Half reactions are usually given as reduction reactions.
It's the difference when you're keeping both anode and cathode 's at their reduction potentials
It's added when you flip the anode reaction (making it go from a reduction to oxidation) and thus flip .
Hope that helps!
Search found 96 matches
- Sun Mar 17, 2019 12:01 am
- Forum: Balancing Redox Reactions
- Topic: calculating standard cell potential
- Replies: 5
- Views: 802
- Sat Mar 16, 2019 11:57 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: state functions
- Replies: 4
- Views: 603
Re: state functions
State functions are path independent. They are: Pressure, density, temperature, volume, Enthalpy (H), Internal energy (U), Gibbs free energy (G), and entropy (s). Lyndon's trick to remembering is: when i'm under PRESSURE and feeling DENSE, all I want to do is watch TV (temperature and volume), and g...
- Sat Mar 16, 2019 9:44 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts
- Replies: 28
- Views: 1794
Re: Catalysts
Catalysts reduce the activation energy between reactants to products, meaning it takes less energy to make the forward reaction occur
- Sat Mar 16, 2019 10:53 am
- Forum: Student Social/Study Group
- Topic: Lyndon's Review Sess
- Replies: 6
- Views: 1119
Re: Lyndon's Review Sess
Hi, it was just upload last night!
- Tue Mar 12, 2019 11:57 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Test 2
- Replies: 3
- Views: 440
Re: Test 2
I have the exact same question! When I was doing the test, I assumed that the gibbs free energy would be greater than 0. However, is it less than 0 (spontaneous) because combustion involves purely adding oxygen and doesn't require heat? (and, would it be correct to say that the BBQ being made from t...
- Sun Mar 10, 2019 1:56 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Ratio of Rate constants = equilibrium constant, K
- Replies: 1
- Views: 520
Re: Ratio of Rate constants = equilibrium constant, K
Yes, it is. K = the concentration of products over the concentration or reactants, which is also used in acids and bases
- Sun Mar 10, 2019 1:54 pm
- Forum: Zero Order Reactions
- Topic: How can you tell a reaction zero order?
- Replies: 4
- Views: 590
Re: How can you tell a reaction zero order?
Correct, there is zero order reactions do not have molecularity and do not have a rate law
- Sun Mar 10, 2019 1:53 pm
- Forum: Van't Hoff Equation
- Topic: Overview
- Replies: 8
- Views: 1125
Re: Overview
The Van't Hoff Equation can be used to calculate K at different temperatures, if you know the standard change in enthalpy.
- Sun Mar 03, 2019 10:28 pm
- Forum: Balancing Redox Reactions
- Topic: Short hand notation
- Replies: 8
- Views: 865
Re: Short hand notation
Jchellis 1I wrote:What does the single line represent then? I thought the single line was the salt bridge?
the single line | represents the interface between phases in contact with each other (including a porous disc/wall)
- Sun Mar 03, 2019 10:14 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Standard cell potential
- Replies: 3
- Views: 456
Re: Standard cell potential
After you balance the half reactions, you can see how many electrons are being transferred (how many are lost in oxidation and how many are gained in reduction, which will be the same #) - that number = n
- Sun Mar 03, 2019 10:08 pm
- Forum: Balancing Redox Reactions
- Topic: Adding H+ and H2O
- Replies: 13
- Views: 2898
Re: Adding H+ and H2O
Jchellis 1I wrote:Wait do you put the OH- on the same or opposite side of H+?
Hi, you put the OH- on the same side as the H+ because OH- + H+ -> H2O. Hope that helps!
- Wed Feb 27, 2019 10:58 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.11d (6th Edition)
- Replies: 1
- Views: 254
14.11d (6th Edition)
Hi! So, I am working on 14.11d, and I am a bit confused. The question is: Pt(s)|O2(g)|H+(aq) || OH-(aq)|O2(g)|Pt(s) and it asks to write the half-reactions and the balanced equation for the cell reaction... When I was writing the half-reaction for the anode side, I originally wrote it H+ -> O2, sinc...
- Mon Feb 25, 2019 12:14 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: What is E?
- Replies: 4
- Views: 445
Re: What is E?
