Search found 102 matches

by nehashetty_2G
Fri Mar 13, 2020 12:28 pm
Forum: General Rate Laws
Topic: 7A.15a
Replies: 4
Views: 85

Re: 7A.15a

For A, you have to ensure that only the concentrations for A are changing. Therefore, the concentrations for B must be the same (The concentration of C doesn't matter in this question specifically, so only worry about B). Based on this logic, you can use a combination of experiments such as Rate 2 a...
by nehashetty_2G
Fri Mar 13, 2020 12:22 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Slow Step Mechanism
Replies: 7
Views: 69

Re: Slow Step Mechanism

I think it really depends on the step mechanism itself. However, for our exam purposes, I believe they will most likely have the slow step in the middle somewhere (my speculation).
by nehashetty_2G
Fri Mar 13, 2020 12:20 pm
Forum: Administrative Questions and Class Announcements
Topic: ENDGAME Review Session
Replies: 71
Views: 2742

Re: ENDGAME Review Session

Thank you for everything Lyndon!!!
by nehashetty_2G
Fri Mar 13, 2020 12:18 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Slow Step Determination
Replies: 5
Views: 72

Re: Slow Step Determination

They will tell you if a step is low usually. You can use that information to decide that the slow step is what determines the rate of the reaction.
by nehashetty_2G
Fri Mar 13, 2020 10:04 am
Forum: Administrative Questions and Class Announcements
Topic: Final
Replies: 2
Views: 57

Re: Final

I think open book means you have access to lecture notes, but I don't think it includes chemistry community. I am unsure about your other questions; Lavelle may speak on those in later emails!
by nehashetty_2G
Sun Mar 08, 2020 10:19 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Rate Laws
Replies: 3
Views: 33

Re: Rate Laws

No, I believe you have to calculate it based off of the rate law equation, or through the method of initial rates.
by nehashetty_2G
Sun Mar 08, 2020 10:16 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 7C.7: Rate laws
Replies: 2
Views: 34

7C.7: Rate laws

The answer key does not include rate laws for the reverse reaction; however, in the book it says every forward reaction has a reverse reaction associated with it. So, I am wondering when do we use/write down a reverse reaction rate and when do we not?
by nehashetty_2G
Sun Mar 08, 2020 10:14 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: how?
Replies: 3
Views: 40

Re: how?

You can use the method of initial rates that we learned in class to determine n and k!
by nehashetty_2G
Sun Mar 08, 2020 10:11 pm
Forum: First Order Reactions
Topic: 7B.3
Replies: 2
Views: 40

Re: 7B.3

You just use stoichiometric relations to find the concentration of A. If 0.034M B was created, that means that two times that amount of A was used in creating B. Therefore, you subtract 0.068 from 0.153 to find [A]t (0.085M).
by nehashetty_2G
Sun Mar 08, 2020 10:06 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 6
Views: 56

Re: Cell Diagrams

Also, when the states are the same, you put the higher charge on the left and lower charge on the right
by nehashetty_2G
Mon Mar 02, 2020 4:31 pm
Forum: Balancing Redox Reactions
Topic: Balancing Redox Reaction in 6L.3(d)
Replies: 1
Views: 36

Re: Balancing Redox Reaction in 6L.3(d)

I used the following half reaction:
2H2O + 4e- + O2 --> 4OH-
I used this half reaction because the cell diagram shows that there is an O2 and an OH-. This is why I didn't use the other half rxns that include species like H+.
by nehashetty_2G
Sun Mar 01, 2020 10:59 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Problem 6N.1 part b
Replies: 4
Views: 97

Problem 6N.1 part b

Both the half reactions for In3+/In2+ and U3+/U4+ use only one electron and it balances out correctly. So, why does the solution manual uses 2e- for n?
by nehashetty_2G
Sat Feb 29, 2020 3:55 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Pt in cell diagrams
Replies: 3
Views: 33

Pt in cell diagrams

When does the Pt go on both sides of the cell diagram and when does it not? For example, in Problem 6M.5 the Pt is only on the right side of the diagram.

