Search found 117 matches

by Tiffany Chao 2H
Thu Mar 12, 2020 8:44 pm
Forum: Administrative Questions and Class Announcements
Topic: Saying Thank You to Dr. Lavelle
Replies: 280
Views: 134497

Re: Saying Thank You to Dr. Lavelle

Thank you Dr. Lavelle! I can't say that this class was easy or didn't make me stay up until ungodly hours of the night studying, but it's been a satisfying and enriching experience. I learned more than I ever thought I could within 2 quarters. Your jokes, music outros, smiley faces, and thoughtful p...
by Tiffany Chao 2H
Thu Mar 12, 2020 8:41 pm
Forum: Administrative Questions and Class Announcements
Topic: ENDGAME Review Session
Replies: 71
Views: 2737

Re: ENDGAME Review Session

Thank you so much for all your hard work Lyndon! You have helped us tremendously and I can't thank you enough. Best of luck to you!
by Tiffany Chao 2H
Tue Mar 10, 2020 5:28 pm
Forum: Administrative Questions and Class Announcements
Topic: Situation for Lecture, Discussion, and Final
Replies: 3
Views: 127

Situation for Lecture, Discussion, and Final

What is going to be done in regards to lecture, discussion, and our final?
by Tiffany Chao 2H
Tue Mar 10, 2020 3:51 am
Forum: First Order Reactions
Topic: kt vs. -kt?
Replies: 1
Views: 29

Re: kt vs. -kt?

Never mind... I figured out that it's because they switch between ln([A0]/[A]) or ln([A]/[A0]).
by Tiffany Chao 2H
Tue Mar 10, 2020 3:16 am
Forum: First Order Reactions
Topic: kt vs. -kt?
Replies: 1
Views: 29

kt vs. -kt?

I'm doing 7B and I've noticed that for first order integrated law, the solutions manual will use the equation ln([A]/[A0]) = kt and other times, ln([A]/[A0]) = -kt. I've been consistently using ln([A]/[A0]) = -kt and will sometimes get a negative value (depending on if I'm calculating k or t). When ...
by Tiffany Chao 2H
Thu Mar 05, 2020 11:00 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Standard Delta G vs Non-Standard Delta G
Replies: 4
Views: 54

Re: Standard Delta G vs Non-Standard Delta G

If you are provided delta G, R, T, and Q, then you can find standard delta G. However, if you are given K, it means that the reaction has reached equilibrium and delta G = 0, therefore you would get the equation standard delta G = -RTlnK.
by Tiffany Chao 2H
Thu Mar 05, 2020 10:57 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Inert electrodes
Replies: 5
Views: 71

Re: Inert electrodes

Typically, ions are usually aqueous. We can't have an electrode that is aqueous, it needs to be a solid. This is when we would use an inert electrode such as platinum or graphite.
by Tiffany Chao 2H
Thu Mar 05, 2020 10:55 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2 Grades
Replies: 22
Views: 279

Re: Test 2 Grades

Next week in your discussion section.
by Tiffany Chao 2H
Thu Mar 05, 2020 10:54 pm
Forum: Administrative Questions and Class Announcements
Topic: Excellence in Chemistry Award!
Replies: 22
Views: 6686

Re: Excellence in Chemistry Award!

Congratulations Rachana!
by Tiffany Chao 2H
Tue Mar 03, 2020 7:17 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Including Inert Electrodes
Replies: 2
Views: 33

Re: Including Inert Electrodes

When you have ions (which are aqueous). We can't have an electrode that aqueous so we can use an inert metal solid such as platinum or graphite. For example, if you have Fe 2+ and Fe, you can have Fe (s) to be the electrode. But if you have Fe 2+ and Fe 3+, you need platinum. There's no difference b...
by Tiffany Chao 2H
Tue Mar 03, 2020 4:48 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Ion-Selective Electrodes
Replies: 1
Views: 27

Ion-Selective Electrodes

Can someone explain to me what ion-selective electrodes are and how they work?