I think another property of standard conditions is 25 degrees C
- Mon Feb 25, 2019 12:12 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Free Energy is a state function?
- Replies: 5
- Views: 633
Re: Free Energy is a state function?
A state function - delta G can be added or subtracted - it doesn't matter what path is taken to get there, which is how we are able to use the three methods to calculate delta G.
- Mon Feb 25, 2019 12:09 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Spontaneous?
- Replies: 13
- Views: 1588
Re: Spontaneous?
When delta G is negative, it is spontaneous
- Wed Feb 13, 2019 1:04 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Entropy at 0 K
- Replies: 4
- Views: 779
Re: Entropy at 0 K
Molecules that are perfectly ordered have no entropy at 0K (ex. CH4). For molecules that are not perfectly ordered, there is positional/residual entropy at 0K.
- Sun Feb 10, 2019 8:27 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
- Replies: 49
- Views: 11724
Re: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
Venya Vaddi 1L wrote:The enthalpy of formation of O2 is zero since it is in its standard state.
Thank you!!!
- Sun Feb 10, 2019 6:02 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
- Replies: 49
- Views: 11724
Re: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
For 4C, are we supposed to find/know the enthalpy of formation for the reactant O2, or should that be given?
Thanks!
Thanks!
- Sun Feb 10, 2019 2:18 pm
- Forum: Calculating Work of Expansion
- Topic: Using Derivative/Integral Equations
- Replies: 5
- Views: 576
Re: Using Derivative/Integral Equations
I think the integrals are just used to understand why the equations were were given in class make sense!
- Sun Feb 10, 2019 1:16 pm
- Forum: Administrative Questions and Class Announcements
- Topic: UA Sessions Today
- Replies: 2
- Views: 365
UA Sessions Today
Are UA sessions in Covel still happening today (February 10)? Thanks!
- Sun Feb 10, 2019 1:09 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Value of Variable Kb
- Replies: 4
- Views: 924
Re: Value of Variable Kb
From my understanding, Kb is the Boltzmann constant, and is derived from the gas constant R divided by Avogadro's number. I don't think you need to know this though, as it is on the formula sheet!
Hope this helps!
Hope this helps!
- Sun Feb 10, 2019 1:05 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy values
- Replies: 3
- Views: 518
Re: Enthalpy values
I think these values will be given!
- Sun Feb 10, 2019 12:51 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: methods
- Replies: 8
- Views: 961
Re: methods
eden tefera 2B wrote:You can also cross out bonds if both the products and reactants both have the same number!
Would you be able to explain what you mean with an example? This seems like a helpful tip, but I'm not sure how to do this in practice. Thank you!
- Sun Feb 03, 2019 11:44 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: How to: Hess's Law
- Replies: 1
- Views: 266
How to: Hess's Law
Would someone be able to explain how they do Hess's Law problems? I'm not able to follow the notes from class as clearly, and the problems in discussion confused me. How do you know when you need to reverse the reaction? Are you trying to get the same compound on both the reaction and products sides...
- Sun Feb 03, 2019 11:42 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Internal energy
- Replies: 5
- Views: 563
Re: Internal energy
According to my notes: Internal energy, U, is a state property. So, changes in U are a function of initial and final states (delta U = Ufinal - U initial). The energy of a closed system can be changed by heating/cooling or compression/expansion. Delta U = energy transferred by heating (+q) + energy ...
- Sun Feb 03, 2019 11:39 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Bomb Calorimeter
- Replies: 5
- Views: 610
Re: Bomb Calorimeter
According to the notes, a bomb calorimeter is an isolated system because nothing is exchanged with the surroundings!
- Wed Jan 30, 2019 11:41 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 6th edition 8.61
- Replies: 2
- Views: 332
Re: 6th edition 8.61
The explanation above is really great! Just a quick correction, delta H = 2(188.32) - 541.66 + 92.22 = -72.90 not 72.90
:)
:)
- Mon Jan 28, 2019 5:58 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Neutralization reactions
- Replies: 6
- Views: 853
Re: Neutralization reactions
I believe they are always exothermic because the acids and bases are breaking bonds.
