Search found 101 matches
- Wed Mar 11, 2020 7:28 pm
- Forum: *Enzyme Kinetics
- Topic: Adsorption vs. Absorption
- Replies: 8
- Views: 1432
Re: Adsorption vs. Absorption
Adsorption and Absorption differ in how they function and the state of the species involved. The above answers explain it well! But, why is it important to understand the difference between the two? In the last lecture he mentioned that reactants sit on the surface of a catalyst (adsorption) becaus...
- Wed Mar 11, 2020 6:02 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: concentration cells
- Replies: 3
- Views: 229
Re: concentration cells
Changing the mass of the cathode doesn't change the concentration of the cathode solution therefore changing the mass of the electrode would have no change / affect on the cell potential. I think you are referring to the second part of that question but he is asking about the first part where the v...
- Wed Mar 11, 2020 5:59 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysis
- Replies: 11
- Views: 845
Re: Catalysis
It is basically the process of speeding up a reaction by providing a new pathway and lowering the activation energy.
- Wed Mar 11, 2020 5:55 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Microscopic Reversibility
- Replies: 3
- Views: 238
Re: Microscopic Reversibility
I think this means that you can assume that the reaction has the same intermediates (same pathway) in the forward and reverse directions.
- Wed Mar 11, 2020 5:53 pm
- Forum: General Rate Laws
- Topic: Rate Determining Step
- Replies: 5
- Views: 367
Re: Rate Determining Step
Yeah I think the rate determining step is usually the slowest step, and it is also called the elementary step sometimes.
- Sun Mar 08, 2020 11:01 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: microscopic reversibility
- Replies: 3
- Views: 251
Re: microscopic reversibility
we can assume that a reaction has microscopic reversibility when the reaction has the same intermediates (same pathway) in a forward and reverse reaction. Also I don't think we need to know a lot about this topic but I may be wrong.
- Sun Mar 08, 2020 10:57 pm
- Forum: Second Order Reactions
- Topic: Second Order Reactions
- Replies: 5
- Views: 442
Re: Second Order Reactions
I think there would just be two reactants, so it would be bimolecular.
- Sun Mar 08, 2020 10:44 pm
- Forum: Ideal Gases
- Topic: When do we change PV=NRT into deltas?
- Replies: 4
- Views: 484
Re: When do we change PV=NRT into deltas?
I think you can change one variable to delta if you change another variable on the other side of the equal sign to delta.
- Sun Mar 08, 2020 10:43 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Purpose of Nernst Equation
- Replies: 5
- Views: 416
Re: Purpose of Nernst Equation
The nernst equation is used to find the max potential before any current flow. It can be used to find cell potential, equilibrium constant, reaction constant, and potentially any other variable in the equation.
- Mon Mar 02, 2020 9:16 pm
- Forum: Balancing Redox Reactions
- Topic: hw 6l7b
- Replies: 2
- Views: 273
Re: hw 6l7b
Are galvanic/volteric cells normally closed? I though they were open but in that case O2 would be available in other redox reactions and that doesn't seem to be the case.
- Sun Mar 01, 2020 10:50 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: When to add Platinum
- Replies: 8
- Views: 489
Re: When to add Platinum
You add platinum or another inert electrode when both oxidized and reduced species are in the same solution. It is easy to tell when you look at the phases in the equation, since the electrode is always a solid, so whenever one side of the cell doesn't have a solid you need to add an inert electrode...
- Sun Mar 01, 2020 10:46 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6M.1 reversed anode and cathode?
- Replies: 3
- Views: 258
Re: 6M.1 reversed anode and cathode?
