Search found 69 matches

by Hannah Lee 2F
Thu Jan 16, 2020 1:45 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Autoprotolysis
Replies: 3
Views: 17

Re: Autoprotolysis

https://upload.wikimedia.org/wikipedia/commons/thumb/6/6a/Autoprotolyse_eau.svg/330px-Autoprotolyse_eau.svg.png The autoprotolysis of water can be used to link the concentrations of H3O+ and OH- in an aqueous solution via the autoprotolysis constant, Kw. Because Kw is essentially an equilibrium con...
by Hannah Lee 2F
Wed Jan 15, 2020 7:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5.39
Replies: 2
Views: 14

Re: 5.39

I was also confused about this! It was most likely a typo in either the solutions manual or textbook, but I just went with the value in the solutions manual; I don't think we should worry too much about it as long as we know how to do the problem.
by Hannah Lee 2F
Wed Jan 15, 2020 6:50 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: HW 5J.5 part C
Replies: 3
Views: 11

Re: HW 5J.5 part C

The equation for (c) is as follows: 4NH3(g)+ 5O2(g) -> 4NO (g) + 6H2O(g) There are 9 moles of gas on the reactant side and 10 moles of gas on the reactant side. Compression implies that pressure (and thus concentration) increases while volume decreases. To counteract this increase in pressure/concen...
by Hannah Lee 2F
Wed Jan 15, 2020 4:41 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ice table/Ph of aqueous solutions
Replies: 2
Views: 10

Re: Ice table/Ph of aqueous solutions

Yes, I think the test will cover that as it is similar to the ICE box problems we did in class.
by Hannah Lee 2F
Wed Jan 15, 2020 4:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Significant figures for acid and base calculations
Replies: 3
Views: 9

Significant figures for acid and base calculations

When considering sig figs for acid/base calculations, do you leave it to the very end to maintain accuracy or cut off digits for sig figs as we go? For instance, for an ICE box problem, if the initial concentration was 6.69 mmol/500mL = 0.01338, would you keep it as 0.01338 or use sig figs which mak...
by Hannah Lee 2F
Sun Jan 12, 2020 5:40 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 5I.13 part c
Replies: 2
Views: 15

5I.13 part c

(c) Use your results from parts (a) and (b) to determine which is thermodynamically more stable relative to its atoms at 1000. K, Cl2 or F2.

Can someone please explain this?
by Hannah Lee 2F
Sun Jan 12, 2020 5:38 pm
Forum: Ideal Gases
Topic: PV = nRT Confusion
Replies: 4
Views: 28

Re: PV = nRT Confusion

PV = nRT is the ideal gas law, where P = pressure, V = volume, n = number of moles, R = ideal gas constant, and T = temperature in K. In the context of this unit, we can use it to convert between partial pressures and molar concentrations by rearranging the equation as follows: P = (n/v)RT = (concen...
by Hannah Lee 2F
Tue Jan 07, 2020 10:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.9
Replies: 3
Views: 51

Re: 5G.9

I agree! The equilibrium constant can be defined in terms of either Kp or Kc. You look at the values given to you to determine whether you will be calculating Kp or Kc - for instance, if the problem gives you moles and volumes, you will probably be using Kc, but if the problem gave you partial press...
by Hannah Lee 2F
Tue Jan 07, 2020 8:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G 9
Replies: 1
Views: 44

Re: 5G 9

(a) The amount of O2 @ eq will be different in the containers. Because container 2 has a higher amount of initial reactant (0.50 mol O3), it will subsequently have a higher amount of product (mol O2) at equilibrium. This is because K must remain constant across both containers, so if the rxn starts ...
by Hannah Lee 2F
Tue Jan 07, 2020 4:45 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.1(d)
Replies: 3
Views: 34

5G.1(d)

State whether the following statements are true or false. If false, explain why. (d) If one starts with higher concentrations of reactants, the equilibrium concentrations of the products will be larger. The answer is true - can someone please explain this? How does higher initial [R] indicate larger...
by Hannah Lee 2F
Mon Jan 06, 2020 9:41 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Module: Equilibrium Part 3 Question 17
Replies: 3
Views: 31

