Search found 90 matches

by kim 2I
Fri Feb 21, 2020 9:09 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt Bridge
Replies: 4
Views: 26

Re: Salt Bridge

Since the salt bridge helps balance the ions on both sides of the solution, the solution of the anode will probably become overly postive whereas the cathode's solution will become overly negative. I think with the solution unbalanced, the transfer of electrons on the wire will most likely stop and ...
by kim 2I
Fri Feb 21, 2020 9:04 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell diagrams
Replies: 1
Views: 12

Re: Cell diagrams

If the metal placed in the solutions are labeled then you could probably tell which metal will gain the electrons and which one will lose them. For example, if we know that the metals placed in the solutions are Zinc and Copper, we can figure out that Cu2+ has a greater pull for the electrons and kn...
by kim 2I
Fri Feb 21, 2020 8:59 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt bridge
Replies: 1
Views: 10

Re: Salt bridge

Salt bridges are used to help balance out the charge in voltaic cells. As the oxidation reaction gives away the electrons from the left cell (the anode) to the right cell (the cathode), the solid metal becomes an ion that is dissolved into the solution it is placed in. Vice versa, the solution in th...
by kim 2I
Fri Feb 21, 2020 8:37 pm
Forum: Balancing Redox Reactions
Topic: oxidation
Replies: 3
Views: 25

Re: oxidation

Yes, oxidation numbers are the charges. You should be able to figure out the oxidation number for most molecules using some of the rules based on the groups on the periodic table. Other rules such as molecules in their elemental state having the oxidation number of 0 and oxygen having the oxidation ...
by kim 2I
Fri Feb 21, 2020 8:32 pm
Forum: Balancing Redox Reactions
Topic: Redox Proton Transfer
Replies: 3
Views: 14

Re: Redox Proton Transfer

I'm pretty sure we will mainly focus on electron transfers in these redox reactions. I wouldn't worry too much about the protons moving around.
by kim 2I
Sat Feb 15, 2020 12:32 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Delta S
Replies: 6
Views: 28

Re: Delta S

Delta S total = 0 for a reversible, isothermal expansion. This means that the delta S system = - delta S surroundings based off of the equation delta total = delta S system + delta S surroundings. Delta S total = 0 since the change of entropy between the system and its surroundings is equal and oppo...
by kim 2I
Sat Feb 15, 2020 12:29 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure and Moles
Replies: 7
Views: 21

Re: Pressure and Moles

Just the coefficients are counted for the number of moles. When pressure is increased, the equilibrium shifts to the side where there are less moles.
by kim 2I
Tue Feb 11, 2020 2:25 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneity
Replies: 3
Views: 13

Re: Spontaneity

An exothermic reactions is spontaneous because it results in an increase of entropy of the surroundings. If you think of the equation △Gr= △Hr-T △Sr, when △Hr is large enough and negative compared to △Sr, the Gibbs Free Energy would be negatvie and therefore making the reaction spontaneous.
by kim 2I
Tue Feb 11, 2020 2:18 am
Forum: Administrative Questions and Class Announcements
Topic: Midterm grading
Replies: 8
Views: 71

Re: Midterm grading

Usually each TA is assigned a page/problem on the midterm so that the grading on that problem would be fair and consistent.
by kim 2I
Tue Feb 11, 2020 2:16 am
Forum: Administrative Questions and Class Announcements
Topic: Memorizing acids and bases
Replies: 2
Views: 20

Re: Memorizing acids and bases

You should know the most common strong acids and bases and think of all else as being a weak acid/base. For the strong acids, you should know HCl, HNO3, H2SO4, HBr, HI, HClO4 and for the strong bases, you should know LiOH, NaOH, KOH, Ca(OH)2, Ba(OH)2, and Sr(OH)2. You probably won't be tested direct...
by kim 2I
Tue Feb 04, 2020 5:59 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 1 Distribution
Replies: 9
Views: 72

Re: Test 1 Distribution

As far as I know, Dr. Lavelle doesn't do curves on the tests, so seeing how you did in comparison to other students would be difficult. For the midterm and final, Dr. Lavelle let's us know the average class score, so you'll be able to get an idea of how well/poorly you did on those exams.
by kim 2I
Tue Feb 04, 2020 5:57 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: closed vs isolated
Replies: 14
Views: 41