Thanks
by Tiffany Chao 2H
Sun Mar 01, 2020 8:19 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: How to determine anode and cathode in 6.57?
Replies: 6
Views: 57

Re: How to determine anode and cathode in 6.57?

this is the half-reaction for the cathode. We know this because there are electrons being added to the reactants, reducing the Fluorine. Sorry I meant F2 (g) + 2 e- --> 2F- is the cathode and F2(g) + 2 H+ (aq) + 2 e- --> 2HF (aq) is the anode according to the solutions manual. It says the E*cell = ...
by Tiffany Chao 2H
Sun Mar 01, 2020 7:26 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: How to determine anode and cathode in 6.57?
Replies: 6
Views: 57

How to determine anode and cathode in 6.57?

6.57: 6.57 Use the data in Appendix 2B and the fact that, for the half- reaction F2(g) + 2 H+ (aq) + 2 e- --> 2HF (aq), E* = + 3.03 V, to calculate the value of Ka for HF.

Based on F2 (g) + 2 e- --> 2F-, E*= +2.87V, how am I suppose to know which one is the cathode and anode?

Thanks
by Tiffany Chao 2H
Sun Mar 01, 2020 4:47 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: When to use units of mole?
Replies: 2
Views: 31

When to use units of mole?

Whenever the problem asks for a calculation that requires the Nernst's equation, the solution manual never shows n (the number of moles) to be in the units of moles. For example, if the redox reaction used 2 moles, it would be 0.0257 V/2 instead of 0.0257 V/2 moles. Is there a reason why for this? W...
by Tiffany Chao 2H
Thu Feb 27, 2020 5:31 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Possible Solution Error on 6N.1 part b
Replies: 5
Views: 84

Possible Solution Error on 6N.1 part b

6N.1.b) Calculate the equilibrium constants for the following reactions: In^3+ (aq) + U^3+ (aq) <--> In^2+ (aq) + U^4+ (aq). My answer differs from the solutions manual. I got 107 instead of the textbook that got 1000 for K. However, I don't understand how they got 2 electrons for the Indium half re...
by Tiffany Chao 2H
Thu Feb 27, 2020 5:28 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Homework 6M.5
Replies: 2
Views: 44

Re: Homework 6M.5

I was talking to my TA in section today and he said that there are a lot of errors in the solutions manual in this section along with 6L. He said that if some things just don't make sense at all, be wary of it.
by Tiffany Chao 2H
Tue Feb 25, 2020 9:10 pm
Forum: Balancing Redox Reactions
Topic: Help on 6L.7 part a
Replies: 2
Views: 60

Help on 6L.7 part a

6L.7.a) Write the half-reactions and devise a galvanic cell (write a cell diagram) to study each of the following reactions: AgBr(s) <--> Ag+ (aq) + Br- (aq). The solutions manual says the half reactions are Ag+(aq) + e- --> Ag(s) and AgBr(s) + e- --> Ag(s) + Br-(aq) but I'm not sure how they were a...
by Tiffany Chao 2H
Tue Feb 25, 2020 12:40 am
Forum: Balancing Redox Reactions
Topic: Help on 6K.3 part d [ENDORSED]
Replies: 3
Views: 78

Help on 6K.3 part d [ENDORSED]

6K.3.d) Balance each of the following skeletal equations by using oxidation and reduction half-reactions. All the reactions take place in acidic solution. Identify the oxidizing agent and reducing agent in each reaction. Reaction of chlorine in water: Cl2(g) --> HClO(aq) + Cl2(g) How should I procee...
by Tiffany Chao 2H
Tue Feb 25, 2020 12:08 am
Forum: Balancing Redox Reactions
Topic: Reducing Agent versus Reduced Species
Replies: 2
Views: 36

Reducing Agent versus Reduced Species

Is there a difference between the two? In addition, the oxidizing agent versus oxidized species.

Thanks,

Tiffany Chao
by Tiffany Chao 2H
Sun Feb 23, 2020 10:05 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Test 2
Replies: 13
Views: 111

Re: Test 2

The end of thermodynamics (like more in-depth on Gibbs Free Energy) and electrochemistry.
by Tiffany Chao 2H
Sun Feb 23, 2020 10:04 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: n
Replies: 13
Views: 169

Re: n

You're likely referring to R. In that case, you would use the constant that cancels out your units.
by Tiffany Chao 2H
Tue Feb 18, 2020 7:45 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: reaction at equilibrium
Replies: 6
Views: 63

Re: reaction at equilibrium

We calculate delta G by doing G of products - G of reactants. If at equilibrium, the G between products and reactants doesn't change. Therefore, delta G = 0
by Tiffany Chao 2H
Tue Feb 18, 2020 6:34 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Answer is different for 5G.15
Replies: 5
Views: 56

Answer is different for 5G.15

I keep getting -2.7 kJ/mol as my answer. However, the book says -27 kJ/mol. Is anyone else getting the same answer as me or did I just calculate something wrong.

