Search found 101 matches

by Amy Xiao 1I
Mon Mar 16, 2020 3:53 pm
Forum: Administrative Questions and Class Announcements
Topic: final grades
Replies: 12
Views: 252

Re: final grades

In addition to being able to see our grades, does anyone also know if we will be able to review our answers? I would like to see the questions I got wrong. How will we be able to see these? Is he releasing the final exams online? We'll be able to see specifically what we missed because we took the ...
by Amy Xiao 1I
Sat Mar 14, 2020 1:27 pm
Forum: Administrative Questions and Class Announcements
Topic: Saying Thank You to Dr. Lavelle
Replies: 281
Views: 134614

Re: Saying Thank You to Dr. Lavelle

Dr. Lavelle, thank you for taking care of us throughout the whole quarter. I admire how quickly you acted to make sure we would be assessed as fairly as possible during these chaotic times, and I really appreciate how selfless you are when you take so much time out of your own day to organize study ...
by Amy Xiao 1I
Sat Mar 14, 2020 11:10 am
Forum: Administrative Questions and Class Announcements
Topic: 1G,1H,1I Discussion, Echem Review
Replies: 1
Views: 432

Re: 1G,1H,1I Discussion, Echem Review

For Number 1 on Test 2, why would you not multiple S or H by 2, because you need to balance the equation first and that doubles the moles of product?
by Amy Xiao 1I
Sat Mar 14, 2020 10:59 am
Forum: Administrative Questions and Class Announcements
Topic: Format?
Replies: 11
Views: 265

Re: Format?

Do we need a printer? I can't imagine doing Chem through my laptop.
by Amy Xiao 1I
Sat Mar 14, 2020 10:57 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Hw 6N.3 a)
Replies: 2
Views: 62

Re: Hw 6N.3 a)

So from the cell diagram, we know that the anode on the left is the oxidation half-reaction and the cathode on the right is the reduction half-reaction. For the oxidation half-reaction we have two species they give you, H 2 (g) and HCl (aq). In this case, since HCl is aqueous, you can think of it a...
by Amy Xiao 1I
Tue Mar 10, 2020 5:27 pm
Forum: Administrative Questions and Class Announcements
Topic: HW10
Replies: 3
Views: 53

Re: HW10

Yes, I would probably do homework on kinetics for this week.
by Amy Xiao 1I
Sun Mar 08, 2020 11:34 pm
Forum: First Order Reactions
Topic: 7B.17b
Replies: 2
Views: 34

7B.17b

Calculate the time required for each of the following second-order reactions to take place: (b)A->2B + C,when [A]0 = 0.15 mol/L, for the concentration of B to increase to 0.19 mol/L, given that kr = 0.0035 L/mol.min in the rate law for the loss of A. Why does the solutions manual include the part wh...
by Amy Xiao 1I
Sun Mar 08, 2020 11:25 pm
Forum: Student Social/Study Group
Topic: Final Jitters
Replies: 132
Views: 33547

Re: Final Jitters

I think one should cram (if you must cram) the full day/night two days before the final and then take it easy the day before; sleep and have a good meal and just review lightly in the 24 hours before the final!
by Amy Xiao 1I
Sun Mar 08, 2020 10:56 pm
Forum: General Rate Laws
Topic: 7B7cd
Replies: 1
Views: 37

7B7cd

Substance A decomposes in a first-order reaction and its half life is 355 s. How much time must elapse for the concentration of A to decrease to ... (c) 15% of its initial concentration; (d) one-ninth of its initial concentration? Why does the solutions manual do the math differently for each step. ...
by Amy Xiao 1I
Sun Mar 08, 2020 10:34 pm
Forum: General Rate Laws
Topic: 7B5a
Replies: 1
Views: 17

7B5a

Dinitrogen pentoxide, N2O5, decomposes by first-order kinetics with a rate constant of 3.7 x 10^-5 /s at 298 K. (a) What is the half-life (in hours) of N2O5 at 298 K?