Re: closed vs isolated

An example of a closed system would be and ice pack used to reduce swelling on injuries (energy can be transferred in and out of the system) and an example of an isolated system would be a thermos with hot liquid in it (no heat/energy/matter can go in and out of the system into the surroundings).
by kim 2I
Tue Feb 04, 2020 5:55 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Temperature in Second Law
Replies: 2
Views: 9

Re: Temperature in Second Law

For calculations regarding entropy, the temperature should be in K. The change in entropy is measured in joules per kelvin, so a celsius calcuation would result in a different answer.
by kim 2I
Tue Feb 04, 2020 5:52 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Big Midterm Review
Replies: 4
Views: 46

Re: Big Midterm Review

The right date and time should be 2/9 Sunday 2-5 since there was a change for conflicting midterms.
by kim 2I
Tue Feb 04, 2020 5:50 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Topics on the Midterm
Replies: 22
Views: 85

Re: Topics on the Midterm

Topics on the midterm would include everything we've learned from week 1 to the end of this week (week 5). ALl of thermodynamics should be on the test!
by kim 2I
Fri Jan 31, 2020 9:29 pm
Forum: Ideal Gases
Topic: final exam pickup
Replies: 10
Views: 88

Re: final exam pickup

Last time I went, they asked for your last chem discussion section, so make sure you remember that as well!
by kim 2I
Fri Jan 31, 2020 9:25 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Self-Test 5G.3A
Replies: 2
Views: 23

Re: Self-Test 5G.3A

That makes a lot more sense. Thank you! What's the concept behind spectator ions allowing us to "cancel" them out like that?
by kim 2I
Fri Jan 31, 2020 9:15 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Equilibrium shift by pressure
Replies: 7
Views: 29

Re: Equilibrium shift by pressure

When the volume decreases (increase in pressure), the reaction will shift to where there are less moles of gas.
When the volume increases (decrease in pressure), the reaction will shift to where there are more moles of gas.
by kim 2I
Fri Jan 31, 2020 9:09 pm
Forum: Ideal Gases
Topic: Temperature
Replies: 17
Views: 46

Re: Temperature

When referring to the change in temperature, you do not have to worry about the units (Kelvin or celsius) on the temperature. The change would be the same regardless and would not affect your calculations.
by kim 2I
Fri Jan 31, 2020 7:04 pm
Forum: Ideal Gases
Topic: pv=nrt
Replies: 9
Views: 35

Re: pv=nrt

R is Rydberg's constant so it can't have a change, but volume (V) and moles (n) can have a change since when the moles of gas changes, the volume changes as well.
by kim 2I
Tue Jan 28, 2020 2:36 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Test 2
Replies: 7
Views: 46

Re: Test 2

From what I remember, only the midterm and the final are cumulative. Test 2 should only cover what comes after the midterm, not everything before.
by kim 2I
Wed Jan 22, 2020 1:11 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5J.5 D
Replies: 5
Views: 31

Re: 5J.5 D

The reaction should be 2HD(g) --> H2(g) + D2(g). Therefore, there is an equal number of moles on each side.
by kim 2I
Wed Jan 22, 2020 1:02 am
Forum: Administrative Questions and Class Announcements
Topic: Chem 14A Final Pick-up
Replies: 1
Views: 51

Re: Chem 14A Final Pick-up

I believe you can pick them up at 3034 Young Hall.
by kim 2I
Wed Jan 22, 2020 12:58 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: suggestions
Replies: 16
Views: 64

Re: suggestions

I think Khan Academy's videos are the most helpful for me, but there are other resources such as Chemistry Libretexts.
by kim 2I
Wed Jan 22, 2020 12:56 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Calculating K
Replies: 15
Views: 57

Re: Calculating K

You should always balance your chemical reactions before doing any sort of calculations so that the molar ratios are accurate. If by unbalanced you're referring to the fact that the reaction hasn't reached equilibrium yet, then the K cannot be calculated since K represents the EQUILIBRIUM constant. ...
by kim 2I
Wed Jan 22, 2020 12:53 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solids and Liquids
Replies: 6
Views: 23

