Search found 142 matches
- Mon Mar 16, 2020 1:29 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ATP QUESTION ON FINAL
- Replies: 9
- Views: 847
Re: ATP QUESTION ON FINAL
Sine it says pi comes from ATP, the two concentrations cancels and K depends on [ADP] only.
- Mon Mar 16, 2020 1:27 pm
- Forum: Administrative Questions and Class Announcements
- Topic: final grades
- Replies: 12
- Views: 995
Re: final grades
Does this class have a curve at the end?
- Mon Mar 16, 2020 1:26 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Final Exam #15
- Replies: 3
- Views: 505
Re: Final Exam #15
On the final, #15 asked us to find \Delta H ionization for H20 --> OH- + H+. How were we supposed to find this? I googled the \Delta H formation of H2O and OH- and used \sum \Delta H products - \sum \Delta H reactants . Was this the right way to go about it or did we have to use the pH or \Delta H ...
- Wed Mar 11, 2020 7:02 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: work
- Replies: 7
- Views: 402
Re: work
The amount of work possible is dependent on the cell potential of the electrochemical cell
- Wed Mar 11, 2020 7:01 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: concentration related to current?
- Replies: 4
- Views: 361
Re: concentration related to current?
Vuong_2F wrote:Eugene Chung 3F wrote:electrons will flow from area of high concentration to an area of low concentration. So, the concentration difference makes potential.
so once there is no concentration difference, there is no more potential?
Yup.
- Sun Mar 08, 2020 11:21 pm
- Forum: Balancing Redox Reactions
- Topic: Redox Table
- Replies: 6
- Views: 384
Re: Redox Table
If all of the reactions in the table represent reductions, for the oxidizing half reaction, it would be made negative, then would the sign in the Ecat-Eanode change to addition or would we subtract it? If you don't want to worry about changing the sign, it's easier to just do Ecat-Eanode and always...
- Sun Mar 08, 2020 11:19 pm
- Forum: Balancing Redox Reactions
- Topic: Why do we flip E for oxidation?
- Replies: 13
- Views: 1055
Re: Why do we flip E for oxidation?
Cindy Adiwidjaja 1B wrote:I know that E is given, however, why do we need to flip the sign when we are trying to use the E for oxidation?
Honestly, for me, I feel like it's easier to do Cathode-anode, that way you don't have to worry about changing the E value given.
- Sun Mar 08, 2020 11:18 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Test 2
- Replies: 7
- Views: 505
Re: Test 2
We know that lower electronegativity and more negative E value means stronger reducing agent. Anode is oxidized and is the reducing agent. So, the one with more negative E value is conventionally the anode.
- Sun Mar 08, 2020 11:16 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagrams
- Replies: 13
- Views: 794
Re: Cell Diagrams
Gabriel Ordonez 2K wrote:When are the instances that we have to add an inert solid to either end of the cell diagram? Is it always one or two ends of it?
When the other elements in the cell diagram is aq. state.
- Sun Mar 08, 2020 11:15 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Use of Platinum
- Replies: 10
- Views: 563
Re: Use of Platinum
using graphite (carbon) is also common, but I think Dr. Lavelle said we would be using platinum for chem 14b
- Mon Mar 02, 2020 12:54 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: work
- Replies: 7
- Views: 402
Re: work
the deltaG for a cell is the amount of useful work obtainable from a system at constant T and P.
- Mon Mar 02, 2020 12:53 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs free energy equations
- Replies: 5
- Views: 392
Re: Gibbs free energy equations
I think the main thing to remember is deltaG = 1nFEcell. You can use any equation to find delta G then, apply this equation to find electrochemical variable values or vice versa.
- Mon Mar 02, 2020 12:51 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: information given
- Replies: 1
- Views: 180
Re: information given
I just jot down all the equations that are relevant to the question and try to mix match them to figure out the variable I'm looking for.
- Mon Mar 02, 2020 12:49 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: concentration related to current?
- Replies: 4
- Views: 361
Re: concentration related to current?
electrons will flow from area of high concentration to an area of low concentration. So, the concentration difference makes potential.