Also, in general, how do you determine when to use Pt? Are there specific rules for it?
by nehashetty_2G
Sat Feb 29, 2020 1:42 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.7b half reactions [ENDORSED]
Replies: 1
Views: 48

6L.7b half reactions [ENDORSED]

I used different half rxns and got the same E. Does it matter which ones you use? If so, how would you tell for this problem?
The overall rxn is: H+ + OH- --> H20
The answer key uses O2 in the half rxns
I used the following half rxns:
2H+ + 2e- --> H2
H2 + 2OH- --> 2e- + 2H20
by nehashetty_2G
Sat Feb 29, 2020 1:29 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Problem 6L.7a: Cell Diagram Notation
Replies: 1
Views: 32

Problem 6L.7a: Cell Diagram Notation

In the answer key, the Ag(s) and AgBr(s) are separated by "|" however, I thought we only use that line when two species are in different phases. Can someone clarify why we use the "|" between Ag(s) and AgBr(s) in this question?
by nehashetty_2G
Sun Feb 23, 2020 6:26 pm
Forum: Balancing Redox Reactions
Topic: Balancing Redox EQs
Replies: 10
Views: 104

Re: Balancing Redox EQs

It depends on if the reaction is occurring in an acidic or basic solution. If it is an acidic solution you use H+ and if it is a basic solution you use OH-
by nehashetty_2G
Sun Feb 23, 2020 6:23 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Units for delta G calculations w/E
Replies: 1
Views: 28

Re: Units for delta G calculations w/E

A lot of times we separately divide the final answer by moles in order to get those units. It's similar to how in the thermo unit, when we calculated delta H of formation we divided by mol to get J/mol even though you normally get just joules by doing products-reactants.
by nehashetty_2G
Sun Feb 23, 2020 6:18 pm
Forum: Van't Hoff Equation
Topic: Notes from 02/14/2020
Replies: 1
Views: 36

Re: Notes from 02/14/2020

Sending it right now!
by nehashetty_2G
Sat Feb 22, 2020 5:16 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 5G.21
Replies: 2
Views: 63

Re: 5G.21

I would use the equation: G=-RTlnK. You calculate G using appendix 2A, and solve for K.
by nehashetty_2G
Sat Feb 22, 2020 5:09 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt Bridge
Replies: 10
Views: 116

Re: Salt Bridge

A salt bridge comes is significant to a galvanic cell because it eases the charge buildup. It allows the ions to transfer when which allows the solutions to stay neutral overtime.
by nehashetty_2G
Fri Feb 14, 2020 11:19 pm
Forum: Calculating Work of Expansion
Topic: Reversible vs Irreversible
Replies: 13
Views: 244

Re: Reversible vs Irreversible

In terms of entropy, when a system is reversible it means that the delta S total is = 0.
by nehashetty_2G
Fri Feb 14, 2020 11:01 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Delta S
Replies: 6
Views: 66

Re: Delta S

Delta S total = 0 to in a reversible reaction not delta S. Remember Delta S implies Delta S of the system.
by nehashetty_2G
Fri Feb 14, 2020 10:48 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: State functions
Replies: 5
Views: 104

Re: State functions

Yes! Lyndon told us this during a review session (capital letters indicate a state function): "if you are Depressed or Pressured, all you want is TV and HUGS." State functions are: density, pressure, temperature, volume, enthalpy, internal energy, gibbs free energy, and entropy.
by nehashetty_2G
Fri Feb 14, 2020 10:29 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy in reversible and irreversible
Replies: 3
Views: 47

Re: Entropy in reversible and irreversible

I don't think it matters for entropy. I believe we always use the RTln(V2/V1).
by nehashetty_2G
Sun Feb 09, 2020 11:35 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: using ICE tables
Replies: 3
Views: 69

Re: using ICE tables

I believe it is just for molarity, that way all the values in your ICE table are consistent and comparable.
by nehashetty_2G
Sun Feb 09, 2020 11:33 am
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: W
Replies: 4
Views: 34