- Mon Jan 28, 2019 4:50 pm
- Forum: Phase Changes & Related Calculations
- Topic: Heat Capacity
- Replies: 10
- Views: 961
Re: Heat Capacity
Molar heat capacity specifies that it is the amount of heat needed to raise the temperature of an object of 1 mole by 1 degrees celsius, while heat capacity does not specify an amount (i.e. 1 mole).
- Wed Jan 23, 2019 6:09 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Strong vs. weak acids and bases?
- Replies: 5
- Views: 618
Re: Strong vs. weak acids and bases?
Thanks! This helps a lot. Follow up question...how do you determine how exactly the weak compounds will dissociate? ex. How would you know that NH2NH2 becomes NH2NH3+?
Thanks again!!!
Thanks again!!!
- Wed Jan 23, 2019 5:51 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Strong vs. weak acids and bases?
- Replies: 5
- Views: 618
Strong vs. weak acids and bases?
The last time I took chemistry was a couple of quarters ago, so I am a bit lost with identifying acids and bases, and whether they are strong or weak. I am most worried with this test that I will be unable to identify how a compound might dissociate in water. Does anyone have any tips on how to do t...
- Sun Jan 20, 2019 10:40 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Shortcut method (finding concentration change)
- Replies: 5
- Views: 424
Re: Shortcut method (finding concentration change)
An analogy that would be easy to understand that highlights this concept is as follows: If a millionaire gave someone who had no money $100, that loss of the $100 wouldn't affect the millionaire. In the same way, removing the -x from the denominator when doing the shortcut method doesn't change the ...
- Sun Jan 20, 2019 10:30 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Pressure Notation
- Replies: 5
- Views: 478
Re: Pressure Notation
I think Kp is only used when the reaction only includes gases, so I would default to Kc
- Sun Jan 20, 2019 10:11 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Changes in Temperature
- Replies: 8
- Views: 1139
Re: Changes in Temperature
Changing temperature changes K.
In an endothermic reaction (heat is added), products are favored.
In an exothermic reaction (heat is released), reactions are favored.
Hope that helps! (:
In an endothermic reaction (heat is added), products are favored.
In an exothermic reaction (heat is released), reactions are favored.
Hope that helps! (:
- Sat Jan 12, 2019 11:06 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: defining Q
- Replies: 6
- Views: 594
Re: defining Q
Yes, the reaction continues until Q = K and equilibrium is reached.
- Sat Jan 12, 2019 11:05 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Phases and Reaction Quotient (HW)
- Replies: 3
- Views: 374
Re: Phases and Reaction Quotient (HW)
Molar concentrations of a pure substance (solid or liquid) does not change in a reaction. Therefore, solids and liquids are not included in the expression.
- Wed Jan 09, 2019 11:53 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kc and Qc
- Replies: 4
- Views: 44127
Re: Kc and Qc
Qc and Kc are calculate the same way, but Qc is used to determine which direction a reaction will proceed, while Kc is the equilibrium constant (the ratio of the concentrations of products and reactants when the reaction is at equilibrium). So, Qc could be = to Kc, but it may not be. When Q < K, the...
- Thu Jun 14, 2018 12:58 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: How Lone Pairs Affect Bond Angles?
- Replies: 1
- Views: 8415
Re: How Lone Pairs Affect Bond Angles?
I don't think I understand how lone pairs change bond angles. Let's say there was a tetrahedral molecule. I know that those bond angles are 109.5, but when lone pairs start getting introduced, do the bond angles increase or decrease and why? Does this apply to all molecules that get lone pairs intr...
- Thu Jun 14, 2018 12:49 pm
- Forum: Properties of Electrons
- Topic: threshold energy
- Replies: 2
- Views: 505
Re: threshold energy
By "it," are you referring to the electron? If so, if the photon does not reach the threshold energy, no electron will be emitted.
- Wed Jun 13, 2018 12:54 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Midterm 1 Q!C
- Replies: 2
- Views: 492
Re: Midterm 1 Q!C
What I did to solve this problem was: 5.00 g KMnO_{4} \cdot \frac{1 mol KMnO_{4}}{158.04 g KMnO_{4}} = 0.0316 mol KMnO_{4} M = \frac{n}{V} = \frac{0.0316 mol KMnO_{4}}{.150L} = 0.211 M KMnO_{4} n = MV = (0.211 M KMnO_{4})(0.020 L) = 0.00422 mol KMnO_{4} (0.00422 mol KMnO_{4})...
