Search found 103 matches
- Tue Mar 17, 2020 11:38 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Concentration Cells
- Replies: 4
- Views: 770
Re: Concentration Cells
Yes, a cell can be both a galvanic and a concentration cell, as long as the concentration cell is spontaneous and can produce electrical energy via its redox reactions.
- Tue Mar 17, 2020 11:32 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Delta G of ionization
- Replies: 3
- Views: 687
Re: Delta G of ionization
Yes, it just specifies that it's the delta G of an ionization reaction.
- Tue Mar 17, 2020 11:25 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Water and voltage
- Replies: 9
- Views: 1336
Re: Water and voltage
If it's a concentration cell, adding water will affect the concentration, and that will in turn affect the voltage.
- Sat Mar 14, 2020 11:05 pm
- Forum: Phase Changes & Related Calculations
- Topic: expansion
- Replies: 5
- Views: 495
Re: expansion
it is also important to know the difference between gradual expansion and sudden expansion, in which you would apply the appropriate formula. The questions I have seen typically state whether the process is occurring gradually or suddenly. Hope this helps! Sorry, could you explain what the appropri...
- Sat Mar 14, 2020 11:00 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Determining if a reaction mechanism is feasible
- Replies: 3
- Views: 343
Re: Determining if a reaction mechanism is feasible
I’m not 100% sure but I think they mean that you should always check that the rate law has the same order. When using K to find concentrations for intermediates, it can be easy to make mistakes while substituting, so just check that it’s done right by making sure the order matches.
- Sat Mar 14, 2020 10:52 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: What was your favorite chem topic?
- Replies: 137
- Views: 8489
Re: What was your favorite chem topic?
Electrochemistry! I think I dreaded it going into it because I always found it confusing before, but I put extra effort into studying and understanding it before Test 2 and now it’s the topic I’m the most comfortable with haha.
- Sat Mar 14, 2020 10:47 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Endgame 5d
- Replies: 3
- Views: 467
Re: Endgame 5d
n=1 because the coefficient of every reactant/product is 2 so you divide the entire reaction by 2 to simplify, leaving you with 1 e-.
- Sat Mar 14, 2020 10:42 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: ENDGAME Q.10
- Replies: 3
- Views: 239
Re: ENDGAME Q.10
If you flip the sign then you add the cell potentials; if you’re subtracting then just use the given reduction potentials without flipping.
- Sat Mar 14, 2020 10:39 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Endgame 15b
- Replies: 5
- Views: 379
Re: Endgame 15b
Yeah I guess the pseudo rate constant allows us to focus on seeing how one specific reactant’s concentration affects rate. By making the concentration of A super high, it’s essentially not changing as the reaction proceeds, and thus we can include it in k’.
- Sat Mar 14, 2020 10:14 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Review slides
- Replies: 1
- Views: 150
Review slides
For the question that asks for what’s wrong with the cell diagram, how is it possible for the left side to only have solids? Don’t you need some form of aqueous solution in a cell?
- Sat Mar 14, 2020 10:10 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Electrode Mass
- Replies: 10
- Views: 4400
Re: Electrode Mass
Changing the mass of the electrode shouldn’t affect cell potential, it will just affect the lifespan of the electrode.
- Sat Mar 14, 2020 10:06 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Problems
- Replies: 3
- Views: 320
Re: Problems
Thanks for the response! Could someone summarize what knowing the type of system would tell you for each system? Like if it’s an isolated system, do I know that a certain value would be 0 or something?
- Sat Mar 14, 2020 10:04 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Ppt Question
- Replies: 2
- Views: 277
Ppt Question
For the question on slide 5 of the final review PowerPoint, why do we only use the delta G for PCl5 and PCl3 when calculating the delta G of the reaction?
- Sat Mar 14, 2020 9:44 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: + or - w
- Replies: 2
- Views: 267
+ or - w
While I was reviewing I watched a few videos that stated the first law as delta u= q - w, and they said that w is positive when work is being done on the surroundings. It threw me off because it’s different from how we’ve been thinking about it, and now I’m confused. How are we treating w on the tes...