Re: W

No, I believe that W is the number of ways a molecule can be arranged. That's why BF3 has W=1 not three. Whereas COF2 has W=1 because the oxygen can be in 1 of three positions.
by nehashetty_2G
Sun Feb 09, 2020 11:32 am
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Residual Entropy
Replies: 5
Views: 29

Re: Residual Entropy

I believe residual entropy is the energy that remains even when a sample is brought to 0 Kelvin caused by disorder in the sample.
by nehashetty_2G
Tue Feb 04, 2020 4:21 pm
Forum: Calculating Work of Expansion
Topic: Problem 4.7a
Replies: 1
Views: 25

Problem 4.7a

How do you calculate the delta n? And what is the delta n?
by nehashetty_2G
Mon Feb 03, 2020 5:32 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Problem 4C.3a
Replies: 1
Views: 23

Problem 4C.3a

The answer key doesn't have an answer for the change in enthalpy. Can someone with the solutions manual confirm or deny if the answer is +765J for delta H? If it isn't, how do we find the correct answer?
by nehashetty_2G
Sat Feb 01, 2020 6:28 pm
Forum: Calculating Work of Expansion
Topic: Reversible Process
Replies: 2
Views: 40

Re: Reversible Process

Yes! When external pressure is constant, it is an irreversible process.
by nehashetty_2G
Sat Feb 01, 2020 6:27 pm
Forum: Calculating Work of Expansion
Topic: Work positive or negative
Replies: 5
Views: 57

Re: Work positive or negative

When the system does work on something outside of the system, it is negative work because they system is losing energy (ex. the piston moves out/expansion). When something else is doing work on the system, it is positive work because the system is gaining energy (ex. piston moves in/compression). I ...
by nehashetty_2G
Sat Feb 01, 2020 6:25 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: reversible vs irreversible expansion
Replies: 4
Views: 44

Re: reversible vs irreversible expansion

For an irreversible expansion, the external pressure is constant and for reversible expansion, external pressure can change.
by nehashetty_2G
Sat Feb 01, 2020 6:24 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Elements
Replies: 8
Views: 41

Re: Elements

When we talk about oxygen or nitrogen gas, we always assume it is in its diatomic form. This is because it the diatomic form the standard state. Therefore, I think of it as being like the standard or 0 kJ/mol because the element is just naturally just found in that state.
by nehashetty_2G
Sat Feb 01, 2020 4:25 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Problem 4D.7
Replies: 1
Views: 9

Problem 4D.7

The question asks for the delta U, but they just give us the delta H and the equation. I don't understand how you calculate this? Can we just assume delta U = delta H? And if so, why?
by nehashetty_2G
Thu Jan 23, 2020 12:10 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test 1 Material
Replies: 3
Views: 50

Re: Test 1 Material

No, definitely not for Test 1. We just need to know in terms of enthalpy (delta H).
by nehashetty_2G
Wed Jan 22, 2020 5:21 pm
Forum: General Science Questions
Topic: Test 1: Sig Figs
Replies: 7
Views: 125

Test 1: Sig Figs

Do sig figs count on the test 1? If so, how do sig figs work with pH and decimals points. For example, if pH = 5.1 and the question asks for the [H+], how many sig figs would the [H+] have?
by nehashetty_2G
Tue Jan 21, 2020 3:15 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Problem 5.39
Replies: 1
Views: 31

Problem 5.39

The question asks to use Table 5E.2. Is it supposed to be 5G.2? Because I can't find a Table 5E.2.
by nehashetty_2G
Tue Jan 21, 2020 3:12 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Table 5G.2
Replies: 1
Views: 20

Table 5G.2

Is the K in the second column just K calculated with partial pressures instead of concentrations?
by nehashetty_2G
Wed Jan 15, 2020 11:29 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier overview
Replies: 3
Views: 31

Le Chatelier overview

Does Le Chatelier's Principle encompass a change in product/reactant concentration, pressure, and temperature? Or is it just a change in product/reactant concentration?
by nehashetty_2G
Wed Jan 15, 2020 11:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Dilute solution cutoff
Replies: 2
Views: 27