- Tue Jun 12, 2018 1:15 pm
- Forum: Dipole Moments
- Topic: Dipole Moment understanding
- Replies: 5
- Views: 2109
Re: Dipole Moment understanding
If the dipole moments do not cancel out, that would lead to a polar molecule.
- Tue Jun 12, 2018 1:14 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Review Sessions Finals Week - Hedrick Hall? [ENDORSED]
- Replies: 6
- Views: 1048
Re: Review Sessions Finals Week - Hedrick Hall? [ENDORSED]
Thank you! I really appreciate it.
- Mon Jun 11, 2018 7:06 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Review Sessions Finals Week - Hedrick Hall? [ENDORSED]
- Replies: 6
- Views: 1048
Review Sessions Finals Week - Hedrick Hall? [ENDORSED]
Are there review sessions in Hedrick Hall this week? I was under the impression that there were from the website (image attached), but the UAs for 5-6pm and 7-9pm weren't here today, so I am unsure if I read something wrong or if there was a mix-up?
Thanks!
Thanks!
- Sun Jun 10, 2018 5:24 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Helpful Chart
- Replies: 18
- Views: 1556
Re: Helpful Chart
We made a similar chart in discussion too. I want to point out that I believe our TA mentioned something about the angles being less than 109.5 in some cases, I'm not exactly sure why or in what instances, but I think he mentioned lone pairs. I also think Lavelle said that we don't have to know the...
- Sat Jun 09, 2018 1:08 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Polydentate
- Replies: 5
- Views: 881
Re: Polydentate
Yes, I believe that multiple atoms in the compound would have to have lone pairs for it to be polydentate. It wouldn't be polydentate if a single N had 3 lone pairs, for example. Instead, it would be polydentate if multiple N had lone pairs.
- Sat Jun 09, 2018 1:06 pm
- Forum: Empirical & Molecular Formulas
- Topic: Empirical to molecular
- Replies: 3
- Views: 4197
Re: Empirical to molecular
You would have to be given the molar mass (which is usually said to be done through mass spectrometry). In this example we did in class: Vitamin C sample of 8.00g is analyzed - the results are C 3.27g, H 0.366g, O 4.36g Let's jump down the steps and assume that you have calculated that the empirical...
- Sat Jun 09, 2018 12:56 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Difference
- Replies: 1
- Views: 406
Re: Difference
I believe that KA stands for the equilibrium constant for an acid, and pKA provides the -log of the concentration of KA. pKA provides you a way to compare other pKAs if that makes sense.... Let's say a KA = 10^{-10} pKA = 10 and a KA = 10^{-8} pKA = 8 (so this is a stronger acid than the previous one)
- Thu May 31, 2018 11:33 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Define Ligands?
- Replies: 10
- Views: 1164
Re: Define Ligands?
Ligands are ions or neutral atoms that bond to central atoms/ions to create a TM complex/organometallic complex/coordination compound. Ligands act as Lewis bases [electron pair donors]. In the example we had in class, the first ligand we looked at was NH3. It donated its lone pair to Ni2+. Another l...
- Thu May 31, 2018 11:23 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: HW 4.9
- Replies: 10
- Views: 2048
Re: HW 4.9
Are we expected to memorize these bonding angles? How do you know that the bonding angle is slightly less than 90 degrees? If there are lone pairs in a molecule, this creates repulsion, pushing certain atoms in the molecule "away," which slightly alters the bond angles that would exist if...
- Thu May 31, 2018 11:04 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Homework 4.15 B
- Replies: 1
- Views: 628
Re: Homework 4.15 B
Hi Sammi! TeCl4 has a see saw shape. Professor Lavelle used a similar example in class using SF4 (I believe on Wednesday of Week 8 if you want to refer to your notes). The reason why TeCl4 and SF4 have a see saw shape is because they have the VSEPR notation of AX4E (4 bonding pairs and 1 lone pair)....
- Thu May 31, 2018 10:50 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Helpful Chart
- Replies: 18
- Views: 1556
Re: Helpful Chart
This helps so much, thank you!!! I was super worried about memorizing them.
