## Search found 50 matches

Sun Mar 18, 2018 2:13 pm
Forum: *Carboxylic Acids
Topic: Functional Groups
Replies: 4
Views: 810

### Re: Functional Groups

My TA said we will probably have to identify them in complex molecules but not have to draw them individually.
Sun Mar 18, 2018 2:12 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Homework 14.15c : KOH in cell diagram
Replies: 2
Views: 222

### Re: Homework 14.15c : KOH in cell diagram

Yes you can use just OH because K is not involved in the redox reactions.
Sun Mar 18, 2018 2:10 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Replies: 5
Views: 465

Doesn't necessarily mean it is always reversible, but it will always be transferred as work because q=0.
Sun Mar 18, 2018 2:08 pm
Forum: General Rate Laws
Topic: The Collision Model and Activated Complex Model
Replies: 3
Views: 429

### Re: The Collision Model and Activated Complex Model

Collision theory has to collide at same time, same orientation and enough energy to overcome the activation energy.
Sun Mar 18, 2018 2:07 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Phase changes and entropy
Replies: 5
Views: 378

### Re: Phase changes and entropy

Delta H is equal to q at a constant pressure.
Sun Mar 18, 2018 2:03 pm
Forum: *Identifying Primary, Secondary, Tertiary, Quaternary Carbons, Hydrogens, Nitrogens
Topic: Final
Replies: 3
Views: 635

### Re: Final

I would assume both just complex because you'd have to understand what the functional groups are
Sun Mar 18, 2018 2:01 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Putting an Ice cube into a glass of water
Replies: 4
Views: 736

### Re: Putting an Ice cube into a glass of water

You're right--you do need delta H of fusion because heat is lost from ice to water.
Sun Mar 18, 2018 1:58 pm
Forum: Second Order Reactions
Topic: Derivations
Replies: 4
Views: 519

### Re: Derivations

It is postitive because y=mx+b so the slope is positive.
Sun Mar 18, 2018 1:58 pm
Forum: Second Order Reactions
Topic: Derivations
Replies: 4
Views: 519

### Re: Derivations

For the first question, in the integrated rate law, kt is positive, so that is why we use pos slope.
Sun Mar 18, 2018 1:49 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Kinetically controlled reactions
Replies: 2
Views: 232

### Re: Kinetically controlled reactions

Yes Alexander is right. Even though a reaction might be thermodynamically favorable, it still has to overcome an activation energy.
Sun Mar 18, 2018 1:46 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Cp and Cv
Replies: 5
Views: 317

### Re: Cp and Cv

Cp and Cv are usually just used for different conditions, either constant pressure or constant volume. I'm not sure when u would switch.
Sun Mar 18, 2018 1:44 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: steady state vs pre equilibrium
Replies: 3
Views: 285

### Re: steady state vs pre equilibrium

Pre equilibrium is easy to use but is not as flexible at steady state approximations which is usually used for complex mechanisms.
Sun Mar 18, 2018 1:42 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Maximum Work
Replies: 3
Views: 313

### Re: Maximum Work

It is a part of the laws of thermodynamics.
Sun Mar 18, 2018 1:40 pm
Forum: Phase Changes & Related Calculations
Topic: carbon
Replies: 4
Views: 319

### Re: carbon

You have to sublimize Carbon to the gaseous state because deltaH has to have them all as gasses.
Fri Mar 16, 2018 10:09 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Strength of Reducing Agents and Strength of Oxidizing Agents
Replies: 3
Views: 303

### Re: Strength of Reducing Agents and Strength of Oxidizing Agents

OIL RIG Oxidation is losing (electrons) and Reduction is gaining (electrons)
Fri Mar 16, 2018 10:08 pm
Forum: *Nucleophiles
Topic: nucleophile?
Replies: 4
Views: 515

### Re: nucleophile?

The molecule that is substituting the leaving group.
Fri Mar 16, 2018 10:08 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 15.109
Replies: 2
Views: 176

### Re: 15.109

In order to subtract the 1/T and 1/T' you have to have a common denominator. so you multiply both by the others denominator.
Fri Mar 16, 2018 9:48 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.91
Replies: 1
Views: 123

### Re: 14.91

The anode is more negative so it makes sense that it is receiving negative electrolytes.
Fri Mar 16, 2018 9:44 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.99
Replies: 1
Views: 188

### Re: 8.99

This is the idea that in a perfect system q(metal)+q(water)=0 so making overall q(water) negative, will be equal to q(metal).
Fri Mar 16, 2018 9:33 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 8.51b
Replies: 1
Views: 174