Re: Dilute solution cutoff

Practically, I would not worry about a cutoff especially for the purpose of this class, because liquids like water are not included in the equilibrium constant expression.
by nehashetty_2G
Wed Jan 15, 2020 11:22 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Units in ICE Table
Replies: 8
Views: 88

Re: Units in ICE Table

No, it has to be concentration. If you just use moles it will mess up your calculations when the stoichiometric coefficient is something other than 1 due to the ^n part of the equilibrium equation.
by nehashetty_2G
Wed Jan 15, 2020 10:57 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka and Kb
Replies: 5
Views: 34

Re: Ka and Kb

No, the B versus the A subscript are just indicative of whether the reaction is an acid or base.
by nehashetty_2G
Wed Jan 15, 2020 5:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.29 Barr units
Replies: 3
Views: 22

5I.29 Barr units

When the problem gives the partial pressure of one of the compounds in barr units do we divide by the volume to get the initial concentration value? I know in this question it isn't much of an issue because it is 1.0L, but I'm asking for future chem problems.
by nehashetty_2G
Wed Jan 08, 2020 6:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Partial Pressures
Replies: 4
Views: 43

Re: Partial Pressures

Nope! Only the mole fractions of all the components of a mixture must add to 1, but we are not dealing with that (right now at least).
by nehashetty_2G
Wed Jan 08, 2020 6:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Finding K without aq
Replies: 4
Views: 50

Re: Finding K without aq

I think the K would just be 1. On a ChemLibre website it just says that solids and liquids are essentially just 1, so for a reaction with all solids and liquids I assume 1 makes the most sense.
by nehashetty_2G
Wed Jan 08, 2020 6:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K for Gases
Replies: 12
Views: 96

Re: K for Gases

For a reaction that involves just gases you would use Kp.
by nehashetty_2G
Wed Jan 08, 2020 6:07 pm
Forum: Ideal Gases
Topic: R constant in PV=nRT
Replies: 9
Views: 68

Re: R constant in PV=nRT

I think it will most likely by R=8.314 J/(Kmol) because that is what Lavelle gave on the formula/constant sheets in 14A. In general just look at the units to figure out what to use, or to see if you need to manipulate the constant.
by nehashetty_2G
Wed Jan 08, 2020 5:27 pm
Forum: Ideal Gases
Topic: K
Replies: 10
Views: 97

Re: K

Yes, it should be! Because, the only reason we use Kp versus Kc is based on the phases of the reactants/products (and whether the concentration or partial pressure is give to us for gases).
by nehashetty_2G
Wed Jan 08, 2020 5:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: changing K
Replies: 4
Views: 58

Re: changing K

Yes! Kp and Kc are really both just different input values to get to K so they must have similar implications in practice.
by nehashetty_2G
Sun Dec 08, 2019 4:39 pm
Forum: Dipole Moments
Topic: Hydrogen bonding AND Dipole-Dipole?
Replies: 3
Views: 104

Re: Hydrogen bonding AND Dipole-Dipole?

Yeah I personally think it is a little redundant, but I believe we are still required to write both.
by nehashetty_2G
Sun Dec 08, 2019 4:07 pm
Forum: Lewis Acids & Bases
Topic: Mg(OH)2 Considered strong or weak base?
Replies: 5
Views: 151

Re: Mg(OH)2 Considered strong or weak base?

I put that it was a strong base because the hydroxides of Group 1 and 2 elements are strong bases.
by nehashetty_2G
Wed Dec 04, 2019 9:07 pm
Forum: Naming
Topic: Problem C.3 part (d)
Replies: 2
Views: 44

Re: Problem C.3 part (d)

Why does the diaqua go before the bisaxalato?
by nehashetty_2G
Wed Dec 04, 2019 8:48 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6B.9 (i)
Replies: 1
Views: 45

6B.9 (i)