- Mon Mar 02, 2020 12:47 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Moles in nernst
- Replies: 4
- Views: 280
Re: Moles in nernst
n is for the moles of electrons being transferred.
- Sun Feb 23, 2020 11:24 pm
- Forum: Balancing Redox Reactions
- Topic: acidic solutions
- Replies: 3
- Views: 284
Re: acidic solutions
I think you just add hydrogen ion H+ where needed.
- Sun Feb 23, 2020 11:21 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Reverse Reaction
- Replies: 1
- Views: 174
Re: Reverse Reaction
Brandon Tao 1K wrote:Is a reaction within a galvanic cell, will it ever reach equilibrium and will we need to find the constants?
I think equilibrium is reached when Ecell = 0 V. This would mean that there is no net electron flow within the cell and the current has stopped.
- Sun Feb 23, 2020 11:18 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: salt bridge
- Replies: 5
- Views: 391
Re: salt bridge
salt bridge maintains the charge balance b/c the electrons are moving from one half cell to the other half cell. the electrons will flow from one adnode to the cathode. So, the reaction reaching equilibrium slows down.
- Sun Feb 23, 2020 11:17 pm
- Forum: Van't Hoff Equation
- Topic: Van't Hoff Equation
- Replies: 3
- Views: 309
Re: Van't Hoff Equation
Jasleen Kahlon wrote:The Van't Hoff Equation shows temperature dependence of K, but I'm still a little confused on what that means, and does the equation in any way connect to ∆H, ∆S, and ∆G?
deltaG = -RtlnK
and since deltaG = deltaH -T*deltaS, we can rearrange it to solve for deltaH and deltaS.
- Sun Feb 23, 2020 11:14 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Gibbs free energy and max work
- Replies: 2
- Views: 190
Re: Gibbs free energy and max work
I think Gibbs free energy is the maximum work at constant temperature and pressure if the system is reversible and the work is non-expansion work form a closed system.
- Sun Feb 16, 2020 9:42 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Isochoric
- Replies: 8
- Views: 536
Re: Isochoric
isocloric is constant volume. This means that there is no work being done. So the work is 0.
- Sun Feb 16, 2020 9:40 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 2
- Replies: 11
- Views: 666
Re: Test 2
It'll be from the second page of thermodynamics outline to what we learn next week.
- Sun Feb 16, 2020 9:39 pm
- Forum: General Science Questions
- Topic: Studying
- Replies: 67
- Views: 3300
Re: Studying
1. Go to LA sessions if you can and TA office hours. Those are really helpful.
2. Do the HW problems.
2. Do the HW problems.
- Sun Feb 16, 2020 9:38 pm
- Forum: Administrative Questions and Class Announcements
- Topic: HW7
- Replies: 14
- Views: 747
Re: HW7
I think it's okay to turn in any homework problems you did to study for the midterm.
- Sun Feb 16, 2020 9:35 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Laws of thermodynamics
- Replies: 4
- Views: 414
Re: Laws of thermodynamics
1. delta U = heat+work
2. For reversible system, deltaS of universe equals 0.
3. at 0K for a perfectly ordered molecule, the entropy change is 0
2. For reversible system, deltaS of universe equals 0.
3. at 0K for a perfectly ordered molecule, the entropy change is 0
- Sun Feb 16, 2020 9:34 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Enthalpy and Heat
- Replies: 3
- Views: 275
Re: Enthalpy and Heat
heat is the energy transferred from high temperature to lower temperature whereas enthalpy is heat transfer at a constant pressure. The heat added or lost from system gives the change of enthalpy.
- Wed Feb 12, 2020 12:20 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Delta S Universe
- Replies: 1
- Views: 123
Re: Delta S Universe
reversible processes have delta S universe = 0. Since deltaS(sys) + deltaS(surr) = deltaS(universe) = 0, deltaS(sys) = -deltaS(surr).
- Mon Feb 10, 2020 1:35 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: average kinetic energy
- Replies: 1
- Views: 128
average kinetic energy
HW question 4.19 says to calculate the molar kinetic energy of Kr at different temperatures. What is the formula for average kinetic energy ? Should we know this for the midterm?
