Search found 61 matches

by Alana Sur 3B
Sat Mar 16, 2019 8:32 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Endergonic
Replies: 2
Views: 11

Re: Endergonic

Yes
by Alana Sur 3B
Sat Mar 16, 2019 8:31 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Exergonic
Replies: 2
Views: 8

Re: Exergonic

Yes
by Alana Sur 3B
Sat Mar 16, 2019 8:27 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Lyndon #13c
Replies: 2
Views: 13

Re: Lyndon #13c

Pre exponential factor is A and you use the arrhenius equation to solve for it : k = A x e^(-Ea/RT)
by Alana Sur 3B
Sat Mar 16, 2019 8:23 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Pre-equilibrium approach q
Replies: 3
Views: 21

Re: Pre-equilibrium approach q

Yes, that's correct
by Alana Sur 3B
Sat Mar 16, 2019 8:21 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Frequency factor
Replies: 2
Views: 15

Frequency factor

What exactly is frequency factor
by Alana Sur 3B
Sat Mar 16, 2019 2:01 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: K reverse and forward
Replies: 1
Views: 13

Re: K reverse and forward

The equilibrium constant K is equal to the ratio of the rate of the forward reaction to the rate of the reverse reaction.At equilibrium, the rate of forward and reverse reactions are equal
by Alana Sur 3B
Sat Mar 16, 2019 1:49 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Microscopic Reversibilty
Replies: 1
Views: 15

Re: Microscopic Reversibilty

I think macroscopic reversibility is when one assumes that the intermediates of a forward and reverse reaction are the same. This occurs when the rate constant of the forward reaction is much larger than that of the reverse reaction
by Alana Sur 3B
Fri Mar 15, 2019 8:33 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Q6 on the midterm
Replies: 3
Views: 21

Re: Q6 on the midterm

Can we say that it is expansion work because the number of moles increased?
by Alana Sur 3B
Fri Mar 15, 2019 8:23 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Pt
Replies: 2
Views: 7

Re: Pt

We use a platinum electrode on whichever side does not have a solid. It could be both or only one of them
by Alana Sur 3B
Fri Mar 15, 2019 8:20 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: state functions?
Replies: 2
Views: 13

Re: state functions?

state functions do not depend on the path to obtain that state - only the final and initial values matter. Energy, pressure, temperature are examples of state functions
by Alana Sur 3B
Fri Mar 15, 2019 8:17 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Temperature Change
Replies: 1
Views: 12

Re: Temperature Change

If a reaction requires heat to form the products (endothermic), then an increase in temperature will favour the formation of products. If a reaction releases heat when forming the products (exothermic), an increase in temperature will favour the reverse reaction, i.e the formation of reactants.
by Alana Sur 3B
Fri Mar 15, 2019 8:14 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Midterm
Replies: 4
Views: 23

Re: Midterm

Kb is boltzmann's constant, which is given in the equation sheet.
for part two, we calculate :
w = orientations ^ # of molecules.
delta S = Kb x w
delta S = (1.38x 10^-23) (4^64)
by Alana Sur 3B
Fri Mar 15, 2019 4:16 am
Forum: Administrative Questions and Class Announcements
Topic: Lyndon's Review Sheets
Replies: 9
Views: 220

Re: Lyndon's Review Sheets

His post says he'll upload them by 9am on saturday
by Alana Sur 3B
Fri Mar 15, 2019 4:08 am
Forum: General Rate Laws
Topic: Determining the order
Replies: 3
Views: 20

Determining the order

If we're given just the balanced equation and no other information, can we figure out the order of the reaction?
by Alana Sur 3B
Thu Mar 14, 2019 10:16 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Standard cell potential and equilibrium
Replies: 3
Views: 13

Re: Standard cell potential and equilibrium

because natural log of any value greater than 1 is positive. the formula used is E = (RT/nF)(ln K)
by Alana Sur 3B
Thu Mar 14, 2019 10:12 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Calomel electrode
Replies: 1
Views: 21

Calomel electrode

Are calomel electrodes anodes? what do we need to know about them?
by Alana Sur 3B
Thu Mar 14, 2019 9:35 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Hmwrk 15.47 6th edition
Replies: 1
Views: 19