I have to find the pH with the information that [H30+] is 1.50 mol/L. The correct answer is a pH of 0.176, but I keep getting -0.176. What am I doing wrong?
by nehashetty_2G
Thu Nov 28, 2019 8:12 pm
Forum: Conjugate Acids & Bases
Topic: 6A.1) c)
Replies: 2
Views: 65

Re: 6A.1) c)

Yes it can act as a base because it has the potential to receive an H+! So, the conjugate acid would be H2CO3.
by nehashetty_2G
Thu Nov 28, 2019 8:09 pm
Forum: Dipole Moments
Topic: Hydrogen Bonding
Replies: 17
Views: 434

Re: Hydrogen Bonding

Matt Sanruk 4F wrote:And O has two hydrogen bonding sites right?

Yes, that's usually correct, but it still depends on how O is arranged on the molecule/compound.
by nehashetty_2G
Thu Nov 28, 2019 7:00 pm
Forum: Polyprotic Acids & Bases
Topic: strength of polyprotic acids/bases
Replies: 2
Views: 51

Re: strength of polyprotic acids/bases

No I don't think so. Being labeled polyprotic vs monoprotic just refers to how much one CAN donate; not how they normally donate. https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Acids_and_Bases/Monopro...
by nehashetty_2G
Thu Nov 28, 2019 6:56 pm
Forum: Naming
Topic: -ido vs -o
Replies: 5
Views: 58

Re: -ido vs -o

I think chloro is the correct form (rather than chlorido) when it is a ligand in a coordination compound. Same with fluoro and cyano.
by nehashetty_2G
Thu Nov 28, 2019 6:53 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Constant K(a)
Replies: 4
Views: 51

Re: Constant K(a)

Yes we should know how to calculate Ka especially since we have the equation for it. Just insert the concentrations.
by nehashetty_2G
Fri Nov 22, 2019 12:56 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: What are Ligands?
Replies: 6
Views: 62

Re: What are Ligands?

A ligand is just something that attaches onto a transition metal central atom in a coordination compound.
by nehashetty_2G
Fri Nov 22, 2019 12:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: polar vs non polar
Replies: 6
Views: 72

Re: polar vs non polar

I personally always draw out the formula (unless it's a common compound that I know is non polar or polar like CH4 or H2O respectively). The reason is that a lot of times there are lone pairs that are not reflected in the compound's formula that are discovered only after drawing the structure. For e...
by nehashetty_2G
Thu Nov 21, 2019 5:24 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond angles for trigonal bipyramidal and octahedral
Replies: 2
Views: 39

Re: Bond angles for trigonal bipyramidal and octahedral

Seesaw: <120 degrees for equatorial atoms and very slightly 180 for the axial atoms.
T-shaped: <90 degrees
Square pyramidal: 90 degrees for atoms on the equatorial plane.
Square planar: 90 degrees.
by nehashetty_2G
Thu Nov 21, 2019 5:22 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: Hydrogen Bonding Homework Problem
Replies: 2
Views: 50

Re: Hydrogen Bonding Homework Problem

To form a hydrogen bond, the NOF atoms need to have a free lone pair. In butanol, the OH is on the end so it has a free long pair to form hydrogen bonds. However, in diethyl ether the oxygen is in the middle of the atom and has no lone pairs therefore it cannot form a hydrogen bond.
by nehashetty_2G
Tue Nov 19, 2019 8:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Problem 3F.3c
Replies: 2
Views: 42

Problem 3F.3c

How do you know the arrangement of the H and Cl for a compound like CH2Cl2?
by nehashetty_2G
Wed Nov 13, 2019 7:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.15
Replies: 3
Views: 35

2E.15

For problem b, why is it not less than 120 degrees instead of 120 degrees for the atoms in the trigonal plane? I thought that because there is a lone pair, the Cl-Te-Cl bond angle would be less than 120 degrees?
by nehashetty_2G
Wed Nov 13, 2019 7:39 pm
Forum: Properties of Light
Topic: Midterm Solution Q2.A
Replies: 2
Views: 146