Thanks
by Tiffany Chao 2H
Wed Feb 12, 2020 12:11 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: different equation in video?
Replies: 1
Views: 41

Re: different equation in video?

I think you may be referring to the physics version of the equation. It's technically the same equation, but depends on the perspective of the system for work. I don't think you should worry about that; just focus on the one we have which is delta U = q+w !

Hope this helped
by Tiffany Chao 2H
Tue Feb 11, 2020 4:17 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Why are exothermic reactions generally spontaneous?
Replies: 16
Views: 223

Why are exothermic reactions generally spontaneous?

I get that exothermic means a -delta H but idk how to interpret the delta S part.

Thanks
by Tiffany Chao 2H
Mon Feb 10, 2020 2:39 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Temperature Changes Along Irreversible Pathway
Replies: 3
Views: 99

Temperature Changes Along Irreversible Pathway

Why does temperature change along an irreversible pathway? Why does it decrease then increase?

Thanks
by Tiffany Chao 2H
Mon Feb 10, 2020 2:30 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Why is delta U = 0 for isothermal reactions?
Replies: 11
Views: 217

Why is delta U = 0 for isothermal reactions?

In my notes, it says that it's because delta U = 3/2(nR*delta T) and if delta T = 0, then delta U will be 0. I can understand that logic but where did that delta U = 3/2(nR*delta T) equation come from? And why is it 0?

Thanks
by Tiffany Chao 2H
Mon Feb 10, 2020 12:41 am
Forum: Phase Changes & Related Calculations
Topic: equation for phase changes
Replies: 3
Views: 31

Re: equation for phase changes

The mass should typically be in moles too but just double check it. For example, the enthalpy of fusion for water is known as 6.01 kJ/mol (I believe) so you would need to multiply it by moles.
by Tiffany Chao 2H
Mon Feb 10, 2020 12:39 am
Forum: Calculating Work of Expansion
Topic: Derivation of Formula
Replies: 3
Views: 48

Re: Derivation of Formula

I don't think we'll be expected to know how to derive it.
by Tiffany Chao 2H
Mon Feb 10, 2020 12:38 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Cv
Replies: 3
Views: 41

Re: Cv

Constant pressure may also be called isobaric and constant volume may be called isochoric.
by Tiffany Chao 2H
Sat Feb 08, 2020 5:56 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Calculating Average Kinetic Energy
Replies: 1
Views: 38

Calculating Average Kinetic Energy

For 4.19, we're supposed to use average kinetic energy = 3/2*RT. I did 3/2(8.314 J/mol.K)(328.85K) and got 4101.09 J/moles. However, the answer key says 4103.2 J/mol. I'm off by a pretty significant amount and I'm not sure what I'm doing wrong since it seems to be a pretty straightforward calculatio...
by Tiffany Chao 2H
Sat Feb 08, 2020 4:51 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Help on 4.15
Replies: 1
Views: 44

Help on 4.15

Can someone help explain how to do 4.15 to me? I don't understand why we have to find the limiting reagent and the tabulated enthalpies of formation.

Thanks!
by Tiffany Chao 2H
Sun Feb 02, 2020 5:26 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calculating q
Replies: 5
Views: 71

Calculating q

I'm doing some heat problems from 4A. I've noticed that to calculate q, sometimes you do q = mass x specific heat capacity x delta T. Other times, it's just q = specific heat capacity x delta T. When do you know to multiply mass or not?

Thanks
by Tiffany Chao 2H
Sun Feb 02, 2020 4:28 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: w = -P*delta V
Replies: 4
Views: 28

w = -P*delta V

This might be a dumb question, but is a negative sign in front of the P*delta V always there? And then if the volume is decreasing (so -deltaV), then work is positive?

Thanks
by Tiffany Chao 2H
Sun Feb 02, 2020 4:26 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Positive or negative work?
Replies: 8
Views: 78

Positive or negative work?