- Sat Mar 14, 2020 12:15 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Problems
- Replies: 3
- Views: 320
Problems
What type of problems could be asked regarding the different types of thermodynamic systems? Like, would there be a question focused solely on this concept, or are they just mentioned as part of a different type of problem?
- Sat Mar 14, 2020 12:07 pm
- Forum: Balancing Redox Reactions
- Topic: Writing balanced half reactions
- Replies: 2
- Views: 244
Re: Writing balanced half reactions
We can also look at the reduction potential values for each half reaction to determine which side the electrons should be on for each half reaction. We want Ecell to be positive (in order to be spontaneous) so the more positive reduction potential is the reduction half reaction (with electrons on th...
- Sat Mar 14, 2020 12:01 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: liquid mercury
- Replies: 3
- Views: 273
Re: liquid mercury
I don't believe we will need to know the specifics about liquid mercury as an electrode for the final, as it is a more complex case and he said the test would be pretty straightforward.
- Fri Mar 13, 2020 1:56 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Calculating Gibbs free energy of 1/2 rxn
- Replies: 3
- Views: 294
Re: Calculating Gibbs free energy of 1/2 rxn
Both equations have to have the same number of electrons being transferred, that's a part of balancing redox reactions. So you'd multiply the Ag half reaction by 2, and n=2 for both equations.
- Wed Mar 11, 2020 11:10 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Downs Process
- Replies: 4
- Views: 387
Re: Downs Process
Since we're already here.. could someone briefly explain what Downs Process is? I'm curious, I don't think I've heard about it before.
- Wed Mar 11, 2020 11:00 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Memorization?
- Replies: 4
- Views: 324
Re: Memorization?
Yes, it would be useful to be able to derive, we might need it to solve a problem.
- Wed Mar 11, 2020 10:57 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Units
- Replies: 8
- Views: 2838
Units
I just want to confirm because I was a bit confused: the units for rate are always the same, but units for rate constants can change depending on the order of the reaction?
- Wed Mar 11, 2020 10:53 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Applying La Chateliers
- Replies: 4
- Views: 285
Re: Applying La Chateliers
In redox reactions (ie. Zn + 2H+ → Zn2+ + H2), the ion from the oxidation half-reaction (the anode) is a product (Zn2+), and the ion from the reduction half-reaction (the cathode) is a reactant (H+). In Le Chateliers principle, when you increase the concentration of reactants or decrease the concent...
- Wed Mar 11, 2020 10:48 am
- Forum: Balancing Redox Reactions
- Topic: Half Reactions
- Replies: 15
- Views: 776
Re: Half Reactions
Always add H2O first to balance out any O in the reactions. Then, depending on whether it's in acidic or basic solution, add H+ or OH- (and H2O on the other side to balance O) in order to balance out the H.
- Wed Mar 11, 2020 10:44 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Relationship Between Ecell and K
- Replies: 9
- Views: 3153
Re: Relationship Between Ecell and K
I agree with all the previous responses, and it makes sense if you think about the meaning of these values. Ecell can describe spontaneity (spontaneous if the value is positive, not spontaneous if the value is negative) while K, the equilibrium constant, describes whether the reaction is product or ...
- Mon Mar 02, 2020 9:31 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Concentration in Cell Notation
- Replies: 2
- Views: 173
Concentration in Cell Notation
Does anyone know if we have to write the concentration of aqueous solutions for cell notation problems on Test 2?
- Sun Mar 01, 2020 2:35 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: C(gr) state
- Replies: 4
- Views: 270
Re: C(gr) state
C(gr) is carbon in the form of solid graphite and is commonly used as an inert electrode.