I am somewhat confused by how the units cancel. Why are the seconds applied to ln2 (numerator) and not the 3.7x10^-5 (denominator)?
by Amy Xiao 1I
Sun Mar 08, 2020 10:18 pm
Forum: General Rate Laws
Topic: 7B3a
Replies: 3
Views: 38

7B3a

Determine the rate constant for each of the following first- order reactions, in each case expressed for the rate of loss of A: (a) A -> B, given that the concentration of A decreases to one-half its initial value in 1000. s Answer: k=0.693/1000s Where did the solutions manual get the 0.693? There w...
by Amy Xiao 1I
Sat Feb 29, 2020 3:57 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

Re: Possible Solution Error on 6N.1 part b

I agree, after asking a UA, we both agreed that there was an error in the solutions because the number of electrons only changes by one in the reduction.
by Amy Xiao 1I
Sat Feb 29, 2020 3:56 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concentration Cells and Nernst Equation
Replies: 4
Views: 52

Concentration Cells and Nernst Equation

What other situations makes use of the Nernst Equation (for our purposes in this class)? Would you only use it when given a concentration cell?
by Amy Xiao 1I
Wed Feb 26, 2020 1:06 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Drawing Cell Diagrams
Replies: 1
Views: 25

Drawing Cell Diagrams

When you have multiple of one state of matter, does it matter the order in which you put them with the commas?
by Amy Xiao 1I
Mon Feb 24, 2020 11:34 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6M5
Replies: 1
Views: 38

6M5

In the cell diagram for part (a) in the solutions manual, they do not include Pt(s) on the left side, but it is present on the right side. I thought Pt(s) had to be present on both sides, can someone explain why this happens?
by Amy Xiao 1I
Mon Feb 24, 2020 11:31 pm
Forum: Balancing Redox Reactions
Topic: Explain the charges in this reaction
Replies: 1
Views: 21

Explain the charges in this reaction

2Hg^(2+) + 2e- --> . Hg2 ^(2+) (see image for clarification)

Can someone explain how this reaction works? I cannot figure out where the 2 e- come in since it seems to me like Hg keeps the same charge.
by Amy Xiao 1I
Tue Feb 18, 2020 9:30 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Arrhenius equation?
Replies: 2
Views: 105

Arrhenius equation?

I was reading 5J3 and there was a box on page 432 that explained the changes on equilibrium constant of temperature. They explained through kinetics and mentioned the Arrhenius equation. Can someone explain what this all means?

Screen Shot 2020-02-18 at 9.29.27 PM.png
by Amy Xiao 1I
Tue Feb 18, 2020 6:41 pm
Forum: Balancing Redox Reactions
Topic: Balancing Basic Solutions
Replies: 2
Views: 42

Re: Balancing Basic Solutions

You would start balancing the Oxygen atoms by adding H2O on one side, but then you need to balance the Hydrogens. For basic solutions, there is a surplus of OH- compared to H+ in acidic solutions, so you would then add OH- to balance the Hydrogens.
by Amy Xiao 1I
Tue Feb 18, 2020 6:25 pm
Forum: Balancing Redox Reactions
Topic: Understanding Half-Reactions
Replies: 11
Views: 133

Understanding Half-Reactions

Can someone explain why we use half-reactions? Dr. Lavelle said it makes it easier to understand the redox reaction as a whole but I am just more confused.
by Amy Xiao 1I
Tue Feb 18, 2020 6:21 pm
Forum: Van't Hoff Equation
Topic: HW for this week?
Replies: 1
Views: 51

HW for this week?

What section of the textbook should we do for this week? The syllabus points us to 5G but I can't find the Van't Hoff Equation there.
by Amy Xiao 1I
Tue Feb 18, 2020 6:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: midterm question// Concentration ratio [ENDORSED]
Replies: 9
Views: 200

Re: midterm question// Concentration ratio [ENDORSED]

What I did was I found Ka and used the pH given to find the concentration of H+. Since the equation for Ka is [H+][A-]/[HA], you can find the ratio of conjugate base to acid by dividing Ka by the concentration of H+. But how would you know if it stays as a salt in the stomach or becomes something e...
by Amy Xiao 1I
Tue Feb 11, 2020 9:10 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Pizza Rolls 10
Replies: 4
Views: 87

Re: Pizza Rolls 10

I did it the way you advised and still got 22.85C as my answer for Tf. For your Step 3, shouldn't the right side of the equation be negative (e.g. -265 g*specific heat of water...)? Why do you not use the specific heat of ice on the right side? (Using the specific heat of ice gives me 20.93C for my ...
by Amy Xiao 1I
Tue Feb 11, 2020 6:58 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Pizza Rolls 10
Replies: 4
Views: 87

Pizza Rolls 10

10: Matt asks me for water with no ice at a dining hall. Just to spite him, I measure 25.0 g of ice at 0.00 oC and drop it into 265 mL of water at 25.0 oC. What is the final temperature of the water?