- Sun Feb 09, 2020 11:54 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: when to change sign of enthalpies
- Replies: 7
- Views: 350
Re: when to change sign of enthalpies
If you mean question 4a, you would flip the sign if u flip the chemical equation.
- Sun Feb 09, 2020 11:52 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: All Laws of Thermodynamics
- Replies: 2
- Views: 152
Re: All Laws of Thermodynamics
I think we have to know what they are at least for calculations. I'm not too sure about concepts. 1st law: delta U = q+w 2nd law: for irreversible process (all real processes), delta S(uni) > 0. (total entropy of surroundings and system increases) 3rd law: for perfect crystal at 0K, deltaS= 0 --> 1 ...
- Sun Feb 09, 2020 11:48 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: HW 4D7
- Replies: 4
- Views: 118
Re: HW 4D7
205154661_Dis2J wrote:For 4D7, why are we using the equation DeltaH= DeltaU + DeltaNRT? I do not quite understand why we are including DeltaNRT.
We know that delta U = heat + w and that in this case, delta H= heat. We also know that w=-P deltaV. The ideal gas law states PV=nRT. So, -P delta V = -delta nRT.
- Sun Feb 09, 2020 11:44 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: graphs
- Replies: 3
- Views: 142
Re: graphs
y-axis is pressure. Since irreversible systems are isobaric, pressure is constant.
- Sun Feb 09, 2020 11:42 pm
- Forum: Calculating Work of Expansion
- Topic: q=C delta T
- Replies: 5
- Views: 1250
Re: q=C delta T
I think the main difference is whether or not C is given per mol/g or just per T. For example, to calculate q of calorimeter, the question would say that the calorimeter has total heat capacity of 80 j/C, in this case it would just be q= CdeltaT
- Sun Feb 09, 2020 11:39 pm
- 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: Positional/Residual Entropy
- Replies: 3
- Views: 193
Re: Positional/Residual Entropy
residual entropy is the left-over entropy at 0K. (perfect crystal). The entropy in this case would only depend on the ways in which molecule can position/orient themselves.
- Sun Feb 09, 2020 11:33 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: State Functions (Pizza Rolls 3H)
- Replies: 1
- Views: 158
Re: State Functions (Pizza Rolls 3H)
I'm guessing it's because heat capacity is the measure of enthalpy (heat required to be transferred in rising T by 1C) and enthalpy is a state function. Also, heat capacity does not depend on how heat was added or how the temperature changed.
- Sun Feb 09, 2020 11:30 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Reversible Reactions vs. Irreversible Reactions
- Replies: 6
- Views: 246
Re: Reversible Reactions vs. Irreversible Reactions
I'm not sure but it wouldn't hurt to know! It's pretty easy because irreversible one would just have a straight horizontal line for y-axis because pressure would be constant. Reversible graph has larger surface area below the curve. The surface area represents work. Less work is done for irreversibl...
- Sun Feb 09, 2020 11:28 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 4D.15
- Replies: 2
- Views: 85
Re: 4D.15
AlyssaYeh_1B wrote:From the data the question gives, I did the calculation: -1500 - (-1300 + 2(-286)) = 312kJ/mol. However, the answer key shows that it's -312kJ/mol. What did I do wrong?
If you add the standard enthalpies up, it should be -1300 +1560 +2(-286) which comes out to -312
- Sun Feb 09, 2020 11:23 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Equations not on eq sheet
- Replies: 1
- Views: 82
Re: Equations not on eq sheet
Dr.Lavelle posted the constants and formulas on 14b class website so you can look at it and fill in formulas that are not on there. I noticed it didn't have W=X^n. Most equations are from another equation so I read through the formula sheet so that I don't have to memorize all of them
- Sun Feb 09, 2020 11:17 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Exothermic reactions
- Replies: 5
- Views: 277
Re: Exothermic reactions
All spontaneous processes have an increase in entropy. In other words, heat will always flow from hot to cold and never cold to hot spontaneously. So, S(universe) >0 for spontaneous process (2nd law of thermo.). We also know that delta H is negative for exothermic reactions and that delta G = delta ...
