Search found 62 matches
- Sun Mar 10, 2019 11:24 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Final Exam
- Replies: 23
- Views: 1724
Re: Final Exam
Yes anything we learned this quarter could be on it.
- Sun Mar 10, 2019 11:24 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Test 2
- Replies: 12
- Views: 1055
Re: Test 2
delta G is negative as a combustion will increase the entropy S, or disorder, of the system and is therefore spontaneous.
- Sun Mar 10, 2019 11:22 pm
- Forum: Second Order Reactions
- Topic: Final
- Replies: 32
- Views: 2274
Re: Final
It should be anything that we learned this quarter, cumulative.
- Sun Mar 03, 2019 8:20 pm
- Forum: Balancing Redox Reactions
- Topic: Strength of reducing agent
- Replies: 10
- Views: 1806
Re: Strength of reducing agent
The more negative the E, the more strong it is as a reducing agent (the thing being oxidized). Another way of saying it is a good donator.
- Sun Mar 03, 2019 8:12 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Melting of ice
- Replies: 9
- Views: 1008
Re: Melting of ice
a solid to a liquid would be a spontaneous reaction so delta G would be negative.
- Sun Mar 03, 2019 8:10 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Does anyone know if test 2 will be curved?
- Replies: 15
- Views: 2949
Re: Does anyone know if test 2 will be curved?
I don't think so, Lavelle usually doesn't curve any tests.
- Sun Feb 24, 2019 10:15 pm
- Forum: Student Social/Study Group
- Topic: Test
- Replies: 17
- Views: 1507
Re: Test
Thermodynamics and electrochemistry up to nerst equation.
- Sun Feb 24, 2019 10:13 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Spontaneous?
- Replies: 13
- Views: 1517
Re: Spontaneous?
When delta G is negative it is exergonic and when it is positive it is endergonic
when delta H is negative it is exothermic and when it is positive it is endothermic.
when delta H is negative it is exothermic and when it is positive it is endothermic.
- Sun Feb 24, 2019 10:12 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Spontaneous?
- Replies: 13
- Views: 1517
Re: Spontaneous?
It is spontaneous if delta G is negative, if (-TdeltaS) is negative, if deltaS is positive, and if delta H is negative
delta G = deltaH -TdeltaS
delta G = deltaH -TdeltaS
- Mon Feb 18, 2019 12:00 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: HW for W7
- Replies: 7
- Views: 649
Re: HW for W7
Chapter 9 questions I believe
- Sun Feb 17, 2019 11:59 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Midterm Grades
- Replies: 35
- Views: 2635
Re: Midterm Grades
My TA said by friday of this upcoming week
- Sun Feb 17, 2019 11:57 pm
- Forum: Student Social/Study Group
- Topic: Best Midterm Review
- Replies: 7
- Views: 723
Re: Best Midterm Review
peer learning sessions will break down fewer problems but go slowly and more in depth, a chance to ask more questions
Midterm reviews cover more problems but go really fast and get less explanation , more for practice if you already understand the topic.
Midterm reviews cover more problems but go really fast and get less explanation , more for practice if you already understand the topic.
- Sun Feb 17, 2019 11:56 pm
- Forum: Student Social/Study Group
- Topic: Test
- Replies: 17
- Views: 1507
Re: Test
My TA said majority of it will be thermodynamics
- Sun Feb 10, 2019 11:01 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: deltaS=nCvln(t2/t1) what is Cv?
- Replies: 7
- Views: 2737
Re: deltaS=nCvln(t2/t1) what is Cv?
when would you use deltaS=nRln(V2/v1) ?
- Sun Feb 10, 2019 10:57 pm
- Forum: Ideal Gases
- Topic: ICE Table Values
- Replies: 9
- Views: 1234
Re: ICE Table Values
I would say look to see what the problem gives you if Kc then use concentration values (mol/L). If "K" or Kp then use partial pressure (bars).
- Sun Feb 10, 2019 10:53 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: conversions
- Replies: 3
- Views: 293
Re: conversions
I would a assume they would give us that conversion if we needed it.
- Sun Feb 10, 2019 10:52 pm
- Forum: Phase Changes & Related Calculations
- Topic: Heat vs Q
- Replies: 5
- Views: 486
Re: Heat vs Q
If it asked for change in enthalpy you would solve for deltaH. If it is asking for heat occurring by the system or on the system solve for q.
