Search found 96 matches

by AnnaYan_1l
Sun Mar 17, 2019 12:01 am
Forum: Balancing Redox Reactions
Topic: calculating standard cell potential
Replies: 5
Views: 208

Re: calculating standard cell potential

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!
by AnnaYan_1l
Sat Mar 16, 2019 11:57 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: state functions
Replies: 2
Views: 168

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...
by AnnaYan_1l
Sat Mar 16, 2019 9:44 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts
Replies: 9
Views: 284

Re: Catalysts

Catalysts reduce the activation energy between reactants to products, meaning it takes less energy to make the forward reaction occur
by AnnaYan_1l
Sat Mar 16, 2019 10:53 am
Forum: Student Social/Study Group
Topic: Lyndon's Review Sess
Replies: 6
Views: 348

Re: Lyndon's Review Sess

Hi, it was just upload last night!
by AnnaYan_1l
Tue Mar 12, 2019 11:57 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Test 2
Replies: 3
Views: 97

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...
by AnnaYan_1l
Sun Mar 10, 2019 1:56 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Ratio of Rate constants = equilibrium constant, K
Replies: 1
Views: 47

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
by AnnaYan_1l
Sun Mar 10, 2019 1:54 pm
Forum: Zero Order Reactions
Topic: How can you tell a reaction zero order?
Replies: 4
Views: 97

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
by AnnaYan_1l
Sun Mar 10, 2019 1:53 pm
Forum: Van't Hoff Equation
Topic: Overview
Replies: 8
Views: 320

Re: Overview

The Van't Hoff Equation can be used to calculate K at different temperatures, if you know the standard change in enthalpy.
by AnnaYan_1l
Sun Mar 03, 2019 10:28 pm
Forum: Balancing Redox Reactions
Topic: Short hand notation
Replies: 8
Views: 176

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)
by AnnaYan_1l
Sun Mar 03, 2019 10:14 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Standard cell potential
Replies: 3
Views: 88

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
by AnnaYan_1l
Sun Mar 03, 2019 10:08 pm
Forum: Balancing Redox Reactions
Topic: Adding H+ and H2O
Replies: 13
Views: 260

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!
by AnnaYan_1l
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: 54

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...
by AnnaYan_1l
Mon Feb 25, 2019 12:14 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: What is E?
Replies: 4
Views: 77

Re: What is E?

I think another property of standard conditions is 25 degrees C
by AnnaYan_1l
Mon Feb 25, 2019 12:12 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Free Energy is a state function?
Replies: 5
Views: 86

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.
by AnnaYan_1l
Mon Feb 25, 2019 12:09 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Spontaneous?
Replies: 13
Views: 202

Re: Spontaneous?

When delta G is negative, it is spontaneous
by AnnaYan_1l
Wed Feb 13, 2019 1:04 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy at 0 K
Replies: 4
Views: 259

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.
by AnnaYan_1l
Sun Feb 10, 2019 8:27 pm
Forum: Administrative Questions and Class Announcements
Topic: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
Replies: 49
Views: 3096

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!!!
by AnnaYan_1l
Sun Feb 10, 2019 6:02 pm
Forum: Administrative Questions and Class Announcements
Topic: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
Replies: 49
Views: 3096

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!
by AnnaYan_1l
Sun Feb 10, 2019 2:18 pm
Forum: Calculating Work of Expansion
Topic: Using Derivative/Integral Equations
Replies: 5
Views: 111

Re: Using Derivative/Integral Equations

I think the integrals are just used to understand why the equations were were given in class make sense!
by AnnaYan_1l
Sun Feb 10, 2019 1:16 pm
Forum: Administrative Questions and Class Announcements
Topic: UA Sessions Today
Replies: 2
Views: 95

UA Sessions Today

Are UA sessions in Covel still happening today (February 10)? Thanks!
by AnnaYan_1l
Sun Feb 10, 2019 1:09 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Value of Variable Kb
Replies: 4
Views: 98

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!
by AnnaYan_1l
Sun Feb 10, 2019 1:05 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy values
Replies: 3
Views: 76

Re: Enthalpy values

I think these values will be given!
by AnnaYan_1l
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: 182

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!
by AnnaYan_1l
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: 43