- Sun Feb 09, 2020 10:57 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: q rev
- Replies: 4
- Views: 261
Re: q rev
In reality, all natural (real) processes are irreversible because biochemical systems often use highly irreversible rxns to speed up processes. Also, all spontaneous processes are irreversible. (like hot going to cold) Reversible reactions are the "ideal" and "perfect" system. (e...
- Fri Feb 07, 2020 4:43 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: hw problem 4D 7 assuming T?
- Replies: 3
- Views: 144
hw problem 4D 7 assuming T?
Hi,
for 4D #7, the problem doesn't give you the temperature but the solutions suggest that it its assumed as 298K (25C).
Do we assume that T is 25C for certain circumstances?
for 4D #7, the problem doesn't give you the temperature but the solutions suggest that it its assumed as 298K (25C).
Do we assume that T is 25C for certain circumstances?
- Sun Feb 02, 2020 10:45 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Spontaneous
- Replies: 4
- Views: 200
Re: Spontaneous
Generally, reactions are favorable when they result in a decreased enthalpy and increased entropy of the system. When the reaction both decrease enthalpy and increase entropy, it occurs natually.
- Sun Feb 02, 2020 10:43 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: expansion
- Replies: 5
- Views: 289
expansion
what exactly is expansion in terms of thermodynamics?
- Sun Feb 02, 2020 10:42 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Week 4 lecture 3 calculating W question
- Replies: 2
- Views: 130
Week 4 lecture 3 calculating W question
In class, we went over calculating w right before it ended. Could someone explain what the microstates are?
- Sun Feb 02, 2020 10:40 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: First law of thermodynamics
- Replies: 3
- Views: 253
First law of thermodynamics
Could someone explain what the first law of thermodynamics states conceptually? I get how to do the calculations but don't quite get what exactly the law is.
- Sun Feb 02, 2020 10:38 pm
- Forum: Phase Changes & Related Calculations
- Topic: about system and surroundings
- Replies: 8
- Views: 327
about system and surroundings
How do you know which is the system and which is the surrounding?
For example, for 4A 1, for mercury in a thermometer or gasoline burning in an automobile engine, could someone tell me what is the system and surrounding in these two cases?
For example, for 4A 1, for mercury in a thermometer or gasoline burning in an automobile engine, could someone tell me what is the system and surrounding in these two cases?
- Fri Jan 24, 2020 3:26 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Finding OH concentration
- Replies: 2
- Views: 121
Re: Finding OH concentration
I'm pretty sure the solution is wrong (I have the same problem). Since [H30][OH]=1*10^-14, the answer would not be what it says in the solutions.
- Fri Jan 24, 2020 3:23 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Partial Pressure
- Replies: 5
- Views: 204
Re: Partial Pressure
If partial pressure of reactant is increased, then, the reaction will favor products to make up for the change and vice versa. If overall pressure is increased, meaning that the volume decreased, the side with less gases will be favored (check the stoichiometric coefficients of the gases) and vice v...
- Fri Jan 24, 2020 3:19 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: HNO2(aq) + H2O(l) -> H3O+(aq) + NO2-(aq)
- Replies: 2
- Views: 275
Re: HNO2(aq) + H2O(l) -> H3O+(aq) + NO2-(aq)
I think of it like I do with spectator ion (ex.cl-). ions like Na+, K+, Ca2+ dissociate so in making ICE table, etc, we don't take them into account in terms of calculations
- Thu Jan 23, 2020 3:36 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Hw problem 5.35 help
- Replies: 3
- Views: 134
Hw problem 5.35 help
I understand a but i don’t understand b.
Do i just approximate the partial pressure for each elements?
Also, how to i figure out the volume?
Do i just approximate the partial pressure for each elements?
Also, how to i figure out the volume?