Re: Solids and Liquids

Yes. Solids and liquids stay out of the equilibrium constant.
by kim 2I
Tue Jan 14, 2020 3:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework 5g.1 B
Replies: 2
Views: 20

Re: Homework 5g.1 B

What you said about the "position" of Q being changed relative to K due to the greater concentration of products is true, but it might be better to say that Q would end up being more than K since the reaction is now going in the reverse direction (or favoring the reactants to the left).
by kim 2I
Tue Jan 14, 2020 3:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Self-Test 5G.3A
Replies: 2
Views: 23

Self-Test 5G.3A

I thought I understood how to find the equation for the equilibrium constant K, but when I saw the answer for this Self-test on page 401 in the textbook, I didn't really understand it. What is the net ionic equation for the reaction 2AgNO3(aq) + 2NaOH(aq) --> Ag2O(s) + 2NaNO3(aq) + H2O(l)?
by kim 2I
Tue Jan 14, 2020 2:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Strong Acids/Bases
Replies: 4
Views: 20

Re: Strong Acids/Bases

Since strong acids and bases dissociate completely, it allows us to find the molarities of all the components that take place in the neutralization reaction through the balanced equation.
by kim 2I
Mon Jan 13, 2020 9:29 pm
Forum: Administrative Questions and Class Announcements
Topic: Are Lectures Bruincasted?
Replies: 10
Views: 60

Re: Are Lectures Bruincasted?

Dr. Lavelle's lectures aren't Bruincasted, so even though attendance isn't required, going to lecture is the best way to learn and to get well-organized notes from his powerpoints.
by kim 2I
Mon Jan 13, 2020 9:27 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Studying tips
Replies: 10
Views: 29

Re: Studying tips

Actually doing the modules are helpful as well! Watch the videos and at the very least, take the post-assessments.
by kim 2I
Thu Jan 09, 2020 2:23 pm
Forum: Ideal Gases
Topic: K value
Replies: 14
Views: 60

Re: K value

If the K value is large (K>10^3), then it means there are more products at equilibrium and that the "equilibrium sits to the right."
If the K value is small (K<10^-3), then it means there are more reactants at equilibrium and that the "equilibrium sits to the left."
by kim 2I
Thu Jan 09, 2020 2:21 pm
Forum: Ideal Gases
Topic: Calculating K when there is multiple phases
Replies: 4
Views: 30

Re: Calculating K when there is multiple phases

When calculating K, all the components should be in the same "form/units." Therefore, the concentration of the gas would have to be calculated using the Ideal Gas Law of PV=nRT (divide by V on both sides, moles (n) over V = concentration, therefore, conc=P/RT). Finally the Kc can be calcul...
by kim 2I
Thu Jan 09, 2020 2:17 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Using the "ICE" box
Replies: 8
Views: 57

Re: Using the "ICE" box

Since the "ICE" box is related to calculations with the equilibrium constant as well, you do not include solids and liquids. The rule applies to both types of problems as it refers to the same type of reactions.
by kim 2I
Thu Jan 09, 2020 2:15 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Initial Concentrations of Reactants and Products
Replies: 2
Views: 17

Re: Initial Concentrations of Reactants and Products

The reaction will continue until the ratio is reached and will STILL continue even after equilibrium is reached. The products will go back to being reactants and vice versa at the same rate throughout.
by kim 2I
Thu Jan 09, 2020 2:10 pm
Forum: Administrative Questions and Class Announcements
Topic: 6th edition and homework problems
Replies: 3
Views: 28

Re: 6th edition and homework problems

I would recommend buying the 7th edition textbook. I have the 6th edition solutions manual and for the most part, the questions/homework problems are aligned with each other (6th and 7th edition) but there are definite changes throughout the book. If you want to make sure you get credit for your hom...
by kim 2I
Sat Dec 07, 2019 1:49 pm
Forum: Administrative Questions and Class Announcements
Topic: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]
Replies: 111
Views: 4121

Re: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]

Joanne Kang 3I wrote:For mini marshmallows 2b, why is the coordination number 4?