Re: Midterm Solution Q2.A

We have to divide by Avagadro's number to get it from J/mol to J/atom, where atom is 1 Au atom.
by nehashetty_2G
Wed Nov 13, 2019 7:37 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.5 b
Replies: 4
Views: 41

Re: 2E.5 b

I'm not exactly sure about radicals and shapes, but I know that for 2E.5 when they ask OClO they aren't asking about a molecule ClO2, they are just taking about the bond formed between those three atoms (O, Cl, and O). Hope that helps!
by nehashetty_2G
Wed Nov 13, 2019 5:34 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Memorizing and Recognizing Molecular Shapes
Replies: 4
Views: 48

Re: Memorizing and Recognizing Molecular Shapes

Yes I believe we will. I think Lavelle will go over the other shapes in class (like with the long pairs).
by nehashetty_2G
Wed Nov 13, 2019 5:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Memorization
Replies: 15
Views: 246

Re: Memorization

Yes, we definitely will for the exam/final.
by nehashetty_2G
Sun Nov 10, 2019 6:40 pm
Forum: General Science Questions
Topic: London
Replies: 4
Views: 79

Re: London

The London Forces! It's a type of intermolecular force and it is interchangeable with dispersion forces, van der waals, and induced dipole-induced dipole forces.
by nehashetty_2G
Sun Nov 10, 2019 6:38 pm
Forum: Student Social/Study Group
Topic: Midterm Average
Replies: 12
Views: 264

Re: Midterm Average

I remember seeing the midterm average on the last slide of last lecture's powerpoint. I think that was last year's midterm average so I'm sure he will release that stat for our quarter too.
by nehashetty_2G
Sun Nov 10, 2019 6:36 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Calculating formal charge
Replies: 4
Views: 73

Re: Calculating formal charge

I think that when calculating formal charge, the concept is not to look at how many electrons an atom has, rather it is to look at the number of SHARED bonds that an atom is involved in.
by nehashetty_2G
Sun Nov 10, 2019 6:34 pm
Forum: Dipole Moments
Topic: Electronegativity
Replies: 3
Views: 34

Re: Electronegativity

Electronegativity is not an interaction between molecules. Electronegativity is a relative measure of an atom's tendency to pull electrons to itself. On the other hand dipole-dipole is an interaction that is characterized by the partial charge of one atom being attracted to the opposite partial char...
by nehashetty_2G
Sun Nov 10, 2019 6:30 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: Boiling point
Replies: 5
Views: 75

Re: Boiling point

Since boiling point is the change from liquid to the solid state it is identified when all the intermolecular bonds are broken. Therefore, the stronger the intermolecular forces (IMF) are the higher the boiling point will be. Hydrogen bonding is one of the stronger intermolecular forces and causes h...
by nehashetty_2G
Sat Nov 02, 2019 1:16 pm
Forum: Photoelectric Effect
Topic: Work Function
Replies: 6
Views: 74

Re: Work Function

Sometimes the work function is given in joules per mole; however, we need it to be just joules in the problem for the equation. Therefore, ensure to divide the joules/mole number by avagadro's number before you input that value into the problem!
by nehashetty_2G
Sat Nov 02, 2019 1:09 pm
Forum: Bond Lengths & Energies
Topic: HW: 2D Q5c
Replies: 2
Views: 38

Re: HW: 2D Q5c

Yes, you use the electronegativity difference to determine if a bond is ionic, covalent, polar covalent, etc. Anything with an EN difference > 2.0 is ionic. In terms of determining C-O vs C-S and which is greater you would need to compare the electronegativity of O and S. Remember that we learned th...
by nehashetty_2G
Sat Nov 02, 2019 11:37 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Ionization Energy
Replies: 3
Views: 42

Re: Ionization Energy

Online it says that the two primary exceptions are that 1) N has an ionization energy greater than O and 2) Be has an ionization energy greater than B. Those are probably the most important to remember since they are located in the first three periods of the periodic table.
by nehashetty_2G
Sat Nov 02, 2019 11:35 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Work function units
Replies: 5
Views: 78