Can someone provide a step-by-step guide on how to solve this?
by Amy Xiao 1I
Tue Feb 11, 2020 6:29 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Pizza Rolls 6
Replies: 3
Views: 99

Re: Pizza Rolls 6

I also can't get the answer for q and w; it seems like he subtracted 23.3 and 9.12 to get 14.2, but I don't understand why you wouldn't add the work values you get for each part of the problem together instead. Edit: it seems that work will be positive if the system is being compressed, like in the ...
by Amy Xiao 1I
Tue Feb 11, 2020 4:51 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Pizza Rolls 4
Replies: 1
Views: 50

Pizza Rolls 4

Can someone walk me through how to solve 4A of Pizza Rolls? I am confused about how to use Hess's Law.
by Amy Xiao 1I
Tue Feb 11, 2020 4:37 pm
Forum: Administrative Questions and Class Announcements
Topic: Pizza Rolls REVIEW Session DOWNLOAD HERE
Replies: 67
Views: 2810

Re: Pizza Rolls REVIEW Session DOWNLOAD HERE

3 E and 3 F Can someone explain why these two statements are false? I don't really understand the wording of 3E, and is it ever possible to have a negative heat capacity? 3E: Removing heat from a system is exothermic, so temperature must decrease. 3F: Heat Capacities can be negative for simple molec...
by Amy Xiao 1I
Sun Feb 09, 2020 10:39 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: q rev
Replies: 4
Views: 56

Re: q rev

In terms of homework or test problems, they will most likely tell you explicitly that the system is being changed reversibly.
by Amy Xiao 1I
Sun Feb 09, 2020 6:05 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 4F.1a
Replies: 4
Views: 49

Re: 4F.1a

Hi Amy Xiao 1I! To answer your question, the question is asking for the rate at which entropy is generated. Rate is typically some value per unit of time. For example, we have MPH, the rate of how far you're traveling (miles) per unit of time (hour). Because we want the rate of entropy generated, w...
by Amy Xiao 1I
Tue Feb 04, 2020 12:40 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 4F17
Replies: 1
Views: 53

4F17

Calculate the standard entropy of vaporization of water at 85C, given that its standard entropy of vaporization at 100C is 109.0 J/Kmol and the molar heat capacities at constant pressure of liquid water and water vapor are 75.3 J/Kmol and 33.6 J/Kmol, respectively, in this range. Why is it necessary...
by Amy Xiao 1I
Tue Feb 04, 2020 12:09 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 4F.1a
Replies: 4
Views: 49

4F.1a

In the solutions manual for 4F.1a, why does it say that the rate of entropy generation is Entropy(of surroundings)/time? What does time have to do with this problem?
by Amy Xiao 1I
Sun Feb 02, 2020 11:30 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeter
Replies: 5
Views: 54

Re: Calorimeter

Areena H 2K wrote:From lecture, we talked about a bomb calorimeter which is an isolated system and insulation, and also an open calorimeter, and adiabatic calorimeters as well.


I don't remember Dr. Lavelle mentioning adiabatic calorimeters, can you explain what those are and their importance?
by Amy Xiao 1I
Sun Feb 02, 2020 11:29 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: qp = ΔH?
Replies: 5
Views: 77

Re: qp = ΔH?

Remember that the definition of enthalpy is the change in heat at a constant pressure.
by Amy Xiao 1I
Wed Jan 29, 2020 9:28 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D.9
Replies: 2
Views: 67

Re: 4D.9

I agree with Justin, I think that since you are dividing by a volume/density, which always has to be positive, you have to get a positive answer.
by Amy Xiao 1I
Wed Jan 29, 2020 9:18 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D1
Replies: 2
Views: 43

Re: 4D1

The way the solutions manual solves it is that it first converts the 197 g of Carbon to mols -> 16.40 mol C. It also divides the energy absorbed by 4 moles of Carbon by 4 so that you will know how much 1 mol Carbon absorbs. After that, you can just multiply that energy by however many moles of carbo...
by Amy Xiao 1I
Wed Jan 29, 2020 9:11 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D.7: Finding change in internal energy through ideal gas equation
Replies: 4
Views: 77

Re: 4D.7: Finding change in internal energy through ideal gas equation

Because the change in thermal energy is equal to q + w and since there isn't any work being done on the system, I believe that the answer is simply delta U = q and q = delta H so the answer is -320 because that is the value of delta H in the reaction for 1 mol of OF2. Where did you get the 320? The...
by Amy Xiao 1I
Sun Jan 26, 2020 9:32 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8034
Views: 1407680

Re: Post All Chemistry Jokes Here

Who is Gibbs, and why is he giving out free energy?
by Amy Xiao 1I
Sun Jan 26, 2020 9:27 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8034
Views: 1407680