How do I know when to put a negative or positive sign when calculating work on a system? For example, pushing a piston into a system?
by Tiffany Chao 2H
Sun Feb 02, 2020 3:38 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: delta U = delta H - P delta V
Replies: 3
Views: 32

delta U = delta H - P delta V

Am I supposed to use this equation to find internal energy of a system that's at constant pressure?

Thanks
by Tiffany Chao 2H
Sun Feb 02, 2020 3:34 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Difference between delta H and q
Replies: 2
Views: 35

Difference between delta H and q

If delta H = qp under constant pressure, what's the difference between them? Like when should I use delta H and qp if the system is under constant pressure or does it not matter?

Thanks
by Tiffany Chao 2H
Sat Feb 01, 2020 6:29 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Pressure in an open beaker
Replies: 12
Views: 102

Re: Pressure in an open beaker

Pressure should be the pressure of the atmosphere
by Tiffany Chao 2H
Tue Jan 21, 2020 11:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Conjugate seesaw
Replies: 3
Views: 46

Re: Conjugate seesaw

Yes. Strong base = weak conj. acid. Weak base = strong conj. acid. And the same for strong/weak acids.
by Tiffany Chao 2H
Tue Jan 21, 2020 11:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6D13 part d
Replies: 2
Views: 33

Re: 6D13 part d

The reaction is a base + water. Therefore, it's important that you use Kb to figure out this question. From then, you can find pOH and then pH.

Hope this helped!
by Tiffany Chao 2H
Tue Jan 21, 2020 11:21 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Prep for Test 1
Replies: 16
Views: 163

Re: Prep for Test 1

Nope just be careful that you use Ka for acids and Kb for bases.
by Tiffany Chao 2H
Tue Jan 21, 2020 11:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: If [H3O+] < 10^-7
Replies: 2
Views: 40

If [H3O+] < 10^-7

In our notes it says if [H3O+] < 10^-7, then the solution is considered neutral. But if it's less than 10^-7, wouldn't it be considered basic? I don't understand what Dr. Lavelle meant by "neutral".

Thanks
by Tiffany Chao 2H
Tue Jan 21, 2020 11:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Why does changing the stoichiometric coefficients by a factor also change the value of K?
Replies: 3
Views: 58

Why does changing the stoichiometric coefficients by a factor also change the value of K?

Doesn't change in concentration not affect K as long as temperature is constant? And if every concentration in the reaction is changed by the same amount, it shouldn't make a difference? I understand it from a mathematical perspective but I don't understand it conceptually.

Thanks
by Tiffany Chao 2H
Sat Jan 18, 2020 3:45 pm
Forum: Administrative Questions and Class Announcements
Topic: Getting Back 14A Final Exam
Replies: 3
Views: 53

Re: Getting Back 14A Final Exam

I heard it'll be available during Week 3 as well!
by Tiffany Chao 2H
Thu Jan 16, 2020 4:51 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Help on 5.35
Replies: 5
Views: 46

Re: Help on 5.35

Rohit Ghosh 4F wrote:You can then use the partial pressures given by the graph along with the reaction A (g) --> B (g) + C (g) to calculate the equilibrium constant.

The answer key says the chemical equation is 2A (g) --> B (g) + 2C (g)
by Tiffany Chao 2H
Thu Jan 16, 2020 4:50 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Help on 5.35
Replies: 5
Views: 46

Re: Help on 5.35

Selena Yu 1H wrote:It says in the problem that compound A decomposes into compounds B and C. So the chemical equation would be A (g) --> B (g) + C (g)

The answer key says the chemical equation is 2A (g) --> B (g) + 2C (g)
by Tiffany Chao 2H
Thu Jan 16, 2020 4:49 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6B.9
Replies: 3
Views: 109

6B.9

For 6B.9 i and ii, I keep getting different answers from the answer key. For i), I do the negative log of 1.50 and get the pH to be -0.176, [OH-] to be 6.67x10^-15, and pOH to be 14.17. This doesn't match the textbook that says pH = 0.176, [OH-] = 1.50x10^-14, and pOH = 13.824. I just don't know wha...
by Tiffany Chao 2H
Wed Jan 15, 2020 11:32 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Help on 5.35
Replies: 5
Views: 46

Help on 5.35

I'm not understanding how to find the chemical equation on 5.35. Can someone help me explain?