Oxalate is a bidentate so it would bind to the central TM in two places making the coordination 4 (2 binding spots for oxalate and 2 from the hydroxide ions).
by kim 2I
Mon Dec 02, 2019 8:39 pm
Forum: Bronsted Acids & Bases
Topic: Fundamentals J.13c
Replies: 2
Views: 21

Re: Fundamentals J.13c

CaO is considered a base because it acts as a proton acceptor. The oxygen atom in CaO binds to the hydrogen ions from the acid HI to form water, and HI is the acid because it loses its hydrogen atom. Also, since it is know that a neutralization reaction produces a salt and water, knowing that HI is ...
by kim 2I
Mon Dec 02, 2019 8:11 pm
Forum: Lewis Acids & Bases
Topic: SO3 acidic
Replies: 3
Views: 28

Re: SO3 acidic

SO3 is a non-metal oxide and non-metal oxides are known to be acidic in nature. It is a Lewis acid in that it accepts electrons, but I'm also a bit confused on how exactly this works.
by kim 2I
Mon Dec 02, 2019 8:02 pm
Forum: Bronsted Acids & Bases
Topic: how to identify
Replies: 2
Views: 35

Re: how to identify

For Bronsted acids, they can be identified from their formulas by their acidic hydrogen atom, a hydrogen atom that can be released as a proton. They are usually written as the first element for inorganic acids (ie. HCL, HNO3). For organic acids, the acidic hydrogen is usually found at the end of the...
by kim 2I
Mon Dec 02, 2019 7:43 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: J3
Replies: 2
Views: 29

Re: J3

When the litmus paper is turned pink, it shows that the solution is acidic. If the litmus paper turns blue, then the solution is basic.
by kim 2I
Mon Dec 02, 2019 7:41 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Water as Monodente
Replies: 1
Views: 18

Re: Water as Monodente

Since both of the lone pairs belong to oxygen, the TM center could only bind to the one oxygen atom. Also, since the lone pairs are on the same atom and are close together, it would be hard for water to have two binding sites that are available.
by kim 2I
Thu Nov 28, 2019 3:21 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: molecular shape
Replies: 8
Views: 47

Re: molecular shape

You should still draw the Lewis structure with the lowest formal charges since the number of bonds/lone pairs could change and therefore affect the molecular shape. However, you don't need to worry about resonance structures.
by kim 2I
Thu Nov 28, 2019 3:17 pm
Forum: Hybridization
Topic: double bonds
Replies: 7
Views: 36

Re: double bonds

Pi-bonds are formed with unhybridized p-orbitalsm, so I'm sure hydridization and double-bonds don't go together. On the other hand, sigma-bonds are usually formed with sp or sp^2 hybrid orbitals.
by kim 2I
Thu Nov 28, 2019 3:13 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Final Exam
Replies: 10
Views: 85

Re: Final Exam

Fundamentals will definitely be on the final, but probably not nearly as much as other topics and sections we have covered later in the quarter.
by kim 2I
Thu Nov 28, 2019 3:09 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Value of pH
Replies: 8
Views: 41

Re: Value of pH

Yes. It is possible to have a negative pH. In fact, it is possible to go beyond the known 0 to 14 pH scale.
by kim 2I
Thu Nov 28, 2019 3:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Test #2 handback
Replies: 11
Views: 75

Re: Test #2 handback

Yes, if your discussion is on Friday, you'll only have two days before the final to really review it. However, I'm sure if you email your TA, there could be a way to meet up and receive it earlier if you really need it beforehand.
by kim 2I
Mon Nov 18, 2019 6:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: resonance structures in molecular structures
Replies: 4
Views: 18

Re: resonance structures in molecular structures

Yep. It doesn't matter. In an example in the textbook, only one of the resonance structures of the carbonate ion was used to figure out what the resulting shape of the molecule is.
by kim 2I
Mon Nov 18, 2019 6:31 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: London dispersion
Replies: 4
Views: 29

Re: London dispersion

London dispersion forces are present in between all molecules, despite the fact that those molecules are nonpolar or polar.
by kim 2I
Mon Nov 18, 2019 6:26 pm
Forum: Hybridization
Topic: hybridization
Replies: 4
Views: 26

Re: hybridization

Hybridization further explains the VSEPR model by assuming the mixing of atomic orbitals to help understand why the some bonds have equal lengths when the valence electrons may not be in the same energy level.
by kim 2I
Mon Nov 18, 2019 6:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AXE formula
Replies: 9
Views: 44

Re: AXE formula

A is the central atom. I'm pretty sure it can't have subscripts since there can only be one central atom when we're talking about molecular shape.
by kim 2I
Mon Nov 18, 2019 6:15 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2 Length
Replies: 9
Views: 68

Re: Test 2 Length

Mandeep Garcha 3C wrote:Just to make sure, hybridization is not on the test right?