- Sat May 26, 2018 9:24 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Shapes with different types of bonds
- Replies: 3
- Views: 408
Re: Shapes with different types of bonds
Yes, bond angles would change, because of electron repulsion :)
- Sat May 26, 2018 9:14 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizing power
- Replies: 10
- Views: 8755
Re: Polarizing power
Anions become highly polarized, while cations have polarizing power.
- Thu May 24, 2018 11:20 pm
- Forum: Dipole Moments
- Topic: Dipole vs. london forces
- Replies: 1
- Views: 346
Re: Dipole vs. london forces
Hi! I think we are considering them as largely similar and interchangeable, but there might be a distinction that we are not focusing on.
- Mon May 21, 2018 10:26 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizing Power
- Replies: 2
- Views: 811
Re: Polarizing Power
This is what I have in the notes: - All ionic bonds have some covalent character (this can be seen in Na+ and Cl-, because the anion's electrons are pulled into the bonding region, giving Na+ and Cl- some covalent character [in other words, the positive cation pulls electrons from negative anions to...
- Sat May 19, 2018 9:16 pm
- Forum: Ionic & Covalent Bonds
- Topic: Octet rule
- Replies: 17
- Views: 2426
Re: Octet rule
As the people above have stated, the octet rule is basically a rule in which atoms combine with other atoms so that they have 8 valence electrons. However, there are exceptions to this rule, so keep this in mind.
- Sat May 19, 2018 9:08 pm
- Forum: Ionic & Covalent Bonds
- Topic: Radicals [ENDORSED]
- Replies: 5
- Views: 765
Re: Radicals [ENDORSED]
How do we determine which atom or ion can be classified as the radical? I think this would depend on the molecule given in a problem...If it had an odd number of electrons (when adding up valence electrons), it would be safe to assume one of the atoms would be considered a radical. This can be seen...
- Sat May 19, 2018 9:05 pm
- Forum: Lewis Structures
- Topic: Exception to Lewis Structure?
- Replies: 4
- Views: 572
Re: Exception to Lewis Structure?
Hi Betty! I was told in my discussion that anything below this line (see attached image) could potentially have more than 8 electrons.
- Sun May 13, 2018 1:59 pm
- Forum: Ionic & Covalent Bonds
- Topic: Lewis Structure vs Resonance Structure
- Replies: 6
- Views: 726
Re: Lewis Structure vs Resonance Structure
One way to think of it is this: Lewis structures are used to show how a molecule may look. However, when you draw a single Lewis structure, you may not be showing all of the possibilities (a double bond could be somewhere else, etc.). So, the Lewis structure you drew would be just a "generalize...
- Tue May 08, 2018 1:11 pm
- Forum: Limiting Reactant Calculations
- Topic: Mass of Reactant/Product
- Replies: 4
- Views: 923
Re: Mass of Reactant/Product
Jacob is correct! This is how you are easily able to determine how much of a product was made as a result of a limiting reactant.
- Tue May 08, 2018 1:05 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Test 2 Q.4
- Replies: 3
- Views: 605
Re: Test 2 Q.4
You can use the wavelength to determine the energy released (where an electron went from a higher energy level to a lower energy level). This energy is the difference in energy between the two states. Hope this helps! Try to work out the problem, and if you are still having trouble I can write out t...
- Tue May 08, 2018 1:01 pm
- Forum: Trends in The Periodic Table
- Topic: question confused
- Replies: 2
- Views: 453
Re: question confused
The "rule" is that 2nd round ionization energy always requires more energy than 1st round. This is because it requires energy to remove the first electron (which makes the element a positive ion). It takes even more energy to remove an electron from the now positive ion than it would have ...
- Mon May 07, 2018 10:26 pm
- Forum: Trends in The Periodic Table
- Topic: Difference between Periodic trends [ENDORSED]
- Replies: 4
- Views: 669
Re: Difference between Periodic trends [ENDORSED]
Electron affinity is a measure of energy change when an electron is added while electronegativity is how attracted an atom is to electrons. While electron affinity is increasing, electronegativity is decreasing since as an atom is less attractive to electrons, it requires more energy to add an elec...