- Sun Jan 19, 2020 5:24 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 5J.1
- Replies: 4
- Views: 223
Re: 5J.1
Le Chatelier's principle tells us that chemical reactions adjust to minimize the effect of changes. Therefore, if CO (reactant) partial pressure increases, the reaction will want to minimize the effect of that change and shift left to produce more CO (kinda like compensating). The result of that is ...
- Sun Jan 19, 2020 5:19 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: ICE tables
- Replies: 3
- Views: 175
Re: ICE tables
ICE table can be used to find K, pH, equilibrium concentrations, etc. It gives information about the initial concentrations and the final equilibrium concentration. We can also calculate how much is remaining after the equilibrium reaction also.
- Sun Jan 19, 2020 5:18 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: conjugate seesaw
- Replies: 4
- Views: 109
Re: conjugate seesaw
To give an example, When HCl (strong acid) dissociate in aqueous solution, than the conjugate base is Cl-, an ion produced as a result of HCl's dissociation. It can technically accept protons to produce acid in reverse direction but because HCl is strong, and dissociates completely, the reaction onl...
- Sun Jan 19, 2020 5:13 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5.I.11/13
- Replies: 2
- Views: 76
Re: 5.I.11/13
It's okay to make the ICE table with just mol (as opposed to mol/L) and then divide it by volume later. But, to be safe, yes, it is better to convert them all beforehand. So, for mmol, you would just multiply 10^-3 and divide by the volume
- Sun Jan 19, 2020 5:10 pm
- Forum: Ideal Gases
- Topic: 5I.15
- Replies: 5
- Views: 419
Re: 5I.15
Since NH4HS is a solid, u can basically ignore it
- Sun Jan 19, 2020 5:06 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Identifying endothermic vs exothermic
- Replies: 7
- Views: 254
Re: Identifying endothermic vs exothermic
A reaction is exothermic if the products have more energy than the reactants, and it is endothermic if the reactants have more energy than the products. Usually, the reaction would give you a deltaH value if it is asking about temperature. DeltaH would be negative if the reaction is exothermic and ...
- Sun Jan 12, 2020 2:35 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Homogenous Equilibrium
- Replies: 13
- Views: 327
Re: Homogenous Equilibrium
for example, N2 + 3H2 - 2NH3 equilibrium reaction we went over in lecture is homogenous since the reactants and products are all in gas phase.
- Sun Jan 12, 2020 2:33 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Factors Affecting K
- Replies: 5
- Views: 185
Re: Factors Affecting K
the c in Kc represents concentration and p partial pressure.
- Sun Dec 08, 2019 3:38 am
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: List of Strong Acids and Weak Acids
- Replies: 2
- Views: 225
Re: List of Strong Acids and Weak Acids
8 strong acids: HCl, HBr, HClO4, HI, HNO3, H2SO4
everything else is considered weak acid
Strong bases: basically group 1 and 2 hydroxides
common weak bases: NH3 (ammonia), CH3NH2 (Methylamine), C2H5NH2 (ethylamine), diethylamine, pyridine C5H5N
everything else is considered weak acid
Strong bases: basically group 1 and 2 hydroxides
common weak bases: NH3 (ammonia), CH3NH2 (Methylamine), C2H5NH2 (ethylamine), diethylamine, pyridine C5H5N
- Sun Dec 08, 2019 3:35 am
- Forum: Calculating the pH of Salt Solutions
- Topic: 6D.11 (d)
- Replies: 2
- Views: 243
Re: 6D.11 (d)
K+ is in group 1 element which is neutral and we can also know this since the K+ is a conjugate acid of a strong base, KOH
and Br- is conjugate base of strong acid, HBr, so we know that it is also neutral.
and Br- is conjugate base of strong acid, HBr, so we know that it is also neutral.
- Sun Dec 08, 2019 3:32 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Uncertainty
- Replies: 7
- Views: 831
Re: Uncertainty
yes, they are used interchangeably
- Sat Dec 07, 2019 8:14 pm
- Forum: Polyprotic Acids & Bases
- Topic: HW 6C.17 Which is the stronger base?
- Replies: 5
- Views: 452
Re: HW 6C.17 Which is the stronger base?