Module: Equilibrium Part 3 Question 17

17. If the initial amounts of CO and H2O were both 0.100 M, what will be the amounts of each reactant and product at equilibrium for the following reaction? Keq = 23.2 at 600K CO (g) + H2O (g) ⇌ CO2 (g) + H2 (g) After using ICE, for my quadratic equation, I solved it from: x^2 / (0.100 - x)^2 = 23.2...
by Hannah Lee 2F
Sat Dec 07, 2019 4:33 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: 6C.19
Replies: 3
Views: 41

Re: 6C.19

You would need to be given the pKa or Ka values to make sure, so if this was given on an exam, you would be provided with that information.
by Hannah Lee 2F
Sat Dec 07, 2019 4:33 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Why is NO2- monodentate?
Replies: 1
Views: 15

Why is NO2- monodentate?

Why can't NO2- also be bidentate and donate the e- pairs from its adjacent O atoms, similar to CO32- (which can be mono- or bi-dentate)?
by Hannah Lee 2F
Fri Dec 06, 2019 3:18 am
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: 6C.21b
Replies: 3
Views: 30

Re: 6C.21b

If you draw out the Lewis structure, the main difference between the two groups is that acetic acid has a methyl group (CH3) where formic acid only has H. Thus, CH3COOH has an e- donating group, CH3, that destabilizes the negative charge of the resulting anion by contributing e- density. This means ...
by Hannah Lee 2F
Fri Dec 06, 2019 3:12 am
Forum: Bronsted Acids & Bases
Topic: Amphiprotic vs amphoteric
Replies: 3
Views: 23

Amphiprotic vs amphoteric

What's the difference between the two terms? Are they normally used interchangeably?
by Hannah Lee 2F
Fri Dec 06, 2019 3:10 am
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: 6C.19
Replies: 3
Views: 41

Re: 6C.19

BrO- would be the stronger base because it is the conjugate base of a weak acid, HBrO. A weak parent acid always indicates a strong conjugate base that must be a relatively good proton acceptor, which can relatively easily form HBrO molecules when added to water in the rxn: BrO- + H2O --> HBrO + OH-...
by Hannah Lee 2F
Thu Dec 05, 2019 8:07 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: help with 6B.9
Replies: 2
Views: 25

Re: help with 6B.9

I also kept on getting answers different from the solutions manual, so the manual itself may be incorrect. It's not on Dr. Lavelle's list of 7th Ed Solution Manual errors though, so I'm not sure. I used the relationship pH = -log[H+] and [H+] x [OH-] = 1.0 x 10^-14 to get the following answers for (...
by Hannah Lee 2F
Wed Dec 04, 2019 3:16 pm
Forum: Properties & Structures of Inorganic & Organic Bases
Topic: Bronsted vs Arrhenius Base: J.1(c) and (e)
Replies: 3
Views: 40

Re: Bronsted vs Arrhenius Base: J.1(c) and (e)

Thank you! It makes sense now :)

And an Arrhenius base is a species that produces hydroxides (OH-) in water. It is restrictive because it does not account for species that produce OH- in solutions other than water, so we normally go with the Bronsted definition.
by Hannah Lee 2F
Tue Dec 03, 2019 10:30 pm
Forum: Properties & Structures of Inorganic & Organic Bases
Topic: Bronsted vs Arrhenius Base: J.1(c) and (e)
Replies: 3
Views: 40

Bronsted vs Arrhenius Base: J.1(c) and (e)

Identify each compound as either a Brønsted acid or a Brønsted base: (c) KOH; (e) Ca(OH)2. It is clear that both KOH and Ca(OH)2 are bases since they are metal hydroxides. However, to align with the Bronsted definition, how would KOH and Ca(OH)2 accept a proton? Do we have to conform to just the Bro...
by Hannah Lee 2F
Tue Dec 03, 2019 4:28 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Difference between chelating ligand and polydentate ligand
Replies: 4
Views: 57

Difference between chelating ligand and polydentate ligand

Are all complexes with a polydentate ligand examples of chelation? Are all complexes that include a polydentate ligand considered chelating complexes? Is any ligand that is not monodentate an example of chelation, or is it restricted to complexes with a large coordination number, like EDTA? Similarl...
by Hannah Lee 2F
Sun Dec 01, 2019 10:29 pm
Forum: Naming
Topic: Non-anionic ligands
Replies: 2
Views: 29

Non-anionic ligands

Can ligands be positively charged? If so, how would you name them?
by Hannah Lee 2F
Sun Dec 01, 2019 10:28 pm
Forum: Naming
Topic: How to name iron in a TM complex?
Replies: 1
Views: 21

How to name iron in a TM complex?

