral/surrounding atoms affect the shape and angles of the overall molecule? If so, how do they change the shape?
by DesireBrown1J
Tue Nov 05, 2019 6:24 pm
Forum: Limiting Reactant Calculations
Topic: Test 1 Question
Replies: 5
Views: 219

Re: Test 1 Question

There is also another way you could solve the problem. In order to determine how many grams of glucose is left over, you would first need to determine how many grams of water the 10.0g of glucose produces. You would convert the grams of glucose that was initially present into moles. Then, you would...
by DesireBrown1J
Tue Nov 05, 2019 6:13 pm
Forum: Limiting Reactant Calculations
Topic: Test 1 Question
Replies: 5
Views: 219

Re: Test 1 Question

So for the moles of O2 initially present, did everyone get about 0.28 moles of O2?
by DesireBrown1J
Sun Nov 03, 2019 10:23 pm
Forum: Student Social/Study Group
Topic: Study Tips
Replies: 58
Views: 1866

Re: Study Tips

Does anyone have some creative tips for memorizing certain things that are not on the constants and equation sheets?
by DesireBrown1J
Sun Nov 03, 2019 10:20 pm
Forum: Electronegativity
Topic: 2D.7
Replies: 2
Views: 50

2D.7

The homework question reads "Compounds having bonds with a high covalent character tend to be less soluble in water than similar compounds that have low covalent character. Use electronegativities to predict which of the following compounds is the more soluble in water". I know that we wou...
by DesireBrown1J
Sun Nov 03, 2019 9:38 pm
Forum: Dipole Moments
Topic: Dipole moment calculation
Replies: 2
Views: 45

Dipole moment calculation

So when you calculate the dipole moment (charge * bond length), would the arrow representing the dipole always be pointed towards the δ- or are they any exceptions to that?
by DesireBrown1J
Sun Nov 03, 2019 9:26 pm
Forum: Photoelectric Effect
Topic: Work function + Threshold energy
Replies: 2
Views: 55

Work function + Threshold energy

So, work function is essentially the same as threshold energy?
by DesireBrown1J
Wed Oct 30, 2019 10:55 am
Forum: Lewis Structures
Topic: Valence electrons
Replies: 5
Views: 65

Re: Valence electrons

Phosphorus actually has 5 valence electrons because its electron configuration is [Ne]3s23p3. 3s23p3 are the outermost orbitals and have the highest energy levels, which make the electrons in here the valence electrons.
by DesireBrown1J
Sun Oct 27, 2019 10:32 pm
Forum: Trends in The Periodic Table
Topic: Electronegativity vs. effective nuclear charge
Replies: 5
Views: 41

Re: Electronegativity vs. effective nuclear charge

As effective nuclear charge increases, atomic radius decreases and ionization energy increases.
by DesireBrown1J
Sun Oct 27, 2019 9:14 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configurations for Exceptions
Replies: 2
Views: 41

Electron Configurations for Exceptions

Is the ground state electron configuration for Cu=[Ar]3d104s1 and Cr=[Ar]3d54s1?
by DesireBrown1J
Sun Oct 27, 2019 9:10 pm
Forum: Electronegativity
Topic: Electronegativity
Replies: 6
Views: 66

Re: Electronegativity

Flourine has the highest electronegativity because noble gases have no electronegativity. They already have a full outer shell, so they will not gain nor lose an electron.
by DesireBrown1J
Tue Oct 22, 2019 7:36 pm
Forum: Properties of Electrons
Topic: d-orbital in the electron configuration
Replies: 3
Views: 56

d-orbital in the electron configuration

When writing the electron configuration, why is it 3d instead of 4d? I was assuming that it would be 4d because it is in the 4th period.

Example: Ge=[Ar]3d104s24p3 instead of Ge=[Ar]4d104s24p3
by DesireBrown1J
Tue Oct 22, 2019 12:50 pm
Forum: Trends in The Periodic Table
Topic: 1F.1 Atomic Radius Differences
Replies: 3
Views: 33

1F.1 Atomic Radius Differences

For problem 1F.1 states "Arrange the elements in each of the following sets in order of decreasing atomic radius: (a) sulfur, chlorine, silicon; (b) cobalt, titanium, chromium; (c) zinc, mercury, cadmium; (d) antimony, bismuth, phosphorus". I used appendix 2D to find the atomic radii and a...
by DesireBrown1J
Sun Oct 20, 2019 10:48 pm
Forum: Properties of Electrons
Topic: Subshell Exceptions
Replies: 6
Views: 106

Re: Subshell Exceptions

In one of the UA sessions that I went to today, the UA told us to write Cr as [Ar]3d54s1 instead of [Ar]4s13d5. I do not know why he said that but can someone better explain this to me?
by DesireBrown1J
Sun Oct 20, 2019 3:37 pm
Forum: Photoelectric Effect
Topic: Work Function
Replies: 9
Views: 137