We know that BrO- is stronger base since it has a negative charge. This means that when it accepts a proton H+, it will become neutral whereas for C17H19O3N, it will become positively charged. Neutral charge is more favorable.
- Sat Dec 07, 2019 8:04 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: ph concept
- Replies: 5
- Views: 310
Re: ph concept
please quote my question so i get a notification, thanks in advance! i know there is something wrong with my thought process, but i cannot figure it out. my thought process is that if a base is weaker, less oh- will be dissociated out. taking the -log of that smaller number will result in a smaller...
- Sat Dec 07, 2019 7:58 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: H2O and Carbonate
- Replies: 3
- Views: 204
Re: H2O and Carbonate
1. Water can't act as a polydentate because it is too small to form multiple bonds to a transition metal central atom. The lone pairs are both on the same O atom. 2. Carbonate can act as both mono and bidentate. Since it has two O atoms with - charge (lone pairs), it can interact in two places. It d...
- Sat Dec 07, 2019 7:50 pm
- Forum: Bond Lengths & Energies
- Topic: Radicals
- Replies: 5
- Views: 477
Re: Radicals
If you mean how do we rank radicals with stability, I believe having resonance increases stability by delocalizing charge.
- Sat Dec 07, 2019 7:47 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Chelates
- Replies: 5
- Views: 449
Re: Chelates
You would look for ligands that act as polydentate. For example, if the coordination compound has ethylenediamine or en, you would know that it is chelating since en is a bidentate.
- Thu Dec 05, 2019 5:47 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: HW problem 6C. 19 (f)
- Replies: 1
- Views: 97
HW problem 6C. 19 (f)
Which is stronger acid and why? (f) H2CO3 or H2GeO3. I understand how higher electronegativity of C will result in it being the stronger acid, but I thought the acidity also depends on the bond length and that weaker (larger) bonds are stronger (Example in lecture was with H-F, H-Cl, H-Br with H-F b...
- Mon Dec 02, 2019 2:41 am
- Forum: Administrative Questions and Class Announcements
- Topic: Calculators on Final
- Replies: 6
- Views: 337
Re: Calculators on Final
since the test is cumulative, i assume that calculators are allowed.
- Mon Dec 02, 2019 2:40 am
- Forum: Conjugate Acids & Bases
- Topic: Ligands
- Replies: 12
- Views: 592
Re: Ligands
ligands are electron pair donors.
- Mon Dec 02, 2019 2:39 am
- Forum: Administrative Questions and Class Announcements
- Topic: Curving in Chem 14A
- Replies: 7
- Views: 549
Re: Curving in Chem 14A
I heard the same. The final distribution can alter your grade by a bit.
- Mon Dec 02, 2019 2:38 am
- Forum: Administrative Questions and Class Announcements
- Topic: Retaking Chem 14A
- Replies: 2
- Views: 209
Re: Retaking Chem 14A
I heard from past students that the final grade might not be as bad as you think! You should not take the final if you want to retake it however.
- Mon Dec 02, 2019 2:37 am
- Forum: Student Social/Study Group
- Topic: Final topics
- Replies: 10
- Views: 487
Re: Final topics
The final will be cumulative but probably focusing on the latter topics
- Sun Nov 24, 2019 8:22 pm
- Forum: Sigma & Pi Bonds
- Topic: Sigma and Pi Bonds
- Replies: 7
- Views: 385
Re: Sigma and Pi Bonds
Sigma bond is the initial, or first bond, so basically all the single bonds and one of the double/triple bonds. Pi bond is the other one/ones in the double/ triple bond, or the bond that comes after sigma bond.
- Sun Nov 24, 2019 8:20 pm
- Forum: Lewis Structures
- Topic: Bent or Angular?
- Replies: 18
- Views: 1021
Re: Bent or Angular?
Bent and angular are use synonymously
- Sun Nov 24, 2019 8:19 pm
- Forum: Dipole Moments
- Topic: Polar or nonpolar
- Replies: 8
- Views: 521
Re: Polar or nonpolar
Most diatomic molecules like o2 are nonpolar.
