Search found 107 matches
- Mon Mar 16, 2020 11:58 am
- Forum: Balancing Redox Reactions
- Topic: Ecell values
- Replies: 12
- Views: 765
Re: Ecell values
The more positive/less negative Ecell value is typically correlated to the cathode (reduced), and the more negative Ecell value is correlated to the anode (oxidized).
- Mon Mar 16, 2020 11:56 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: adding platinum
- Replies: 8
- Views: 534
Re: adding platinum
Platinum (solid) is needed when there is no electrode for a given anode/cathode.
- Mon Mar 16, 2020 11:55 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Lewis structures
- Replies: 4
- Views: 359
Re: Lewis structures
If bonds are being broken, then that is endothermic (requires energy), but if bonds are being made then that is generally exothermic (releases energy).
- Mon Mar 16, 2020 11:54 am
- Forum: Administrative Questions and Class Announcements
- Topic: final grades
- Replies: 12
- Views: 989
Re: final grades
My TA said that she still has to input all of our homework grades, but I'm sure they should be out by around next weekend, like last time. However, due to the circumstances, I'm not sure when exactly they will be posted.
- Mon Mar 16, 2020 11:51 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ATP QUESTION ON FINAL
- Replies: 9
- Views: 846
Re: ATP QUESTION ON FINAL
I believe that the question stated that the phosphate actually came from ATP, not ADPayushibanerjee06 wrote:it said that all inorganic phosphate came from ADP so you can use the stoichiometry to find how much Pi you have. you can calculate Q from there
- Fri Mar 13, 2020 2:03 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: HW 7D.5
- Replies: 1
- Views: 146
HW 7D.5
Hi, can someone walk me through the steps of how to solve for the rate constant? In particular, I don't understand where the 0.59 value comes from (as per the solutions manual).
- Sun Mar 08, 2020 8:01 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Electrode masses
- Replies: 8
- Views: 522
Re: Electrode masses
Changing the mass of the electrodes will not affect cell potential, only the time of the reaction.
- Sun Mar 08, 2020 8:00 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: How to calculate for n
- Replies: 7
- Views: 551
Re: How to calculate for n
You must find n by balancing the half reactions and seeing how many electrons are transferred (which is your n value)
- Sun Mar 08, 2020 7:58 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Solids/Liquids
- Replies: 3
- Views: 261
Re: Solids/Liquids
Because solids and liquids do not have a concentration, they are not included in the rate law.
- Sun Mar 08, 2020 7:56 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Basic Redox Reactions
- Replies: 6
- Views: 451
Re: Balancing Basic Redox Reactions
It is pretty much the same as balancing a reaction in an acidic solution, but you must balance the Hydrogens with OH- instead of H+
- Sun Mar 08, 2020 7:54 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagrams
- Replies: 13
- Views: 794
Re: Cell Diagrams
We use an inert solid when there is none present in the anode, cathode, or both. It varies from case to case, so it isn't always at one end or the other, or even both.
- Sun Mar 01, 2020 7:10 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: usage of platinum of cell diagrams
- Replies: 5
- Views: 369
Re: usage of platinum of cell diagrams
You would simply use a Platinum electrode where there isn't a solid metal electrode present for a certain cell.
- Sun Mar 01, 2020 7:09 pm
- Forum: Balancing Redox Reactions
- Topic: OH and H
- Replies: 8
- Views: 452
Re: OH and H
OH- and H+ can be both reactants and products in your redox reaction. This varies case to case, so you would have to balance each of your half reactions and see what needs to be balanced in order to determine where the OH- or H+ is needed.
- Sun Mar 01, 2020 7:07 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidizing/reducing agent
- Replies: 18
- Views: 992
Re: Oxidizing/reducing agent
An oxidizing agent refers to the item being reduced, which allows for the other species to be oxidized. A reducing agent is exactly the opposite: it is being oxidized in order for another species to be reduced.