- Sun May 06, 2018 7:10 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Test 1. Q 2
- Replies: 3
- Views: 822
Re: Test 1. Q 2
I didn't use M(initial)V(initial)=M(final)V(final) because more solution wasn't being added to the aqueous solution. The idea of M(initial)V(initial)=M(final)V(final) is that you would be adding more solution with NiCl2 (for example), and the original solution would still be in the beaker (if that m...
- Sun May 06, 2018 1:28 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: HW 2.39
- Replies: 2
- Views: 352
Re: HW 2.39
Hi Maya! So you can basically determine whether an electron is in a ground state or an excited state by seeing whether the electron configurations violate Aufbau principle, Hund's rule, or the Pauli's exclusion principle. If an electron configuration violates any principle/rule, then it is represent...
- Sun May 06, 2018 1:23 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Confusion with problem 1.57 [ENDORSED]
- Replies: 4
- Views: 987
Re: Confusion with problem 1.57 [ENDORSED]
Hi, Anna! I had the same issue with this problem originally. It is important to remember that Balmer series means that the electron transitions from a higher energy level to n=2. So, we can assume that: 656.3 nm is a transition from n=3 to n=2 486.1 nm is a transition from n=4 to n=2 434.0 nm is a t...
- Sun May 06, 2018 1:14 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Test 1. Q 2
- Replies: 3
- Views: 822
Re: Test 1. Q 2
I did not have the same version of the test, but here is what I think are the correct steps: So, it says that 50.0 mL of .200M of NiCl2 aqueous solution is prepared (called electrolyte). An electrode surface is placed into the solution, and after the electrodeposition process, some of the Ni is depo...
- Wed May 02, 2018 12:59 pm
- Forum: *Shrodinger Equation
- Topic: How are orbitals corresponding to m sub l numbers
- Replies: 2
- Views: 474
Re: How are orbitals corresponding to m sub l numbers
I am a little confused as to how an orbital can be a negative number. Say n=3 so you are in the 3d subshell. Th orbitals it says can be: -2,-1,0,1,2 but I don't understand what these numbers correspond to? For a 3d subshell, n = 3 l = 2 (because a d-orbital responds to an l of 2) (the allowed value...
- Tue May 01, 2018 2:00 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: 2.17
- Replies: 4
- Views: 506
Re: 2.17
The question is referring to ml, so: For part a, when l = 0 (it is an s orbital), there is only one possible value for ml (which is 0), so the answer is 1. When l = 2, this means ml can be: -2, -1, 0, 1, 2 (5 values) When l = 1, this means that ml can be: -1, 0, 1 (3 values) When l = 3, this means t...
- Tue May 01, 2018 1:41 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: In class problem [ENDORSED]
- Replies: 6
- Views: 857
Re: In class problem [ENDORSED]
Yes, I agree with the people above. Additionally, in the video module, Professor Lavelle showed the correct atomic model: The electron is not confined to the nucleus and we now know, from experimental observation that the size of an atom is determined by its electrons outside of the nucleus. For a H...
- Thu Apr 26, 2018 8:17 pm
- Forum: Properties of Electrons
- Topic: electron mass
- Replies: 15
- Views: 1670
Re: electron mass
It depends on what you're talking about, but yes, they have a definite mass that can be important in some contexts.
- Thu Apr 26, 2018 8:15 pm
- Forum: DeBroglie Equation
- Topic: DeBroglie
- Replies: 7
- Views: 782
Re: DeBroglie
I agree with the people above! p (which means momentum) is = to (mass)(velocity) which is usually given to you in some shape or form in the question. It is for a moving object (not light)
- Thu Apr 26, 2018 8:12 pm
- Forum: Properties of Light
- Topic: test 2
- Replies: 18
- Views: 1648
Re: test 2
When memorizing the general order of wavelengths of the rays from gamma ray to radio waves, do we need to know the general trend of the wavelengths within the visible light as well as the numerical range for the waves? You just need to know generally the electromagnetic spectrum so like the differe...
- Fri Apr 20, 2018 7:58 pm
- Forum: Photoelectric Effect
- Topic: Plastic vs Metal [ENDORSED]
- Replies: 3
- Views: 497
Re: Plastic vs Metal [ENDORSED]
Hi! The experiment requires a conductive material (metal), and since plastics and other materials are not conductive, the experiment wouldn't work with the use of a non-metal surface. Hope this clarifies things for you!