Re: Post All Chemistry Jokes Here

Silver walks up to Gold in a bar and says, "AU, get outta here!"
by Amy Xiao 1I
Sun Jan 26, 2020 9:24 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Week 4 Homework
Replies: 11
Views: 116

Week 4 Homework

What homework problem sets should we be doing for this week on enthalpy?
by Amy Xiao 1I
Sun Jan 26, 2020 9:22 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Reaction Enthalpy
Replies: 3
Views: 49

Re: Standard Reaction Enthalpy

If the bond enthalpies are not available you can calculate the standard reaction enthalpy using the standard enthalpy of formation of all products and subtracting that from the standard enthalpy of formation of all reactants. To add on to that, Dr. Lavelle talked about this being the third method t...
by Amy Xiao 1I
Wed Jan 22, 2020 5:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6D.5
Replies: 2
Views: 56

Re: 6D.5

[quote="Connor Ho 1B"] For part (a), here's how I went through it: [b]2. From the table in the chapter, we know that the K b of NH 3 is 1.8 x 10 -5 . We would plug this number into the K equation for this chemical reaction (Note: this is less than 10 -3 , so you can later estimate x by rem...
by Amy Xiao 1I
Wed Jan 15, 2020 5:19 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: HW 5I.3
Replies: 2
Views: 38

HW 5I.3

"In a gas-phase equilibrium mixture of H2, I2, and HI at 500. K, [HI] is 2.21 x 10^-3 mol/L and [I2] is 1.46 x 10^-3 mol/L. Given the value of the equilibrium constant in Table 5G.2, calculate the equilibrium molar concentration of H2." How do you solve this? I looked at the table and I th...
by Amy Xiao 1I
Wed Jan 15, 2020 4:56 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sig Figs on HW 5H.1c
Replies: 4
Views: 48

Re: Sig Figs on HW 5H.1c

Jamie Lee 1F wrote:41 is two sig figs, so your answer should also be two sig figs, so 1.7 x 10^3!


If that is so, can you explain why the answer for 5I.1 is 1.4 when the answer you get is 1.370, and every other given number has more sigfigs than 1.4?
by Amy Xiao 1I
Wed Jan 15, 2020 4:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5.H.3
Replies: 3
Views: 74

Re: 5.H.3

I am also confused, can someone explain which two equations would form this one?
by Amy Xiao 1I
Wed Jan 15, 2020 4:32 pm
Forum: Ideal Gases
Topic: What is the Importance of homogeneous vs heterogeneous equilibria [ENDORSED]
Replies: 12
Views: 166

Re: What is the Importance of homogeneous vs heterogeneous equilibria [ENDORSED]

It's also important to note that for a homogeneous gas equilibrium, we can calculate Kp, but we cannot calculate Kp for a heterogeneous equilibrium that involves both gas and aqueous species. Thank you for pointing that out! We would have to convert everything into concentrations, not partial press...
by Amy Xiao 1I
Wed Jan 15, 2020 4:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sig Figs on HW 5H.1c
Replies: 4
Views: 48

Sig Figs on HW 5H.1c

If you have 41^2, that becomes 1681. Why is the answer written as 1.7 x 10^3?
by Amy Xiao 1I
Fri Jan 10, 2020 12:19 am
Forum: Ideal Gases
Topic: What is the Importance of homogeneous vs heterogeneous equilibria [ENDORSED]
Replies: 12
Views: 166

Re: What is the Importance of homogeneous vs heterogeneous equilibria [ENDORSED]

It's also important to note that for a homogeneous gas equilibrium, we can calculate Kp, but we cannot calculate Kp for a heterogeneous equilibrium that involves both gas and aqueous species. Thank you for pointing that out! We would have to convert everything into concentrations, not partial press...
by Amy Xiao 1I
Fri Jan 10, 2020 12:18 am
Forum: Ideal Gases
Topic: 5G.11
Replies: 6
Views: 47

Re: 5G.11

I think if you are not given any values, you would simply write out the Q expression with the molecular formula placeholders in the square brackets. Q and K would be the same if no values are given, considering Q is calculated during a specific point in the reaction when there must be actual values ...
by Amy Xiao 1I
Fri Jan 10, 2020 12:11 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K of Ionic Compounds in Solution
Replies: 4
Views: 42