- Sun Mar 01, 2020 7:06 pm
- Forum: Balancing Redox Reactions
- Topic: H+ or H2O
- Replies: 4
- Views: 286
Re: H+ or H2O
When the solution is acidic, H2O is added in order to balance the oxygen, and H+ is used when balancing the hydrogens. However, It is usually safest to balance the oxygen before balancing the hydrogens.
- Sun Mar 01, 2020 7:04 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Cell Diagram
- Replies: 4
- Views: 247
Re: Cell Diagram
Yes, I believe they only taught us one way to write a cell diagram, so we can use it for both.
- Sun Feb 23, 2020 7:30 pm
- Forum: Balancing Redox Reactions
- Topic: Half Reactions
- Replies: 12
- Views: 794
Re: Half Reactions
A half reaction is either the reduction reaction (gaining electrons) or oxidation reaction (losing electrons) that make up your redox reaction.
- Sun Feb 23, 2020 7:29 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic Cells
- Replies: 3
- Views: 287
Re: Galvanic Cells
I found that this Khan Academy video may be helpful/relevant in answering your question: https://www.khanacademy.org/science/che ... ree-energy
- Sun Feb 23, 2020 7:26 pm
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: rust
- Replies: 9
- Views: 675
Re: rust
https://www.youtube.com/watch?v=B_em0quwuSw --> I found this video to be helpful in explaining the rusting process and how it relates to redox reactions
- Sun Feb 23, 2020 7:21 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Le Chatelier’s Principle
- Replies: 11
- Views: 638
Re: Le Chatelier’s Principle
Le Chatelier's Principle just refers to how adding more of a substance in either cell can cause movement of cell potential either up or down depending on what you are adding and to which side of the reaction it belongs to (reduction or oxidation).
- Sun Feb 23, 2020 7:18 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Half reactions
- Replies: 13
- Views: 683
Re: Half reactions
A half reaction is either the reduction reaction or oxidation reaction that comprise the redox reaction
- Sun Feb 16, 2020 3:41 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Delta S
- Replies: 8
- Views: 611
Re: Delta S
Delta S of the system is the entropy of the system, Delta S of the surroundings is the entropy of the surroundings (usually just the opposite/negative of Delta S), and the Delta S (total) is 0 for isothermal reversible reactions and is usually equal to Delta S (sys) for irreversible reactions.
- Sun Feb 16, 2020 3:37 pm
- Forum: Phase Changes & Related Calculations
- Topic: Heating curve
- Replies: 5
- Views: 641
Re: Heating curve
Phase changes correlate to the plateau of a heating curve, and there, you can use q = mΔh if you are given mass or q = nΔh if you are given moles. If you are calculating the diagonal/rise in temperature, you will use q = mCΔT or q = nCΔT.
- Sun Feb 16, 2020 3:16 pm
- Forum: Ideal Gases
- Topic: pv=nrt
- Replies: 19
- Views: 1073
Re: pv=nrt
PV = nRT can be used at STP if you plug in 273.15 Kelvin for the temperature (T) and 1 atm for pressure (P)
- Sun Feb 16, 2020 3:10 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Why are exothermic reactions generally spontaneous?
- Replies: 16
- Views: 1025
Re: Why are exothermic reactions generally spontaneous?
Exothermic reactions are generally spontaneous, because unlike endothermic reactions, they do not require heat input
- Sun Feb 16, 2020 2:48 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: endo/exo and temp
- Replies: 12
- Views: 1058
Re: endo/exo and temp
Think of energy/heat being a reactant in endothermic reactions (heat must be supplied), and as a product in exothermic reactions (heat is being released). So when you increase temperature in an endothermic reaction, you are increasing the amount of reactants so the reaction will favor the products, ...
- Sun Feb 09, 2020 8:35 pm
- Forum: Ideal Gases
- Topic: reversing reactions
- Replies: 83
- Views: 4706
Re: reversing reactions
The K of a reverse reaction is just the inverse of K (or 1/K)
- Sun Feb 09, 2020 8:33 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: spontaneity
- Replies: 18
- Views: 646
Re: spontaneity
You can tell that a reaction is spontaneous when Gibbs free energy (delta G) is negative, which means that it is releasing free energy.