- Sun Mar 01, 2020 11:17 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Cell doing work
- Replies: 1
- Views: 198
Re: Cell doing work
One thing that's useful for understanding the effect of concentration cells is Le Chatelier's principle. In redox reactions (ie. Zn + 2H+ → Zn2+ + H2), the ion from the oxidation half-reaction (the anode) is a product (Zn2+), and the ion from the reduction half-reaction (the cathode) is a reactant (...
- Sun Mar 01, 2020 11:06 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Potential
- Replies: 3
- Views: 276
Re: Cell Potential
To add on to this, we can calculate the cell potential under nonstandard conditions using the Nernst equation.
- Sun Mar 01, 2020 11:02 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Graphite VS. Platinum
- Replies: 2
- Views: 743
Re: Graphite VS. Platinum
I don't believe there's a difference between using graphite vs platinum as an inert electrode, although we did hear a bit more about platinum in class, so that's the one I default to.
- Sun Mar 01, 2020 10:56 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Stronger Reducing Agent
- Replies: 2
- Views: 202
Re: Stronger Reducing Agent
First of all, remember the reducing agent is the one being oxidized, so you have to flip the given standard reduction potential equation to get the standard reduction potential of the oxidation half-reaction. When calculating the reduction potential of the cell, we want the value to be positive beca...
- Mon Feb 24, 2020 10:17 am
- Forum: Balancing Redox Reactions
- Topic: Oxidizing/Reducing Agent
- Replies: 8
- Views: 566
Oxidizing/Reducing Agent
How do you identify the oxidizing agent or the reducing agent? Is it typically on the left or right side of a chemical reaction?
- Mon Feb 24, 2020 10:08 am
- Forum: Balancing Redox Reactions
- Topic: 6K.3 part d
- Replies: 3
- Views: 253
6K.3 part d
This question asks us to balance the redox reaction of chlorine in water, with the reaction being Cl2 gas going to HClO and Cl2 gas again. How would you go about starting this? I'm having a hard time identifying the oxidation half-reaction and the reduction half-reaction.
- Thu Feb 13, 2020 1:24 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: change in Kc
- Replies: 5
- Views: 389
Re: change in Kc
I agree with the previous response. If you think about it, it makes sense because you're changing the coefficient of each reactant/product by the same factor, and the coefficients determine what power the values are raised to. For example, if the overall reaction is multiplied by 2, then each reacta...
- Wed Feb 12, 2020 10:25 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Net Charge of an Acid [ENDORSED]
- Replies: 1
- Views: 315
Net Charge of an Acid [ENDORSED]
How do you find the net charge of an acid given the pH and the pKa?
- Wed Feb 05, 2020 1:27 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: Entropy in an isolated system
- Replies: 3
- Views: 184
Re: Entropy in an isolated system
To be at maximum entropy is to be at the “most random” state. That’s not the best wording but I think Dr. Lavelle’s example in class is helpful: if he opened a sealed beaker of argon gas in the lecture hall, it would diffuse and spread through the entire room until it was at maximum entropy.
- Wed Feb 05, 2020 1:19 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Question 4C.11
- Replies: 4
- Views: 225
Re: Question 4C.11
You need to add the energy required to melt the ice cube to the energy required to raise the temperature of the (liquid) water in order to get the total energy that needs to be used in this process.
- Wed Feb 05, 2020 1:15 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ch 5I question #19
- Replies: 2
- Views: 138
Re: Ch 5I question #19
If you're asking if the final equilibrium value of HI is 2(60% of H2 + 1.60 mol of I2), then no, that's not entirely correct. When you set up an ICE table, you can see that for the "C(hange)" row, the change in the value of HI is +2*x because there are two moles. To find x, you use the fac...
- Tue Feb 04, 2020 2:13 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Thermochemistry vs Thermodynamics
- Replies: 2
- Views: 202
Thermochemistry vs Thermodynamics
Could someone please explain the difference between thermochemistry and thermodynamics? I'm a bit confused about the distinction.
- Sun Feb 02, 2020 10:12 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: 4B.5
- Replies: 2
- Views: 183
Re: 4B.5
I agree with what the previous reply said. In these types of problems, it's important to keep track of the signs of the values. A negative w value means the system is performing work on its surroundings, while a positive w value means the surroundings are performing work on the system. Likewise, a n...
