## Search found 102 matches

Tue Mar 17, 2020 8:09 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Endgame 5d
Replies: 3
Views: 203

### Re: Endgame 5d

The original equation has 2e- but since every molecule has a stoichiometric coefficient of 2 you can divide the equation by 2, so n=1 instead of 2
Sat Mar 14, 2020 9:39 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalyst's effect on overall reaction
Replies: 7
Views: 74

### Re: Catalyst's effect on overall reaction

One way to think of it is remembering the saying "a chain is only as strong as its weakest link". So, if you make the fast step faster, it won't change the fact that the slow step is still slow, which makes the reaction slow, or the "chain weak". In order to make the reaction fas...
Sat Mar 14, 2020 9:34 am
Forum: Second Order Reactions
Topic: Third Order Reactions
Replies: 3
Views: 93

### Third Order Reactions

Will we be asked to assess third order reactions on the final? There are a few assigned homework problems which involve them. I think I remember Dr. Lavelle saying we wouldn't address them in this class, but there are assigned problems involved third order reactions
Sat Mar 14, 2020 9:29 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: when doesn't a solid's temp change?
Replies: 2
Views: 118

### Re: when doesn't a solid's temp change?

I'm sure it does change but for the purposes of this question I don't think it matters. That may be a topic addressed in more advanced classes but this class seems to simplify thermodynamics to a certain extent, because it is a really complicated topic
Sat Mar 14, 2020 9:26 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: 7B.1
Replies: 3
Views: 83

### Re: 7B.1

I think if you're only given one thing (like mass) then you have to plug it in and it will work as long as you are using like values
Sat Mar 14, 2020 9:24 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Substituing in the rate law
Replies: 1
Views: 22

### Substituing in the rate law

How do you know when you need to substitute in the rate law? I.e. like the last example in Dr. Lavelle's review slides
Wed Mar 04, 2020 3:49 pm
Forum: Van't Hoff Equation
Topic: 5J.15
Replies: 3
Views: 128

### Re: 5J.15

There are multiple ways to get the answer, Van't Hoff's equation is one, but you can use △G=-RTlnK and just change the T value when solving for K which would give you K at that temperature
Wed Mar 04, 2020 3:46 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Liquids in cell diagrams
Replies: 2
Views: 42

### Re: Liquids in cell diagrams

Yeah, as the previous poster said you dont need to include H2O because it is assumed to be in the equation. But, if there is another liquid, you do have to include it. Additionally, if the two reactions occur in the same solution, then you have to add Platinum (Pt)
Wed Mar 04, 2020 3:43 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6N.3 part c
Replies: 2
Views: 60

### Re: 6N.3 part c

Yes, you need to convert Torr into atm. The conversion is 1atm=760 Torr
Wed Mar 04, 2020 3:41 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Calculating Gibbs Free Energy
Replies: 6
Views: 112

### Re: Calculating Gibbs Free Energy

G=H-TS

Enthalpy (H) and entropy (S) take into account stoichiometric coefficients, so I guess you could say that G requires you take into account stoichiometric coefficients. However, when calculating G in regards to electrochemistry, you do not take them into account.
Mon Mar 02, 2020 4:36 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Electrolysis
Replies: 2
Views: 57

### Electrolysis

What is electrolysis and how does it apply to what we've learned about redox reactions, etc?
Fri Feb 28, 2020 2:48 pm
Forum: Balancing Redox Reactions
Topic: 6K.1 part b
Replies: 1
Views: 17

### Re: 6K.1 part b

You add electrons to balance the charges of either side of the reaction. Also, you have to multiply an equation by a number sometimes in order to get the electrons in both half reactions to cancel out
Fri Feb 28, 2020 2:40 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Corrosion Causes
Replies: 1
Views: 27

### Corrosion Causes

What causes corrosion and how is it an example of a redox reaction?
Fri Feb 28, 2020 2:37 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: finding top of your series
Replies: 3
Views: 41

### Re: finding top of your series

I think the strongest oxidizing agent is the one that has the most positive E value. So, for example Ag+ + e- -> Ag (E=.80V) and AgBr + e- -> Ag + Br-(E= .07V). In this case, the first reaction is the better oxidizing agent
Fri Feb 28, 2020 2:29 pm
Forum: Balancing Redox Reactions
Topic: Writing half reactions
Replies: 9
Views: 130

