## Search found 44 matches

Sun Feb 03, 2019 2:54 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: kJ vs J
Replies: 9
Views: 225

### Re: kJ vs J

I think it depends on your answer, for example, if the answer is a very large value of J, you should convert it to kJ. Or if the problem gives you what units to have your answer in, that's always what you should go with.
Sun Feb 03, 2019 2:52 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Review
Replies: 14
Views: 505

### Re: Midterm Review

Will the Peer Learning Sessions continue with the week's content, content for Week 5, or will they be backtracking in order to help with Midterm review?
Sun Feb 03, 2019 2:46 pm
Forum: Calculating Work of Expansion
Topic: What is Work?
Replies: 5
Views: 164

### What is Work?

When reading Chapter 8 of the Sixth edition I became confused to what work actually is... is it the energy required to perform an action or is it the total energy of the reaction?
Sun Feb 03, 2019 2:44 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Gas vs solid
Replies: 5
Views: 176

### Re: Gas vs solid

Why is the entropy of a gas in an aqueous solution less than the entropy of a solid in an aqueous solution? To answer your question piggybacking off of the previous reply, entropy should increase as you go from solid to liquid to gas. Therefore the entropy of gas should be more than the entropy of ...
Thu Jan 17, 2019 9:08 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction Quotient
Replies: 10
Views: 334

### Re: Reaction Quotient

K describes a reaction when it is at equilibrium, while the reactant quotient (value Q), can describe a reaction that is not at equilibrium, helping deduce whether the reaction is moving forward or in reverse depending on if it is sitting/shifting to the right or to the left, respectively.
Thu Jan 17, 2019 9:05 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Percentage Ionization
Replies: 4
Views: 197

### Re: Percentage Ionization

Depending on whether you are talking about an acid or base, yes, similar to the difference between pH and pOH
Thu Jan 17, 2019 9:03 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: "Shifting"
Replies: 15
Views: 1051

### Re: "Shifting"

During the lecture on January 8th, Dr. Lavelle referenced other terms for shifting or lying, stating that the preferred term is sitting when analyzing the size of the value K.
Thu Jan 17, 2019 9:01 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Hydronium Concentration
Replies: 3
Views: 137

### Re: Hydronium Concentration

The reaction is considered neutral because both the pH and pOH are equal to 7, canceling each other out and making it a neutral reaction.
Thu Jan 17, 2019 9:00 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: K and Q [ENDORSED]
Replies: 7
Views: 229

### Re: K and Q[ENDORSED]

Even though K and Q are calculating the same way, K occurs at equilibrium and we calculate Q in order to know if the reaction is at equilibrium or if it working as a forward or reverse reaction, shifting right or left, respectively.
Thu Jan 17, 2019 8:54 pm
Forum: Ideal Gases
Topic: [Products] over [Reactants] cancellations
Replies: 3
Views: 159

### [Products] over [Reactants] cancellations

Why is it that you can sometimes cancel the x on the reactants portion before using the quadratic formula to solve for x in ICE tables?
Sat Dec 08, 2018 2:43 pm
Forum: Significant Figures
Topic: when to round?
Replies: 2
Views: 342

### Re: when to round?

You focus on the givens, not the constant for significant figures
Sat Dec 08, 2018 2:42 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted base, Lewis acid
Replies: 2
Views: 98

### Re: Bronsted base, Lewis acid

A bronsted base is a proton acceptor, and lewis acid is an electron pair acceptor, so unless B(OH)2 had an additional H added, it is not a bronsted base. There would have to be a reaction where H3O forms to have a clear picture of what is the bronsted base and bronsted acid.
Sat Dec 08, 2018 2:42 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted base, Lewis acid
Replies: 1
Views: 86

### Re: Bronsted base, Lewis acid

Is it possible for something to act as both a bronsted base and a lewis acid? As B(OH)2 accepts electron pairs (OH) from water, it also accepts the OH atoms. Or does bronsted base exclusively refer to unattached H protons? A bronsted base is a proton acceptor, and lewis acid is an electron pair acc...
Sun Nov 18, 2018 4:35 pm
Forum: Resonance Structures
Topic: Resonance structures
Replies: 7
Views: 483

### Re: Resonance structures

resonance structures are all of the possible structures, while the hybrid resonance is the average of the resonance structures (the actual structure of the molecule)
Sun Nov 18, 2018 4:32 pm
Forum: Resonance Structures
Topic: Drawing resonance structures
Replies: 5
Views: 423

### Re: Drawing resonance structures

you have to draw all of the resonance structures to show that you know it can be any of them, but will be an average of them all to have the most stable structure
Sun Nov 18, 2018 4:31 pm
Forum: Resonance Structures
Topic: Drawing resonance
Replies: 17
Views: 972