- Sun Feb 02, 2020 10:06 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Test 1
- Replies: 3
- Views: 205
Test 1
Wait, when did everyone get their tests back? We didn't get ours during our last discussion...
- Mon Jan 27, 2020 1:37 am
- Forum: Phase Changes & Related Calculations
- Topic: State functions
- Replies: 5
- Views: 226
State functions
Why is enthalpy a state function, but not heat? I understand how a property like distance isn't a state function, but it's harder for me to understand with heat.
- Mon Jan 27, 2020 1:34 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Acid and Base Concentration
- Replies: 3
- Views: 127
Re: Acid and Base Concentration
It's easier to determine the strength with the Ka or Kb values, the concentration can't really tell you much about how much the acid/base dissociates.
- Mon Jan 27, 2020 1:26 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: calculating % ionization
- Replies: 4
- Views: 250
Re: calculating % ionization
I agree with the previous response, you do [A-]/[HA], and then x100 to get the percentage.
- Thu Jan 23, 2020 12:26 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Test 1
- Replies: 4
- Views: 191
Re: Test 1
The test covers up to acids & bases (so outline 1 & 2), and I'd recommend being very comfortable with ICE tables.
- Mon Jan 20, 2020 11:34 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kw temperature
- Replies: 8
- Views: 144
Re: Kw temperature
Kw=1x10^-14 at 25*C.
- Mon Jan 20, 2020 11:29 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Pressure changes
- Replies: 7
- Views: 182
Re: Pressure changes
When it comes to the partial pressure of a reactant/product changing, you can basically think of it as a change in concentration. So if the partial pressure of a reactant increased, then the reaction would shift to the right/to the products. But if they're talking about the pressure of the reaction ...
- Mon Jan 20, 2020 11:25 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5% rule clarification
- Replies: 2
- Views: 114
Re: 5% rule clarification
Yes, if you approximate for a small x value (when K<10^-3), you have to check that the value of x is less than 5% of the initial concentration in order for the approximation to be valid.
- Mon Jan 20, 2020 11:22 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kp units
- Replies: 2
- Views: 119
Re: Kp units
I think it's atm or bar, but keep in mind that Kp itself won't have units.
- Sun Jan 12, 2020 4:49 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5I. 19
- Replies: 3
- Views: 146
Re: 5I. 19
Since you know 60% of H2 reacted, you know 40% is remaining at equilibrium. Thus, you can find the equilibrium value of H2 by multiplying the initial value of H2 by 0.4.
- Sun Jan 12, 2020 4:37 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: When to Use Ice Tables?
- Replies: 3
- Views: 176
Re: When to Use Ice Tables?
If they ask for the "equilibrium composition", that's generally an indication to use an ICE table. Also, if they ask for K and they give some initial values and some equilibrium values, you should probably use an ICE table to find all the equilibrium values to calculate K.
- Sun Jan 12, 2020 4:35 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Help on 5H.3
- Replies: 1
- Views: 128
Re: Help on 5H.3
I think section 5H.2 in the textbook on composite reactions is helpful in understanding how to do this problem. Basically, in 5H.3, the reaction they give us is a composite reaction, and we have to use Table 5G.2 to find the two reactions that are added together to make the reaction we're given. Onc...
- Sun Jan 12, 2020 2:46 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: x is small approximation
- Replies: 6
- Views: 491
x is small approximation
How do we determine when we can use the "x is small" approximation? Do we look at the value of K for this?
- Fri Jan 10, 2020 10:33 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kp vs Kc
- Replies: 6
- Views: 118
Kp vs Kc
How do we determine when we should use Kp versus when we should use Kc? I find myself defaulting to Kc, only to find that the answer is given in Kp.
- Sun Dec 08, 2019 3:45 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final Grade
- Replies: 5
- Views: 409
Final Grade
Does anyone know when we'll get our final grade? Do we have to wait until we pick it up winter quarter?