Re: Work Function

What are some practice problems from the book that require us to use the work function equation hv-Φ=1/2mv2?
by DesireBrown1J
Sat Oct 19, 2019 8:39 pm
Forum: Administrative Questions and Class Announcements
Topic: Accessing the E-textbook [ENDORSED]
Replies: 21
Views: 4458

Accessing the E-textbook [ENDORSED]

I know that a few students bought the e-textbook instead of the regular textbook. I'm interested in buying that one instead but I don't know which bundle on the Macmillan Learning student store includes the e-textbook. Do all of them include the e-textbook or only specific bundles? Loose-Leaf Versio...
by DesireBrown1J
Thu Oct 17, 2019 10:31 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Homework Problem 1B.27
Replies: 6
Views: 88

Re: Homework Problem 1B.27

AlyssaYeh_1C wrote:When doing your calculation, the Δv you should use is 10m/s, which is your maximum uncertainty.


Why do we have to use the maximum uncertainty velocity in the Heisenberg Indeterminacy equation?
by DesireBrown1J
Wed Oct 16, 2019 5:23 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Test 1 [ENDORSED]
Replies: 107
Views: 4753

Re: Test 1 [ENDORSED]

Would we be able to go to office hours and review our test with a TA for any problems we got incorrect?
by DesireBrown1J
Sun Oct 13, 2019 11:39 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Test 1 [ENDORSED]
Replies: 107
Views: 4753

Re: Test 1 [ENDORSED]

If someone was able to complete the Angstrom question, can you please explain to me (step by step) how to solve the problem?
by DesireBrown1J
Sun Oct 13, 2019 10:01 pm
Forum: DeBroglie Equation
Topic: HW Question 1B.23
Replies: 2
Views: 57

HW Question 1B.23

The question states "What is the velocity of a neutron of wavelength 100. pm?". I know that DeBroglie's equation has to be changed to find v and we have the wavelength and Planck's constant. However, how do we find the mass for 1 neutron? Are we supposed to know that from high school chem?
by DesireBrown1J
Sun Oct 13, 2019 9:31 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Indeterminancy In Class
Replies: 7
Views: 63

Indeterminancy In Class

Did we go over the Indeterminacy equation in class on Friday? I see that I wrote it down as a fundamental equation for Quantum mechanics but I only remember discussing and taking notes on De Broglie's wave equation.
by DesireBrown1J
Sun Oct 13, 2019 8:38 pm
Forum: SI Units, Unit Conversions
Topic: Percent Yield
Replies: 6
Views: 213

Re: Percent Yield

Maya Serota 3G wrote:The actual value will be given to you in the question. From there the equation for percent yield is (theoretical/actual) x 100.



Sorry, but the percent yield would be the actual amount over the theoretical amount. So, (actual yield/theoretical yield)x100%.
by DesireBrown1J
Thu Oct 10, 2019 1:00 am
Forum: Properties of Light
Topic: Hw Question 1A.9
Replies: 5
Views: 72

Re: Hw Question 1A.9

For this homework problem, the given wavelength is in nm. Should we covert all the wavelengths we need to find to nm? We are also given two different frequencies, one in Hz and one in MHz. Should the answers for the other two frequencies be in Hz or MHz?
by DesireBrown1J
Sat Oct 05, 2019 12:05 pm
Forum: Administrative Questions and Class Announcements
Topic: Week 2 Homework Problems [ENDORSED]
Replies: 67
Views: 3187

Week 2 Homework Problems [ENDORSED]

For the week 2 homework, should we only be doing the problems from the Quantum World section? I just wanted to make sure before getting started on it. 
by DesireBrown1J
Thu Oct 03, 2019 10:51 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Aqueous, solid, gas
Replies: 11
Views: 186

Re: Aqueous, solid, gas

The periodic table is color coded and it will indicate whether an element is a liquid, solid, or gas. I am not sure how to figure out if it is aqueous.
by DesireBrown1J
Thu Oct 03, 2019 8:56 pm
Forum: Balancing Chemical Reactions
Topic: adding a product
Replies: 6
Views: 75

Re: adding a product

You can only change the number of moles in the equation to balance it.
by DesireBrown1J
Thu Oct 03, 2019 8:32 pm
Forum: Balancing Chemical Reactions
Topic: Homework
Replies: 4
Views: 81

Re: Homework

He wants us to have our name, UID, and our section on the top corner of the paper. I put it on each paper just in case they come apart from the staple.
by DesireBrown1J
Wed Oct 02, 2019 11:01 pm
Forum: Balancing Chemical Reactions
Topic: Balancing Chemical Equations Formatting
Replies: 6
Views: 165

Balancing Chemical Equations Formatting

In some homework problems, reactant/products are sometimes formatted like Mg(N3)2(s). How should I be interpreting problems like this in order to balance them correctly? Should I see it as equal to MgN6(s) or Mg2N6(s) or some other way?

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