### Re: Writing half reactions

I think it's best to keep oxidized molecules on the left and reduced on the right because this is how you write out cell diagrams (oxidized II reduced)
Fri Feb 28, 2020 2:26 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 5g. 13)
Replies: 3
Views: 52

### Re: 5g. 13)

The solution is simply substituting variables; standard delta G = -RTlnK to give the equation Delta G= -RTlnK + RTlnQ. I don't believe it has anything to do with equilibrium
Wed Feb 19, 2020 7:33 pm
Forum: Balancing Redox Reactions
Topic: Balancing Redox
Replies: 5
Views: 66

### Re: Balancing Redox

What about for the transition metals? How do you determine the charges of those?
Wed Feb 19, 2020 7:31 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: E as intensive property
Replies: 5
Views: 61

### E as intensive property

In class it was said that E was an intensive property. What does that mean and what are the implications for our use of E and calculating it?
Wed Feb 19, 2020 7:28 pm
Forum: Van't Hoff Equation
Topic: 5G.21
Replies: 4
Views: 149

### Re: 5G.21

You’d use the equation G=-RTlnK. You want to solve for K so you’d rearrange the equation to be -G/RT=lnK. You have all the values needed besides G which you can get from appendix 2A, and then you solve for K!
Wed Feb 19, 2020 7:25 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 5G.3 Reading in Outline 4
Replies: 1
Views: 28

### Re: 5G.3 Reading in Outline 4

I would assume not if it’s not in the outlines on the class website. There’s a lot of topics in the book that aren’t taught so just look at the syllabus for clarification
Wed Feb 19, 2020 5:56 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: converting T to kelvin
Replies: 21
Views: 379

### Re: converting T to kelvin

I think it's important to convert C to K just to be safe; a lot of times using K will make it so the units cancel, so I just always convert C to K to be safe
Tue Feb 11, 2020 9:18 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Partial Pressure equilibrium problems
Replies: 2
Views: 37

### Partial Pressure equilibrium problems

How do you go about solving problems asking for the partial pressure of the reactants/products? Would you solve for the partial pressure first and then complete the ICE table or...?
Tue Feb 11, 2020 9:16 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: U(total)=(3/2)nrt
Replies: 2
Views: 43

### Re: U(total)=(3/2)nrt

using 3/2R is for if there is constant volume in the process
Tue Feb 11, 2020 9:14 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: 4G.5 Trans Isomer
Replies: 1
Views: 21

### Re: 4G.5 Trans Isomer

The two red molecules only have to be opposite of each other; so, they can be in the orientation shown in the diagram, or they could be on the horizontal plane, across from each other in two different ways
Tue Feb 11, 2020 9:11 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 4F.3 Reversible Process
Replies: 2
Views: 28

### Re: 4F.3 Reversible Process

Maybe it's because the heat can be given off from the copper block?
Tue Feb 11, 2020 9:09 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Delta S(total)
Replies: 3
Views: 29

### Re: Delta S(total)

Since entropy is a state function, Delta S could be equal to zero if you return to your "starting point". So, if you increase the volume of a container containing gas and then compress it to its original volume, delta S would be zero
Wed Feb 05, 2020 2:57 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: q/T=H/T
Replies: 1
Views: 38

### q/T=H/T

Today in lecture, Dr Lavelle had a slide going over entropy in phase changes and one equation on that page said q(rev)/T=deltaH/T. Can someone please explain this concept?
Wed Feb 05, 2020 2:55 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: heat given off by rxn = - heat absorbed by solution
Replies: 6
Views: 80

### Re: heat given off by rxn = - heat absorbed by solution

Yeah, whenever a system loses energy in whatever form, that value will be negative. But, that energy must go somewhere else so the energy will be absorbed by another system, so it will be positive for that system
Wed Feb 05, 2020 2:53 pm
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: 3rd Law
Replies: 4
Views: 39

### 3rd Law

Can someone please explain what the 3rd law of thermo says? I wasn't quite clear on it when Lavelle explained it, I felt like it was very brief. Thanks!
Wed Feb 05, 2020 2:51 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: internal energy of an ideal gas
Replies: 2
Views: 42