- Sat Dec 07, 2019 11:21 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: 6B.9
- Replies: 1
- Views: 116
6B.9
I'm a bit confused about the pH for row i). I plug the given H30+ concentration, 1.50 M, into the pH equation, so -log(1.50 M)= -.176, but the answer should be .176 according to the solutions manual. What is going on?
- Sat Dec 07, 2019 5:47 pm
- Forum: Biological Examples
- Topic: Final
- Replies: 6
- Views: 481
Final
What are the most important biological examples that we should know for the final?
- Sat Dec 07, 2019 5:45 pm
- Forum: Hybridization
- Topic: How to recognize
- Replies: 1
- Views: 175
How to recognize
How can we tell if an atom goes through hybridization or not?
- Sat Dec 07, 2019 5:40 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Disobeying the octect rule
- Replies: 4
- Views: 268
Re: Disobeying the octect rule
Yeah, basically all elements period 3 and beyond can disobey the octet rule because they have room in the d-orbitals of their valence shell.
- Sun Dec 01, 2019 9:20 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: Test 2: Number of Hydrogen Bonding Sites Question
- Replies: 3
- Views: 341
Re: Test 2: Number of Hydrogen Bonding Sites Question
I'm a bit confused by the mixed answers too, I put 8 and got it right on my test. There were 4 N with 1 lone pair each, so that's 4 hydrogen bonding sites; there were 2 O with 2 lone pairs each, so that's another 4 hydrogen bonding sites, giving me 8 in total. In theory, if there were any H attached...
- Sun Dec 01, 2019 9:03 pm
- Forum: Naming
- Topic: -bis, -tris, etc
- Replies: 5
- Views: 424
Re: -bis, -tris, etc
We use bis-, tris-, etc. when the ligand's name already contains di-, tri-, etc, or when the ligand is polydentate.
- Sun Dec 01, 2019 8:55 pm
- Forum: Bronsted Acids & Bases
- Topic: Difference between Arrhenius, Bronsted, and Lewis Acids/Bases
- Replies: 2
- Views: 218
Re: Difference between Arrhenius, Bronsted, and Lewis Acids/Bases
This is pretty helpful, thanks for sharing! Does anyone happen to know which definition is used most commonly, and why?
- Sun Dec 01, 2019 8:52 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: J.9
- Replies: 2
- Views: 167
J.9
How can you tell if an acid/base will dissociate into ions in water?
- Sun Dec 01, 2019 8:49 pm
- Forum: Bronsted Acids & Bases
- Topic: J.17
- Replies: 1
- Views: 175
J.17
How do you tell if it's the cation or the anion that's going to be involved in the proton transfer with the water?
- Sun Nov 24, 2019 6:36 pm
- Forum: Naming
- Topic: Order in Naming
- Replies: 12
- Views: 670
Re: Order in Naming
I think you have to write the atomic symbols of the ligands in alphabetical order, at least according to Toolbox 9C.1 in the textbook.
- Sun Nov 24, 2019 5:56 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Molecular shape vs Electron Configuration
- Replies: 4
- Views: 409
Re: Molecular shape vs Electron Configuration
Molecular shape is the shape we get while looking mostly at the bonds (I say 'mostly' because lone pairs do affect molecular shape), while electronic geometry considers both bonds and lone pairs in the shape. Thus, electronic geometry only has the basic shapes (ie tetrahedral, trigonal bipyramidal, ...
- Sun Nov 24, 2019 5:39 pm
- Forum: Naming
- Topic: Chemistry Community
- Replies: 4
- Views: 267
Re: Chemistry Community
I also have trouble asking questions sometimes. I've found that one good way to come up with questions is having Chemistry Community open while doing homework, and making a post when I get really stuck on a problem. Also, I'll correct my homework, and if I don't understand why I got something wrong,...
- Sun Nov 24, 2019 5:30 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: What is a coordinate number?