Thanks
by Tiffany Chao 2H
Wed Jan 15, 2020 9:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Help on 5I.17
Replies: 1
Views: 24

Help on 5I.17

After I do the ICE table and try to calculate the equilibrium constant, I'm having trouble. For Kc, I have written Kc = (2x)^2/(0.114-x)^2 = 1.00 x 10^-5. I originally did this by multiplying it out and then doing quadratic equation. I got an answer, x = 7.52 x 10^-4 but the answer key did a differe...
by Tiffany Chao 2H
Wed Jan 15, 2020 9:25 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: When to use Kc or Kp
Replies: 2
Views: 20

Re: When to use Kc or Kp

Kc can also be used for gas problems. It just depends on the units the equilibrium concentrations are in. If its in atm or bars, you would use Kp because it's based on partial pressure. But sometimes gas concentrations can be in molarity too, which would be given in mol/L where you can use Kc to cal...
by Tiffany Chao 2H
Sun Jan 12, 2020 5:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Units for K
Replies: 21
Views: 206

Re: Units for K

No because K is a constant. We use brackets around equilibrium concentration. The brackets indicate molar concentration so we omit actual units.
by Tiffany Chao 2H
Sun Jan 12, 2020 5:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Difference between Kc/Kp and Q
Replies: 2
Views: 32

Re: Difference between Kc/Kp and Q

Kc is typically used for molar concentrations for aqueous and gasses. Kp is used for gas equilibrium when we use partial pressure (which will typically be indicated by equilibrium concentration in bars or atm). Q stands for the reaction quotient. On its own, it doesn't mean much. To use it, we compa...
by Tiffany Chao 2H
Sun Jan 12, 2020 4:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Help on 5H.3
Replies: 1
Views: 27

Help on 5H.3

Can someone help me explain how 5H.3 works?

Thanks
by Tiffany Chao 2H
Sun Jan 12, 2020 4:28 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 1 date
Replies: 4
Views: 49

Re: Test 1 date

Starts on Tuesday, 1/21, and will be in your discussion.
by Tiffany Chao 2H
Sun Jan 12, 2020 3:55 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Units for Kc and Kp
Replies: 3
Views: 38

Units for Kc and Kp

I understand that when we calculate Kc, we omit the units and put brackets instead to indicate molar concentration. However, is it the same rule for when we calculate Kp? Do parentheses indicate gas concentration so therefore we don't need to put units like bars or atms?

Thanks
by Tiffany Chao 2H
Sat Dec 07, 2019 11:45 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Explanation on a Part of the Notes
Replies: 2
Views: 56

Explanation on a Part of the Notes

Can someone explain to me a section of the notes? It was when he asked "Q2: A biological acid, HA, has pKa = 4.22. What's the Ka value of the acid?" I don't understand the part after that says "Is the acid neutral or negatively charged at pH 6?" and the little section under it. T...
by Tiffany Chao 2H
Sat Dec 07, 2019 10:59 pm
Forum: Bronsted Acids & Bases
Topic: List of Strong/Weak Acids/Bases
Replies: 2
Views: 105

List of Strong/Weak Acids/Bases

I tried looking for a list on Dr. Lavelle's website but I can't find it. Can someone tell me what are the strong and weak acids and bases that we need to know for the class. Thanks!
by Tiffany Chao 2H
Sat Dec 07, 2019 6:35 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: EDTA 6 Bonding Sites
Replies: 1
Views: 39

EDTA 6 Bonding Sites

I don't completely understand why EDTA 4- has 6 bonding sites. I understand that there is 2 from the 2 nitrogen atoms which each has a lone pair. However, there are 4 double bonded oxygen atoms with 2 lone pairs each and 2 single bonded oxygens with 3 lone pairs each. Why is it that the single bonde...
by Tiffany Chao 2H
Thu Dec 05, 2019 12:34 am
Forum: Biological Examples
Topic: Biological Significance
Replies: 2
Views: 70

Re: Biological Significance

Our notes mention cisplantin for chemotherapy, myoglobin/hemoglobin for oxygen transportion in blood cells, chromium to assist insulin, iron for myoglobin/hemoglobin, cobalt for vitamin B12, and Mn, Ni, Cu, Zn for enzyme function.
by Tiffany Chao 2H
Thu Dec 05, 2019 12:29 am
Forum: Bronsted Acids & Bases
Topic: Strong Bases
Replies: 3
Views: 49

Re: Strong Bases

Oxides and hydroxides with group 1 and 2 elements. Also, metal oxides react with water to form strong bases.
by Tiffany Chao 2H
Thu Dec 05, 2019 12:28 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Equilibrium sign?
Replies: 1
Views: 42

Re: Equilibrium sign?