- Fri Apr 20, 2018 11:41 am
- Forum: Photoelectric Effect
- Topic: Energy levels
- Replies: 7
- Views: 8925
Re: Energy levels
Why does a drop from n2 to n1 have more energy than a drop from n4 to n1? I thought I heard Professor Lavelle say on Monday, when answering someone's question that, a drop from n3 to n1 and then n2 to n1 emits 2 photons but has the same energy as a drop from n3 to n1? In this way, why wouldn't a dro...
- Fri Apr 20, 2018 11:31 am
- Forum: Balancing Chemical Reactions
- Topic: Balancing Equation
- Replies: 7
- Views: 1371
Re: Balancing Equation
I really like Komal's method! I tried to do something similar on Test 1.
- Fri Apr 20, 2018 11:29 am
- Forum: Properties of Electrons
- Topic: Geiger -Marsden experiment [ENDORSED]
- Replies: 5
- Views: 645
Re: Geiger -Marsden experiment [ENDORSED]
NabilaNizam-1K wrote:Do we have to study the experiment in detail or do we just have to know the concepts and result of the experiment?
I don't think that we need to know the experiment in detail. Just understand the results/concepts!
- Fri Apr 20, 2018 11:26 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: work example in class from April 16
- Replies: 2
- Views: 199
Re: work example in class from April 16
In the equation E subscript n = (-hR)/(n^2), n = energy level. So in the worked example, at that point of the problem, we were calculating the energy at energy level 4 (n = 4):
E subscript 4 = - (hR)/(4^2)
In the next step:
E subscript 2 = (-hR)/(2^2)
I hope this was helpful.
E subscript 4 = - (hR)/(4^2)
In the next step:
E subscript 2 = (-hR)/(2^2)
I hope this was helpful.
- Fri Apr 20, 2018 11:17 am
- Forum: Naming
- Topic: Naming and Polyatomic Ions
- Replies: 6
- Views: 1017
Re: Naming and Polyatomic Ions
Gabi Landes 1-H wrote:Is it expected of us to memorize the polyatomic ions?
I don't think it's expected to memorize the polyatomic ions yet! I think that will be expected later on in the course, but we haven't focused too much on it yet so I wouldn't worry about it until then (:
- Fri Apr 20, 2018 11:15 am
- Forum: Significant Figures
- Topic: Basic Sig Figs
- Replies: 13
- Views: 1986
Re: Basic Sig Figs
When you get the final answer for a problem, for example, #2. CHEM, an FM radio station, broadcasts at 99.5 MHz. What is the wavelength of the corresponding radio waves?" (from TA worksheet 2) would the resulting answer have be rounded to 3 sig figs because of the "99.5 MHz"? Yes, 3 ...
- Fri Apr 20, 2018 11:13 am
- Forum: General Science Questions
- Topic: Notation
- Replies: 3
- Views: 685
Re: Notation
There is no difference between notations, so you can use either notation when writing out your problems!
- Fri Apr 20, 2018 11:12 am
- Forum: Photoelectric Effect
- Topic: Threshold Energy [ENDORSED]
- Replies: 12
- Views: 1820
Re: Threshold Energy [ENDORSED]
What occurs to the kinetic energy that is the excess when the energy of the photon is greater than the threshold energy? I believe that in the photoelectric experiment, this kinetic energy is detected by a detector which shows the excess energy of the photon that surpassed the threshold energy (sin...
- Fri Apr 20, 2018 11:03 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Heisenberg Equation & Test 2
- Replies: 4
- Views: 500
Re: Heisenberg Equation & Test 2
The Heisenberg Equation will not be tested in Test 2 (:
- Fri Apr 20, 2018 11:00 am
- Forum: Properties of Light
- Topic: Memorizing Wavelengths [ENDORSED]
- Replies: 4
- Views: 518
Re: Memorizing Wavelengths [ENDORSED]
I believe it would be helpful to know, just in case. I think it'll help to have a general idea of how large each type of electromagnetic wave is (especially to know visible is between 400 and 700 nm, for example), if only to help you double check your work on the test. Hope that helps!