- Replies: 3
- Views: 235
Re: What is a coordinate number?
In the case of coordination compounds, the coordination number is simply the number of ligands attached to the central metal. We can find it by looking at the subscripts of the ligands. [Co(CN)5(OH2)] has a coordination number of 6: 5 CN + 1 OH2
- Sun Nov 24, 2019 5:16 pm
- Forum: Naming
- Topic: using brackets
- Replies: 5
- Views: 408
Re: using brackets
We use brackets around the complex, which is the entire species with the central metal ion and the ligands. We use parenthesis within the brackets, around any ligands that need it. For example, there's [Fe(CN)6]; the whole thing in brackets is the complex, and the parenthesis are around the ligand, ...
- Sun Nov 17, 2019 11:26 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Radicals and molecular shape
- Replies: 5
- Views: 343
Re: Radicals and molecular shape
I think Dr. Lavelle said radicals are treated as one region of electron density when it comes to determining shape.
- Sun Nov 17, 2019 11:19 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR Notation
- Replies: 4
- Views: 376
Re: VSEPR Notation
In VSEPR notation, there are 3 symbols you need to know: A - the central atom; X - bonded atoms; and E - lone pairs. Then you look at the Lewis structure, see how many bonded atoms and lone pairs there are, and write those numbers in the subscripts by their symbols. For example, H 2 O is AX 2 E 2 , ...
- Sun Nov 17, 2019 8:59 pm
- Forum: Electronegativity
- Topic: 2D.3
- Replies: 3
- Views: 374
Re: 2D.3
Keep the electronegativity trends in mind: F is the most electronegative atom, so as you move away from F on the periodic table, the atoms become less electronegative. Since Ba is further from F than Be is, Ba is less electronegative than Be. This means that the electronegativity difference between ...
- Sun Nov 17, 2019 8:51 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizable vs polarizing power
- Replies: 6
- Views: 436
Re: Polarizable vs polarizing power
I think cations tend to be better at polarizing atoms than they are at being polarized, and vice versa for anions, which is why we tend to talk about cations in terms of their polarizing power and anions in terms of their polarizability. If cations have polarizability and anions have polarizing powe...
- Sun Nov 17, 2019 8:46 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Drawing the Lewis Structure of N20 (2E.13d)
- Replies: 5
- Views: 847
Re: Drawing the Lewis Structure of N20 (2E.13d)
First we add up the valence electrons, and we find that we have 16 electrons to work with. We know N is the central atom because it has lower ionization energy than O. So we start off with N-N-O. We could use all the electrons to complete the octets for the outside N & O, but then we see that th...
- Sun Nov 10, 2019 11:42 pm
- Forum: Trends in The Periodic Table
- Topic: Ionization
- Replies: 5
- Views: 615
Re: Ionization
It's kind of similar to why Cr and Cu have electron configurations different from what we expect - stability. It is more stable to have those 3 half filled orbitals in nitrogen than it is to have 1 pair of electrons, and then two unpaired electrons like in oxygen. Since it wants to be more stable, i...
- Sun Nov 10, 2019 11:36 pm
- Forum: Resonance Structures
- Topic: Orbitals
- Replies: 4
- Views: 350
Re: Orbitals
Orbitals aren't actual physical "places" for electrons to stay in, they just describe the probability of finding an electron in a specific region. So if an electron isn't "in" an orbital, that orbital doesn't exist, because the probability of finding an electron there is zero.
- Sun Nov 10, 2019 11:20 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizing Calculations
- Replies: 2
- Views: 152
Re: Polarizing Calculations
I don't think so. I don't believe we've learned how to do that, or if that's possible? Maybe just keep in mind how the size/charge of the atom affects polarizability and polarizing power.