How would you name iron in a TM complex? Would it just be iron (Roman numeral), or is there another unique name for it?
by Hannah Lee 2F
Sun Dec 01, 2019 10:24 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: D-block
Replies: 4
Views: 45

Re: D-block

D-block elements can experience multiple oxidation states since they may have incomplete inner subshells that do not restrict valence e- to the outer shell. They are also a good source of e- due to their ability to form expanded octets, and they can form complexes via coordinate covalent bonds with ...
by Hannah Lee 2F
Mon Nov 25, 2019 2:33 am
Forum: Biological Examples
Topic: Porphyrin Ligand Drawing
Replies: 1
Views: 42

Re: Porphyrin Ligand Drawing

It represents the protein binding to the heme complex, forming myoglobin. This ultimately forms an octahedral complex when Fe binds 1 O2, which is why myoglobin contributes to the transport of O2 in muscle cells.
by Hannah Lee 2F
Mon Nov 25, 2019 12:45 am
Forum: Hybridization
Topic: Are terminal atoms hybridized?
Replies: 2
Views: 24

Are terminal atoms hybridized?

Are terminal atoms hybridized? When can we tell if they are?

For instance, in 2.45, the O double-bonded to the central C atom has sp2 hybridization. How about in the case of CS2 in 2.59(b), would the S atoms be hybridized to sp2 as well? How about terminal atoms that are halogens?
by Hannah Lee 2F
Sun Nov 24, 2019 4:50 pm
Forum: Hybridization
Topic: Concept
Replies: 3
Views: 30

Re: Concept

Hybridization results from orbital overlap and stabilizes the molecule by lowering the overall energy. It allows orbitals to "blend" into new hybrid orbitals that align with the pairing of electrons in forming covalent bonds according to the VSEPR theory.
by Hannah Lee 2F
Sun Nov 24, 2019 4:46 pm
Forum: Hybridization
Topic: dsp3 vs sp3d
Replies: 4
Views: 33

dsp3 vs sp3d

What's the difference between writing hybridization with the d before sp vs the d after sp? I know both of them mean basically the same thing, but can someone explain to me why Dr. Lavelle chooses to write it so that d comes before sp?
by Hannah Lee 2F
Sun Nov 24, 2019 4:44 pm
Forum: Hybridization
Topic: Sigma and Pi bonds
Replies: 13
Views: 57

Re: Sigma and Pi bonds

I agree! The triple bond will be drawn the same way - 1 sigma, 2 pi bonds, and just label them on the Lewis structure.
by Hannah Lee 2F
Sun Nov 24, 2019 4:40 pm
Forum: Hybridization
Topic: Hybrid orbitals
Replies: 5
Views: 23

Re: Hybrid orbitals

To determine hybrid orbitals, you count the number of electron densities around the central atom. That should align with the hybridization of the central atom, since the number of hybrid orbitals is always the same as the number of atomic orbitals used in their construction. For instance, PCl5 uses ...
by Hannah Lee 2F
Wed Nov 20, 2019 11:39 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: Ordering Intermolecular Forces Clarification
Replies: 2
Views: 26

Ordering Intermolecular Forces Clarification

In the notes, it says that dipole-dipole, dipole-induced dipole, and induced dipole-induced dipole all typically have around -2 kJ/mol of E. However, I thought that the order of IMF strength went from dipole-dipole > dipole-induced dipole > induced dipole-induced dipole? Can someone clarify this for...
by Hannah Lee 2F
Sun Nov 17, 2019 8:22 pm
Forum: Electronegativity
Topic: More electronegative?
Replies: 3
Views: 30

Re: More electronegative?