Yeah I think the book reversed it because the value was negative and you typically shouldn't use negative values for the cell. And I think it is also more accurate to use E(cathode) - E(anode)
- Sun Mar 01, 2020 10:40 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Degree symbol
- Replies: 10
- Views: 1020
Re: Degree symbol
The symbol means standard of reaction, so for example standard reduction potential (E knot) is the voltage difference between two standard electrodes and it is a constant. It is not related to the degrees symbol for temperature
- Sun Mar 01, 2020 10:34 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst equation and ph
- Replies: 2
- Views: 235
Re: Nernst equation and ph
You can use the Nernst equation to solve for Q, and then once you find Q use it to solve for the concentration of H+ or OH- depending on the reaction. And you only use log when the temperature is 25 degrees celcius and the equation replaces RT/nF with 0.0591/n
- Sun Mar 01, 2020 10:31 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6L.5
- Replies: 1
- Views: 168
Re: 6L.5
I think this is because one of the half reactions is Ag+ (aq) + e- --> Ag (s) and another is AgBr (s) + e- --> Ag (s) + Br- (aq) so when you reverse the half reaction and add them together the Ag(s) cancels out, but you would still include it in the cell diagram
- Fri Feb 21, 2020 12:11 pm
- Forum: Balancing Redox Reactions
- Topic: Adding Water in Redox Reactions
- Replies: 3
- Views: 402
Re: Adding Water in Redox Reactions
You can add H+ or OH- when it is a basic solution because H+ +OH- --> H2O
but you only do this if there are extra H+ on one side of the reaction and H2O on the other to cancel out extra molecules
Sorry this isn't very helpful I don't fully understand it either
but you only do this if there are extra H+ on one side of the reaction and H2O on the other to cancel out extra molecules
Sorry this isn't very helpful I don't fully understand it either
- Thu Feb 20, 2020 9:53 pm
- Forum: Balancing Redox Reactions
- Topic: oxidation numbers
- Replies: 4
- Views: 312
Re: oxidation numbers
But generally I'm pretty sure that an element is oxidized when the oxidation number is increased, and is reduced when the oxidation number decreases
- Thu Feb 20, 2020 9:46 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Redox Reaction in Acidic vs. Alkaline Condition
- Replies: 3
- Views: 299
Re: Balancing Redox Reaction in Acidic vs. Alkaline Condition
My TA said we should add OH- or H+ when it is a basic solution if you have a redox reaction with leftover H+ on one side of the reaction, so convert it into H2O since H+ + OH- ---> H2O (only in a basic solution)
Sorry that's not very helpful I didn't fully understand it in section either...
Sorry that's not very helpful I didn't fully understand it in section either...
- Thu Feb 20, 2020 9:42 pm
- Forum: Balancing Redox Reactions
- Topic: 6L.5
- Replies: 1
- Views: 234
Re: 6L.5
In the answer key it says that an inert electrode like Pt is necessary when the solution has both oxidized and reduced species and also for gas/ion electrode reactions
- Thu Feb 20, 2020 9:38 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Homework 6M.1
- Replies: 1
- Views: 129
Re: Homework 6M.1
I think you can just try the problem both ways with each one being the cathode and anode and choose the identification that gives you a positive E cell value.
- Sun Feb 16, 2020 2:17 pm
- Forum: Balancing Redox Reactions
- Topic: oxidation vs reduction
- Replies: 19
- Views: 1026
Re: oxidation vs reduction
How do you determine an elements oxidation number ? I think its just the number of electrons that were lost or gained during a reaction, so you would basically just count them. If you look back at when we studied transition metals in 14A we also learned about this there. You have to count the numbe...
- Sun Feb 16, 2020 1:58 pm
- Forum: Balancing Redox Reactions
- Topic: oxidation vs reduction
- Replies: 19
- Views: 1026
Re: oxidation vs reduction
Personally, I've always just memorized it as reduction being a reduction in the charge. So if the charge is reduced, then that has to mean an electron is gained. But does this always work? for example in molecules in which the net charge stays the same, but the number of electrons in each atom is d...