- Sun Nov 24, 2019 8:16 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Explain VSEPR conceptually
- Replies: 12
- Views: 746
Re: Explain VSEPR conceptually
Basically, the VSEPR model is the 3D model of a molecule where all ‘things’ are as far as they can be.
- Sun Nov 24, 2019 8:15 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polarity
- Replies: 4
- Views: 174
Re: Polarity
I would first draw the lewis structure, identify the vsepr shape to find out if the molecule is symmetrical or not. If it is symmetrical then it is most likely nonpolar since the dipole moments will cancel out. But if it isn’t symmetrical, draw the dipole moment arrows (towards the more electronegat...
- Sun Nov 17, 2019 5:45 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Consequences of polarizability
- Replies: 4
- Views: 525
Re: Consequences of polarizability
higher polarizability means there will be stronger LDF. So, the molecules will attract one another more strongly and the melting/ boiling points of these covalent substances will increase with size because bigger the size= higher the polarizability.
- Sun Nov 17, 2019 5:41 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Preferential
- Replies: 3
- Views: 113
Re: Preferential
I think what he was trying emphasize is that stability is preferred and we can observe some patterns for different elements to reach that stability by sharing e-, etc
- Sun Nov 17, 2019 5:40 pm
- Forum: Electronegativity
- Topic: Bond type for FeO2?
- Replies: 3
- Views: 844
Re: Bond type for FeO2?
I believe it is a polar covalent bond with ionic character
- Sun Nov 17, 2019 5:38 pm
- Forum: Student Social/Study Group
- Topic: What will Test 2 be on?
- Replies: 8
- Views: 514
Re: What will Test 2 be on?
I would focus on Intermolecular forces and VSEPR theory.
- Sun Nov 17, 2019 5:37 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: identifying forces
- Replies: 2
- Views: 71
Re: identifying forces
bond between non-metal and non-metal is usually a covalent bond and between non-metal and metal is ionic bond. Ion-Ion interaction is between ions, the particles with unequal # of protons and electrons (look at charge). Ion-dipole interaction is between ion and someting with partial charge. dipole d...
- Sun Nov 03, 2019 11:51 pm
- Forum: Lewis Structures
- Topic: Valence Electrons
- Replies: 2
- Views: 151
Re: Valence Electrons
Writing out the electron configuration for Cu, there is one valence electron: [Ar] 3d10 4s1
- Sun Nov 03, 2019 11:41 pm
- Forum: Photoelectric Effect
- Topic: Best way to study for this topic?
- Replies: 8
- Views: 386
Re: Best way to study for this topic?
There are a video module and assessment questions available on the class website. I find it helpful to work out the problems on there because they deal with both conceptual and calculation problems.
- Sun Nov 03, 2019 11:37 pm
- Forum: Properties of Light
- Topic: UV
- Replies: 2
- Views: 107
Re: UV
I believe it is 100nm to 400nm.
- Sun Nov 03, 2019 11:31 pm
- Forum: Lewis Structures
- Topic: hw problem 2c.3
- Replies: 1
- Views: 94
hw problem 2c.3
Should we be able to know the formula (and the charge) based on the names?
- Sat Nov 02, 2019 7:59 pm
- Forum: Lewis Structures
- Topic: ONF lewis structure
- Replies: 2
- Views: 91
ONF lewis structure
Since the general guideline for determining the central atom is to choose the one with lowest ionization energy, I expected O to be the central atom. However, the solution provides N as central. Could anyone explain to me why?
- Sun Oct 27, 2019 2:06 pm
- Forum: Properties of Light
- Topic: Value for C
- Replies: 8
- Views: 237
Re: Value for C
During test, they will give you all the constants you need in the front page. I would try to use the ones that are given by the class on the front page.
- Sun Oct 27, 2019 2:05 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Atomic spectra post assessment question 42
- Replies: 2
- Views: 152
Atomic spectra post assessment question 42
I tried using this formula first,
1.14 x 10^14 = 3.29x10^15((1/n^2)- (1/16)
But i ended up getting n=3.