You would typically use it for weak acids and bases because the ions wouldn't completely dissociate and thus, an equilibrium is formed. A strong acid or base in water would completely dissociate, which is when you would use an arrow.
by Tiffany Chao 2H
Thu Dec 05, 2019 12:26 am
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Ice tables
Replies: 3
Views: 44

Re: Ice tables

No. That will be 14B.
by Tiffany Chao 2H
Thu Dec 05, 2019 12:24 am
Forum: DeBroglie Equation
Topic: Quantum Help
Replies: 5
Views: 173

Re: Quantum Help

I typically start off by writing all of the variables the problem gives me. For example, if it gives me wavelength = 900 nm. Then, I write the variable the problem is asking for, so like energy = ? for example. Lastly, I write out all the equations that contains the variables (like wavelength and en...
by Tiffany Chao 2H
Sun Dec 01, 2019 8:33 pm
Forum: Bronsted Acids & Bases
Topic: For J. 9., when do we separate H+ from the acid?
Replies: 2
Views: 63

For J. 9., when do we separate H+ from the acid?

J. 9. says: Identify the salt that is produced from the acid–base neutralization reaction between (a) potassium hydroxide and acetic acid, CH 3 COOH; (b) ammonia and phosphoric acid; (c) calcium hydroxide and bromous acid; (d) sodium hydroxide and hydrosulfuric acid, H2S (both H atoms react). Write ...
by Tiffany Chao 2H
Sun Dec 01, 2019 8:31 pm
Forum: Bronsted Acids & Bases
Topic: Explanation for J. 17.
Replies: 1
Views: 50

Explanation for J. 17.

Can someone help me explain how to do 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.

Thanks!
by Tiffany Chao 2H
Fri Nov 29, 2019 5:06 pm
Forum: Naming
Topic: New Naming Rules or Old Ones?
Replies: 1
Views: 30

New Naming Rules or Old Ones?

Did Dr. Lavelle ask us to use the new naming rules or it doesn't matter? For example, cyano (old) vs cyanido (new). Thanks
by Tiffany Chao 2H
Fri Nov 29, 2019 3:45 pm
Forum: Bronsted Acids & Bases
Topic: Difference between Bronsted and Lewis
Replies: 2
Views: 32

Difference between Bronsted and Lewis

What's the difference between a Bronsted acid/base and a Lewis acid/base? It seems that they're opposite of each other but that's making me confused. Thanks
by Tiffany Chao 2H
Fri Nov 29, 2019 3:40 pm
Forum: Calculating the pH of Salt Solutions
Topic: pH vs. pOH
Replies: 17
Views: 318

Re: pH vs. pOH

To add onto Mingdah, pH and pOH have an inverse relationship.
by Tiffany Chao 2H
Fri Nov 29, 2019 3:39 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: pH scale
Replies: 4
Views: 51

Re: pH scale

It could but I think all that we should know will stay in between 1 and 14.
by Tiffany Chao 2H
Tue Nov 26, 2019 7:21 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Summary for Naming Coordination Compounds
Replies: 3
Views: 49

Summary for Naming Coordination Compounds

I am extremely confused while reading the notes for naming coordination compounds. Is anyone able to give me a brief summary to help me better understand the rules?