O has only one e- less than F, giving it a high nuclear charge and a greater ability to attract e-. On the other hand, Cl is below F with an entirely new shell of valence e- added to it, which decreases the nuclear charge experienced by outer e- and decreases its ability to attract e- compared to th...
by Hannah Lee 2F
Sun Nov 17, 2019 8:17 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles for molecules w/ multiple central atoms
Replies: 1
Views: 20

Re: Bond Angles for molecules w/ multiple central atoms

When there is more than 1 central atom, the bonding about each atom is treated independently, so the same rules for bond angles would apply. For instance, for ethylene (CH2=CH2), there are 3 regions of high e- density around each central atom, with 3 bonding pairs and 0 lone pairs. Therefore, the e-...
by Hannah Lee 2F
Sun Nov 17, 2019 8:13 pm
Forum: Administrative Questions and Class Announcements
Topic: test 2
Replies: 2
Views: 32

Re: test 2

I'm pretty sure it will be around the same length since we are allowed the same amount of time, but you can double-check with your TA. Dr. Lavelle might also mention the length of the test in tomorrow's lecture.
by Hannah Lee 2F
Sun Nov 17, 2019 8:09 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar and Nonpolar
Replies: 6
Views: 47

Re: Polar and Nonpolar

2E.25 Draw the Lewis structure and predict whether each of the following molecules is polar or nonpolar: (a) CH2Cl2; (b) CCl4; (c) CS2; (d) SF4. How can I tell if molecules are polar or nonpolar? To determine whether a molecule is polar or nonpolar, you would determine its molecular shape based on ...
by Hannah Lee 2F
Sat Nov 16, 2019 11:21 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Axial and Equatorial
Replies: 2
Views: 37

Axial and Equatorial

What are "axial" and "equatorial" atoms? What do we need to know about them when determining molecular shaping using VSEPR?
by Hannah Lee 2F
Thu Nov 14, 2019 9:56 am
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.11d)
Replies: 2
Views: 21

2E.11d)

Use Lewis structures and the VSEPR model to give the VSEPR formula for each of the following species and predict its shape: (d) xenon trioxide. When drawing the Lewis structure for XeO3, does it have to be structured in a tetrahedral arrangement (other than the 1 lone pair)? I thought that the prese...
by Hannah Lee 2F
Mon Nov 11, 2019 7:26 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: 3F.5 Part c
Replies: 2
Views: 49

Re: 3F.5 Part c

In Problem 3F.5 part c, it says that CHI3 has stronger intermolecular forces than CHF3 and will have a higher melting point. This difference is attributed to the difference in strength of induced dipole-induced dipole forces between the two molecules. I understand why CHI3 has stronger London force...
by Hannah Lee 2F
Mon Nov 11, 2019 7:20 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: 3F.19
Replies: 1
Views: 20

Re: 3F.19

(a) The melting point of solid xenon is -112 C and that of solid argon is 2189 C. (b) The vapor pressure of diethyl ether (C2H5OC2H5) is greater than that of water. (c) The boiling point of pentane, CH3(CH2)3CH3, is 36.1 C, whereas that of 2,2-dimethylpropane (also known as neopentane), C(CH3)4, is...
by Hannah Lee 2F
Mon Nov 11, 2019 6:42 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: Hydrogen bonding
Replies: 5
Views: 31

Re: Hydrogen bonding

Adding onto the previous answer, both the electronegativity and small sizes of N, O, and F allow it to bond to H. You can think of H-bonding as a stronger version of dipole-dipole bonds.
by Hannah Lee 2F
Tue Nov 05, 2019 10:00 pm
Forum: Properties of Light
Topic: Using de Broglie's wavelength to find frequency
Replies: 1
Views: 29

Using de Broglie's wavelength to find frequency

Is it possible to use de Broglie's equation to find frequency, considering we can't use the equations for EM radiation? Do we have to know how to do that for the midterm?
by Hannah Lee 2F
Tue Nov 05, 2019 9:54 pm
Forum: Properties of Light
Topic: When do you use light equations?
Replies: 3
Views: 58

Re: When do you use light equations?