Re: Hmwrk 15.47 6th edition

It's a typo
by Alana Sur 3B
Thu Mar 14, 2019 9:33 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Hydronium
Replies: 2
Views: 21

Re: Hydronium

From what I've understood, you include it only when it's in the given equation. You can't combine ions though, just write them as given in the equations
by Alana Sur 3B
Thu Mar 14, 2019 9:27 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Calculating Entropy with Change in Temperature
Replies: 1
Views: 5

Re: Calculating Entropy with Change in Temperature

we use Cv to calculate the heat capacity of an ideal gas with constant volume. You add the two delta S values
by Alana Sur 3B
Thu Mar 14, 2019 9:21 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: cell diagram question
Replies: 1
Views: 9

Re: cell diagram question

Usually, the anode is on the left side of the salt bridge and the cathode is on the right
by Alana Sur 3B
Thu Mar 14, 2019 9:00 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: What is the difference between electrochemical series and reduction potentials?
Replies: 1
Views: 19

Re: What is the difference between electrochemical series and reduction potentials?

The electrochemical series is a series of electrodes arranged according to their decreasing order of standard reduction potentials.
by Alana Sur 3B
Tue Mar 12, 2019 11:53 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6th edition - self test 12.14A
Replies: 1
Views: 17

6th edition - self test 12.14A

I wasn't sure how to write the equation for this because of the NH3+ :

Self-Test 12.14A Estimate the pH of 0.10 m CH3NH3Cl(aq), aqueous methylammonium chloride; the cation is CH3NH3+
by Alana Sur 3B
Tue Feb 26, 2019 12:19 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 9.81 6th edition
Replies: 1
Views: 16

Re: 9.81 6th edition

Can someone pls explain why an equation that interconverts the compounds determines the more stable compound?
by Alana Sur 3B
Mon Feb 25, 2019 10:45 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Equations to use
Replies: 2
Views: 27

Equations to use

When calculating change in Gibbs free energy, when do we use the equation with change entropy and enthalpy and when do we use the gibbs free energy of formation of products and reactants? In the textbook (6th ed), the questions just say refer to appendix 2A but some of the solutions use entropy and ...
by Alana Sur 3B
Thu Jan 31, 2019 4:18 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Work Calculation
Replies: 3
Views: 48

Re: Work Calculation

I think it's because the system loses energy
by Alana Sur 3B
Thu Jan 31, 2019 4:17 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Different Kinds of Symptoms
Replies: 6
Views: 44

Re: Different Kinds of Systems

So basically a system is identified by its interaction with its surroundings. - An open system: Matter and energy can exchange with the surroundings. Eg. A glass of water - The water can evaporate and the glass does not provide any insulation. - A closed system: The amount of matter is fixed, but th...
by Alana Sur 3B
Thu Jan 24, 2019 12:55 am
Forum: Administrative Questions and Class Announcements
Topic: Final Exam Papers
Replies: 1
Views: 39

Final Exam Papers

Hi, I think Professor Lavelle said we'd get out final exams back in week 3. Does anyone know where we can get them?
by Alana Sur 3B
Wed Jan 23, 2019 9:56 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chemical Equilibrium Post Assessment part 3 q20
Replies: 2
Views: 45

Chemical Equilibrium Post Assessment part 3 q20

I'm getting a complicated polynomial equation and I'm pretty sure it's incorrect. Can someone please explain how to do this question? A vial of SO2 (0.522 mol.L-1) and O2 (0.633 mol.L-1) react and reach equilibrium. Calculate the equilibrium concentrations of the products and reactants given that KC...
by Alana Sur 3B
Tue Jan 22, 2019 10:49 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chemical equilibrium post assessment part q24
Replies: 1
Views: 31

Chemical equilibrium post assessment part q24

Can someone pls explain q24 of the Chemical Equilibrium Part 2 Post Assessment? Q. The equilibrium constant, KP, for the reaction SO2 (g) + O2 (g) ⇌ SO3 (g) at 700 K is 3 x 104. A mixture of SO2, O2, and SO3, each at 65 bars was introduced into a container at 700 K. Is the reaction at equilibrium? I...
by Alana Sur 3B
Sun Dec 09, 2018 12:46 am
Forum: Naming
Topic: Ligand Names
Replies: 4
Views: 89