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...
by AnnaYan_1l
Sun Feb 03, 2019 11:42 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Internal energy
Replies: 5
Views: 128

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 ...
by AnnaYan_1l
Sun Feb 03, 2019 11:39 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Bomb Calorimeter
Replies: 5
Views: 121

Re: Bomb Calorimeter

According to the notes, a bomb calorimeter is an isolated system because nothing is exchanged with the surroundings!
by AnnaYan_1l
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: 56

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

:)
by AnnaYan_1l
Mon Jan 28, 2019 5:58 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Neutralization reactions
Replies: 6
Views: 94

Re: Neutralization reactions

I believe they are always exothermic because the acids and bases are breaking bonds.
by AnnaYan_1l
Mon Jan 28, 2019 4:50 pm
Forum: Phase Changes & Related Calculations
Topic: Heat Capacity
Replies: 10
Views: 170

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).
by AnnaYan_1l
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: 246

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!!!
by AnnaYan_1l
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: 246

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...
by AnnaYan_1l
Sun Jan 20, 2019 10:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Shortcut method (finding concentration change)
Replies: 5
Views: 99

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 ...
by AnnaYan_1l
Sun Jan 20, 2019 10:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pressure Notation
Replies: 5
Views: 115

Re: Pressure Notation

I think Kp is only used when the reaction only includes gases, so I would default to Kc
by AnnaYan_1l
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: 144

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! (:
by AnnaYan_1l
Sat Jan 12, 2019 11:06 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: defining Q
Replies: 6
Views: 119

Re: defining Q

Yes, the reaction continues until Q = K and equilibrium is reached.
by AnnaYan_1l
Sat Jan 12, 2019 11:05 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Phases and Reaction Quotient (HW)
Replies: 3
Views: 84

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.
by AnnaYan_1l
Wed Jan 09, 2019 11:53 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc and Qc
Replies: 4
Views: 2089

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...
by AnnaYan_1l
Thu Jun 14, 2018 12:58 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: How Lone Pairs Affect Bond Angles?
Replies: 1
Views: 2594

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...
by AnnaYan_1l
Thu Jun 14, 2018 12:49 pm
Forum: Properties of Electrons
Topic: threshold energy
Replies: 2
Views: 289

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.
by AnnaYan_1l
Wed Jun 13, 2018 12:54 pm
Forum: Molarity, Solutions, Dilutions
Topic: Midterm 1 Q!C
Replies: 2
Views: 189

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})...
by AnnaYan_1l
Tue Jun 12, 2018 1:15 pm
Forum: Dipole Moments
Topic: Dipole Moment understanding
Replies: 5
Views: 366

Re: Dipole Moment understanding

If the dipole moments do not cancel out, that would lead to a polar molecule.
by AnnaYan_1l
Mon Jun 11, 2018 7:06 pm
Forum: Administrative Questions and Class Announcements
Topic: Review Sessions Finals Week - Hedrick Hall? [ENDORSED]
Replies: 6
Views: 408

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!
by AnnaYan_1l
Sun Jun 10, 2018 5:24 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Helpful Chart
Replies: 18
Views: 551

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...
by AnnaYan_1l
Sat Jun 09, 2018 1:08 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate
Replies: 5
Views: 296

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.
by AnnaYan_1l
Sat Jun 09, 2018 1:06 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical to molecular
Replies: 3
Views: 415

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...
by AnnaYan_1l
Sat Jun 09, 2018 12:56 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Difference
Replies: 1
Views: 177

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)
by AnnaYan_1l
Thu May 31, 2018 11:33 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Define Ligands?
Replies: 10
Views: 332

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...
by AnnaYan_1l
Thu May 31, 2018 11:23 am
Forum: Determining Molecular Shape (VSEPR)
Topic: HW 4.9
Replies: 10
Views: 577

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...
by AnnaYan_1l
Thu May 31, 2018 11:04 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Homework 4.15 B
Replies: 1
Views: 121

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)....
by AnnaYan_1l
Thu May 31, 2018 10:50 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Helpful Chart
Replies: 18
Views: 551

Re: Helpful Chart

This helps so much, thank you!!! I was super worried about memorizing them.
by AnnaYan_1l
Sat May 26, 2018 9:24 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shapes with different types of bonds
Replies: 3
Views: 146