- Sun Feb 09, 2020 8:29 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Enthalpy versus heat
- Replies: 11
- Views: 494
Re: Enthalpy versus heat
Delta H is equal to q + w, so when there is no work being done on or by the system (or when w = 0), then delta H = q
- Sun Feb 09, 2020 8:27 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: difference between molar entropies?
- Replies: 6
- Views: 320
Re: difference between molar entropies?
For each mole of lead, there are more protons, electrons, and neutrons than in carbon, so on a sub-atomic level, there is more entropy because these particles' movements contribute to the atom's overall entropy.
- Sun Feb 09, 2020 8:24 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies
- Replies: 6
- Views: 271
Re: Bond Enthalpies
Bond enthalpy questions usually give you the reaction (A + B --> C) and then you just look at each molecule that is in the reaction and look up their bond enthalpy values. Bonds broken are usually correlated to those of the reactants and bonds formed correlate to those of the products.
- Sun Feb 02, 2020 8:31 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Positive or negative work?
- Replies: 8
- Views: 242
Re: Positive or negative work?
Positive work = the surroundings are doing work on the system (i.e. positive delta H when heat (energy) is being added to a system)
Negative work = the system is doing work to its surroundings (i.e. negative delta H when heat (energy) is leaving a system)
Negative work = the system is doing work to its surroundings (i.e. negative delta H when heat (energy) is leaving a system)
- Sun Feb 02, 2020 8:27 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Test 1 #6
- Replies: 6
- Views: 316
Re: Test 1 #6
HF is not a strong acid, therefore it does not completely ionize (100%)
- Sun Feb 02, 2020 8:25 pm
- Forum: Ideal Gases
- Topic: PV=nRT
- Replies: 74
- Views: 4133
Re: PV=nRT
P = Pressure, V = Volume, n = number of moles, R = gas constant, and T = Temperature
- Sun Feb 02, 2020 8:24 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Temperature
- Replies: 14
- Views: 504
Re: Temperature
A negative delta H is exothermic because that means that energy is leaving (-) the system.
- Sun Feb 02, 2020 8:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Test 1
- Replies: 6
- Views: 198
Re: Test 1
If Q is less than K, that means that the ratio of products to reactants is lower than at equilibrium, so the reaction will favor the products. If the Q is greater than K, then the ratio of products to reactants is higher than at equilibrium, so the reaction will favor the reactants.
- Sun Jan 26, 2020 10:07 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Gas Constant
- Replies: 13
- Views: 503
Re: Gas Constant
The gas constant (R) depends on what other units are given to you when calculating PV = nRT. The units are included on the formula/equation sheet.
- Sun Jan 26, 2020 10:03 pm
- Forum: Ideal Gases
- Topic: Determining N
- Replies: 9
- Views: 371
Re: Determining N
PV = nRT is the Ideal Gas Constant, so it applies to gases, not aqueous solutions.
- Sun Jan 26, 2020 10:02 pm
- Forum: Ideal Gases
- Topic: R Constant
- Replies: 18
- Views: 1018
Re: R Constant
The R depends on what other units you are working with in your PV = nRT calculation.
- Sun Jan 26, 2020 10:01 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: ICE BOX
- Replies: 27
- Views: 717
Re: ICE BOX
If your K is less than 10^-3, you can approximate the denominator.
- Sun Jan 26, 2020 10:00 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: pH
- Replies: 7
- Views: 240
Re: pH
If they give you the pKa, they would likely also have given the concentration of either [OH-] or [H3O+] or you would have to solve for them, and then you could use that value to do -log([H3O+]/[OH-]) and find the pH/pOH.
- Sun Jan 19, 2020 7:20 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: X was ignored
- Replies: 27
- Views: 948
Re: X was ignored
If the given K is less than 10^-3, then you can use approximation, meaning that you can disregard the X because it is small enough that it would not profoundly impact your equilibrium expression.