Whenever you're dealing with photons and electromagnetic radiation, you use E = hv, c = lambda x frequency, etc. However, when you're dealing with particles WITH mass (like electrons, protons, neutrons, etc), then you'd use de Broglie's equation, λ = h / p --> λ = h / mv. You can't use E = hv or c =...
by Hannah Lee 2F
Sun Nov 03, 2019 11:15 pm
Forum: Trends in The Periodic Table
Topic: Dino Nugget Mini review
Replies: 3
Views: 64

Re: Dino Nugget Mini review

Polarizing power refers to the ability of an atom/ion to "distort" the electron cloud of another atom/ion. In ionic bonds, this can create a covalent character, since the positive charge on the cations will pull the electrons from the anion into the bonding region. Because of this, higher ...
by Hannah Lee 2F
Sun Nov 03, 2019 8:00 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarity vs Polarizability
Replies: 3
Views: 42

Polarity vs Polarizability

What is the relationship, if any, between polarity and polarizability? Can polarizability contribute to nonpolar covalent bonds?
by Hannah Lee 2F
Sat Nov 02, 2019 7:50 pm
Forum: Resonance Structures
Topic: HW 2C.3
Replies: 1
Views: 32

HW 2C.3

For part (a) of 2C.3, it asks: "Draw the Lewis structure, including typical contributions to the resonance structure (where appropriate, allow for the possibility of octet expansion, including double bonds in different positions), for (a) periodate ion." Then for the resonance structures, ...
by Hannah Lee 2F
Sat Nov 02, 2019 5:49 pm
Forum: Octet Exceptions
Topic: Cl as an expanded octet
Replies: 3
Views: 28

Cl as an expanded octet

How can Cl form an expanded octet? And can someone please provide an example of a compound in which Cl acts as an expanded octet?
by Hannah Lee 2F
Sat Nov 02, 2019 5:39 pm
Forum: Formal Charge and Oxidation Numbers
Topic: CNS- formal charge
Replies: 2
Views: 23

Re: CNS- formal charge

I don't recall seeing that structure in my notes, but assuming that carbon is the central atom, the most electronegative atom should carry the negative formal charge. In this case, N should have the negative charge since it's more electronegative than sulfur. So the most stable structure would go: S...
by Hannah Lee 2F
Sat Nov 02, 2019 4:59 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: How do we draw the electron configurations for transition metal atoms?
Replies: 2
Views: 27

Re: How do we draw the electron configurations for transition metal atoms?

The electron configuration of Sb is [Kr]4d105s25p3. Because valence electrons are used in bonding, they are always in the highest-energy, outermost orbitals. In the case of Sb, this would be n = 5, and we would exclude the completely filled 4d-subshell (which would not participate in bonding). 5s2 a...
by Hannah Lee 2F
Sat Nov 02, 2019 4:45 pm
Forum: Lewis Structures
Topic: Determining most stable Lewis structure
Replies: 5
Views: 41

Determining most stable Lewis structure

When determining the most stable structure, does symmetry or formal charge come first? For instance, for question 2B15) which asked to draw ClNO2, I mistakenly drew the Cl attached to the oxygen instead of the nitrogen, making an L-shape, because I thought that each atom's formal charge had to amoun...
by Hannah Lee 2F
Fri Oct 25, 2019 11:26 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 4
Views: 29

Re: Formal Charge

You can find an example of a question dealing with formal charge in Example 2B.4 (page 85)! There's also a short section devoted to formal charge that starts on page 84.
by Hannah Lee 2F
Fri Oct 25, 2019 11:21 pm
Forum: Ionic & Covalent Bonds
Topic: Electronegativity
Replies: 4
Views: 38

Re: Electronegativity

Electronegativity refers to the tendency of an atom to attract e-, while ionization energy refers to the amount of energy it takes to remove an e- in the gas phase. Both follow similar trends in the periodic table, increasing from left to right across a period as effective nuclear charge increases a...
by Hannah Lee 2F
Fri Oct 25, 2019 11:09 pm
Forum: Photoelectric Effect
Topic: 1.31
Replies: 1
Views: 19