### Re: internal energy of an ideal gas

In addition to the previous poster, since the reaction is isothermal, the temperature is constant, so the heat can slowly enter the system and offset the energy lost by work. It's important to note that this happens when the reaction is isothermal
Wed Feb 05, 2020 2:48 pm
Forum: Calculating Work of Expansion
Topic: Understanding equation for work at constant pressure
Replies: 3
Views: 34

### Re: Understanding equation for work at constant pressure

Do you mean w= -nRTln(V2/V1)? This equation comes from taking the integral of (nRT)(dV)/V. You can pull the constants out in front of the integral sign so you have -nRT multiplied by the integral of dv/V from V1 to V2, which is ln(V2/V1)
Fri Jan 31, 2020 7:10 pm
Forum: Calculating Work of Expansion
Topic: Difference between irreversible/reversible reaction?
Replies: 2
Views: 39

### Difference between irreversible/reversible reaction?

What is the difference between irreversible/reversible reactions? Can someone please give an example?
Fri Jan 31, 2020 7:08 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: When to leave out reactants/products from enthalpy calculations
Replies: 4
Views: 40

### When to leave out reactants/products from enthalpy calculations

How do you know when a compound is in its purest form, aka when it won't impact enthalpy change?
Fri Jan 31, 2020 7:04 pm
Forum: Phase Changes & Related Calculations
Topic: Phase Changes
Replies: 17
Views: 166

### Re: Phase Changes

The temperature must be high enough to cause the phase change but not high enough to cause the system to change temperature
Fri Jan 31, 2020 7:02 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: q=nCT
Replies: 2
Views: 23

### q=nCT

For this equation, will n always be in moles? In the book solutions, I've seen both moles and grams used and am not sure when to use which
Fri Jan 31, 2020 6:50 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4A.13
Replies: 4
Views: 43

### 4A.13

In the solution, it shows q(reaction) equal to -q(calorimeter). Why is this? And how do you know when to use this method?
Thu Jan 23, 2020 12:58 pm
Forum: Ideal Gases
Topic: Equilibrium Constant
Replies: 7
Views: 73

### Re: Equilibrium Constant

K is represented by the products/reactants. So, if K is really small (less than 10^-3) then there are more reactants than products
Thu Jan 23, 2020 12:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Buffers
Replies: 3
Views: 35

### Buffers

How do you know when it's appropriate to make a buffer? As in, what in a question tells you you need to make a buffer?
Thu Jan 23, 2020 12:25 pm
Forum: Phase Changes & Related Calculations
Topic: State Property
Replies: 6
Views: 65

### Re: State Property

A state property does not depend on the path taken to obtain that state. Some examples are energy, pressure, volume, and temperature
Thu Jan 23, 2020 12:22 pm
Forum: Phase Changes & Related Calculations
Topic: Heating curve
Replies: 2
Views: 56

### Re: Heating curve

https://s3-us-west-2.amazonaws.com/courses-images/wp-content/uploads/sites/752/2016/09/26195026/ating-20curve-20of-20water.jpeg maybe this picture of the heating curve for water will help. As the previous poster said, it requires a lot of energy to turn water into a vapor which is why steam can cau...
Thu Jan 23, 2020 12:12 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Buffers
Replies: 3
Views: 55

### Re: Buffers

Lavelle gave an example of creating a buffer in class so I would think it's possible for it to be on the test, or even the midterm and final
Thu Jan 16, 2020 4:01 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Change in pressure effect on reactions
Replies: 3
Views: 28

### Change in pressure effect on reactions

How does a reaction respond in response to pressure? I was confused when Lavelle was explaining this in class
Thu Jan 16, 2020 3:57 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: When to find pressure for equilibrium problems
Replies: 3
Views: 29

### When to find pressure for equilibrium problems

When do we have to find the partial pressure for the gases involved in an equilibrium problem? There are gases in essentially every equilibrium problem but their partial pressures are not always calculated.
Thu Jan 16, 2020 3:54 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q and K
Replies: 4
Views: 40

### Q and K

What does it mean in terms of which way the reaction will proceed if Q is less than K? Greater than K?
Thu Jan 16, 2020 3:53 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: percentage reacted
Replies: 3
Views: 58