Re: Shapes with different types of bonds

Yes, bond angles would change, because of electron repulsion :)
by AnnaYan_1l
Sat May 26, 2018 9:14 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizing power
Replies: 10
Views: 572

Re: Polarizing power

Anions become highly polarized, while cations have polarizing power.
by AnnaYan_1l
Thu May 24, 2018 11:20 pm
Forum: Dipole Moments
Topic: Dipole vs. london forces
Replies: 1
Views: 113

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.
by AnnaYan_1l
Mon May 21, 2018 10:26 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizing Power
Replies: 2
Views: 370

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...
by AnnaYan_1l
Sat May 19, 2018 9:16 pm
Forum: Ionic & Covalent Bonds
Topic: Octet rule
Replies: 17
Views: 568

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.
by AnnaYan_1l
Sat May 19, 2018 9:08 pm
Forum: Ionic & Covalent Bonds
Topic: Radicals [ENDORSED]
Replies: 5
Views: 220

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...
by AnnaYan_1l
Sat May 19, 2018 9:05 pm
Forum: Lewis Structures
Topic: Exception to Lewis Structure?
Replies: 4
Views: 164

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.
by AnnaYan_1l
Sun May 13, 2018 1:59 pm
Forum: Ionic & Covalent Bonds
Topic: Lewis Structure vs Resonance Structure
Replies: 6
Views: 176

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...
by AnnaYan_1l
Tue May 08, 2018 1:11 pm
Forum: Limiting Reactant Calculations
Topic: Mass of Reactant/Product
Replies: 4
Views: 324

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.
by AnnaYan_1l
Tue May 08, 2018 1:05 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Test 2 Q.4
Replies: 3
Views: 250

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...
by AnnaYan_1l
Tue May 08, 2018 1:01 pm
Forum: Trends in The Periodic Table
Topic: question confused
Replies: 2
Views: 194

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 ...
by AnnaYan_1l
Mon May 07, 2018 10:26 pm
Forum: Trends in The Periodic Table
Topic: Difference between Periodic trends [ENDORSED]
Replies: 4
Views: 279

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...
by AnnaYan_1l
Sun May 06, 2018 7:10 pm
Forum: Molarity, Solutions, Dilutions
Topic: Test 1. Q 2
Replies: 3
Views: 330

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...
by AnnaYan_1l
Sun May 06, 2018 1:28 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: HW 2.39
Replies: 2
Views: 110

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...
by AnnaYan_1l
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: 362

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...
by AnnaYan_1l
Sun May 06, 2018 1:14 pm
Forum: Molarity, Solutions, Dilutions
Topic: Test 1. Q 2
Replies: 3
Views: 330

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...
by AnnaYan_1l
Wed May 02, 2018 12:59 pm
Forum: *Shrodinger Equation
Topic: How are orbitals corresponding to m sub l numbers
Replies: 2
Views: 171

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...
by AnnaYan_1l
Tue May 01, 2018 2:00 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 2.17
Replies: 4
Views: 137

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...
by AnnaYan_1l
Tue May 01, 2018 1:41 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: In class problem [ENDORSED]
Replies: 6
Views: 350

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...
by AnnaYan_1l
Thu Apr 26, 2018 8:17 pm
Forum: Properties of Electrons
Topic: electron mass
Replies: 15
Views: 598

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.
by AnnaYan_1l
Thu Apr 26, 2018 8:15 pm
Forum: DeBroglie Equation
Topic: DeBroglie
Replies: 7
Views: 271

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)
by AnnaYan_1l
Thu Apr 26, 2018 8:12 pm
Forum: Properties of Light
Topic: test 2
Replies: 18
Views: 618

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...
by AnnaYan_1l
Fri Apr 20, 2018 7:58 pm
Forum: Photoelectric Effect
Topic: Plastic vs Metal [ENDORSED]
Replies: 3
Views: 166

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!
by AnnaYan_1l
Fri Apr 20, 2018 11:41 am
Forum: Photoelectric Effect
Topic: Energy levels
Replies: 7
Views: 281

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...
by AnnaYan_1l
Fri Apr 20, 2018 11:31 am
Forum: Balancing Chemical Reactions
Topic: Balancing Equation
Replies: 7
Views: 548