Re: K of Ionic Compounds in Solution

Basically, it's telling you to ignore spectator ions like Li+, Na+, K+, Rb+, Sr2+, Ba2+, Cl-, Br-, I-, NO3-, ClO4-, SO4(2-), etc. because these ions occur in the same form on the left and right side of the chemical equation. So when you're writing your equilibrium constant expression they'd cancel ...
by Amy Xiao 1I
Fri Jan 10, 2020 12:07 am
Forum: Ideal Gases
Topic: Calculating K when there is multiple phases
Replies: 4
Views: 45

Re: Calculating K when there is multiple phases

Thank you for clarifying why aqueous solutions cannot have partial pressure; I was under the impression that you could convert either to partial pressure or concentration for each of them.
by Amy Xiao 1I
Wed Jan 08, 2020 11:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K of Ionic Compounds in Solution
Replies: 4
Views: 42

K of Ionic Compounds in Solution

"A final point is that, when a reaction involves fully dissociated ionic compounds in solution, the equilibrium constant should be written for the net ionic equation by using the activity for each type of ion. The concentrations of the spectator ions cancel and so do not appear in the equilibri...
by Amy Xiao 1I
Sat Dec 07, 2019 12:39 pm
Forum: Student Social/Study Group
Topic: Final Jitters
Replies: 132
Views: 33547

Re: Final Jitters

Drake Choi_1I wrote:Does anyone know when Test 2 will be passed back?


Your TA should have passed it back by now in discussion.
by Amy Xiao 1I
Sat Dec 07, 2019 12:38 pm
Forum: Student Social/Study Group
Topic: Final Jitters
Replies: 132
Views: 33547

Re: Final Jitters

Get enough sleep the night before and don't cram the day of. Pack all your materials the night before so you don't scramble for it. Eat a good breakfast and give yourself some time to relax before it starts.
by Amy Xiao 1I
Sat Dec 07, 2019 12:29 pm
Forum: Significant Figures
Topic: Sig Figs on Midterm Q4 Part 2
Replies: 3
Views: 149

Sig Figs on Midterm Q4 Part 2

Why does the answer (0.08567) have only 4 sig figs when the information given to you is 102.557 (nm) and 100 kJ? Does the use of Avogadro's number (6.022 x 1023) affect this?
by Amy Xiao 1I
Sat Dec 07, 2019 12:21 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Midterm Question 4 Part 2, photon absorption
Replies: 1
Views: 126

Midterm Question 4 Part 2, photon absorption

"Light with a wavelength of 102.557 nm excites a hydrogen-atom gas sample . . . If 100 kJ of energy was absorbed by the gas sample, how many photons in total caused electronic excitations? How many moles of hydrogen were excited assuming one photon interacted with one unique hydrogen atom?"...
by Amy Xiao 1I
Fri Dec 06, 2019 11:21 am
Forum: Bond Lengths & Energies
Topic: Hydrogen Bonding
Replies: 9
Views: 246

Re: Hydrogen Bonding

It should also be noted that if O happens to have 2 lone pairs, H-bonding can happen at each of those sites, meaning that O can H-bond twice.
by Amy Xiao 1I
Sun Dec 01, 2019 12:26 pm
Forum: Amphoteric Compounds
Topic: Amphiprotic
Replies: 11
Views: 130

Re: Amphiprotic

Would water be considered both amphiprotic and amphoteric?
by Amy Xiao 1I
Sun Dec 01, 2019 12:21 pm
Forum: Lewis Acids & Bases
Topic: Lewis vs. Bronsted
Replies: 3
Views: 31

Lewis vs. Bronsted

Which one do we use in lecture most often, and is it necessary to specify on exams?
by Amy Xiao 1I
Sun Dec 01, 2019 12:17 pm
Forum: Amphoteric Compounds
Topic: 6A. 11
Replies: 3
Views: 56

Re: 6A. 11

For each (a) and (b), you would get two equations, one where the compound acts as a base and one where it acts as an acid.
by Amy Xiao 1I
Mon Nov 25, 2019 11:39 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Multiple Bonding Sites
Replies: 1
Views: 32

Multiple Bonding Sites

If given the molecular formula of a ligand would you be able to figure out how many possible bonding places of the ligand there are without having to draw the Lewis structure?
by Amy Xiao 1I
Mon Nov 25, 2019 11:31 am
Forum: Naming
Topic: 9C.3d
Replies: 1
Views: 25

9C.3d

What is the purpose of having the "diaqua" in parentheses in sodiumbisoxalato(diaqua)ferrate(III)? What does that tell you?
by Amy Xiao 1I
Sun Nov 24, 2019 9:17 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Numbers
Replies: 4
Views: 51

Coordination Numbers

If you were just given a transition metal, would you be able to estimate what coordination numbers it would have? I am under the impression that coordination numbers tell you how many bonds that TM can form.
by Amy Xiao 1I
Sun Nov 24, 2019 9:12 pm
Forum: Naming
Topic: Order in Naming
Replies: 12
Views: 135

Re: Order in Naming

Leslie Almaraz wrote:When given the name of the compound, does it matter the order in which you formulate the atomic symbols?