Re: Ligand Names

On Prof. Lavelle's website, the link to naming of coordinate compounds says that both are acceptable.
by Alana Sur 3B
Sun Dec 09, 2018 12:45 am
Forum: Conjugate Acids & Bases
Topic: Chemical Equations
Replies: 6
Views: 70

Re: Chemical Equations

an acid donates a proton to give a conjugate base. Similarly, a base accepts a proton to give its conjugate acid
by Alana Sur 3B
Sun Dec 09, 2018 12:41 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Test 3 6b
Replies: 2
Views: 52

Re: Test 3 6b

Cations that are small and highly charged have a high polarizing power. So as you go down a group, polarizing power decreases. The order was Cs < Ba < Ca < Li
by Alana Sur 3B
Sun Dec 09, 2018 12:36 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: homework problem 6B.1
Replies: 2
Views: 34

Re: homework problem 6B.1

I assumed the initial conc = 0.1 and final conc = 0.012, calculated both pH separately and then got the difference
by Alana Sur 3B
Sun Dec 09, 2018 12:34 am
Forum: Naming
Topic: Carbonato and Sulfato - Bidentate?
Replies: 1
Views: 43

Re: Carbonato and Sulfato - Bidentate?

They're both polydentate. In the q17.33 of the 6th edition, they ask whether carbonato is polydentate
by Alana Sur 3B
Sun Dec 09, 2018 12:31 am
Forum: Quantum Numbers and The H-Atom
Topic: quantum number, spin
Replies: 3
Views: 58

Re: quantum number, spin

Magnetic spin
by Alana Sur 3B
Sun Dec 09, 2018 12:31 am
Forum: Naming
Topic: Chloro vs Chlorito
Replies: 8
Views: 75

Re: Chloro vs Chlorito

I don't think chlorito is correct. You can use either chloro or chlorido - they're both on Prof. Lavelle's website. Here's the link - https://lavelle.chem.ucla.edu/wp-conten ... pounds.pdf
by Alana Sur 3B
Sat Dec 08, 2018 11:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond angles
Replies: 3
Views: 49

Re: Bond angles

Thanks!!
by Alana Sur 3B
Sat Dec 08, 2018 11:51 pm
Forum: Naming
Topic: Order of ligands
Replies: 6
Views: 74

Order of ligands

When we're writing the formula of coordination compound , does the order in which we put the ligands in the square bracket matter?
by Alana Sur 3B
Sat Dec 08, 2018 9:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VESPR Shapes
Replies: 3
Views: 56

Re: VESPR Shapes

This is sooo helpful, thank you!!!
by Alana Sur 3B
Sat Dec 08, 2018 9:30 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Shape vs Molecular Geometry
Replies: 3
Views: 45

Re: VSEPR Shape vs Molecular Geometry

If it says geometry, it always means the shape with lone pairs and bond pairs
by Alana Sur 3B
Sat Dec 08, 2018 9:24 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond angles
Replies: 3
Views: 49

Bond angles

will the bond angles for square planar and square pyramidal be less than 90 degrees
by Alana Sur 3B
Sat Dec 08, 2018 9:16 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Calculating pH of salt solution with acidic cation
Replies: 5
Views: 70

Re: Calculating pH of salt solution with acidic cation

We don't include the products and reactants in liquid state when calculating that^^
by Alana Sur 3B
Sat Dec 08, 2018 9:15 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Calculating pH of salt solution with acidic cation
Replies: 5
Views: 70

Re: Calculating pH of salt solution with acidic cation

I don't think we don't need to remember the constants but you should know the formula for calculating Ka and Kb The formula for calculating Ka is just -log(PKa) and the formula for calculating Kb is just -log(PKb) right? And that Ka = [Concentration of product1][ Concentration of product2]/ [Concen...
by Alana Sur 3B
Sat Dec 08, 2018 9:14 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T-shaped structures
Replies: 3
Views: 47

T-shaped structures

What is the bond angle for T-shaped molecules
by Alana Sur 3B
Sat Dec 08, 2018 5:34 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Calculating pH of salt solution with acidic cation
Replies: 5
Views: 70