### Re: Drawing resonance

you should draw all of the resonance structures as the true structure will be an average of them all (so by drawing all of them, you show that you know that it can be any of the structures, but is an average in reality)
Sun Nov 18, 2018 4:28 pm
Forum: Resonance Structures
Topic: Formal Charge
Replies: 13
Views: 758

### Re: Formal Charge

the formal charge that is not equal to zero should not be on the central atom (as it makes the molecule very unstable), and should ideally be on the outer atom that is most/more electronegative
Sun Nov 18, 2018 4:26 pm
Forum: Resonance Structures
Topic: Polar
Replies: 8
Views: 490

### Re: Polar

You calculate the formal charge of each possibility and focus on the one that has an f.c. closest to zero
Sun Nov 18, 2018 4:23 pm
Forum: Administrative Questions and Class Announcements
Replies: 135
Views: 31252

Last week we left off on hybridization, which we will go over this week and will be on Test 3. I will NOT be holding workshops over Thanksgiving break, which means that I will not see you all until after Test 3. However, I should have covered everything that will be on Test 3 by tomorrow. Almost th...
Fri Nov 16, 2018 12:44 pm
Forum: Student Social/Study Group
Topic: curve?
Replies: 20
Views: 1609

### Re: curve?

There's no curve for grades higher than a 70% I believe, then they just stay with the regular grade guidelines (70%~C, 80%~B, 90%~A), so I think 50-79% will range within C- to C+
Fri Nov 16, 2018 12:26 pm
Forum: Lewis Structures
Topic: Picking Central Atom Special Cases
Replies: 2
Views: 110

### Re: Picking Central Atom Special Cases

When we draw the Lewis structure for ClO2, we usually pick the atom with the lowest ionization energy. However, between the two atoms, there is a conflicting trend where Cl gets more rightward and gets more downward in comparison to O. This is counterintuitive because ionization energy increased ri...
Fri Nov 16, 2018 12:21 pm
Forum: Sigma & Pi Bonds
Topic: Significance of sigma and pi bonds
Replies: 2
Views: 143

### Re: Significance of sigma and pi bonds

also a single bond is a sigma bond, while any bond larger is one sigma bond plus the remaining # being pi bonds
Mon Nov 05, 2018 6:45 am
Forum: Quantum Numbers and The H-Atom
Topic: s,p,d,f
Replies: 8
Views: 414

### Re: s,p,d,f

Why does the number order change going from S to D? 4s to 3d instead of 4d? In electron configurations, the order goes by principle quantum number (n) so for the most part 3d will go before 4s, except for the elements Chromium ([Ar]4s^1 3d^5) and Copper ([Ar] 4s^1 3d^10) in order for these atoms to...
Mon Nov 05, 2018 6:34 am
Forum: Octet Exceptions
Topic: Formal charge
Replies: 7
Views: 361

### Re: Formal charge

Soyoung Park 1H wrote:Do you always check for formal charges even for single bonds?

Yes to make sure that your Lewis structure is the most stable form or if additional bonds need to be made (with respect to the octet rule) in order to increase stability
Mon Nov 05, 2018 6:32 am
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 11
Views: 346

### Re: Lewis Structures

kimberlyrose4D wrote:
505095793 wrote:How do we know which atom to put in the center of a Lewis structure?

It's the atom with the lowest ionization energy, and if there's multiple of the other atoms in the compound, it'll be the atom that there is one of.

Also: Hydrogen can never be the center atom
Mon Nov 05, 2018 6:31 am
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 11
Views: 346

### Re: Lewis Structures

505095793 wrote:How do we know which atom to put in the center of a Lewis structure?

It's the atom with the lowest ionization energy, and if there's multiple of the other atoms in the compound, it'll be the atom that there is one of.
Mon Nov 05, 2018 6:30 am
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 11
Views: 346

### Re: Lewis Structures

Soyoung Park 1H wrote:When do you use brackets around the lewis structures?

Once you have completed the Lewis structure and know the charge is when you put brackets and the charge in the top right corner on the outside of the brackets
Mon Nov 05, 2018 6:26 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 3d and 4s
Replies: 4
Views: 247

### Re: 3d and 4s

Although the s-orbital fills before the d-orbital when writing the electron configuration, we go by numerical order, that is why 3d will go before 4s
Sun Oct 28, 2018 9:28 pm
Forum: Lewis Structures
Topic: Dot's in the Lewis Structure
Replies: 10
Views: 381

### Re: Dot's in the Lewis Structure

There is no order, although you should have one electron on each of the four sides before having two on the same side. You should also take a look at/aim for symmetry (having two on the right side, as well as the left side if the element has six valence electrons).
Sun Oct 28, 2018 9:27 pm
Forum: Lewis Structures
Topic: Dots in Lewis Stucture
Replies: 14
Views: 457