Re: Balancing Equation

I really like Komal's method! I tried to do something similar on Test 1.
by AnnaYan_1l
Fri Apr 20, 2018 11:29 am
Forum: Properties of Electrons
Topic: Geiger -Marsden experiment [ENDORSED]
Replies: 5
Views: 210

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!
by AnnaYan_1l
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: 89

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.
by AnnaYan_1l
Fri Apr 20, 2018 11:17 am
Forum: Naming
Topic: Naming and Polyatomic Ions
Replies: 6
Views: 463

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 (:
by AnnaYan_1l
Fri Apr 20, 2018 11:15 am
Forum: Significant Figures
Topic: Basic Sig Figs
Replies: 13
Views: 1014

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 ...
by AnnaYan_1l
Fri Apr 20, 2018 11:13 am
Forum: General Science Questions
Topic: Notation
Replies: 3
Views: 359

Re: Notation

There is no difference between notations, so you can use either notation when writing out your problems!
by AnnaYan_1l
Fri Apr 20, 2018 11:12 am
Forum: Photoelectric Effect
Topic: Threshold Energy [ENDORSED]
Replies: 12
Views: 410

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...
by AnnaYan_1l
Fri Apr 20, 2018 11:03 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg Equation & Test 2
Replies: 4
Views: 207

Re: Heisenberg Equation & Test 2

The Heisenberg Equation will not be tested in Test 2 (:
by AnnaYan_1l
Fri Apr 20, 2018 11:00 am
Forum: Properties of Light
Topic: Memorizing Wavelengths [ENDORSED]
Replies: 4
Views: 186

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!
by AnnaYan_1l
Fri Apr 20, 2018 10:55 am
Forum: Properties of Light
Topic: Homework 1.9
Replies: 2
Views: 133

Re: Homework 1.9

Hi, yes! You just refer to the electromagnetic spectrum to see where the wavelengths you found lie.
by AnnaYan_1l
Thu Apr 19, 2018 12:04 am
Forum: Einstein Equation
Topic: When to use E=hc/wavelength
Replies: 6
Views: 367

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!
by AnnaYan_1l
Sun Apr 15, 2018 7:24 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg Formula, 1.13 HW
Replies: 4
Views: 163

Re: Rydberg Formula, 1.13 HW

Yes, I believe this would be the best way to look at it.
by AnnaYan_1l
Sat Apr 14, 2018 2:15 pm
Forum: Properties of Electrons
Topic: History of experiments on the model of atom
Replies: 7
Views: 344

Re: History of experiments on the model of atom

I do not think this will be tested. :)
by AnnaYan_1l
Sat Apr 14, 2018 2:03 pm
Forum: Student Social/Study Group
Topic: Study Group
Replies: 10
Views: 660

Re: Study Group

I'm super interested in this! Could you make a groupme?
by AnnaYan_1l
Thu Apr 12, 2018 9:38 pm
Forum: Properties of Light
Topic: Units of speed of light [ENDORSED]
Replies: 2
Views: 118

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!
by AnnaYan_1l
Wed Apr 11, 2018 8:26 pm
Forum: Properties of Light
Topic: Clarification on Hz
Replies: 5
Views: 177

Re: Clarification on Hz

Yes, 1 Hz = 1 s-1 (one cycle per second).
by AnnaYan_1l
Mon Apr 09, 2018 8:58 pm
Forum: Limiting Reactant Calculations
Topic: M19 - Combustion Analysis
Replies: 2
Views: 138

Re: M19 - Combustion Analysis

Thank you!!! That makes so much sense now.
by AnnaYan_1l
Mon Apr 09, 2018 3:14 pm
Forum: Limiting Reactant Calculations
Topic: M19 - Combustion Analysis
Replies: 2
Views: 138

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 ...
by AnnaYan_1l
Sun Apr 08, 2018 8:50 pm
Forum: SI Units, Unit Conversions
Topic: Sig figures
Replies: 9
Views: 331

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...
by AnnaYan_1l
Sun Apr 08, 2018 10:59 am
Forum: Molarity, Solutions, Dilutions
Topic: G.5 Part A) Molarity [ENDORSED]
Replies: 9
Views: 375

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...
by AnnaYan_1l
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: 643

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...

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