- Sun Nov 10, 2019 11:13 pm
- Forum: Ionic & Covalent Bonds
- Topic: Solid v. Liquid v. Gas
- Replies: 8
- Views: 403
Re: Solid v. Liquid v. Gas
I think it will typically be given to us. Perhaps in some cases, with common substances like water, they might give us a temperature and expect us to know the state. Otherwise, I'm pretty sure we aren't expected to know this? Maybe look at bond strengths, and just know that the stronger the intermol...
- Sun Nov 10, 2019 11:06 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizability
- Replies: 4
- Views: 323
Re: Polarizability
Larger atoms have higher polarizability not only because their electrons are more loosely held, but also because the larger area makes it more feasible for many electrons to gather at one end of the atom, creating a more noticeable polarity than smaller atoms.
- Sun Nov 03, 2019 11:20 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Wave Functions on the Midterm
- Replies: 1
- Views: 116
Wave Functions on the Midterm
What exactly do we need to know about wave functions for the midterm? I'm a bit confused about it. Will we have to use Schrodinger's equation?
- Sun Nov 03, 2019 11:17 pm
- Forum: Ionic & Covalent Bonds
- Topic: Figuring out the Lewis Structure
- Replies: 3
- Views: 177
Re: Figuring out the Lewis Structure
Covalent bonds are typically between two nonmetals (right side of periodic table), while ionic bonds are between a metal and a nonmetal, so be sure to keep that in mind too!
- Sun Nov 03, 2019 11:14 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Trends
- Replies: 3
- Views: 229
Trends
What is an easy way to remember the trends of polarizability/polarizing power on the periodic table?
- Sun Nov 03, 2019 11:06 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Showing Work
- Replies: 6
- Views: 276
Showing Work
Do you think we have to write out the entire equation for formal charge on the midterm? Or can we just calculate it in our head, and write the formal charge by the element? I don't want to spend too much time writing out work if it's unnecessary. Thank you!
- Tue Oct 29, 2019 8:38 pm
- Forum: Ionic & Covalent Bonds
- Topic: HW 2A.5
- Replies: 2
- Views: 193
HW 2A.5
Why do we take electrons from the s orbital rather than the d orbital? As in, why is the Ga3+ ion [Ar]3d^10 rather than [Ar]3d^8 4s^2?
- Sun Oct 27, 2019 11:14 pm
- Forum: Trends in The Periodic Table
- Topic: Exact radii/ionization energies
- Replies: 1
- Views: 128
Exact radii/ionization energies
In the solutions manual, for questions that require us to arrange atoms in order of increasing/decreasing radii or ionization energy, it gives us the actual radii/ionization energy in parenthesis. Are we required to actually know any of these? Or just have a general idea of the size of atoms/ionizat...
- Sun Oct 27, 2019 11:11 pm
- Forum: Trends in The Periodic Table
- Topic: 1F.5a
- Replies: 4
- Views: 141
1F.5a
Can someone explain why Na has a smaller first ionization energy than Al? Their valence electrons are both the first electrons in a subshell (3s1 vs 3p1).
- Sun Oct 27, 2019 12:41 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 1E.17b
- Replies: 1
- Views: 82
1E.17b
For Mn, why is an electron removed from the 4s orbital to form a +1 ion, rather than the 3d orbital?
- Sun Oct 27, 2019 12:37 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Question 1E.25
- Replies: 1
- Views: 86
Re: Question 1E.25
I also got (n-1)d3ns2, and the solutions manual I checked says that this is correct.
- Sun Oct 27, 2019 12:29 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: HW 1E.7
- Replies: 1
- Views: 110
HW 1E.7
How can you tell that a) and b) are in the excited state? I can see that c) is excited and d) is in the ground state, but I'm not sure how the first two are.
- Tue Oct 22, 2019 8:07 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Hw Help 1D.25
- Replies: 3
- Views: 125
Re: Hw Help 1D.25
I like to go about this by first associating the letter with its orbital angular momentum quantum number (l). So s -> l=0, p -> l=1, d -> l=2, and so on. Then compare that number to the first number, which is the principal quantum number (n). We know that l must be less than n, so if the second numb...