- Fri Apr 20, 2018 10:55 am
- Forum: Properties of Light
- Topic: Homework 1.9
- Replies: 2
- Views: 462
Re: Homework 1.9
Hi, yes! You just refer to the electromagnetic spectrum to see where the wavelengths you found lie.
- Thu Apr 19, 2018 12:04 am
- Forum: Einstein Equation
- Topic: When to use E=hc/wavelength
- Replies: 6
- Views: 2720
Re: When to use E=hc/wavelength
Jocelyn1B wrote:Sorry this is off topic but do we have to memorize these two equations or is it going to be given to us?
Hi Jocelyn! These equations as well as constants will be given on the test!
- Sun Apr 15, 2018 7:24 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg Formula, 1.13 HW
- Replies: 4
- Views: 420
Re: Rydberg Formula, 1.13 HW
Yes, I believe this would be the best way to look at it.
- Sat Apr 14, 2018 2:15 pm
- Forum: Properties of Electrons
- Topic: History of experiments on the model of atom
- Replies: 7
- Views: 846
Re: History of experiments on the model of atom
I do not think this will be tested. :)
- Sat Apr 14, 2018 2:03 pm
- Forum: Student Social/Study Group
- Topic: Study Group
- Replies: 10
- Views: 1620
Re: Study Group
I'm super interested in this! Could you make a groupme?
- Thu Apr 12, 2018 9:38 pm
- Forum: Properties of Light
- Topic: Units of speed of light [ENDORSED]
- Replies: 2
- Views: 388
Re: Units of speed of light [ENDORSED]
I agree with Marisol! Frequency is shown as a s^-1 and wavelength is shown as m. When multiplied to get constant, this gives you m/s or m.s^-1. Hopefully this makes sense!
- Wed Apr 11, 2018 8:26 pm
- Forum: Properties of Light
- Topic: Clarification on Hz
- Replies: 5
- Views: 370
Re: Clarification on Hz
Yes, 1 Hz = 1 s-1 (one cycle per second).
- Mon Apr 09, 2018 8:58 pm
- Forum: Limiting Reactant Calculations
- Topic: M19 - Combustion Analysis
- Replies: 2
- Views: 461
Re: M19 - Combustion Analysis
Thank you!!! That makes so much sense now.
- Mon Apr 09, 2018 3:14 pm
- Forum: Limiting Reactant Calculations
- Topic: M19 - Combustion Analysis
- Replies: 2
- Views: 461
M19 - Combustion Analysis
The question asks, "A stimulant in coffee and tea is caffeine, a substance of molar mass 194 g mol 1. When 0.376 g of caffeine was burned, 0.682 g of carbon dioxide, 0.174 g of water, and 0.110 g of nitrogen were formed. Determine the empirical and molecular formulas of caffeine, and write the ...
- Sun Apr 08, 2018 8:50 pm
- Forum: SI Units, Unit Conversions
- Topic: Sig figures
- Replies: 9
- Views: 606
Re: Sig figures
There are different rules for different operations. Multiplication and division are pretty straight forward, but addition and subtraction are a little bit different. Multiplication and division: Round to the least number of significant figures of the numbers in the problem. (ex. 3.5 * 2.03 = 7.1) Ad...
- Sun Apr 08, 2018 10:59 am
- Forum: Molarity, Solutions, Dilutions
- Topic: G.5 Part A) Molarity [ENDORSED]
- Replies: 9
- Views: 978
Re: G.5 Part A) Molarity [ENDORSED]
I understand/agree with how Kuldeep got the answer to part A! I just have a couple quick questions...How does the portion of the question that says, "Some of this solution was transferred to a buret" relate to the question? Also, this might be a dumb question but how would you know the mol...
- Sun Apr 08, 2018 10:11 am
- Forum: SI Units, Unit Conversions
- Topic: writing out conversions in one long line vs. steps
- Replies: 16
- Views: 1475
Re: writing out conversions in one long line vs. steps
I usually do what works for the problem/how comfortable I am with the concept. So, for the first few problems I might break everything up into steps so I understand what I'm doing, and then when I feel more comfortable with the problem, I might write everything out on one line. Whatever helps you un...