- Sun Jan 19, 2020 7:18 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: pH and pOH
- Replies: 5
- Views: 203
Re: pH and pOH
If you know the pH, for example pH = 6, then according to the equation pH + pOH = 14 (derived from pKw = pH + pOH) then you would just set pOH = 14 - pH (6) so your pOH would equal 8.
- Sun Jan 19, 2020 7:16 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Approximation
- Replies: 6
- Views: 339
Re: Approximation
It's just a general rule to check whether or not your approximation is valid because the amount (X) should be small enough that it wouldn't profoundly impact your equilibrium expression.
- Sun Jan 19, 2020 7:09 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 5% rule
- Replies: 10
- Views: 423
Re: 5% rule
The 5% rule is for checking whether or not your approximation is valid. This is usually if the K is less than 10^-3 and you take out the X from the denominator of your equilibrium expression.
- Sun Jan 19, 2020 7:08 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ice boc
- Replies: 7
- Views: 202
Re: ice boc
You can only take out the X in the denominator if the K is less than 10^-3. The ice box helps to visualize and take inventory of what you start with and what is changing at the equilibrium.
- Fri Jan 10, 2020 12:41 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K for Heterogeneous Equilibria
- Replies: 4
- Views: 224
Re: K for Heterogeneous Equilibria
Kp is more particular to gases, and Kc applies to when concentrations are being used, so it would probably be safer to use Kc or just to leave K as is. I’m not completely sure, though...
- Fri Jan 10, 2020 12:36 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: using Kp vs Kc
- Replies: 13
- Views: 1490
Re: using Kp vs Kc
*Kc can be used for when concentrations are being used, while Kp is more particular to partial pressures and is more specific to gases.
- Fri Jan 10, 2020 12:33 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: using Kp vs Kc
- Replies: 13
- Views: 1490
Re: using Kp vs Kc
If all of the reactants and products are in the gas phase, then you must use Kp if only the partial pressures are given. Kc* is used for concentrations, and is thus used when the reactants and products are in the aqueous phase. I think it depends on what you are given.
- Fri Jan 10, 2020 12:30 pm
- Forum: Ideal Gases
- Topic: Solving for K (coefficients)
- Replies: 11
- Views: 472
Re: Solving for K (coefficients)
The coefficients are attached to the particular reactant/product as you balance the equation. This coefficient becomes the exponent to the same reactant/product when calculating Q or K.
- Fri Jan 10, 2020 12:24 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Do solids and liquids count in Q?
- Replies: 5
- Views: 181
Re: Do solids and liquids count in Q?
As the others have said, because Q is calculated in the same manner as K, solids and pure liquids are not included in the expression.
- Sat Dec 07, 2019 12:38 pm
- Forum: Air Pollution & Acid Rain
- Topic: Acid Rain & Solutions
- Replies: 4
- Views: 419
Re: Acid Rain & Solutions
Some solutions to reducing the acidity of the rain could include producing less excess carbon dioxide or sulfur dioxide in the atmosphere so that these gases do not react with the H2O to form acids. I'm not sure if that answers your question about "lessening the acidity," though.
- Sat Dec 07, 2019 12:34 pm
- Forum: Ionic & Covalent Bonds
- Topic: Boiling point
- Replies: 4
- Views: 413
Re: Boiling point
Yes, hydrogen bonding would result in a higher boiling point because compared to the PH3, Nitrogen has far greater electronegativity, which means that it is able to form much stronger (hydrogen) bonds which require more energy to break (as in boiling).
- Sat Dec 07, 2019 12:30 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Polydentates and Chelates
- Replies: 4
- Views: 336
Re: Polydentates and Chelates
Yes, because the polydentates have multiple binding sites, they are able to form a "claw" or loop around the metal cation.
- Thu Dec 05, 2019 6:16 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: HW 6D.11
- Replies: 1
- Views: 68
Re: HW 6D.11
Also, as a follow-up, how can we tell whether the metal -- in conjunction with the fact that it is attached to a conjugate base from a strong acid -- will produce either a basic or acidic pH in solution?