Could you clarify what you mean by "atomic symbol"?
by Amy Xiao 1I
Sun Nov 24, 2019 9:11 pm
Forum: Naming
Topic: Week 9 and Week 10 HW?
Replies: 21
Views: 245

Re: Week 9 and Week 10 HW?

Can anyone clarify about the homework under Molecular Shape and Structure in the syllabus that is 2F? Has Lavelle ever gone over the topics in 2F, and should we do homework problems from that set?
by Amy Xiao 1I
Sun Nov 24, 2019 8:49 pm
Forum: Hybridization
Topic: Basics
Replies: 2
Views: 36

Re: Basics

Hybridization is when atomic orbitals are mixed into hybrid orbitals so that chemical bonding is easier. Basically, electrons can move into new hybrid orbitals and these orbitals are used to create bonds with other hybrid orbitals in different atoms in order to for a molecule. Can you explain what ...
by Amy Xiao 1I
Mon Nov 18, 2019 10:57 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AXE formula
Replies: 9
Views: 82

Re: AXE formula

If there is no central atom, there would simply be no A in the formula. For example, in I3-, the formula is X2E3 because there is no central atom. (This is problem 2E13A)
by Amy Xiao 1I
Mon Nov 18, 2019 10:54 pm
Forum: Lewis Structures
Topic: Bent or Angular?
Replies: 15
Views: 338

Bent or Angular?

Is bent or angular the best term to use to describe a trigonal planar/tetrahedral with one lone pair? VSEPR charts online use the term "bent," but the textbook calls them "angular".
by Amy Xiao 1I
Mon Nov 18, 2019 10:51 pm
Forum: Lewis Structures
Topic: Organic Compounds
Replies: 2
Views: 55

Re: Organic Compounds

I can see where you would be confused, because I am as well. All I know is that on the tests, when there are complex compounds, the test question seems to indicate where the central atoms are and what they are bonded to, and then you could probably go from there.
by Amy Xiao 1I
Mon Nov 18, 2019 10:48 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: ion dipole interactions
Replies: 3
Views: 37

Re: ion dipole interactions

I think so, because mixing ions into water (which is polar) would cause the more positive dipole on the H of water to attract/be attracted to the chlorine ion. I think the term polar would apply to ions in this case; polar seems to just be if there is a net charge that is not zero.
by Amy Xiao 1I
Mon Nov 18, 2019 10:43 pm
Forum: Lewis Structures
Topic: Octet Rule
Replies: 7
Views: 253

Octet Rule

Can elements that break the octet rule only do so until their formal charge becomes zero, or is the formal charge not a major factor for the octet rule?
by Amy Xiao 1I
Mon Nov 18, 2019 10:39 pm
Forum: Sigma & Pi Bonds
Topic: Sigma Bonds
Replies: 2
Views: 50

Sigma Bonds

Is it possible for a central atom to have multiple sigma bonds, each connected to a different atom? Or does the one sigma bond rule hold true for the entire atom?
by Amy Xiao 1I
Sat Nov 09, 2019 6:15 pm
Forum: Dipole Moments
Topic: 3F.19
Replies: 1
Views: 31

3F.19

Can someone explain parts B and C? For B, I am confused about why the hydrogen bonding in water is stronger than the attractive forces in diethyl ether. I thought diethyl ether would also have hydrogen bonding. For C, why does a lower surface area due to the compactness of dimethylpropane cause it t...
by Amy Xiao 1I
Sat Nov 09, 2019 5:59 pm
Forum: Dipole Moments
Topic: 3F.5
Replies: 2
Views: 31

3F.5

Can someone explain why CHI3 has a higher melting point that CHF3? If fluorine is more electronegative than chlorine, wouldn't it have a stronger hold on the electrons and cause there to be a higher melting point instead?
by Amy Xiao 1I
Sat Nov 09, 2019 5:44 pm
Forum: Dipole Moments
Topic: Summary of all the Different Possible Forces?
Replies: 1
Views: 31

Summary of all the Different Possible Forces?