- Sun Feb 10, 2019 10:50 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: answer format
- Replies: 4
- Views: 415
Re: answer format
I would say convert it to joules just in case if they don't specify
- Sun Feb 10, 2019 10:49 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Isochoric
- Replies: 3
- Views: 411
Re: Isochoric
if V=0
w=-Pext delta V
w=-P(0) so work =0
w=-Pext delta V
w=-P(0) so work =0
- Sun Feb 03, 2019 11:27 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: deriving the work equation: -P*deltaV
- Replies: 2
- Views: 259
Re: deriving the work equation: -P*deltaV
I don't think so Lavelle usually just shows derivatives as a way of understanding where the equations came from.
- Sun Feb 03, 2019 11:25 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Closed Systems
- Replies: 6
- Views: 451
Re: Closed Systems
An example of isolated system would be soup in an insulated container (assuming insulation is sufficient). An example of open system would be boiling water in an open pan on the stove, matter and energy are transferred. A closed system would be putting a lid on the pan, no matter transfer just energy.
- Sun Feb 03, 2019 11:20 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Closed Systems
- Replies: 6
- Views: 451
Re: Closed Systems
In a closed system the matter remains constant but energy can be transferred between surroundings and the system.
An isolated system neither energy or matter can be transferred.
An isolated system neither energy or matter can be transferred.
- Sun Feb 03, 2019 11:16 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Midterm [ENDORSED]
- Replies: 49
- Views: 4691
Re: Midterm [ENDORSED]
I would say the homework problems, and the extra study guides some of the UA's post like I know Lyndon usually does one.
- Sun Jan 27, 2019 6:12 pm
- Forum: Phase Changes & Related Calculations
- Topic: Steam
- Replies: 7
- Views: 637
Re: Steam
Also think about how fast steam phase changes back to liquid on your skin, because the process happens so fast it releases a very large amount of heat energy in a very short amount of time. If it was released over a longer period of time, it wouldn't be nearly as harmful.
- Sun Jan 27, 2019 6:08 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Catalysts in Kc
- Replies: 6
- Views: 674
Re: Catalysts in Kc
Catalysts change the speed at which the reaction occurs, not the components.
- Sun Jan 27, 2019 6:07 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Lecture Slides
- Replies: 5
- Views: 462
Re: Lecture Slides
Lavelle doesn't post them, if you missed one day you could just read the textbook and be fine though.
- Sun Jan 27, 2019 6:05 pm
- Forum: Phase Changes & Related Calculations
- Topic: Delta H
- Replies: 11
- Views: 1932
Re: Delta H
+H = endothermic the reactions needs heat
-H = exothermic the reaction gives off heat
-H = exothermic the reaction gives off heat
- Sun Jan 27, 2019 6:02 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5%
- Replies: 10
- Views: 743
Re: 5%
5% rule is a way you can test if you assume x is so small of a number it is negligible in finding x. for example if Kc= x^2 / (.55-x) you could try the assumption and calculate for x like this Kc=x^2 /(.55). Once you get a value you can test if it is less than 5% of the initial concentration given. ...
- Thu Jan 24, 2019 10:20 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 179
- Views: 22770
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
How did the NH3 become 11.3* 10^-7 On worksheet 1 4d
- Mon Jan 14, 2019 12:01 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: K and Q [ENDORSED]
- Replies: 7
- Views: 663
Re: K and Q [ENDORSED]
Even though K and Q have the same formula P/R it is the numbers that you plug in that are different. Only once the reaction reaches equilibrium can you plug in for K. But Q is at any point during the reaction. K is only one number, whereas Q can be many different numbers.
- Sun Jan 13, 2019 11:48 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: HW PROBELM 1 PART D
- Replies: 4
- Views: 453
Re: HW PROBELM 1 PART D
The reasoning is Le Chatelier's Principle= chem reactions adjust so as to minimize the effect of changes.
- Sun Jan 13, 2019 11:45 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatelier's Principle
- Replies: 7
- Views: 453
Re: Le Chatelier's Principle
It is basically the concept that chemical reactions by nature adjust so as to minimize the effect of changes. When equilibria is changed, like if more reactant was added more product is produced until original P/R ratio is attained. Or if more product is added, more reactant will form until the the ...
- Sun Jan 13, 2019 11:35 pm
- Forum: Student Social/Study Group
- Topic: New to Lavelle
- Replies: 32
- Views: 5185
Re: New to Lavelle
Some of the UAs will post practice Tests before the midterm and final that are really helpful for studying, last quarter Lyndon posted them.
- Sun Dec 02, 2018 10:31 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent vs angular?
- Replies: 15
- Views: 1126
Re: Bent vs angular?