- Sun Feb 16, 2020 1:54 pm
- Forum: Balancing Redox Reactions
- Topic: half reaction
- Replies: 8
- Views: 477
Re: half reaction
When writing half reactons why is the number of electrons written in the equation being added? For example in this oxidation: 5Fe = Fe3+ + 5e- Why is the 5e- added and not subtracted? I think this is because the net number of electrons cannot change, since the reaction is balanced and no new electr...
- Sun Feb 16, 2020 1:48 pm
- Forum: Balancing Redox Reactions
- Topic: Number of electrons
- Replies: 5
- Views: 268
Re: Number of electrons
But do you have to write the electrons in a chemical equation to show reduction or oxidation?
- Sun Feb 16, 2020 1:47 pm
- Forum: Administrative Questions and Class Announcements
- Topic: about the Midterm...
- Replies: 8
- Views: 596
Re: about the Midterm...
Also you're not alone!! I did not feel good about that midterm either and basically everyone I have talked to about it so far has said the same thing :(
But I agree that practicing is definetly one of the best things you can do to prepare.
But I agree that practicing is definetly one of the best things you can do to prepare.
- Sun Feb 09, 2020 8:18 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Content
- Replies: 6
- Views: 377
Re: Midterm Content
We have to know the first page of the thermodynamics outline, so I think that has parts of 4J.1 and 4J.2 but I'm not entirely sure.
- Sun Feb 09, 2020 8:12 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Cv vs. Cp
- Replies: 2
- Views: 139
Re: Cv vs. Cp
Usually you can tell from the context of the question whether or not there is a change in pressure or volume, but if not then I think you usually use Cv (that's what they said in the review session today but they didn't say why)
- Sun Feb 09, 2020 8:07 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Volume decrease
- Replies: 7
- Views: 283
Re: Volume decrease
The rule is that the reaction will favor the side with less moles of gas for a volume decrease, you didn't mention gases so maybe the moles you counted weren't for gases?
- Sat Feb 08, 2020 9:03 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Adding Reactions
- Replies: 2
- Views: 187
Re: Adding Reactions
You would square the constant when the stoichiometric coefficients of the reaction are doubled.
- Sat Feb 08, 2020 7:36 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Delta U in an Open System
- Replies: 1
- Views: 95
Re: Delta U in an Open System
I would think that the question would have to tell you whether or not there was a volume change, but I'm not sure about gasses.
- Sun Feb 02, 2020 7:21 pm
- Forum: *Organic Reaction Mechanisms in General
- Topic: K meaning
- Replies: 29
- Views: 2264
Re: K meaning
K is Boltzmann's constant and it is approximately 1.380649×10−23 J/K
- Sun Feb 02, 2020 7:07 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: 4G.5
- Replies: 1
- Views: 110
Re: 4G.5
I think you have to think about the shape and the definitions of cis and trans to figure it out. Since trans means the two atoms are opposite each other, then there are only three options in the picture they show in the question. Since cis means the molecules are next to each other there are 12 poss...
- Sun Feb 02, 2020 7:00 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: method two
- Replies: 3
- Views: 117
Re: method two
If you can figure out which bonds are broken and formed without drawing the lewis structures then you shouldn't need to draw them
- Sun Feb 02, 2020 6:54 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 4E.5
- Replies: 1
- Views: 87
Re: 4E.5
I think you would just do the C-C bond enthalpies for the bonds that break and form and subtract them, so it would be 3(837) kJ/mol - 6(518)kJ/mol = -597 kJ/mol (assuming you're talking about part a)
- Fri Jan 31, 2020 5:33 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: 4A.11
- Replies: 3
- Views: 117
Re: 4A.11
I think it comes from the equation q=delta H=n*C*delta T but they didn't give you moles or mass so there is no n, and you just solve for C= delta H/delta T
- Sat Jan 25, 2020 10:04 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpy Method
- Replies: 5
- Views: 244
Re: Bond Enthalpy Method
But why is Hess's method more accurate than the third method we learned?