### Re: Dots in Lewis Stucture

There is no order, although you should have one electron on each of the four sides before having two on the same side. You should also take a look at/aim for symmetry (having two on the right side, as well as the left side if the element has six valence electrons).
Sun Oct 28, 2018 9:26 pm
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 8
Views: 287

### Re: Lewis Structures

Each dot represented a valence electron (the number of electrons in the outermost orbital), for single atoms/elements, this is the atomic number, but for bonds, we use the sum of the atomic numbers of the elements presented in the problem.
Sun Oct 28, 2018 9:24 pm
Forum: Lewis Structures
Topic: Lewis Structure Drawing
Replies: 6
Views: 189

### Re: Lewis Structure Drawing

It might have been correct in your high school course, but Prof. Lavelle suggested using it only for shared bonds, so mixing the two might make it difficult for completing problems, and according to Lavelle, is incorrect for his course.
Sun Oct 28, 2018 9:22 pm
Forum: Lewis Structures
Topic: Lewis Dot Order
Replies: 10
Views: 233

### Re: Lewis Dot Order

There is no order, although you should have one electron on each of the four sides before having two on the same side. You should also take a look at/aim for symmetry (having two on the right side, as well as the left side if the element has six valence electrons).
Mon Oct 22, 2018 10:06 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenbergy Uncertainty Equation
Replies: 3
Views: 171

### Re: Heisenbergy Uncertainty Equation

It should be either (h bar)/2 or h/4pi because h bar is equal to h/2pi
Mon Oct 22, 2018 10:03 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Re: Heisenberg Uncertainty Principle
Replies: 2
Views: 136

### Re: Heisenberg Uncertainty Principle

As you become more certain in momentum, the uncertainty of position increases; and vice versa. That's why it's Heisenberg's Uncertainty Principle, because you can only be certain in one or the other, never both at the same time.
Mon Oct 22, 2018 8:07 am
Forum: Properties of Electrons
Topic: Wave Properties
Replies: 4
Views: 168

### Re: Wave Properties

Yes! Although larger objects display particle-like properties, they also emit wave-like properties. So most objects can have wave properties, they're just easier to see in smaller objects like electrons.
Mon Oct 22, 2018 8:04 am
Forum: Properties of Electrons
Topic: Electron Spin
Replies: 7
Views: 521

### Re: Electron Spin

you can determine the electron spin by drawing the electron configuration, the details of the electron spin itself aren't essential but do provide a little background. Basically, if you draw the configuration, you'll have an arrow pointing up or down in the end, so this will tell you whether it is +...
Mon Oct 22, 2018 8:00 am
Forum: Properties of Light
Topic: kg or g [ENDORSED]
Replies: 11
Views: 601

### Re: kg or g[ENDORSED]

kg since that is what our SI units tell us (convert grams to 10^-3 kg)
Mon Oct 22, 2018 7:59 am
Forum: Properties of Light
Topic: Intensity vs energy
Replies: 6
Views: 300

### Re: Intensity vs energy

Intensity is the amount of photons, while energy is per photon (smaller scale as it is describing individual photons)
Mon Oct 22, 2018 7:56 am
Forum: Properties of Light
Topic: Visible Light Spectrum... ?
Replies: 6
Views: 199

### Visible Light Spectrum... ?

For remembering the order of the visible light spectrum (ROYGBV), do we have to know the wavelengths between each color, or is knowing that visible light is between 400-700 nanometers adequate enough?
Thu Oct 04, 2018 3:23 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Calculating the number of atoms
Replies: 5
Views: 203

### Re: Calculating the number of atoms

First you multiply the number of grams by the atomic mass of the element (if a compound, then you would add together all of the individual atomic masses together) and that will give you the number of moles present in the sample. You would then multiply this value by Avogadro's Number (6.022 x 10^23)...
Thu Oct 04, 2018 3:18 pm
Forum: Balancing Chemical Reactions
Topic: Balancing Chemical Reactions with Heat
Replies: 6
Views: 226

### Re: Balancing Chemical Reactions with Heat

It's miscellaneous information at the moment, added in order to further describe the reaction. But you don't need to pay attention to it in order to balance the equation.
Thu Oct 04, 2018 3:15 pm
Forum: Significant Figures
Topic: Sig Fig's in Problem E.21.d
Replies: 3
Views: 161

### Re: Sig Fig's in Problem E.21.d

For most periodic tables, the mass of hydrogen is given as 1.0079, with five significant figures so the final answer would be given in a value of five significant figures, following the sig figs rules.
Thu Oct 04, 2018 3:13 pm
Forum: Significant Figures
Topic: sig fig for avogadros number
Replies: 3
Views: 454

### Re: sig fig for avogadros number

Based on Professor Lavelle's lectures, he uses four significant figures (6.022 x 10^23) so I'd recommend doing the same to avoid any large errors upon completion of a problem and the answer key he's made