Can someone give a quick and easy-to-remember summary for all the forces? (Ion-Dipole, Dipole-Dipole, London, and Hydrogen Bonding) Can you also provide examples where multiple can exist in the same molecule?
by Amy Xiao 1I
Sat Nov 09, 2019 5:39 pm
Forum: Dipole Moments
Topic: How do i know if a molecule has a dipole moment?
Replies: 7
Views: 110

Re: How do i know if a molecule has a dipole moment?

To summarize, all molecules have dipole moments unless they are between the same element and/or symmetrical?
by Amy Xiao 1I
Wed Nov 06, 2019 12:31 pm
Forum: Empirical & Molecular Formulas
Topic: Number 1 in Dino Nuggets
Replies: 3
Views: 188

Re: Number 1 in Dino Nuggets

Your explanation was super helpful, but can you explain why you don't know where the O is coming from? Why can't you just add the mol of Oxygen from CO2 and H2O?
by Amy Xiao 1I
Tue Oct 29, 2019 9:09 pm
Forum: Ionic & Covalent Bonds
Topic: Midterm
Replies: 10
Views: 174

Re: Midterm

I think that we need a blue book, since it is an official midterm, as well as a scientific calculator for basic calculations. Other than that, some extra pens would be good to have on hand too. And I haven't heard anything about the midterm locations yet, so he will probably be sending out an email...
by Amy Xiao 1I
Tue Oct 29, 2019 9:03 pm
Forum: Ionic & Covalent Bonds
Topic: HW 2A19
Replies: 1
Views: 37

HW 2A19

For part e, why are there two unpaired electrons for Ni2+?
by Amy Xiao 1I
Tue Oct 29, 2019 8:10 pm
Forum: Ionic & Covalent Bonds
Topic: Homework 2A15
Replies: 3
Views: 49

Re: Homework 2A15

For Gallium to give away 3 electrons requires lower energy compared to accepting 5 electrons.
by Amy Xiao 1I
Tue Oct 29, 2019 8:00 pm
Forum: Ionic & Covalent Bonds
Topic: Textbook question 2A.1
Replies: 2
Views: 32

Re: Textbook question 2A.1

Going off of what Connie said, the 3d block is already filled so you don't have to include those electrons in when you count; a good rule of thumb for me is to see what column (group) the element is in and use that number. Sb is in the 5th group from the left if you disregard the d block of metals.
by Amy Xiao 1I
Tue Oct 29, 2019 7:55 pm
Forum: Ionic & Covalent Bonds
Topic: How to count valence electrons with the d block
Replies: 4
Views: 53

Re: How to count valence electrons with the d block

The textbook problem 2A.1c states that Mn has 7 valence electrons, but it is very clear about "including d electrons."
by Amy Xiao 1I
Sun Oct 27, 2019 1:44 pm
Forum: Lewis Structures
Topic: Expanded Octet
Replies: 6
Views: 64

Re: Expanded Octet

If that is the case, why even have the Octet rule? I understand that it is an easy rule of thumb for many elements, but if it does not really apply after the d-orbital comes into play, is it really helpful?
by Amy Xiao 1I
Sun Oct 27, 2019 1:43 pm
Forum: Ionic & Covalent Bonds
Topic: "Delocalized" Electrons
Replies: 5
Views: 76

Re: "Delocalized" Electrons

I am also confused. I thought covalent bonds were ones in which the electron was already free to move around, so I am not understanding how an electron can be free to move around the entire molecule instead. What allows it to do so?
by Amy Xiao 1I
Sun Oct 27, 2019 1:39 pm
Forum: Ionic & Covalent Bonds
Topic: Writing Electron Configurations for an Ion
Replies: 6
Views: 77

Re: Writing Electron Configurations for an Ion

I'm not too confident on this topic either, but I'm pretty sure you remove or add an electron to the highest energy level depending on whether you want a cation or anion. For example, to change Zinc from its ground-state to Zn+, you take the ground state configuration [Ar]3d^104s^2 and remove an el...
by Amy Xiao 1I
Sun Oct 27, 2019 1:37 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8034
Views: 1407680

Re: Post All Chemistry Jokes Here

Do you know any good jokes about Sodium Hypobromite?

NaBrO
by Amy Xiao 1I
Sun Oct 27, 2019 1:34 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8034
Views: 1407680

Re: Post All Chemistry Jokes Here

Why are noble gases good at singing?

Because their resonance is the most stable!
by Amy Xiao 1I
Sun Oct 20, 2019 11:12 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8034
Views: 1407680

Re: Post All Chemistry Jokes Here

Have you seen the new James Bond movie?