Re: 1.31

The lithium photomultiplier basically means that upon absorption of a photon of light to the surface of the lithium cell, electrons are emitted. This implies that we are dealing with the photoelectric effect, and the laser the agents choose has to discharge enough energy/emit a high-enough frequency...
by Hannah Lee 2F
Fri Oct 25, 2019 10:49 pm
Forum: Trends in The Periodic Table
Topic: HW: 1.13
Replies: 2
Views: 25

Re: HW: 1.13

Ionization energies usually increase on going from left to right across the periodic table. The ionization energy for oxygen, however, is lower than that of either nitrogen or fluorine. Explain this anomaly. If you look at the filling of e- in the p-subshells for O, N, and F: - N has three unpaired...
by Hannah Lee 2F
Fri Oct 25, 2019 1:10 am
Forum: Photoelectric Effect
Topic: HW Question 1.31
Replies: 1
Views: 45

HW Question 1.31

In a recent suspense film, two secret agents must penetrate a criminal's stronghold monitored by a lithium photomultiplier cell that is continually bathed in light from a laser. If the beam of light is broken, an alarm sounds. The agents want to use a hand- held laser to illuminate the cell while t...
by Hannah Lee 2F
Fri Oct 18, 2019 7:47 pm
Forum: Properties of Light
Topic: 1D.13
Replies: 1
Views: 25

Re: 1D.13

b) How many values of ml are allowed for an electron in the 6d subshell? We know that a 6d subshell equates with a principal quantum number n = 6 and angular momentum quantum number l = 2. Since the allowed values of m l range between -l and l, the total possible values are -2, -1, 0, 1, 2, which m...
by Hannah Lee 2F
Fri Oct 18, 2019 7:42 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Noble planes
Replies: 1
Views: 25

Re: Noble planes

What does it mean for something to have a noble plane and why do the p and d orbitals have it? Nodal planes are essentially areas with zero probability of electron density (in other words, the probability of finding an electron is 0). Nodal planes are present between the lobes of the p and d orbita...
by Hannah Lee 2F
Thu Oct 17, 2019 8:41 pm
Forum: Photoelectric Effect
Topic: E = pc
Replies: 3
Views: 36

E = pc

When would we have to use the E = pc equation that is listed in the equations sheet and mentioned briefly in our notes? Can someone clarify for me in what problems/situations feature this equation? I don't think I've ever encountered it before in the homework.
by Hannah Lee 2F
Wed Oct 16, 2019 8:43 pm
Forum: Properties of Light
Topic: HW 1B15
Replies: 1
Views: 47

Re: HW 1B15

Hi, guys! Does anyone know why you can't use the c=λv equation to derive the wavelength for part (c)? In the solutions manual, they add together the energy put in (hv) to the energy that is leaving (1/2mv^2) and then use those to find the wavelength, but I'm confused as to why that is a necessary s...
by Hannah Lee 2F
Wed Oct 16, 2019 5:07 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbital and Wavefunction Clarification
Replies: 2
Views: 38

Orbital and Wavefunction Clarification

I'm having trouble conceptually visualizing what an orbital is and how it relates to the wavefunction. Can someone help explain what exactly an orbital is, and how it relates to Schrodinger's wave function equation? To what extent do we need to know the wave function equation on upcoming exams?
by Hannah Lee 2F
Sat Oct 12, 2019 11:20 pm
Forum: DeBroglie Equation
Topic: De Broglie Lecture Question
Replies: 2
Views: 24

Re: De Broglie Lecture Question

The mass of an electron is me = 9.109383 x 10-31 kg, so that's where the number came from in the answer. It's also on our constants and equations sheets so we don't have to memorize it.