Re: Calculating pH of salt solution with acidic cation

I don't think we don't need to remember the constants but you should know the formula for calculating Ka and Kb
by Alana Sur 3B
Sat Dec 08, 2018 3:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: ClO2- lewis structure
Replies: 4
Views: 53

Re: ClO2- lewis structure

Cl can form double bonds due to the presence of d orbitals. The electronic configuration is an expanded octet
by Alana Sur 3B
Sat Dec 08, 2018 3:13 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Relation between Equilibrium Constant and pH
Replies: 1
Views: 27

Relation between Equilibrium Constant and pH

Is there a formula that calculates the pH when the Ka is given?
by Alana Sur 3B
Sat Dec 08, 2018 2:14 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: 6th edition q6.1
Replies: 2
Views: 48

Re: 6th edition q6.1

So in this case the fact that there are four oxygen atoms bonded to Se at equal angles has no effect because the electron pull is outwards?
by Alana Sur 3B
Sat Dec 08, 2018 2:12 pm
Forum: Calculating the pH of Salt Solutions
Topic: 6th Edition Example 12.10 -12.11
Replies: 2
Views: 43

6th Edition Example 12.10 -12.11

Do we need to know how to solve these kind of questions? It's between 12.13 and 12.14, which is in syllabus.
by Alana Sur 3B
Fri Dec 07, 2018 11:05 pm
Forum: Hybridization
Topic: Hybridization of pi bonds
Replies: 3
Views: 50

Re: Hybridization of pi bonds

I found it easier to calculate hybridization by ignoring the same number of p orbitals as there are pi bonds in a molecule and then determining the hybridization with the remaining orbitals. For example, in HCN, C has one sigma bond with H and one with N, along with two pi bonds. Since there are two...
by Alana Sur 3B
Fri Dec 07, 2018 10:59 pm
Forum: Hybridization
Topic: Lyndon’s practice question #17
Replies: 2
Views: 54

Re: Lyndon’s practice question #17

sigma(C2sp2, C2sp2) is describing the bond between the two carbon atoms. We can't use C2sp2 because we have to describe the hybridization of both atoms and I think the 2sp2 is just more specific about the principle quantum number compared to sp2
by Alana Sur 3B
Fri Dec 07, 2018 10:49 pm
Forum: Hybridization
Topic: Coefficients for hybridization
Replies: 2
Views: 70

Re: Coefficients for hybridization

I've noticed that the TAs don't put the principal quantum number when the question just asks for the hybridization but they use it when the question is about describing a bond (eg. - sigma(C 2sp3 - H 1s)
by Alana Sur 3B
Fri Dec 07, 2018 10:39 pm
Forum: Hybridization
Topic: Labeling hybridization in Test 3
Replies: 2
Views: 41

Re: Labeling hybridization in Test 3

Your hybridization was correct - 4 regions of electron density should be an sp3 hybridization
by Alana Sur 3B
Fri Dec 07, 2018 10:32 pm
Forum: Hybridization
Topic: Hybridization on Test
Replies: 3
Views: 47

Re: Hybridization on Test

Yes because we consider a lone pair as one region of electron density, which you need to determine the hybridization.
by Alana Sur 3B
Fri Dec 07, 2018 10:30 pm
Forum: Hybridization
Topic: Composition of a sigma bond with Hydrogen
Replies: 1
Views: 23

Re: Composition of a sigma bond with Hydrogen

yeah, but I think it's a safer option to write the 1 in front of the s orbital of Hydrogen - sigma (C 2sp^3, H 1s)
by Alana Sur 3B
Fri Dec 07, 2018 10:26 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond angle
Replies: 5
Views: 80

Re: Bond angle

Thank you!!!
by Alana Sur 3B
Tue Nov 27, 2018 10:17 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond angle
Replies: 5
Views: 80

Bond angle

Do AX2E and AX2E2 have the same bond angles?
by Alana Sur 3B
Fri Nov 02, 2018 10:41 pm
Forum: Bond Lengths & Energies
Topic: Bond length energies
Replies: 3
Views: 43

Re: Bond length energies

I think it's because the additional bonding electrons attract the nuclei more strongly and pull the atoms closer together, hence the length is shorter.

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