Yep. There will be no hybridization on Test 2. That will only be on the final.
by kim 2I
Sun Nov 17, 2019 1:46 am
Forum: General Science Questions
Topic: Test 2 Review
Replies: 8
Views: 96

Re: Test 2 Review

I'm pretty sure that the topics on test 2 will cover: -VSEPR -dipole moments and shape (non-polar/polar) -identifying intermolecular interations -lone pairs and the reason for their locations -sigma and pi bonds Dr. Lavelle also said that whatever we cover in the Monday lecture will also be on the t...
by kim 2I
Tue Nov 12, 2019 2:05 pm
Forum: Quantum Numbers and The H-Atom
Topic: Finding orbitals without given ml quantum number
Replies: 2
Views: 33

Re: Finding orbitals without given ml quantum number

I'm pretty sure the number of orbitals is based on the orbital angular momentum # (l) so for part a), the orbital associated with l=1 is the p-orbital. 2p has three orbitals (since ml= -1, 0, +1).
by kim 2I
Tue Nov 12, 2019 2:00 pm
Forum: Administrative Questions and Class Announcements
Topic: Extra Credit?
Replies: 6
Views: 80

Re: Extra Credit?

I don't think Test 2 topics have been confirmed by any of the TA's nor by Dr. Lavelle just yet. I'm assuming it would cover the rest of Outline 3 (what wasn't on the midterm) and then Outline 4 (Molecular Shape and Structure). Essentially, it should cover everything we go over in lectures that were ...
by kim 2I
Tue Nov 12, 2019 1:58 pm
Forum: Administrative Questions and Class Announcements
Topic: Extra Credit?
Replies: 6
Views: 80

Re: Extra Credit?

From rereading the syllabus, Dr. Lavelle doesn't seem to have any extra credit. Your final grade should be based on the weekly homework, the two tests, the weekly chemistry community, the midterm, and the final. I would just focus on getting all the points you can from these catergories!
by kim 2I
Tue Nov 12, 2019 1:52 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Grades
Replies: 3
Views: 47

Re: Midterm Grades

I don't think Dr. Lavelle will use lecture time to go over the questions on the midterms since we have Test 2 coming up soon. Someone's TA said that the TA's will be handing out the midterms on Wednesday after the lecture.
by kim 2I
Mon Nov 11, 2019 3:44 pm
Forum: Dipole Moments
Topic: Dipoles
Replies: 3
Views: 20

Re: Dipoles

All molecules have dipole forces. However in class, we will most likely only focus on the electric dipole moment (a partial positive charge next to an equal but opposite partial negatvie charge) that are formed by two atoms in a polar covalent bond.
by kim 2I
Mon Nov 11, 2019 12:18 am
Forum: Ionic & Covalent Bonds
Topic: Bond Strength
Replies: 8
Views: 46

Re: Bond Strength

Ionic bonds are stronger because there is a greater electronegativity difference between the two atoms (greater than 2.0). Also, while covalent bonds share electrons, ionic bonds are formed by the mutual attraction from both of the oppositely charged ions.
by kim 2I
Tue Nov 05, 2019 1:40 pm
Forum: Administrative Questions and Class Announcements
Topic: Discussion on Wednesday 11/6
Replies: 2
Views: 23

Re: Discussion on Wednesday 11/6

You still have discussions on 11/6 Wednesday. The only thing cancelled is lecture.
by kim 2I
Tue Nov 05, 2019 1:38 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: +/- speed
Replies: 3
Views: 46

Re: +/- speed

Another way to think about it is to actually subtract and add 5.0 m/s to the given 5.00 m/s. So then the range would be from 0.00 m/s to 10/00 m/s. Therefore, the deltaV would be 10.00 m/s. There is an error in the solutions manual! (Delta V is NOT 5.00 m/s). Make sure you check the link on the chem...
by kim 2I
Tue Nov 05, 2019 1:34 pm
Forum: Photoelectric Effect
Topic: max and min frequency
Replies: 1
Views: 30