- Sun Oct 20, 2019 10:44 am
- Forum: Limiting Reactant Calculations
- Topic: Missed this Question on Test1
- Replies: 5
- Views: 646
Re: Missed this Question on Test1
So I looked back at my test to check what I did for this problem, and I realized that I can't seem to find this question on my test. I guess this means there's different versions of the test out there? (Also, based on what you've said for the question, I think you could also convert from 5 grams of ...
- Sat Oct 19, 2019 10:46 am
- Forum: DeBroglie Equation
- Topic: 1B.19
- Replies: 1
- Views: 155
1B.19
I know we didn't have to end up reporting the difference as a percentage of the wavelength of the neutron because the wavelengths were the same at 3 significant figures, but if we did, how would we go about doing that?
- Sat Oct 19, 2019 10:41 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: HW 1B.27
- Replies: 2
- Views: 135
HW 1B.27
Why is the uncertainty in velocity 5 m/s when given 5.00 ± 5.0 m/s, when in the example in the text they gave ±1.00mm/s and had the uncertainty as 2mm/s?
- Sat Oct 19, 2019 10:38 am
- Forum: Einstein Equation
- Topic: HW 1B.15c
- Replies: 1
- Views: 168
HW 1B.15c
I just directly plugged the frequency they gave us in part b into the c=λν equation, but that's not correct. How do we know when we have to take kinetic energy into account as well?
- Sun Oct 13, 2019 10:12 pm
- Forum: Properties of Light
- Topic: 1A.9
- Replies: 5
- Views: 136
Re: 1A.9
Thanks for the replies! The equation needed wasn't in section 1A, but then I realized it was one of the first things to show up in 1B ^^|| I'll be sure to remember the equation from now on!
- Sun Oct 13, 2019 10:09 pm
- Forum: Properties of Light
- Topic: 1A.3
- Replies: 1
- Views: 75
1A.3
The question is "which of the following happens when the frequency of electromagnetic radiation decreases?" And I picked (c) "The extent of the change in the electrical field at a given point decreases" by process of elimination, because I knew the other answers weren't correct. ...
- Sun Oct 13, 2019 4:12 pm
- Forum: Properties of Light
- Topic: problem 1A.15
- Replies: 4
- Views: 172
Re: problem 1A.15
I think in order to solve this problem, you have to be able to recognize that UV radiation is in the Lyman series and therefore n1=1.
- Sun Oct 13, 2019 3:39 pm
- Forum: Properties of Light
- Topic: 1A.9
- Replies: 5
- Views: 136
1A.9
I know we use wavelength x frequency= c to convert between frequency and wavelength, but what equation do we use to find the energy of the photon? I can't seem to find it in the text.
- Sun Oct 13, 2019 2:46 pm
- Forum: Limiting Reactant Calculations
- Topic: About Finding Limiting Reactant
- Replies: 7
- Views: 403
Re: About Finding Limiting Reactant
Yeah, I agree with the others, you can have it in either moles or grams since it won't affect the final answer. Unless the question specifically asks for the amount of product in grams, I find it easiest to just leave it moles for the sake of finding the limiting reactant.
- Sun Oct 06, 2019 11:03 am
- Forum: Molarity, Solutions, Dilutions
- Topic: Symbols for Molarity
- Replies: 8
- Views: 1265
Re: Symbols for Molarity
Actually, I think the book uses c to represent molarity and M to represent molar mass in equations. I was a bit confused by this too, since M is the symbol for units in molarity (ie .5 M). So in the equation m=cMV, it's basically mass=molarity x molar mass x volume.
- Sun Oct 06, 2019 10:58 am
- Forum: Molarity, Solutions, Dilutions
- Topic: Procedure in G21/G23
- Replies: 1
- Views: 101
Procedure in G21/G23
In order to solve these problems, I went through a (probably unnecessarily) long process of first finding the mass percentage of the ions, multiplying that number by the mass, dividing that by molar mass to get moles, and then adding up all the moles if necessary, before finally dividing by volume t...