### Re: 8.51b

Yes it is because it is already in kJ/mol
Fri Mar 16, 2018 9:21 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Work and derivations
Replies: 2
Views: 281

### Re: Work and derivations

For calculating delta n (change in moles) we look at gas phase molecules in the chem equation because those are the only ones that will affect work done. In this problem, were given 6mol H20 and 6 mol CO2 in gas phase on products, totaling 12 moles, and 6 mol O2 on gas phase on the reactants (we ign...
Fri Mar 16, 2018 9:17 pm
Forum: Balancing Redox Reactions
Topic: determining cathode from anode
Replies: 11
Views: 524

### Re: determining cathode from anode

You would look at the standard cell potentials. The most positive is the cathode. Also, cathode-(anode) should be positive.
Fri Mar 16, 2018 9:13 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: Degeneracy
Replies: 1
Views: 185

### Re: Degeneracy

Number of orientations raised to the number of molecules. This tells you all of the possible orientations the molecules can have.
Fri Mar 16, 2018 9:11 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 15.61
Replies: 2
Views: 139

### Re: 15.61

We didn't go over this derivation and also are not responsible for knowing it.
Fri Mar 16, 2018 9:10 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: delta S for reversible and irreversible reactions
Replies: 1
Views: 174

### Re: delta S for reversible and irreversible reactions

When it is reversible, the system is at equilibrium so it =0. When deltaS >0 the reaction is spontaneous, which is a part of the second law of thermodynamics
Fri Mar 16, 2018 9:07 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: 14.119
Replies: 2
Views: 408

### Re: 14.119

The half reactions only include the elements that are being oxidized or reduced. The net ionic equation will include all elements (and spectator ions) to balance the two sides.
Fri Mar 16, 2018 9:03 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: S and delta S
Replies: 4
Views: 302

### Re: S and delta S

S is the residual entropy while delta S is the change in entropy.
Fri Mar 16, 2018 9:02 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: electrode surface area and voltage
Replies: 1
Views: 168

### Re: electrode surface area and voltage

Cell potential only depends on concentration so electrode surface area doesn't affect it.
Sun Jan 14, 2018 5:26 pm
Forum: Phase Changes & Related Calculations
Topic: 8.41
Replies: 4
Views: 237

### Re: 8.41

You have to solve by melting the ice, and then by bringing the liquid to the final temperature (which is endothermic/requiring heat). Heat absorbed by ice cube = (50g/18.02g*mol )(6.01*10^3 J*mol^-1) + 50g*4.184J*C^-1 *g^-1 * (Final Temperature-0 degrees C) Heat released by liquid water = (400g)(4.1...
Sun Jan 14, 2018 5:15 pm
Forum: Phase Changes & Related Calculations
Topic: 8.45 part C
Replies: 2
Views: 161

### Re: 8.45 part C

I used a ratio so I set up 358.8kj/4 molCS2 = 415kj/x moles and then I solved for x.
Sun Dec 10, 2017 12:45 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Percent Ionization Formula
Replies: 1
Views: 394

### Re: Percent Ionization Formula

The amount ionized(starting-ending)/starting amount *100 would be the percentage
Sun Dec 10, 2017 12:39 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Effect of water
Replies: 2
Views: 256

### Re: Effect of water

It depends on if the reactants or products are aqueous. If they were, adding water would change the molarity and thus the reaction and how it proceeds.
Sun Dec 10, 2017 12:38 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Test 4 #6
Replies: 2
Views: 291

### Re: Test 4 #6

For my test 4 #6, There were only 3 values? A + B <---> 2C. If you are asking about the 2 on the 2C, it would come into play for the change line of the ICE table (and be 2x instead of x).
Sun Dec 10, 2017 12:36 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Replies: 2
Views: 256

^^^ Yes I also believe this to be right. The equation would specify by including the physical properties of the reactants and products in the equation. If any were aqueous then you would know to watch out for that
Sun Dec 10, 2017 12:34 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Compression effect on a system
Replies: 2
Views: 239

### Re: Compression effect on a system

Just to expand, the equation will shift towards the side with less moles of gas in an attempt to reduce the pressure and return to equilibrium
Sun Dec 10, 2017 12:33 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Significant figures in calculations
Replies: 1
Views: 204

### Re: Significant figures in calculations

Yes it would be the same number of SF as the K value
Sun Dec 10, 2017 12:32 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Changing Stoichiometric Coefficients
Replies: 2
Views: 435

### Re: Changing Stoichiometric Coefficients

The coefficients are superscripts for equilibrium expressions so when it said half coefficients, I put the half in the superscript of the x. If it said double all coefficients, you would have x^2
Wed Nov 15, 2017 1:13 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Bond Order
Replies: 5
Views: 351