- Sat Jan 25, 2020 10:00 pm
- Forum: Ideal Gases
- Topic: PV=NRT
- Replies: 7
- Views: 304
Re: PV=NRT
The distance is 3.87nm... but did we learn how to calculate this? I thought we just need to know that delta Hf degrees of oxygen gas is zero
- Sat Jan 25, 2020 9:53 pm
- Forum: Phase Changes & Related Calculations
- Topic: Bond Enthalpies with State Changes
- Replies: 4
- Views: 153
Re: Bond Enthalpies with State Changes
Are you talking about what we covered in lecture on Friday or Wednesday?
- Sat Jan 25, 2020 9:48 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Acid and Bases
- Replies: 3
- Views: 212
Re: Acid and Bases
H2SO4 is a strong acid, so the equilibrium concentration of products is the same number as the initial concentration of H2SO4. Then you can calculate pH using -log of the concentration of hydronium
- Sat Jan 25, 2020 9:45 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Acid and Bases
- Replies: 4
- Views: 210
Re: Acid and Bases
You would make an ice table and use Ka to find x (the change in concentration) and the concentration of hydronium, and then find the pH using -log of this concentration. Then you would find pOH using pH+ pOH=14
- Sat Jan 18, 2020 4:52 pm
- Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
- Topic: Buffer questions
- Replies: 4
- Views: 737
Re: Buffer questions
If they weren't assigned in the homework do we have to know about them for the test?
- Sat Jan 18, 2020 4:43 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6D. 7
- Replies: 3
- Views: 150
Re: 6D. 7
Yeah I'm pretty sure you would need to be given Ka and Kb, because using the pH you can find the concentrations of H3O+ and OH-, but not the constants. I think they would give them to us on the test.
- Sat Jan 18, 2020 4:37 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kc sig figs
- Replies: 4
- Views: 185
Re: Kc sig figs
I'm not entirely sure but I think for sig figs you just use the least given amount, and it doesn't really matter where it comes from unless otherwise stated.
- Sat Jan 18, 2020 3:46 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5G.1
- Replies: 2
- Views: 108
Re: 5G.1
Yeah, this is right as long as the temperature stays constant
- Sat Jan 18, 2020 3:40 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Effect of Temperature on Halogen Reaction (Homework 5J.11)
- Replies: 3
- Views: 196
Re: Effect of Temperature on Halogen Reaction (Homework 5J.11)
In the answer key it says that its an endothermic reaction because it requires energy to break an X-X bond, but the values of b can be calculated.
- Fri Jan 17, 2020 12:50 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Why is there Negative pH
- Replies: 1
- Views: 94
Re: Why is there Negative pH
When you calculate ph you normally do -log(10^a negative number), and the negatives cancel out. If you get a negative ph, that means you would have
-log(10^a positive number), and the negative would not cancel out. So the concentration would be larger than 1.
-log(10^a positive number), and the negative would not cancel out. So the concentration would be larger than 1.
- Fri Jan 10, 2020 12:41 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Calculating eq constants with only one variable
- Replies: 3
- Views: 111
Re: Calculating eq constants with only one variable
Can you post the question that you need help with?
- Fri Jan 10, 2020 12:35 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: using Kp vs Kc
- Replies: 13
- Views: 1571
Re: using Kp vs Kc
I think you should get the same number for both, but I'm not entirely sure.
- Fri Jan 10, 2020 12:31 pm
- Forum: Ideal Gases
- Topic: Textbook Help
- Replies: 4
- Views: 346
Re: Textbook Help
Also if you can't figure it out you can also go to the textbook store and they will help you
- Fri Jan 10, 2020 12:23 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Effect of Inert Gases
- Replies: 9
- Views: 354
Re: Effect of Inert Gases
In the video modules he explained that inert gasses do not affect the reaction because they do not change the concentration of products or reactants. When pressure increases by decreasing volume, the concentration increases, so the reaction is affected, but adding inert gasses does not increase or d...