Hopefully this helped!
by Hannah Lee 2F
Sat Oct 12, 2019 9:19 pm
Forum: Properties of Light
Topic: 1A.3
Replies: 4
Views: 34

Re: 1A.3

(a) The speed of the radiation decreases. Speed of radiation is constant and is described as speed of light, where c = 3.00 x 10^8 m/s. (b) The wavelength of the radiation decreases. Wavelength would actually increase, because frequency and wavelength share an inversely proportional relationship, as...
by Hannah Lee 2F
Sat Oct 12, 2019 8:32 pm
Forum: Properties of Light
Topic: Help with Homework 1A.15
Replies: 3
Views: 32

Re: Help with Homework 1A.15

In the ultraviolet spectrum of atomic hydrogen, a line is observed at 102.6 nm. Determine the values of n for the initial and final energy levels of the electron during the emission of energy that leads to this spectral line. First, you would find the change in energy (ΔE). The equations we know ar...
by Hannah Lee 2F
Fri Oct 11, 2019 1:56 pm
Forum: Properties of Light
Topic: HW Problem A15
Replies: 2
Views: 30

HW Problem A15

1A.15) In the ultraviolet spectrum of atomic hydrogen, a line is observed at 102.6 nm. Determine the values of n for the initial and final energy levels of the electron during the emission of energy that leads to this spectral line. Is there any way to solve this without the Rydberg equation, using...
by Hannah Lee 2F
Fri Oct 11, 2019 11:56 am
Forum: Properties of Light
Topic: Equations for quantum mechanics
Replies: 3
Views: 32

Re: Equations for quantum mechanics

c = λv or λ = c / v describes the inverse relationship between wavelength and frequency, with c = speed of light, and is used to describe electromagnetic radiation. You would use this equation when dealing with a photon of light or particles without mass. E = hv describes the energy of a photon, wit...
by Hannah Lee 2F
Fri Oct 04, 2019 12:10 am
Forum: Molarity, Solutions, Dilutions
Topic: G 13
Replies: 3
Views: 46

Re: G 13

To prepare a fertilizer solution, a florist dilutes 1L of 2M NH4NO3 by adding 3L of Water. The florist then adds 100mL of the diluted solution to each plant. How many moles of nitrogen atoms will each plant receive? For this equation, you would need to use M1V1 = M2V2 in order to first find the fin...
by Hannah Lee 2F
Thu Oct 03, 2019 12:46 am
Forum: Limiting Reactant Calculations
Topic: M 19
Replies: 2
Views: 33

Re: M 19

After finding the mass of C, H, and N, add them all together to find the total mass. Then subtract that total mass from 0.376, which is the mass of caffeine burned. So, roughly: 0.376 - (0.1861 + 0.01947 + 0.1100) = 0.06042 g. This amount left over should be the mass of O, which you can then convert...
by Hannah Lee 2F
Wed Oct 02, 2019 9:34 pm
Forum: Empirical & Molecular Formulas
Topic: Fundamentals Section M Homework M19
Replies: 3
Views: 53

Re: Fundamentals Section M Homework M19

In this problem, they don't give you the mass of each element in a compound, but rather the masses of the compounds that were produced as a result of the burning of caffeine. Because of this, you have to take an extra step and "break down" the compounds into their component elements in ord...
by Hannah Lee 2F
Wed Oct 02, 2019 8:51 pm
Forum: Molarity, Solutions, Dilutions
Topic: Unit Conversion for Molarity/Dilution
Replies: 3
Views: 27

Re: Unit Conversion for Molarity/Dilution

It's easier if you convert it to L first because it's typically the standard unit you measure volume in chemistry, unless they ask you to put it in mL.
by Hannah Lee 2F
Wed Oct 02, 2019 5:31 pm
Forum: Molarity, Solutions, Dilutions
Topic: HW problem G21
Replies: 3
Views: 40

Re: HW problem G21

I agree with Mansi! The concentration of ions in a solution usually depend on the mole ratios between the dissolved substance in the solution and the cations and/or anions it forms — in this case, the question is asking for K+ and S 2- . After dividing the mass of each compound by the molar mass to ...
by Hannah Lee 2F
Mon Sep 30, 2019 5:54 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 129
Views: 2864

Re: Advice from a Medical Student - Part II [ENDORSED]

Thank you so much for sharing your experience! We appreciate the time you're taking to answer our questions. When did you first decide you wanted to go to medical school? Was being pre-med something you've always known, or something you decided as the quarters went on in UCLA?

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