### Re: percentage reacted

To find x, you would set .133-x (the statement for the final H2 concentration) equal to .40 x .133mol/L because 60% of the H2 was used, so 40% remains
Thu Jan 16, 2020 3:47 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Inert Gas
Replies: 7
Views: 72

### Inert Gas

How do you tell if a gas is an inert gas?
Sat Jan 11, 2020 7:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: States of matter [ENDORSED]
Replies: 4
Views: 31

### Re: States of matter[ENDORSED]

solids/liquids aren't included in the equilibrium constant because their concentrations don't change enough to affect K
Tue Jan 07, 2020 3:16 pm
Forum: Ideal Gases
Topic: ICE Table Variables
Replies: 6
Views: 99

### Re: ICE Table Variables

Using "x" in the ICE tables would definitely be helpful if the problem is complicated enough, but if it's simple and you can figure out the change without variables, that might be easier
Tue Jan 07, 2020 3:10 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: How to make ICE box
Replies: 17
Views: 349

### How to make ICE box

I understand the initial and equilibrium rows in the ICE box but how do you figure out the change row? That is, how do you figure out what the change in concentration will be?
Tue Jan 07, 2020 3:06 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: HW 5I.5
Replies: 3
Views: 57

### HW 5I.5

What does the unit bar stand for in problem I5? Is it just another unit for pressure?
Tue Jan 07, 2020 3:03 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc vs Kp
Replies: 2
Views: 47

### Kc vs Kp

when do you write the equilibrium constant as Kc as opposed to Kp?
Mon Dec 02, 2019 1:56 pm
Forum: Octet Exceptions
Topic: 2.27
Replies: 7
Views: 232

### Re: 2.27

Yes, only species with odd numbers of electrons are radicals (ex CH3 has 7 valence electrons so it is a radical)
Mon Dec 02, 2019 1:51 pm
Forum: Lewis Acids & Bases
Topic: Relationship between Bronsted and Lewis Acids and Bases
Replies: 2
Views: 33

### Relationship between Bronsted and Lewis Acids and Bases

What is the relationship between Bronsted and Lewis acids and bases? Can a molecule be both?
Mon Dec 02, 2019 1:44 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: Stronger london forces
Replies: 1
Views: 64

### Stronger london forces

what can make london forces stronger?
Mon Dec 02, 2019 1:38 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelating complexes
Replies: 6
Views: 98

### Chelating complexes

What makes it possible for a chelate to form and how could you tell if it was possible?
Mon Dec 02, 2019 1:33 pm
Forum: Biological Examples
Topic: Chromium, Iron, Cobalt functioms
Replies: 1
Views: 72

### Chromium, Iron, Cobalt functioms

What are the functions of Cr, Fe, and Co in biological systems? And how deeply will we be expected to know how they perform their function?
Mon Dec 02, 2019 1:25 pm
Forum: Hybridization
Topic: Textbook Focus
Replies: 2
Views: 59

### Re: Textbook Focus

I don't think there's any specific reason why sp3 is focused on. It is very common but there isn't anything special about it as far as I know.
Mon Dec 02, 2019 1:24 pm
Forum: Conjugate Acids & Bases
Topic: Conjugate vs Bronsted acids/bases
Replies: 4
Views: 55

### Re: Conjugate vs Bronsted acids/bases

Bronsted acid: a species that donates a proton Bronsted base: a species that accepts a proton Conjugate base: what is left over after an acid donates a proton Conjugate acid: what is formed when a base accepts a proton Bronsted acids have conjugate bases and Bronsted bases have conjugate acids. In t...
Mon Dec 02, 2019 1:18 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: seesaw
Replies: 4
Views: 89

### Re: seesaw

KA x KB= KW

So, as KA increases, KB will decrease. As KB increases, KA will decrease. The two values must always equal KW so they will change in accordance with the concentration of one another.
Mon Dec 02, 2019 1:16 pm
Forum: Amphoteric Compounds
Topic: 6A17
Replies: 2
Views: 42

### Re: 6A17

For me, I had trouble with knowing how c and d were amphoteric. Metalloids are amphoteric and they are marked on the periodic table as the elements that are between the metals and nonmetals; they follow a diagonal band.
Mon Dec 02, 2019 1:13 pm
Forum: Bronsted Acids & Bases
Topic: Lecture 12/2
Replies: 3
Views: 41