- Fri Jan 10, 2020 12:15 pm
- Forum: Ideal Gases
- Topic: Chatelier’s Principle
- Replies: 8
- Views: 253
Re: Chatelier’s Principle
The principle basically says that chemical reactions will adjust to minimize the effect of any changes. When pressure increases by a decrease in volume, and there are more moles of gas on the reactant side, then the reaction will produce more products. When pressure increases by a decrease in volume...
- Tue Dec 03, 2019 2:34 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Percentage Deprotonation
- Replies: 2
- Views: 135
Re: Percentage Deprotonation
Do we have to know this for the final?
- Tue Dec 03, 2019 2:19 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Sig Figs for ph/pOH calculations
- Replies: 1
- Views: 151
Re: Sig Figs for ph/pOH calculations
I haven't heard this mentioned anywhere else, did he mention it in lecture? and should we do it this way on the final?
- Tue Dec 03, 2019 2:15 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: 6B.9 Row 2&1
- Replies: 2
- Views: 134
Re: 6B.9 Row 2&1
In row 1 the pH of H30+ with 1.5M is -0.176, so when you do ([H30+]= 10^-pH, it looks like, ([H30+]= 10^-(-0.176)=1.5M. The negative signs cancel out so the equation does work, even though the pH is negative.
- Tue Dec 03, 2019 2:08 pm
- Forum: Hybridization
- Topic: Conceptual meaning of hybridization
- Replies: 3
- Views: 237
Re: Conceptual meaning of hybridization
Hybridization lowers the overall energy level by moving electrons around and creating hybrid orbitals to free up all of the electrons. The energy levels of the electrons will be between that of the two orbitals that are hybridized.
- Mon Nov 25, 2019 2:02 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Focus 2.63
- Replies: 1
- Views: 162
Re: Focus 2.63
The bond angles for a and c are 120 degrees because of the trigonal planar shape, and 109.5 degrees for b because it is tetrahedral.
- Mon Nov 25, 2019 1:50 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Focus 2.27
- Replies: 1
- Views: 153
Re: Focus 2.27
The lewis structures are all pretty straightforward, and none of these are radicals, but the bond angles depend on the shape and VSEPR theory. This is what I got for increasing bond angle: CH2 (2-) < CH3 (-) < CH4 < CH2 < CH3 (+) < CH2 (2+) The structures with a positive charge have a larger bond an...
- Mon Nov 25, 2019 1:45 pm
- Forum: Hybridization
- Topic: 2F.9
- Replies: 1
- Views: 124
Re: 2F.9
PCl4+ is sp3 because there are four bonds, PCl6- is sp3d2 because there are six bonds (phosphorus has an expanded octet), PCl5 is sp3d because there are five bonds, and PCl3 is sp3 because there are three bonds and one lone pair
- Mon Nov 25, 2019 1:40 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E.29
- Replies: 3
- Views: 284
Re: 2E.29
The first two isomers are polar because the C-Cl bond dipoles are not pointing in opposite directions and do not cancel out. The first form has the largest dipole moment because the bond angle between the two Cl's is the smallest.
- Mon Nov 25, 2019 1:38 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E.27
- Replies: 1
- Views: 278
Re: 2E.27
Pyridine is polar because the N is not bonded to a hydrogen so the dipoles don't cancel out. Ethane is nonpolar because the dipole moments cancel out and there is no electronegativity difference between the two carbons. Trichloromethane is polar because the dipole moments for chlorine point are stro...