Thanks
by Tiffany Chao 2H
Fri Nov 22, 2019 1:54 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape and Polarity
Replies: 5
Views: 80

Re: Molecular Shape and Polarity

If you're talking about a molecule like CHCl3, it's polar. However, the polarity of it doesn't affect the fact that its tetrahedral and all bond angles are 109.5 degrees. The only time bond angles/shape is affected would be due to lone pairs.
by Tiffany Chao 2H
Fri Nov 22, 2019 1:53 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: QUiz 2
Replies: 2
Views: 59

Re: QUiz 2

I think the most significant thing we need to know about ion-ion forces is that its the strongest IMF. But I believe the test will mainly focus around dipole-dipole, LDF, and H-bonds.
by Tiffany Chao 2H
Fri Nov 22, 2019 1:51 am
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 Atoms
Replies: 6
Views: 79

Re: Hydrogen Bonding Atoms

I believe hydrogen can form H-bonds with any N, O, F that have lone pairs regardless of whether it's already attached to a hydrogen or not.
by Tiffany Chao 2H
Fri Nov 22, 2019 1:49 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: london forces
Replies: 9
Views: 92

Re: london forces

The one with the bigger molar mass (and more electrons). It allows for more interactions which increases the London Dispersion Force.
by Tiffany Chao 2H
Fri Nov 22, 2019 1:47 am
Forum: Sigma & Pi Bonds
Topic: significance
Replies: 2
Views: 47

Re: significance

Sigma bonds allow for the molecule to rotate while pi bonds don't allow it to rotate because they are side by side. Like Lavelle showed in class, if you put 3 EXPO markers in between your two pointer fingers and twist, two markers would fall (pi) while one marker remains in place (sigma).
by Tiffany Chao 2H
Sat Nov 16, 2019 6:20 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Long pairs
Replies: 3
Views: 36

Re: Long pairs

Lone pairs create a strong electron-electron repulsion which pushes all other atoms closer to together. For example, if you had a trigonal pyramidal with a lone pair at the top, it would push the atoms that are part of the structure closer together, creating a smaller bond angle between the atoms.
by Tiffany Chao 2H
Sat Nov 16, 2019 6:17 pm
Forum: Bond Lengths & Energies
Topic: Quiz for Next week dashes/wedges
Replies: 11
Views: 136

Re: Quiz for Next week dashes/wedges

Even if there is, it's easy to remember that wedges mean the bond is towards you and dashes are pointing away from you.
by Tiffany Chao 2H
Sat Nov 16, 2019 6:15 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge vs Octet Rule
Replies: 5
Views: 159

Re: Formal Charge vs Octet Rule

Just treat drawing Lewis structures for molecules as drawing a normal Lewis structure. Afterwards, go onto VSEPR.
by Tiffany Chao 2H
Sat Nov 16, 2019 6:13 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: 3F.5 c)
Replies: 3
Views: 36

Re: 3F.5 c)

You are correct in that they both have London forces. However, CHI3 has stronger London forces because it has more electrons than CHF3, therefore stronger London forces.
by Tiffany Chao 2H
Sat Nov 16, 2019 6:11 pm
Forum: Octet Exceptions
Topic: Octet expansion
Replies: 6
Views: 171

Re: Octet expansion

I think the most important thing we need to know is that the atoms C, N, O, F must fulfill the octet rule. Any other atoms can either have an expanded octet (or don't fulfill the octet rule at all).
by Tiffany Chao 2H
Mon Nov 04, 2019 11:17 pm
Forum: Bond Lengths & Energies
Topic: Midterm
Replies: 8
Views: 126

Re: Midterm

8 but it's likely that there'll be different parts to each questions such as a. b. c. etc.
by Tiffany Chao 2H
Mon Nov 04, 2019 11:12 pm
Forum: Photoelectric Effect
Topic: Details about the photoelectric experiment
Replies: 3
Views: 85

Re: Details about the photoelectric experiment

I highly doubt it. Just know about the concepts that came to light (haha) about the photoelectric experiment (ex. particle-like properties.)
by Tiffany Chao 2H
Mon Nov 04, 2019 11:10 pm
Forum: SI Units, Unit Conversions
Topic: Unit Conversion
Replies: 2
Views: 147

Re: Unit Conversion

You can put it in any unit you want unless the question specifies what unit it wants your answer to be in.
by Tiffany Chao 2H
Mon Nov 04, 2019 11:09 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability Periodic Trend
Replies: 5
Views: 70

Re: Polarizability Periodic Trend

The smaller radius and highly charged cations have the strongest polarizability.
For anions, larger atomic radius and less electronegativity are more highly polarizable.
by Tiffany Chao 2H
Mon Nov 04, 2019 11:06 pm
Forum: Administrative Questions and Class Announcements
Topic: Class Wed 11/6
Replies: 3
Views: 52