Re: Work function units

I have also seen questions that give the work function in the units eV, and in that case just remember that you can convert from eV to Joules using the conversion factor give on the conversion sheet which is 1ev is equal to 1.602 × 10-19 J.
by nehashetty_2G
Sat Nov 02, 2019 11:31 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Cu and Cr
Replies: 11
Views: 100

Re: Cu and Cr

Yes! Because all of the elements in that group have the same valence electron orbital formation; therefore, all of them will exhibit similar characteristics when it comes to arranging valence electrons.
by nehashetty_2G
Fri Oct 25, 2019 9:58 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 4
Views: 63

Re: Formal Charge

So formal charge is different from ionic charge. Formal charge takes into consideration the bonding in terms of electrons for each individual atom in the compound. Therefore, Cl in a compound does not always have a formal charge of -1. It could also have a formal charge of 0. We don't have to know h...
by nehashetty_2G
Fri Oct 25, 2019 9:54 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Topics
Replies: 5
Views: 75

Re: Midterm Topics

Professor Lavelle has not put up any information about the midterm yet. However, until then I would look over everything we have covered in class so far (and compare your notes with peers to ensure you did not miss anything). I believe the midterm will also cover the content from Exam #1, but I woul...
by nehashetty_2G
Fri Oct 25, 2019 9:51 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: second quantum number
Replies: 2
Views: 48

Re: second quantum number

Yes! Those l values will always correspond to their respective s, p, d or f subshells. The only thing that changes when you move up shells (ex. n=2 to n=4) is the possibility of subshells or l-values that work for that shell. For n=2, an electron can be in l=0 or 1 and for n=4, an electron can be in...
by nehashetty_2G
Fri Oct 25, 2019 9:49 pm
Forum: Lewis Structures
Topic: Drawing Lewis Structures
Replies: 2
Views: 34

Re: Drawing Lewis Structures

That's correct! Because the compound is neutral and abides by the normal electron states of the atoms.
by nehashetty_2G
Fri Oct 25, 2019 2:11 pm
Forum: Lewis Structures
Topic: Formal Charges
Replies: 4
Views: 56

Re: Formal Charges

Also remember that if you are calculating the total formal charge of an ionic compound by adding all the individual formal charges of the elements, you want the final value to equal to the charge of the ionic compound. For example in SO4 2- the final value should add to -2 NOT ZERO. Instead, to dete...
by nehashetty_2G
Fri Oct 25, 2019 2:07 pm
Forum: Lewis Structures
Topic: Double Bonds
Replies: 6
Views: 72

Re: Double Bonds

Before considering formal charge, you usually use double bonds when you are trying to make every element satisfy the octet rule. So for example, if a compound has only 24 electrons and with your initial Lewis Structure with only single bonds you notice you are at 26 electrons, you would most likely ...
by nehashetty_2G
Fri Oct 18, 2019 12:10 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 1D. Quantum Numbers and Orbitals
Replies: 2
Views: 36

Re: 1D. Quantum Numbers and Orbitals

The number of orbitals in a subshell can be determined by ml which is equal to 2l+1. Therefore, because we know that l equal to 0 refers to the s-orbital, 1 is the p-orbital,...3 is the f-orbital, we can use this information in the question. For a) since we are looking at p, which has an l value of ...
by nehashetty_2G
Fri Oct 18, 2019 12:01 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal Planes
Replies: 10
Views: 108

Re: Nodal Planes

Nodal planes are any areas where the is zero probability of electron density. Therefore, there will be no electrons in that area.
by nehashetty_2G
Fri Oct 18, 2019 12:00 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 1D. Quantum Numbers and Orbitals
Replies: 1
Views: 41

Re: 1D. Quantum Numbers and Orbitals

The question is basically testing you on if you know the meaning of l in the context of orbitals. Remember that l equals 0 refers to the s subshell, 1 to p, 2 to d, and 3 to f. And within each of the subshells, s has 1 orbital, p has 3, d has 5, and f has 7. Therefore, for D24a the answer should be ...
by nehashetty_2G
Fri Oct 18, 2019 11:52 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 1D. Quantum Numbers and Orbitals
Replies: 2
Views: 62