- Thu Dec 05, 2019 6:09 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: HW 6D.11
- Replies: 1
- Views: 68
HW 6D.11
For parts (e) and (f), I get that they're acidic because the conjugate bases come from strong acids (HCl and HNO3, respectively), but how would you be able to tell that the cation would have to be analyzed rather than the anion?
- Thu Dec 05, 2019 12:28 am
- Forum: Polyprotic Acids & Bases
- Topic: HW 6C.17 Which is the stronger base?
- Replies: 5
- Views: 452
HW 6C.17 Which is the stronger base?
How do we find out which base is stronger -- either BrO- or C17H19O3N -- without knowing the pKb value?
- Sun Dec 01, 2019 5:28 pm
- Forum: Lewis Acids & Bases
- Topic: acid v. base?
- Replies: 16
- Views: 851
Re: acid v. base?
Lewis bases usually have a lone pair so that it has electrons to donate while Lewis acids usually have a positive charge attached to them, meaning that they will likely accept an electron pair.
- Sun Dec 01, 2019 5:24 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 Grades
- Replies: 6
- Views: 391
Re: Test Grades
My test 2 grade is also a 0/50, as well... I believe that the TA's should input these at a later time, though. I'm not sure why, but my homework category is also a 0/50 even though my TA hasn't technically collected all of our homework yet.
- Sun Dec 01, 2019 5:22 pm
- Forum: Naming
- Topic: How to Know the Charge of Ions
- Replies: 7
- Views: 464
Re: How to Know the Charge of Ions
If you want to calculate the charges using your knowledge of the periodic table and elemental charges that occur from it, you could do that, but it is time consuming and tedious. Like the person above mentioned, it would be in your best interest to just memorize these charges in order to conserve ti...
- Sun Dec 01, 2019 5:18 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: structure of water
- Replies: 4
- Views: 209
Re: structure of water
Due to a water molecule's orbital geometry, only one of its lone pairs can be correctly oriented to 'bond' while the other lone pair will point away from the central atom.
- Sun Dec 01, 2019 5:15 pm
- Forum: Lewis Acids & Bases
- Topic: bronsted vs lewis
- Replies: 9
- Views: 522
Re: bronsted vs lewis
The difference is that Bronsted acids and bases focus on the exchange of H+ ions (protons) while Lewis acids and bases deal with the exchange of electrons.
- Sun Nov 24, 2019 6:10 pm
- Forum: Hybridization
- Topic: Strength of sigma vs pi bonds
- Replies: 6
- Views: 149
Strength of sigma vs pi bonds
Which is stronger: a sigma or a pi bond, and why?
- Sun Nov 24, 2019 4:50 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: square planar vs tetrahedral
- Replies: 5
- Views: 376
Re: square planar vs tetrahedral
Using the VSEPR formula, AX4 is tetrahedral because it has no lone pairs (E). However, if it is AX4E2, the shape is square planar because the two lone pairs of electrons cause the bonded electrons to be arranged in a square shape, which allows them to be farthest from one another.
- Sun Nov 24, 2019 4:46 pm
- Forum: Hybridization
- Topic: Sigma and Pi bonds
- Replies: 13
- Views: 619
Re: Sigma and Pi bonds
You must also indicate that there is a sigma bond present, in addition to the pi bond.
- Sun Nov 24, 2019 4:45 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent Shape
- Replies: 31
- Views: 2750
Re: Bent Shape
If the molecule has 3 regions of electron density, but one is a lone pair, then it can be bent (< 120 degrees). However, if the molecule has 4 regions of electron density, and two of them are lone pairs, then it can also be bent (< 109.5 degrees).
- Sun Nov 24, 2019 4:42 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: pi and sigma bonds
- Replies: 4
- Views: 309
Re: pi and sigma bonds
Sigma bonds overlap end to end while pi bonds overlap side by side, with one nodal plane containing the internuclear axis.