Dr. Lavelle said they are the same thing.
- Sun Dec 02, 2018 10:30 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: How to draw dipoles
- Replies: 3
- Views: 1027
Re: How to draw dipoles
The dipole should point to the more electronegative element in a bond of two elements. Example between O and F, the dipole would point to F. If two different dipoles point opposite directions they cancel each other out, if all cancel out the molecule is non-polar. If they have a net dipole moment th...
- Sun Dec 02, 2018 10:22 pm
- Forum: Hybridization
- Topic: hybridization
- Replies: 13
- Views: 1736
Re: hybridization
I think you have to draw out the Lewis structure for sure, then count electron densities and find subsequent and matching spd number
s=1
sp=2
sp2 =3
sp3 =4
sp3d =5 etc
s=1
sp=2
sp2 =3
sp3 =4
sp3d =5 etc
- Sun Dec 02, 2018 10:18 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Square Planar
- Replies: 12
- Views: 1934
Re: Square Planar
The two lone pairs balance each other out on top and bottom, and the four bonds make a plus shape on one plane, each exactly 90 degrees apart.
- Sun Nov 25, 2018 10:34 pm
- Forum: Lewis Structures
- Topic: Expanded Octet
- Replies: 8
- Views: 864
Re: Expanded Octet
Row 2 elements usually never have expanded octet.
- Sun Nov 25, 2018 10:33 pm
- Forum: Hybridization
- Topic: Test 3
- Replies: 7
- Views: 857
Re: Test 3
My TA said the test should be similar in number to the other tests, so about 8 questions
- Sun Nov 25, 2018 10:31 pm
- Forum: Properties of Light
- Topic: Speed of light
- Replies: 13
- Views: 3840
Re: Speed of light
My TA said to use the number given on the equation sheet otherwise rounding may affect your final answer and they can take points off for that.
- Sun Nov 18, 2018 11:00 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles for H2O
- Replies: 8
- Views: 8866
Re: Bond Angles for H2O
The lone pairs push the bonding pairs H-O on both sides to increase the angle between lone pair and the hydrogen oxygen bond, but this decreases the angle between the two bonding pairs to 104.5 instead of 109.5
- Sun Nov 18, 2018 10:54 pm
- Forum: Hybridization
- Topic: Bond Angles
- Replies: 12
- Views: 1110
Re: Bond Angles
If you know the VSEPR model , you should be able to remember the bond angle associated with it like 120, or 109.5, or 90 degrees. Then figure out how the lone pairs push on the bonding pairs and affect the angles ( I find this is easiest by drawing it).
- Sun Nov 18, 2018 10:48 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: lone pairs
- Replies: 11
- Views: 827
Re: lone pairs
Lone pairs have a large affect on the shape of the molecule, lone pairs push nearby bonding pairs away creating a greater angle than if it were a bonding pair to bonding pair. Making the other angles decrease.
- Sun Nov 11, 2018 10:19 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge
- Replies: 12
- Views: 1211
Re: Formal Charge
I think you should always show your calculations for formal charge, each TA grades differently but my TA said the more work you show the greater chance you will earn more points.
- Sun Nov 11, 2018 10:14 pm
- Forum: Octet Exceptions
- Topic: learning octet excptions
- Replies: 4
- Views: 355
Re: learning octet excptions
My TA said you don't have to memorize these just know that it could be possible in periods 3 and on, but not in period 1 or 2.
- Sun Nov 11, 2018 10:07 pm
- Forum: Resonance Structures
- Topic: Drawing resonance
- Replies: 17
- Views: 1816
Re: Drawing resonance
One of the TA's said we are not able to tell yet if a structure has resonance, we will learn that later. We will be told when to draw resonance structures as of now.
- Sun Nov 04, 2018 11:58 pm
- Forum: Sigma & Pi Bonds
- Topic: Midterm1
- Replies: 10
- Views: 1112
Re: Midterm1
I don't think so. If it was not mentioned in class it won't be on the test.
- Sun Nov 04, 2018 11:57 pm
- Forum: Lewis Structures
- Topic: Expanded Octet Rule
- Replies: 4
- Views: 450
Re: Expanded Octet Rule
Someone in a review session today said it could be more than 10, don't think we have to know the specifics.
- Sun Nov 04, 2018 11:56 pm
- Forum: Trends in The Periodic Table
- Topic: Periodic Trends: Diagonal Relationships
- Replies: 3
- Views: 974
Re: Periodic Trends: Diagonal Relationships
In a review session today they said they would not ask us this without giving us values for which one has a higher ionization.