Re: 1D. Quantum Numbers and Orbitals

No, Lavelle said we are not required to know how to draw any of the orbitals. Although, I think it's probably good to be familiar with what they look like (especially s and p)
by nehashetty_2G
Fri Oct 18, 2019 11:49 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbitals and Probability
Replies: 2
Views: 41

Re: Orbitals and Probability

psi by itself represents a wave function, or the position of a wave at (x,y,z). In simpler terms, one can just think of it as the height of a wave, or its position. psi^2 represents the probability of finding an e-. Also, Professor Lavelle mentioned in class that psi^2 is always positive because, #1...
by nehashetty_2G
Sun Oct 13, 2019 5:56 pm
Forum: Photoelectric Effect
Topic: confirmation.
Replies: 5
Views: 73

Re: confirmation.

Basically yeah. It always depends on the threshold frequency; any frequency less that the threshold value won't be enough energy to eject the electron.
by nehashetty_2G
Sun Oct 13, 2019 5:48 pm
Forum: Properties of Light
Topic: Speed of light.
Replies: 10
Views: 105

Re: Speed of light.

Yes - I believe at this point we will consider the speed of light/radiation as a constant because there are no changing mediums in the problems we are dealing with.
by nehashetty_2G
Sun Oct 13, 2019 5:31 pm
Forum: Photoelectric Effect
Topic: Problem 1B.15 (c)
Replies: 1
Views: 45

Problem 1B.15 (c)

How do you do 1B.15(c)? You are given that the frequency of the minimum radiation needed to eject an electron is 2.50 x 10^16 Hz and the velocity of an electron that is emitted from a metallic surface by a photon is 3.6 x 10^3 km/s. I thought this was a simple problem but I keep getting 1.2x10^-8 m ...
by nehashetty_2G
Sun Oct 13, 2019 5:26 pm
Forum: Properties of Electrons
Topic: Friday Lecture
Replies: 2
Views: 26

Re: Friday Lecture

Yeah! Essentially, electrons are described as a circular standing wave around the nucleus. Therefore, the connected line indicated a wave in line or in phase, which is stable whereas the disconnected line is a wave out of phase which is not stable. It is basically explaining why electrons have quant...
by nehashetty_2G
Sun Oct 13, 2019 2:09 pm
Forum: Properties of Light
Topic: speed of light
Replies: 10
Views: 96

speed of light

Does the speed of light always stay the same? If not, under what circumstances can it change?
by nehashetty_2G
Mon Oct 07, 2019 2:17 pm
Forum: Properties of Light
Topic: 1A- Electromagnetic Radiation
Replies: 4
Views: 70

Re: 1A- Electromagnetic Radiation

What exactly is meant by option C: "The extent of the change in the electrical field at a given point decreases"? I don't know what it has to do with electromagnetic radiation.
by nehashetty_2G
Thu Oct 03, 2019 10:32 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Avogadro's number
Replies: 9
Views: 165

Re: Avogadro's number

If you want to get into specifics, Avagadro's number is the number of Carbon-12 atoms in 1 mol of Carbon-12 (6.022x10^23 atoms). I believe that's how the number was determined way back in the day!
by nehashetty_2G
Thu Oct 03, 2019 10:27 pm
Forum: Significant Figures
Topic: Sig Fig Addition and Subtraction
Replies: 5
Views: 127

Re: Sig Fig Addition and Subtraction

I think it depends, but definitely follow rules both depending on the step you are on. Usually, you do sig figs at the end of a sequence (like in dimensional analysis); in that case you usually do the normal sig figs rules at the very end of the multiplication. But if you are adding and subtracting ...
by nehashetty_2G
Thu Oct 03, 2019 10:55 am
Forum: Balancing Chemical Reactions
Topic: Products of combustion reactions
Replies: 7
Views: 117

Re: Products of combustion reactions

I believe combustion reactions always only produce H20 and CO2. I have never seen anything other than that. The only other product other than H20 and CO2 that I can think of would be heat.

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