- Fri Nov 22, 2019 1:48 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: bent v. angular
- Replies: 27
- Views: 1347
Re: bent v. angular
Bent and angular refer to the same type of shape. Either works when naming AX2E and AX2E2 molecules.
- Wed Nov 13, 2019 8:56 pm
- Forum: Ionic & Covalent Bonds
- Topic: HW 2D #9
- Replies: 2
- Views: 194
Re: HW 2D #9
Because smaller, highly charged cations (which, due to their lower electronegativity, have lose electrons) have smaller radii, the force of their positively-charged nucleus can better attract electrons, causing their polarizing power to be larger.
- Wed Nov 13, 2019 8:46 pm
- Forum: Ionic & Covalent Bonds
- Topic: HW 2D #3
- Replies: 2
- Views: 190
Re: HW 2D #3
Essentially, if we go by periodic trends, Ba has the biggest electronegativity difference with Br compared to B and Be, making it the most ionic bond (ionic bond strength increases as the electronegativity difference increases between to atoms).
- Wed Nov 13, 2019 8:38 pm
- Forum: Dipole Moments
- Topic: HW Question 3F1
- Replies: 5
- Views: 357
Re: HW Question 3F1
Because there is an uneven charge distribution (of electrons) between S and O (oxygen is more electronegative), there are dipole moments that form between them, creating dipole interactions.
- Wed Nov 13, 2019 8:32 pm
- Forum: Dipole Moments
- Topic: Hydrogen bonds
- Replies: 17
- Views: 678
Re: Hydrogen bonds
No, only hydrogen atoms that are bonded to nitrogen, oxygen, and fluorine are able to form hydrogen bonds.
- Wed Nov 13, 2019 8:29 pm
- Forum: Dipole Moments
- Topic: Do lone pairs repel more?
- Replies: 5
- Views: 251
Re: Do lone pairs repel more?
A lone electron pair will repel its surroundings more than a bonded electron would because its negative charge isn't being distributed/shared unlike the bonded pair, thus its negative charge and repulsion is more concentrated/stronger.
- Tue Nov 12, 2019 7:21 pm
- Forum: Bond Lengths & Energies
- Topic: Van Der Waals BP
- Replies: 6
- Views: 267
Re: Van Der Waals BP
Ionic bonds are the strongest because the electrons are actually being donated to the more electronegative atom, and thus it would be hardest to pull these apart because it would take a relatively large amount of energy to remove electron(s) from such pairings
- Tue Nov 12, 2019 7:16 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: Help of 3F.11
- Replies: 5
- Views: 156
Re: Help of 3F.11
In order for a molecule to form hydrogen bonds, at least one hydrogen atom in the molecule must be bonded to either a oxygen, nitrogen, or fluorine atom.
- Thu Nov 07, 2019 11:52 am
- Forum: Bond Lengths & Energies
- Topic: Resonance structure bond lengths?
- Replies: 3
- Views: 210
Re: Resonance structure bond lengths?
I think that the bond lengths are more of an arbitrary approximation to gauge which atoms share how many electrons between their electron clouds. The more electrons that they share in close proximity (i.e. how many bonds they have between each other), the closer the electrons will be between those a...
- Thu Nov 07, 2019 11:47 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: D Subshell
- Replies: 7
- Views: 688
Re: D Subshell
The angular momentum quantum number for the d subshell is l=2, and its corresponding magnetic quantum numbers can have the values -2, -1, 0, 1,& 2 (5 in total). In each of these, there can be 2 electrons, which means that there are a total of 10 electrons that can be placed in the d subshell.
- Thu Nov 07, 2019 11:44 am
- Forum: Trends in The Periodic Table
- Topic: ionic radii
- Replies: 4
- Views: 215
Re: ionic radii
An anion has a larger radius than its neutral atom because when you add an electron, the repulsive forces between the electrons is relatively greater than the pull of the positively-charged nucleus, thus causing the electrons to further apart, making the anion's radius larger.