Re: Class Wed 11/6

I'm in the 12:00 pm lecture. Dr. Lavelle said that we won't be having any class this Wednesday. He just forgot to tell the other lectures.
by Tiffany Chao 2H
Sat Nov 02, 2019 5:27 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Ionic Character in Covalent Molecules and Vice-Versa
Replies: 2
Views: 68

Ionic Character in Covalent Molecules and Vice-Versa

Hi, I'm getting confused on the difference between ionic character in covalent molecules and covalent character in ionic molecules. Based on my notes, it seems like for both types of molecules, the ionic/covalent character is that electrons are unevenly distributed. For example of ionic character in...
by Tiffany Chao 2H
Thu Oct 31, 2019 4:17 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Which orbital would contain the highest ionization energy?
Replies: 3
Views: 45

Re: Which orbital would contain the highest ionization energy?

Orbitals don't necessarily have to do with the ionization energy levels. Just know the periodic table trend for ionization energy: The further right you go in a row, the higher the ionization energy is. The further down you go in a column, the lower the ionization energy.
by Tiffany Chao 2H
Thu Oct 31, 2019 4:09 pm
Forum: Student Social/Study Group
Topic: Video Module For New Material
Replies: 4
Views: 122

Re: Video Module For New Material

He told me that there are no more video modules for the topics after Heisenberg. He said the best way to get something similar to the video modules was to use Sapling Learning.
by Tiffany Chao 2H
Thu Oct 31, 2019 4:07 pm
Forum: Lewis Structures
Topic: Question 2A9
Replies: 4
Views: 72

Re: Question 2A9

The 2+ charge means that 2 electrons are removed. The outermost/highest energy electrons are usually the first to go, thus the removal of the 2 4s electrons.
by Tiffany Chao 2H
Thu Oct 31, 2019 4:06 pm
Forum: Ionic & Covalent Bonds
Topic: Lewis structure
Replies: 3
Views: 47

Re: Lewis structure

The atom that goes in the middle is the one with the lowest ionization energy. You can figure that out using the periodic table trends for ionization energy. The further right you go in a row, the higher the ionization energy is. The further down you go in a column, the lower the ionization energy. ...
by Tiffany Chao 2H
Thu Oct 31, 2019 4:02 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge equation
Replies: 9
Views: 80

Re: Formal Charge equation

I think you should just stick with the one Dr. Lavelle gave us. The problem probably wouldn't give you bond length in the first place so you couldn't figure out the formal charge with the equation your TA gave you.
by Tiffany Chao 2H
Tue Oct 22, 2019 9:06 pm
Forum: General Science Questions
Topic: Units
Replies: 4
Views: 83

Re: Units

velocity: m/s
threshold energy: J or kg. m^2. s^-2
Planck's constant: 6.626 x 10^-34 Js or kg.m^2. s^-1
frequency: Hz or s^-1
by Tiffany Chao 2H
Tue Oct 22, 2019 8:58 pm
Forum: Administrative Questions and Class Announcements
Topic: Homewrok
Replies: 2
Views: 30

Re: Homewrok

One question.
by Tiffany Chao 2H
Tue Oct 22, 2019 8:57 pm
Forum: Properties of Electrons
Topic: Electron with wavelike/particle like properties?
Replies: 1
Views: 54

Re: Electron with wavelike/particle like properties?

Depending on the different experiments that have been done, we can determine whether an light acts like a particle or wave depending on the situation. Particle-like property: This can refer to the Photoelectric experiment. So basically, if we shoot light at a piece of metal, it has to surpass the th...
by Tiffany Chao 2H
Tue Oct 22, 2019 8:47 pm
Forum: Photoelectric Effect
Topic: Work Function?
Replies: 7
Views: 119

Re: Work Function?

Work function is the threshold energy. It basically means that its the minimum energy needed from the light source to shoot off an electron.
by Tiffany Chao 2H
Tue Oct 22, 2019 8:46 pm
Forum: Trends in The Periodic Table
Topic: 1F. 21
Replies: 2
Views: 35

1F. 21

Hi,

F. 21.: 1F.21 Identify the following elements as metals, nonmetals, or
metalloids: (a) lead; (b) sulfur; (c) zinc; (d) silicon; (e) antimony;
(f) cadmium.

Will we have to know the answer for elements like antimony or cadmium?

Thanks

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