### Lecture 12/2

At the end of class Lavelle said that something about weak acids and bases affecting pH... did he say that weak acids and bases DO affect pH or do NOT affect pH? I didn't catch it. Thanks!
Sat Nov 23, 2019 10:25 pm
Forum: Naming
Topic: English v Latin names
Replies: 2
Views: 37

### English v Latin names

When is it appropriate to use the English and latin name of an element when naming a coordination compound?
Sat Nov 23, 2019 10:24 pm
Forum: Resonance Structures
Topic: Bond Length/Delocalized Electrons
Replies: 2
Views: 140

### Re: Bond Length/Delocalized Electrons

Resonance structures cause the length of a bond to change slightly. Although there are multiple lewis structures for resonance structures, the true structure of the molecule is a blend of the resonance structures. This means the bond lengths are a blend between single, double bonds, causing the bond...
Sat Nov 23, 2019 10:21 pm
Forum: Sigma & Pi Bonds
Topic: HW 2F.3.
Replies: 2
Views: 51

### Re: HW 2F.3.

Yes, the most important thing is to draw the Lewis structure correctly and then from there it should be simple using the rules the previous poster stated to count the sigma and pi bonds
Sat Nov 23, 2019 10:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T-shaped v. Trigonal pyramid
Replies: 9
Views: 109

### Re: T-shaped v. Trigonal pyramid

T- shaped has a trigonal bipyramidal arrangement, but has 2 lone pairs and 3 bonds (AX3E2). Trigonal pyramid has a tetrahedral arrangement but has one lone pair and 3 bonding pairs (AX3E)
Thu Nov 21, 2019 4:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond angles for trigonal bipyramidal and octahedral
Replies: 2
Views: 42

### Bond angles for trigonal bipyramidal and octahedral

What are the bond angles for Trigonal Bipyramidal and octahedral arrangements when they have one and two lone pairs? i.e. bond angles for seesaw, t shaped, square pyramidal and square planar?
Sat Nov 16, 2019 4:32 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: strongest intermolecular forces
Replies: 7
Views: 141

### strongest intermolecular forces

What are the strongest intermolecular forces in order? I know induced dipole-induced dipole is the weakest but where do the other forces fall into the ranking of strongest intermolecular forces?
Sat Nov 16, 2019 4:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Octahedral with lone pair(s) shape
Replies: 1
Views: 26

### Octahedral with lone pair(s) shape

What shape would you get if a molecule with an octahedral arrangement has one lone pair? Two lone pairs?
Sat Nov 16, 2019 4:15 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: Types of Forces
Replies: 2
Views: 41

### Re: Types of Forces

All molecules can have induced dipole-induced dipole bonding, even polar ones. Problem 3f.1 in the book is an example of this. Part (a) and (d) are listed as being able to have induced dipole-induced dipole interactions along with dipole-dipole interactions
Sat Nov 16, 2019 4:12 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: Dipole-dipole in H2SeO4
Replies: 3
Views: 54

### Re: Dipole-dipole in H2SeO4

The structure of this molecule would have Se at the center and 4 oxygen's around it, then hydrogens bonded to the oxygens. This causes the molecule to be polar because O and H have a significant enough electronegativity difference to cause a polar bond. Therefore this molecule can have dipole-dipole...
Sat Nov 16, 2019 4:09 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 Points
Replies: 9
Views: 135

### Boiling Points

What intermolecular forces cause higher boiling points? Lower boiling points? And what are some examples?
Sat Nov 09, 2019 6:29 pm
Forum: Dipole Moments
Topic: Dipole-Dipole Interactions / H-bonding
Replies: 2
Views: 30

### Re: Dipole-Dipole Interactions / H-bonding

Yes, hydrogen bonding is a type of dipole-dipole interaction. It is not as strong as covalent or ionic bond
Sat Nov 09, 2019 6:25 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarisability
Replies: 3
Views: 52

### Re: Polarisability

Larger molecules are more polarizable because the electrons in the outer shell are easier to take away. This is because they are "shielded" from the nucleus by the other electrons so they can be taken away from the atom easier.
Sat Nov 09, 2019 6:18 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polairzability characteristics
Replies: 3
Views: 73