- Thu Nov 07, 2019 11:38 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Bohr Frequency
- Replies: 6
- Views: 282
Re: Bohr Frequency
When energy is absorbed by an atom, it is receiving energy, so the change in energy is positive, causing an electron to become excited and move from a lower energy level (let's say, n=1) to a higher energy level (i.e. n=2).
- Tue Nov 05, 2019 4:04 pm
- Forum: Ionic & Covalent Bonds
- Topic: HW 2A.9 part (a)
- Replies: 3
- Views: 122
Re: HW 2A.9 part (a)
Ah, so because it's asking for a +2 metal, the ion's electron configuration for the d orbital is still the same as the neutral atom's because you're taking the 2 electrons from the s orbital... Understood!
- Tue Nov 05, 2019 3:57 pm
- Forum: Ionic & Covalent Bonds
- Topic: HW 2A.9 part (a)
- Replies: 3
- Views: 122
Re: HW 2A.9 part (a)
And also, can someone explain why this also applies to part (b), and why it is Fe^2+?
- Tue Nov 05, 2019 3:54 pm
- Forum: Ionic & Covalent Bonds
- Topic: HW 2A.9 part (a)
- Replies: 3
- Views: 122
HW 2A.9 part (a)
Why would the M^2+ metal for [Ar]3d^7 be Co^2+? Shouldn't it be Cu^2+ since the metal in question supposedly lost 2 electrons and now has the electron configuration [Ar]3d^7?
- Fri Nov 01, 2019 1:33 pm
- Forum: Trends in The Periodic Table
- Topic: Noble Gases
- Replies: 10
- Views: 593
Re: Noble Gases
No, the noble gases do not follow the periodic trends (i.e. electronegativity, electron affinity, etc.) the way that the Group 1, 2, and so on elements do. They each have a complete valence shell, so they do not usually attract electrons.
- Fri Nov 01, 2019 1:28 pm
- Forum: Bond Lengths & Energies
- Topic: bond lengths
- Replies: 10
- Views: 518
Re: bond lengths
The bond length is determined by how many bonded electrons there are. The more electrons are bonded (i.e. a triple bond in which 6 electrons are bonded), the shorter the bond length. That means that a triple bond has the shortest length (and has the most attraction/energy bringing the two atoms toge...
- Fri Nov 01, 2019 1:24 pm
- Forum: Bond Lengths & Energies
- Topic: Lone electron pairs weakening bonds
- Replies: 4
- Views: 139
Re: Lone electron pairs weakening bonds
The lone pairs of the electrons found on neighboring atoms weaken these bonds due to electron repulsion. The neighboring atoms in a molecule that have lone pair electrons are not bonded as tightly because the lone pair electrons of both atoms repel one another.
- Fri Nov 01, 2019 1:13 pm
- Forum: Trends in The Periodic Table
- Topic: Electron Affinity
- Replies: 8
- Views: 229
Re: Electron Affinity
Electron affinity increases rightwards across a row, and then decreases downward, down a group/column.
- Fri Nov 01, 2019 1:11 pm
- Forum: Ionic & Covalent Bonds
- Topic: Anions and Cations
- Replies: 9
- Views: 418
Re: Anions and Cations
Anions are generally larger than its corresponding neutral atom because adding electrons increases the number of electron-electron repulsion interactions that take place. Cations are smaller than the corresponding neutral atoms, since the valence electrons, which are furthest away from the nucleus, ...
- Sun Oct 27, 2019 9:29 pm
- Forum: Trends in The Periodic Table
- Topic: Ionization Energy
- Replies: 9
- Views: 360
Re: Ionization Energy
Just think of it as having to insert energy (+) in order to take out the electron because the electron is being held to the atom by the positive charge of the nucleus.
- Sun Oct 27, 2019 9:22 pm
- Forum: Resonance Structures
- Topic: Resonance Structures
- Replies: 4
- Views: 142
Re: Resonance Structures
If there are multiple places where the center atom can bond with the outer atoms and these bonds are interchangeable, I believe that you just have to count/take account of all of these different forms to get the number of resonance structures.