- Sun Oct 28, 2018 10:51 pm
- Forum: Ionic & Covalent Bonds
- Topic: Difference Between Ionic and Covalent Bonds
- Replies: 4
- Views: 353
Re: Difference Between Ionic and Covalent Bonds
On the periodic table metals form cations, they have low ionization energy. Which means they have larger size, and electrons are farther from nucleus, so they are easily removed from s and p orbitals and do not require a lot of energy for the process. The p-block nonmetals form anions, meaning they ...
- Sun Oct 28, 2018 10:36 pm
- Forum: Ionic & Covalent Bonds
- Topic: Cation/Anion Size
- Replies: 3
- Views: 669
Re: Cation/Anion Size
Essentially the number of protons and electrons equal each other in a neutral atom. And after a neutral atom loses a certain amount of electrons, this new cation now has less electrons in comparison to protons. Now that the positive charge protons outnumber the e-, the e- are pulled in tighter to th...
- Sun Oct 28, 2018 10:29 pm
- Forum: Lewis Structures
- Topic: Lewis Structure for Compounds
- Replies: 6
- Views: 434
Re: Lewis Structure for Compounds
Cations lose their outermost electrons causing it to change from a neutral atom to a +positively charged atom. Two cations would repel each other since both would be +positive.
- Wed Oct 24, 2018 8:16 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Grading question
- Replies: 11
- Views: 1731
Re: Grading question
Chem_Mod wrote:No. All it means it that 250/500 is needed to pass with the class (likely a C- because that is the minimum grade needed to pass the class).
What amount of points would be a B- or A-? Is there a set scale now or only provided by the end of the quarter?
- Sun Oct 21, 2018 11:59 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Class Grading
- Replies: 9
- Views: 1092
Re: Class Grading
Does anyone know the range of an A in the class, a B, and C. In terms of points or percentage. I am a little confused because on the syllabus it says a passing grade C- is a 50%... ??
- Sun Oct 21, 2018 11:52 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Electron Spin States?
- Replies: 4
- Views: 208
Re: Electron Spin States?
I think all we need to know is that no two electrons in the same atom have the same four quantum #s. And that spin states can either be+1/2 or -1/2 .
- Sun Oct 21, 2018 11:49 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: h with a line through it?
- Replies: 8
- Views: 1872
Re: h with a line through it?
H bar is just a short hand notation, that is used just to simplify what is written. ( Hbar= h/2 pi) (H bar/2 = h/4 pi)
- Sun Oct 14, 2018 11:31 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Writing in Pen
- Replies: 13
- Views: 962
Re: Writing in Pen
My TA said that if you write in pencil on your test he has to write over everything you wrote in pen, so you can't change your answers later. But do whatever makes you feel less stressed and more focused. I use to hate writing in pen but forcing your self to use it more and more will help. Usually a...
- Sun Oct 14, 2018 11:26 pm
- Forum: Student Social/Study Group
- Topic: Class Grades
- Replies: 4
- Views: 486
Re: Class Grades
I personally like using benegg.net as my grade calculator. Easy to understand and helpful in giving you a close estimate of your final grade. I agree with others in that writing down your grades on little assignments as you go is the best way to keep track. Sometimes TAs do make mistakes.
- Sun Oct 14, 2018 11:21 pm
- Forum: Student Social/Study Group
- Topic: Note Taking
- Replies: 145
- Views: 15068
Re: Note Taking
I also find handwritten notes to be the best way for me to take notes. I am a very visual learner, so I often use colors too. I find that if I highlight "too much" information I tend to loose focus of what formulas and topics are the most important. Recently I have been actively working on...
- Sun Oct 07, 2018 11:56 pm
- Forum: Student Social/Study Group
- Topic: HW Schedule?
- Replies: 7
- Views: 908
Re: HW Schedule?
My Ta said the same thing, homework for outline 2 (quantum) and test will be due on your discussion day. They said the test will be 40 min.
- Sun Oct 07, 2018 11:54 pm
- Forum: SI Units, Unit Conversions
- Topic: How does grading for discussion posts work?
- Replies: 80
- Views: 8142
Re: How does grading for discussion posts work?
Also a question about the cutoff, is each week's post due that Sunday by midnight..?
- Sun Oct 07, 2018 11:50 pm
- Forum: Significant Figures
- Topic: Formula sheet?
- Replies: 5
- Views: 603
Formula sheet?
Are we going to be told what will be on the formula sheet for Test one next week in discussion? Do we even get a formula sheet?