- Fri Nov 22, 2019 10:31 am
- Forum: Biological Examples
- Topic: EDTA
- Replies: 3
- Views: 232
Re: EDTA
I believe it also has a negative 4 charge because of 4 singly bonded oxygens making it attractive to single electron atoms easily
- Fri Nov 22, 2019 10:15 am
- Forum: Hybridization
- Topic: 2F.15
- Replies: 2
- Views: 152
Re: 2F.15
Yes, I think that generally when the s character in a hybrid bond increases, the angle also increases
- Fri Nov 22, 2019 8:24 am
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: AXE
- Replies: 5
- Views: 365
Re: AXE
The only problem with this is molecules with double bonds can have the same formula as those with no double bonding, so they would still have the same shape and angle, but the single bonded molecule would be able to rotate while the double bonded molecule could not
- Fri Nov 22, 2019 8:18 am
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: sigma bond
- Replies: 11
- Views: 759
Re: sigma bond
The overlaps are referring to their electron in the orbitals overlapping making them shared
- Fri Nov 22, 2019 8:07 am
- Forum: Hybridization
- Topic: hybridizing d orbitals
- Replies: 7
- Views: 452
Re: hybridizing d orbitals
You can also write it like sp^3d or 2sp^3d
- Thu Nov 14, 2019 2:26 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Electrons
- Replies: 9
- Views: 480
Re: Electrons
Basically if the electrons were closer together they would want to repel, making them unstable, but if they are as far apart as possible they have nowhere to go, so they are stable.
- Thu Nov 14, 2019 2:20 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: difference between bent and angular
- Replies: 4
- Views: 255
Re: difference between bent and angular
Bent or angular refers to when there are three or four groups of electrons around an atom, but only two of them are bonding groups, meaning the other(s) are lone pairs. One example is H2O
- Thu Nov 14, 2019 2:13 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Homework 2E.11
- Replies: 3
- Views: 124
Re: Homework 2E.11
So for example in iodine trichloride the VSEPR formula would be AX3E2 because there are three bonds to the central atom and two lone pairs on the central atom.
- Thu Nov 14, 2019 2:09 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 2
- Views: 101
Re: Bond Angles
Yes but for most of them you can just memorize the angles that go with each shape.
- Thu Nov 14, 2019 2:07 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angle
- Replies: 9
- Views: 545
Re: Bond Angle
You should probably say that it is less than 109.5 degrees because that is technically more correct.
- Fri Nov 08, 2019 4:57 pm
- Forum: Electronegativity
- Topic: Periodic Trend
- Replies: 13
- Views: 816
Re: Periodic Trend
You can also use effective nuclear charge to describe the electronegativity trend, because it also increases in the top right corner of the periodic table. This means that atoms hold their electrons more tightly because the elements with more electrons and smaller radius have more protons, so there ...
- Fri Nov 08, 2019 4:54 pm
- Forum: Bond Lengths & Energies
- Topic: Sigma Pi
- Replies: 2
- Views: 176
Re: Sigma Pi
The sigma bond is just a covalent bond, and every bond has a sigma, and the pi bonds represent the overlapping of another bond, which is why triple bonds have 2 pi's.
- Fri Nov 08, 2019 4:49 pm
- Forum: Photoelectric Effect
- Topic: Frequency and number of electrons ejected
- Replies: 2
- Views: 320
Re: Frequency and number of electrons ejected
I'm not entirely sure but this seems correct because if one photon needs a certain amount of energy to emit one electron, then the next photon would need that same amount of energy to emit the next electron, making the total energy double in the end.
- Fri Nov 08, 2019 4:46 pm
- Forum: Lewis Acids & Bases
- Topic: diff b/w lewis acid and base
- Replies: 12
- Views: 711
Re: diff b/w lewis acid and base
Also acids are usually positively charged and bases are more likely negatively charged
- Fri Nov 08, 2019 4:41 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSPER
- Replies: 1
- Views: 100
Re: VSPER
I think it is when there is a polarizing cation and a polarizable anion in close contact
- Sun Nov 03, 2019 7:13 pm
- Forum: Coordinate Covalent Bonds
- Topic: Atom Sharing
- Replies: 5
- Views: 350
Re: Atom Sharing
There is also an electronegativity difference, because coordinate covalent bonds are more polar
- Sun Nov 03, 2019 6:55 pm
- Forum: Resonance Structures
- Topic: Resonance structures
- Replies: 6
- Views: 528
Re: Resonance structures
It's basically when you can place a bond in multiple places in the Lewis structure without drastically changing the structure or charge.