### Re: Bond Order

The .5 in bond order indicates resonance. 1.5 bond order is going to be the average of single and double bonds in a resonance hybrid
Wed Nov 15, 2017 1:09 pm
Forum: Bond Lengths & Energies
Topic: Factors that control bond length
Replies: 3
Views: 832

### Re: Factors that control bond length

For covalent, the difference in electro negativity will determine if the bond is either polar or non polar. And yes the increasing number of bonds decreases the bond length. Higher bond order (number of bonds) indicated more attraction between electrons and the atoms will be held closer together
Wed Nov 15, 2017 1:04 pm
Forum: Electronegativity
Topic: Isoelectronic [ENDORSED]
Replies: 11
Views: 661

### Re: Isoelectronic[ENDORSED]

Also means they have the same electronic structure and will have similar chemical properties
Wed Nov 15, 2017 1:02 pm
Forum: Octet Exceptions
Topic: Why do octets expand?
Replies: 4
Views: 327

### Why do octets expand?

I have memorized that there can be octet expansions for elements in the 3rd period and beyond but I don't think I really understand why that is? I usually remember things better when I understand everything versus just memorizing so can someone please explain? Thanks!
Wed Nov 15, 2017 12:57 pm
Forum: Hybridization
Topic: Hybridization beyond d orb
Replies: 1
Views: 119

### Hybridization beyond d orb

We have mostly just looked at the hybridizations of elements with a maximum of d orbitals, but what would the hybridization for an atom with say an f orbital look like?
Wed Nov 15, 2017 12:53 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration of Gallium
Replies: 3
Views: 1065

### Re: Electron Configuration of Gallium

Yes, even though you fill the 4s before the 3d orbital, you should write it in order of ascending energy, which would be 3d then 4s. This also makes it easier to see what electrons will be ionized (from the highest energy orbital)
Wed Nov 15, 2017 12:50 pm
Forum: Lewis Structures
Topic: Expanded Valence Shell
Replies: 2
Views: 169

### Re: Expanded Valence Shell

I believe that in general, not more that 16 electrons will be involved
Wed Nov 15, 2017 12:46 pm
Forum: Sigma & Pi Bonds
Topic: # of sigma and pi bonds [ENDORSED]
Replies: 4
Views: 314

### Re: # of sigma and pi bonds[ENDORSED]

And in each double/triple bond, the first bond will be a sigma bond, and then the successive bond(s) will be pi bonds
Sun Oct 29, 2017 8:27 pm
Forum: Properties of Electrons
Topic: Ending Frequency [ENDORSED]
Replies: 3
Views: 350

### Re: Ending Frequency[ENDORSED]

If you are talking about the Bohr frequency model (just because it includes E and results in frequency) then you are going to use the delta E/change in energy
Sun Oct 29, 2017 8:24 pm
Forum: Properties of Electrons
Topic: Energy level question [ENDORSED]
Replies: 2
Views: 264

### Energy level question[ENDORSED]

Why is it that n=1 is the lowest energy level?
Tue Oct 10, 2017 1:03 pm
Forum: Properties of Light
Topic: chapter 1 question 27
Replies: 2
Views: 153

### Re: chapter 1 question 27

Okay so you were right to want to use E=h·ν but you rearrange it because v ("nu" or frequency)=c/λ so we can use E=hc/λ =(6.626·10^-34 Js)·( 2.997·10^8m/s)/ (470·10-9 m)=4.225*10^-19 J. The lamp emits 32J/s so in 2 seconds, the lamp emits (32*2=) 64J. So we use E(per mol of photons)=N(phot...
Tue Oct 10, 2017 12:43 pm
Forum: Properties of Light
Topic: Photoelectric Effect Post-Module Assessment (28B) [ENDORSED]
Replies: 1
Views: 188

### Re: Photoelectric Effect Post-Module Assessment (28B)[ENDORSED]

The work function is given to us in kJ/mol but we want it per electron so we use Avogadro's constant. First I converted kJ to J by multiplying my 10^3 because that's what's easiest for me in terms of conversions. (150*10^3 J/mol) x (1 mol/6.02*10^23)...moles cancel out so we are left with 2.50*10^-1...
Tue Oct 03, 2017 6:23 pm
Forum: Significant Figures
Topic: Sig Figs in 0.0380 [ENDORSED]
Replies: 5
Views: 415

### Sig Figs in 0.0380[ENDORSED]

In class, Lavelle said there were 3 sig figs and I was just confused on which zero was included in the 3 SF? Thanks!