So i just tried with n=5 and n=6 and chose 6.
Is the above formula correct? Or am i missing something?
1.14 x 10^14 = 3.29x10^15((1/n^2)- (1/16)
But i ended up getting n=3.
So i just tried with n=5 and n=6 and chose 6.
Is the above formula correct? Or am i missing something?
- Sun Oct 27, 2019 2:05 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Atomic spectra post assessment question 42
- Replies: 2
- Views: 123
Atomic spectra post assessment question 42
I tried using this formula first,
1.14 x 10^14 = 3.29x10^15((1/n^2)- (1/16)
But i ended up getting n=3.
So i just tried with n=5 and n=6 and chose 6.
Is the above formula correct? Or am i missing something?
1.14 x 10^14 = 3.29x10^15((1/n^2)- (1/16)
But i ended up getting n=3.
So i just tried with n=5 and n=6 and chose 6.
Is the above formula correct? Or am i missing something?
- Sun Oct 27, 2019 2:08 am
- Forum: Formal Charge and Oxidation Numbers
- Topic: 2B. 23
- Replies: 2
- Views: 160
Re: 2B. 23
Formal charge of an atom indicates gain/loss of electrons while forming covalent bond. So, to assign formal charge of an atom, first, determine the number of valence electrons for each bound atom, then compare the number of bounding (shared, S) electron and the number of lone pairs (L) of free atom ...
- Sun Oct 27, 2019 2:02 am
- Forum: DeBroglie Equation
- Topic: Post-assessment question 34
- Replies: 2
- Views: 133
Re: Post-assessment question 34
okay thanks! One more thing, if the answer was 10^-5, would it still be reasonable?
- Fri Oct 25, 2019 5:56 pm
- Forum: DeBroglie Equation
- Topic: Post-assessment question 34
- Replies: 2
- Views: 133
Post-assessment question 34
I got 1.00 x 10^-5 m/s and thought it was reasonable since it is smaller than the speed of light. Could anyone explain why this is wrong?
- Wed Oct 23, 2019 12:34 am
- Forum: Photoelectric Effect
- Topic: post module assignment Q 19
- Replies: 4
- Views: 151
post module assignment Q 19
is the answer D? I feel like A, B, C are right because they explain the main photoelectric effect equation showing conservation of energy
- Wed Oct 23, 2019 12:09 am
- Forum: Photoelectric Effect
- Topic: module assessment Q #29
- Replies: 2
- Views: 101
Re: module assessment Q #29
thank you so much!
- Tue Oct 22, 2019 4:38 pm
- Forum: Photoelectric Effect
- Topic: module assessment Q #29
- Replies: 2
- Views: 101
module assessment Q #29
Since the work function is 150.6 kJ, I just converted in from KJ to J by multiplying10^3 and chose B.
Can someone help me understand how to solve this problem?
Can someone help me understand how to solve this problem?
- Sun Oct 20, 2019 11:24 pm
- Forum: SI Units, Unit Conversions
- Topic: Accuracy vs Precision
- Replies: 11
- Views: 727
Re: Accuracy vs Precision
This image should help!
- Sun Oct 20, 2019 11:19 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Clarification on electron configuration
- Replies: 5
- Views: 233
Re: Clarification on electron configuration
i noticed in some HW questions, it includes more than just first row of d-block. So, it might be helpful to make sure you understand how to do it.
- Sun Oct 20, 2019 11:15 pm
- Forum: Properties of Light
- Topic: speed of light and velocity
- Replies: 6
- Views: 197
Re: speed of light and velocity
in terms of calculations in this class, I believe it doesn't matter. But, it would help a lot in the future to know that they are two different concepts for Physics.
- Mon Oct 14, 2019 12:25 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Are these equations only specific to H-atoms?
- Replies: 2
- Views: 139
Are these equations only specific to H-atoms?
So, from what I understand, the Bohr Frequency Condition and equation for calculating energy of different n levels are specific to H atoms. Professor Lavelle mentioned C-atom during the lecture and I was wondering if we know the condition for C-atoms? Just to make sure, are these condition and equat...