- Sun Nov 03, 2019 6:51 pm
- Forum: Bond Lengths & Energies
- Topic: Bonding
- Replies: 7
- Views: 450
Re: Bonding
I don't think there is a specific number of electrons that each expanded octet can hold that we need to know, just know that it is more than 8
- Sun Nov 03, 2019 6:48 pm
- Forum: Octet Exceptions
- Topic: 2C.5
- Replies: 2
- Views: 129
Re: 2C.5
There would only be a radical if there is an unpaired electron, so an odd number of valence electrons. There is a good example in 2C.13 part b, where ClO2 has one unpaired electron.
- Sun Nov 03, 2019 6:46 pm
- Forum: Octet Exceptions
- Topic: Expanded Valence Shells
- Replies: 6
- Views: 224
Re: Expanded Valence Shells
I thought that all elements in or past the third period can have expanded octets because they have an empty d orbital where the extra electron can go.
- Thu Oct 24, 2019 4:10 pm
- Forum: Bond Lengths & Energies
- Topic: Bond lengths
- Replies: 15
- Views: 1044
Re: Bond lengths
Then if the bond length is always the same why is it important?
- Thu Oct 24, 2019 4:05 pm
- Forum: Octet Exceptions
- Topic: Max number of valence e
- Replies: 6
- Views: 657
Re: Max number of valence e
When you say 18 valence electrons is the most, does that mean 18 electrons fill the shell? and if the shell is full wouldn't that mean that there are no valence electrons?
- Thu Oct 24, 2019 4:00 pm
- Forum: Octet Exceptions
- Topic: Octet Rule
- Replies: 6
- Views: 276
Re: Octet Rule
I thought I heard that the octet rule is more of a guideline, but the exceptions are H, He, Li, and Be
- Thu Oct 24, 2019 3:54 pm
- Forum: Ionic & Covalent Bonds
- Topic: Understanding the electron affinity equation
- Replies: 3
- Views: 219
Re: Understanding the electron affinity equation
Also electron affinity is the energy released when an electron is added to a gas phase atom
- Thu Oct 24, 2019 3:51 pm
- Forum: Ionic & Covalent Bonds
- Topic: What's the difference between valence electrons and the valence of an atom?
- Replies: 3
- Views: 375
Re: What's the difference between valence electrons and the valence of an atom?
Also the valence of an atom depends on the number of valence electrons, for example if there were 3 valence electron then the atom should typically be able to form 3 bonds.
- Wed Oct 16, 2019 8:36 pm
- Forum: Photoelectric Effect
- Topic: 1B.9
- Replies: 2
- Views: 140
Re: 1B.9
Just to clarify you get the total energy using the equation E = W(j/s) * t (s) to get 64 J
- Wed Oct 16, 2019 8:31 pm
- Forum: Photoelectric Effect
- Topic: Post Assessment Help
- Replies: 2
- Views: 203
Re: Post Assessment Help
But since the question gives you the work function there is another equation that uses both which is
kinetic energy = energy of photon - work function (energy required to remove photon
kinetic energy = energy of photon - work function (energy required to remove photon
- Wed Oct 16, 2019 8:28 pm
- Forum: Photoelectric Effect
- Topic: Energy per Photon
- Replies: 4
- Views: 260
Re: Energy per Photon
Another equation that might be relevant here is E = W(j/s)*t (s)
- Wed Oct 16, 2019 8:19 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Why divide h by 4pi?
- Replies: 5
- Views: 363
Re: Why divide h by 4pi?