- Sun Oct 27, 2019 9:20 pm
- Forum: Trends in The Periodic Table
- Topic: Electron affinity.
- Replies: 8
- Views: 223
Re: Electron affinity.
Electron affinity is simply the potential of an atom to accept an electron (or more than one) based on its size (how many shells does it have/how far is its valence shell from its nucleus) and whether or not it almost has a full valence shell (lefthand side of the periodic table of elements tend to ...
- Sun Oct 27, 2019 9:16 pm
- Forum: Electronegativity
- Topic: Electronegativity
- Replies: 6
- Views: 526
Re: Electronegativity
Fluorine is the most electronegative element because it almost has a full valence shell, and since its atomic radius is relatively smaller than the other elements in its column/group, the positively-charged nucleus has a higher chance of attracting the last negatively charged electron to fill this s...
- Sun Oct 27, 2019 9:12 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic VS. Covalent Bond
- Replies: 8
- Views: 402
Re: Ionic VS. Covalent Bond
An ionic bond is usually between a cation and an anion, and there is a transfer of electrons between the two. However, with covalent bonds, the electrons are merely shared between the two atoms.
- Fri Oct 18, 2019 1:27 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric Effect
- Replies: 6
- Views: 292
Re: Photoelectric Effect
I believe that it is only momentarily "removed" from the metal, but the only possible way for it to "leave" the metal is if there is excess energy (if the photon's energy is greater than the energy to remove the electron) and in that situation, the electron is ejected from the me...
- Fri Oct 18, 2019 1:23 pm
- Forum: *Shrodinger Equation
- Topic: Schrodinger and De Broglie's Equation
- Replies: 3
- Views: 212
Re: Schrodinger and De Broglie's Equation
I forgot to add that you can also use De Broglie's if you are given the wavelength and you need to find either mass or velocity (λ = h/mv).
- Fri Oct 18, 2019 1:19 pm
- Forum: *Shrodinger Equation
- Topic: Schrodinger and De Broglie's Equation
- Replies: 3
- Views: 212
Re: Schrodinger and De Broglie's Equation
If you're dealing with quantum numbers and atomic orbitals in a question, you will most likely use Schrodinger's wave function equation. De Broglie's would be to find the wavelength (for instance, if you are given the mass and/or velocity of an object, then you would use De Broglie's equation).
- Thu Oct 17, 2019 8:25 pm
- Forum: Properties of Electrons
- Topic: HW Question Topic 1B #1B.5
- Replies: 2
- Views: 189
Re: HW Question Topic 1B #1B.5
Oh, I see, I didn't realize at first that it was a constant. Thank you!
- Thu Oct 17, 2019 5:55 pm
- Forum: Properties of Electrons
- Topic: HW Question Topic 1B #1B.5
- Replies: 2
- Views: 189
HW Question Topic 1B #1B.5
In the solutions manual, can someone explain where the 1.6022x10^-19 J*Ev^-1 comes from when converting the given value in the problem to Joules?
- Fri Oct 11, 2019 1:13 pm
- Forum: Limiting Reactant Calculations
- Topic: percent yield
- Replies: 10
- Views: 775
Re: percent yield
It depends on what you are given. They will usually ask for it, or if they give you the experimental data for something like a problem where you have to find the empirical formula, then you should calculate it to help you with the final answer.
- Fri Oct 11, 2019 1:08 pm
- Forum: Balancing Chemical Reactions
- Topic: Fractions
- Replies: 34
- Views: 1288
Re: Fractions
I remember Prof. Lavelle suggesting that we should convert the fractional stoichiometric coefficients into whole integers.
- Fri Oct 11, 2019 1:06 pm
- Forum: SI Units, Unit Conversions
- Topic: Showing work/ rearranging equations
- Replies: 8
- Views: 696
Re: Showing work/ rearranging equations
My TA said that to be safe and secure partial credit in the case that your final answer is somehow incorrect, you should show as many steps as possible/necessary to indicate each step of a problem. It is totally up to you, though.