### Polairzability characteristics

In lecture on Friday, Lavelle said that if an atom is highly polarizable, it is solid at room temperature. Why is this?
Sat Nov 09, 2019 6:14 pm
Forum: Bond Lengths & Energies
Topic: Hydrogen Bonding melting point
Replies: 3
Views: 53

### Hydrogen Bonding melting point

Why does hydrogen bonding explain higher melting points? I missed Lavelle's explanation on why this was the case
Sat Nov 09, 2019 6:06 pm
Forum: Electronegativity
Topic: Periodic Trend
Replies: 13
Views: 199

### Re: Periodic Trend

Electronegativity increases up a column and left to right across a period. The noble gasses are exceptions because they have a full octet so they are not trying to take any electrons. One way to think of electronegativity is how bad an atom wants an electron.
Sat Nov 02, 2019 9:23 am
Forum: Resonance Structures
Topic: Tips for drawing resonance structures
Replies: 3
Views: 51

### Tips for drawing resonance structures

Does anyone have any advice for figuring out the various resonance structures?
Sat Nov 02, 2019 9:21 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron configuration rules
Replies: 1
Views: 47

### Electron configuration rules

What do each of the rules for electron configurations ( pauli's, hund's, aufbau) mean and what would and electron configuration look like if you violated them?
Sat Nov 02, 2019 9:19 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Electron configuration rules
Replies: 1
Views: 39

### Electron configuration rules

What do each of the rules for electron configurations ( pauli's, hund's, aufbau) mean and what would and electron configuration look like if you violated them?
Sat Nov 02, 2019 9:15 am
Forum: Trends in The Periodic Table
Topic: Electronegativity trend exception
Replies: 3
Views: 54

### Electronegativity trend exception

Last night in the review session with Lyndon, it was said that Nitrogen has a higher electronegativity than oxygen. Can someone explain why this is?
Sat Nov 02, 2019 9:13 am
Forum: Properties of Light
Topic: Wavelengths
Replies: 2
Views: 66

### Re: Wavelengths

yeah, I don't think we need to know exact cutoffs but it is important to know in what range visible light is and the ranges for infrared and ultraviolet. ultraviolet light is less than 400nm and infrared is more than 700nm. You don't have to state any info about the light type or if its visible unle...
Sat Nov 02, 2019 9:06 am
Forum: Octet Exceptions
Topic: Octet Exception
Replies: 5
Views: 77

### Re: Octet Exception

The elements in period three and the subsequent periods along with the column 13 elements are exceptions to the octet rule
Fri Oct 25, 2019 4:17 pm
Forum: Ionic & Covalent Bonds
Topic: ground-state configuration of ions
Replies: 4
Views: 48

### Re: ground-state configuration of ions

Yes, it is [Ar] 3d^10 because Cu+ loses an electron. When this type of situation comes up, you always remove or add an electron from the outer shell
Fri Oct 25, 2019 4:13 pm
Forum: Octet Exceptions
Topic: Determining Exceptions
Replies: 3
Views: 86

### Re: Determining Exceptions

So far the only exception to the octet rule that we've learned is that atoms in period 3 and higher can have more than 8 electrons in their outer shell due to the possibility of having a d orbital (as l can equal 0,1, and 2 when n=3)
Fri Oct 25, 2019 4:09 pm
Forum: Trends in The Periodic Table
Topic: Stable Structures
Replies: 5
Views: 112

### Re: Stable Structures

Yes, you use FC = V - (L + S/2). Not all structures will have a formal charge equal to 0 but you want to find the structure that is closest to that value. Also, remember you have to find the formal charge for each atom
Fri Oct 25, 2019 4:04 pm
Forum: Resonance Structures
Topic: Delocalization
Replies: 2
Views: 60

### Re: Delocalization

Like the previous poster said, delocalization is when there is resonance in the structure of the molecule. You know an electron is delocalized when it is possible for structures to have multiple bonds in different locations (ex. NO3 example from class; the double bond with nitrogen and oxygen can be...
Fri Oct 25, 2019 3:59 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 6
Views: 471