Also I think there is a derivation for the equation that would explain why h/4pi is there, but Dr. Lavelle said it was too complicated for us to work through the whole derivation because it uses things we haven't learned yet.
- Wed Oct 16, 2019 8:15 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Momentum
- Replies: 7
- Views: 335
Re: Momentum
Momentum is also important because some small objects may not have a measurable mass, but they have momentum, so we can still use the equation for them because of momentum.
- Fri Oct 11, 2019 10:46 pm
- Forum: Photoelectric Effect
- Topic: Wavelengths
- Replies: 4
- Views: 171
Re: Wavelengths
Also wavelength is inversely proportional to frequency, increasing one decreases the other, so with a short wavelength of light, there would be a higher frequency and the electron would eject.
- Fri Oct 11, 2019 10:40 pm
- Forum: Properties of Electrons
- Topic: Clarification on particle vs wave properties
- Replies: 3
- Views: 264
Re: Clarification on particle vs wave properties
The main property of waves that I understood was diffraction patterns displayed when electrons passed through a crystal. It might help to look up a picture or diagram of this also.
- Fri Oct 11, 2019 10:37 pm
- Forum: Properties of Electrons
- Topic: Wave Properties of Electrons
- Replies: 4
- Views: 296
Re: Wave Properties of Electrons
Destructive interference and out of phase waves basically mean the same thing. Also if two waves are completely out of phase and are the same size, they can cancel each other out.
- Fri Oct 11, 2019 10:27 pm
- Forum: Properties of Light
- Topic: Amplitude
- Replies: 12
- Views: 575
Re: Amplitude
The only time I really noticed amplitude making a difference was in constructive and destructive interference, because it seemed to increase in constructive and decrease in destructive.
- Fri Oct 11, 2019 10:24 pm
- Forum: Properties of Light
- Topic: Wavelength
- Replies: 4
- Views: 191
Re: Wavelength
Also note that in constructive interference the amplitude gets larger and in destructive interference it gets smaller.
- Fri Oct 11, 2019 10:22 pm
- Forum: Properties of Light
- Topic: Adding formulas
- Replies: 5
- Views: 176
Re: Adding formulas
Another way of saying it is that it is used to find the energy needed to move electron, or threshold energy.
- Thu Oct 03, 2019 5:00 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Fundamentals E.3
- Replies: 7
- Views: 435
Re: Fundamentals E.3
I started the problem by finding how many grams of gallium there were so I knew how much astatine I needed to balance the scale, which was 3.794 grams. Then I divided that by the molar mass of astatine, and got 1.8066 x 10^24 moles, and then I divided that by Avogadro's constant to get 3 atoms of as...
- Thu Oct 03, 2019 4:41 pm
- Forum: Significant Figures
- Topic: Confused about sig figs
- Replies: 2
- Views: 207
Re: Confused about sig figs
I think that either way of writing the answer works since 33.03 x10^2 is written with a number higher than 10 (assuming this problem came from the textbook?), but both answers are technically the same number.
- Mon Sep 30, 2019 3:27 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Symbol for Molarity
- Replies: 7
- Views: 780
Re: Symbol for Molarity
Also while the symbol for molar mass is M, when given a molar mass in homework or test problems it will have units of g/mol, which may help distinguish it from molarity.
- Mon Sep 30, 2019 3:20 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Homework problem E23
- Replies: 5
- Views: 253
Re: Homework problem E23
The problem is:
Calculate the amount in moles of Cu^2+ ions in 3.00g of CuBr2.
I thought the ratio would be 1Cu: 2Br because the 2+ attached to the Cu is referring to the charge, not amount, while the Br2 is referring to the amount, but on the solutions manual the ratio was 1:1
Calculate the amount in moles of Cu^2+ ions in 3.00g of CuBr2.
I thought the ratio would be 1Cu: 2Br because the 2+ attached to the Cu is referring to the charge, not amount, while the Br2 is referring to the amount, but on the solutions manual the ratio was 1:1