The name's Bond. Covalent Bond.
by Amy Xiao 1I
Sun Oct 20, 2019 11:11 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8034
Views: 1407680

Re: Post All Chemistry Jokes Here

Why is Helium the best audience for a comedy show?

Because it always says He He He.
by Amy Xiao 1I
Sun Oct 20, 2019 11:08 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Purpose of the Equation
Replies: 9
Views: 116

Re: Purpose of the Equation

The more you know about the velocity, the less you know about the speed, and vice versa. The reason for this according to Dr. Lavelle is that the process of observing either one of those influences the other. If you set up more sensors to get accurate velocities, you will move the electron off cours...
by Amy Xiao 1I
Sun Oct 20, 2019 12:58 pm
Forum: Photoelectric Effect
Topic: Work Function
Replies: 9
Views: 158

Re: Work Function

Dr. Lavelle uses those terms practically interchangeably when discussing the photoelectric effect.
by Amy Xiao 1I
Thu Oct 17, 2019 10:31 pm
Forum: Properties of Electrons
Topic: 1B.3
Replies: 3
Views: 73

Re: 1B.3

I think Dr. Lavelle went over this in class while explaining the photoelectric effect. He did not go over black body radiation much, and atomic spectra relates to electrons, not electromagnetic radiation, so that narrows it down to either electron diffraction or the photoelectric effect. I chose to ...
by Amy Xiao 1I
Sat Oct 12, 2019 10:29 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8034
Views: 1407680

Re: Post All Chemistry Jokes Here

My Chem teacher argued that Iron Man was a woman.

Fe-male
by Amy Xiao 1I
Sat Oct 12, 2019 10:28 pm
Forum: Administrative Questions and Class Announcements
Topic: Tutoring? [ENDORSED]
Replies: 71
Views: 72175

Re: Tutoring? [ENDORSED]

I reached out to Alpha Chi Sigma and was told that tutoring would start Week 3, so make sure to contact them once Monday starts!
by Amy Xiao 1I
Sat Oct 12, 2019 10:24 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8034
Views: 1407680

Re: Post All Chemistry Jokes Here

What element best describes me?

The element of indecision: Imnotsurium
by Amy Xiao 1I
Sat Oct 12, 2019 10:22 pm
Forum: Student Social/Study Group
Topic: Final Jitters
Replies: 132
Views: 33547

Re: Final Jitters

I took Quiz 1 after running into the room 3 minutes late and I was panicking, but I calmed down and thought out my answers. I would say that the best thing to do is review everything that you need on the syllabus: pen, non-graphing calculator, etc. If something will be given, don't try to remember e...
by Amy Xiao 1I
Sat Oct 12, 2019 10:16 pm
Forum: Properties of Light
Topic: Light intensity and Kinetic Energy
Replies: 7
Views: 117

Re: Light intensity and Kinetic Energy

I think that Lily is right in saying that there is no correlation between light intensity and the kinetic energy in the equation E=hv.
by Amy Xiao 1I
Sat Oct 12, 2019 9:56 pm
Forum: Properties of Light
Topic: 1A.3
Replies: 4
Views: 62

Re: 1A.3

C would be the correct answer. Think of the "change in the electrical field" as slope-- how steep a wave goes. As frequency decreases, the waves stretch out farther and the slope would be less steep because they are now farther apart.
by Amy Xiao 1I
Wed Oct 02, 2019 10:11 pm
Forum: Properties of Light
Topic: Electric Field and Magnetic Field
Replies: 3
Views: 92

Re: Electric Field and Magnetic Field

What effect does the magnetic field have on the electrons, then?
by Amy Xiao 1I
Sun Sep 29, 2019 10:15 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical Formulas Rounding and Multiplying
Replies: 11
Views: 221

Re: Empirical Formulas Rounding and Multiplying

I personally feel like the general rule of thumb for round should include only integers ending in 0.5 or 0.33. Anything else, can either be rounded up or down. For example: If your result is a number that is 2.55, obviously round that to just 2.5. I understand that you would round 2.55 to 2.5, but ...
by Amy Xiao 1I
Sat Sep 28, 2019 5:23 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical Formulas Rounding and Multiplying
Replies: 11
Views: 221

Re: Empirical Formulas Rounding and Multiplying

What should the threshold be for decimals when solving for empirical formulas? I think that if the results are 0.1 away from the nearest whole number, then you round to that whole number. Otherwise, I think you multiply to the nearest whole number. However, I see in some example problems, like one ...

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