### Re: Formal Charge

The formal charge is the charge on each atom and it is calculated after a Lewis structure is made. They are useful to calculate so you know "good" you structure is; the closer the formal charge is to zero, the better the model
Thu Oct 17, 2019 10:13 am
Forum: Properties of Electrons
Topic: 1B. 15C [ENDORSED]
Replies: 4
Views: 132

### Re: 1B. 15C[ENDORSED]

The energy required to remove the electron is added to the electron's kinetic energy because you need the total energy that caused the electron not only to be ejected but to be ejected at 3.63 x 10^3 km/s. So, because the electron was ejected at that speed, the energy required to eject it is added t...
Thu Oct 17, 2019 10:08 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbital shapes
Replies: 3
Views: 58

### Orbital shapes

Is there a trick to remembering what all the orbital shapes look like? As in, is there a method to remembering what dxy, dy2, d2x,dx2y2, etc all look like?
Thu Oct 17, 2019 10:02 am
Forum: Properties of Light
Topic: Vacuum
Replies: 3
Views: 59

### Re: Vacuum

I agree with the previous post, but to simplify it, being in a vacuum means there are no outside forces working on a given thing.
Thu Oct 17, 2019 10:00 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: HW D13
Replies: 3
Views: 72

### HW D13

For part c and d, how would you go about determining the values asked for from the given state of the electron? I guess my bigger question is how would you figure out values of n,l, and ml from a given 6d subshell, or something like that?
Thu Oct 17, 2019 9:57 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Spin State
Replies: 17
Views: 150

### Spin State

What do the +1/2 and -1/2 mean with regards to spin state? Is it the direction in which the electron spins? And how would the spin state be determined?
Sat Oct 12, 2019 3:16 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Textbook 1B.25
Replies: 1
Views: 35

### Re: Textbook 1B.25

The equation for the uncertainty equation is (delta p)(delta x)>(h)/(4pi), where h is planck's constant of 6.63x10^-34, delta p is the spread in values of momentum, and delta x is the spread in values of distance.

Hopefully that helps with the mathematical representation.
Sat Oct 12, 2019 3:07 pm
Forum: Photoelectric Effect
Topic: Molecular Spectroscopy
Replies: 3
Views: 84

### Re: Molecular Spectroscopy

It can be, as, just like various atoms, various molecules absorb different types of light, just like atoms.
Sat Oct 12, 2019 2:59 pm
Forum: Properties of Electrons
Topic: Wavelike properties of electrons
Replies: 3
Views: 67

### Re: Wavelike properties of electrons

Wavelike properties can be seen in very small things (like an electron) with a high velocity. This why wavelike properties are noticed in electrons, and not other objects like a car. All things have wavelike properties but they are not detectable. In the car example, it is too large for its waveleng...
Sat Oct 12, 2019 2:52 pm
Forum: Properties of Light
Topic: Equations
Replies: 4
Views: 52

### Re: Equations

Most of the equations we've learned to apply to EMR, but as others have said, not the De Broglie Equation. Something that may help you remember this is that most of the equations we've learned have similar or related variables and the De Broglie equation involves mass and velocity (momentum) so they...
Sat Oct 12, 2019 2:45 pm
Forum: Limiting Reactant Calculations
Topic: percent yield
Replies: 10
Views: 351

### Re: percent yield

I believe you only find the percent yield if it is asked in the question, but there may be some scenarios where you need it for a step in the problem. Also, questions don't always explicitly ask what they want you to find so be aware of that
Thu Oct 03, 2019 3:07 pm
Forum: Limiting Reactant Calculations
Topic: Fundamentals M15
Replies: 3
Views: 63

### Fundamentals M15

Thu Oct 03, 2019 3:02 pm
Forum: Balancing Chemical Reactions
Topic: Fundamentals H21
Replies: 2
Views: 94

### Fundamentals H21

For this problem, how would you write its chemical formula? I understand the corresponding compounds for carbon dioxide, oxygen, and water, but I'm not sure about the aqueous solution part of the products.
Thu Oct 03, 2019 2:51 pm
Forum: Balancing Chemical Reactions
Topic: Fundamentals L39
Replies: 2
Views: 101

### Fundamentals L39

I'm a bit confused on how to go about this problem. Does anybody have any hints or ideas? How would we know what the oxide is?