Re: max and min frequency

You're right about the kinetic energy being 0. Since you are looking for the minimum frequency needed for the photoejection of an election, there wouldn't be (excess energy) kinetic energy for the ejected eletron. However, the work function would be set equal to hV in order to find the frequency.
by kim 2I
Tue Nov 05, 2019 1:28 pm
Forum: Administrative Questions and Class Announcements
Topic: Class Wed 11/6
Replies: 3
Views: 33

Re: Class Wed 11/6

I'm in the 2:00 pm lecture and Dr. Lavelle mentioned that there is no class that day. Since you're in one of the earlier lecture, he probably forgot to let your lecture know.
by kim 2I
Tue Nov 05, 2019 1:26 pm
Forum: Lewis Structures
Topic: Midterm
Replies: 3
Views: 36

Re: Midterm

Hybridization should be on Test 2, but not on the midterm!
by kim 2I
Mon Oct 28, 2019 10:15 pm
Forum: Ionic & Covalent Bonds
Topic: When is the midterm?
Replies: 5
Views: 48

Re: When is the midterm?

Dr. Lavelle said that he will keep us posted on the location. In terms of the date, he said there could be possible changes if he is unable to reserve a large enough room for all of us.
by kim 2I
Mon Oct 28, 2019 10:14 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Drawing Lewis Structures
Replies: 5
Views: 56

Re: Drawing Lewis Structures

Usually beyond period 3, there are lewis structure exceptions but Boron (in period 2) can also have only 6 electrons bonded to it.
by kim 2I
Mon Oct 28, 2019 10:10 pm
Forum: Ionic & Covalent Bonds
Topic: grading
Replies: 5
Views: 65

Re: grading

Another thing to be aware of is that homework grades are out of 50 points and should be updated weekly by your TA, so don't worry if it seems like full credit was not received.
by kim 2I
Mon Oct 28, 2019 10:06 pm
Forum: Trends in The Periodic Table
Topic: electronegativity table
Replies: 5
Views: 38

Re: electronegativity table

The basic periodic trends would not be provided for us on the tests, but just knowing that electronegativity increases as the elements are closer to the upper right-hand corner of the table should be enough.
by kim 2I
Mon Oct 28, 2019 10:04 pm
Forum: Lewis Structures
Topic: Drawing Lewis Structures
Replies: 4
Views: 40

Re: Drawing Lewis Structures

I don't think it would necessarily be considered wrong, but having a lower formal charge means greater stability, so drawing the Lewis Structure accordingly would be the best answer. Probably if the test specifically asks for the Lewis Structure with the lowest formal charge, then drawing out each o...
by kim 2I
Mon Oct 28, 2019 10:00 pm
Forum: Ionic & Covalent Bonds
Topic: How to count valence electrons with the d block
Replies: 4
Views: 27

Re: How to count valence electrons with the d block

Valence electrons in the d block are usually determined by their group number, or the number of electrons in their valence shell. In general, the transitional metals have 2 valence electrons.
by kim 2I
Mon Oct 21, 2019 8:14 pm
Forum: Photoelectric Effect
Topic: Intensity of Light
Replies: 4
Views: 34

Re: Intensity of Light

It is important to consider light as photon packets of energy where a single photon interacts with a single electron. Therefore, each individual photon must have enough energy to remove each electron. Increasing the intensity only increased the number of photons that are hitting the surface of the m...
by kim 2I
Mon Oct 21, 2019 8:06 pm
Forum: Quantum Numbers and The H-Atom
Topic: Spin Quantum Number
Replies: 4
Views: 34

Re: Spin Quantum Number

The spin magnetic quantum number is important because it describes the direction in which the electron spins. There are only two spin states that can be represented with an up or down arrow. A +1/2 is indicated with an up arrow, while -1/2 is indicated with a down arrow. The arrow pointing up can be...
by kim 2I
Mon Oct 21, 2019 7:55 pm
Forum: Photoelectric Effect
Topic: Module Assessment Question
Replies: 2
Views: 35

Re: Module Assessment Question

The correct answer in this case is E=hv since the question is solely asking about the energy of the light and its frequency. Since the question has nothing to do with the energy required to remove an electron from the metal, the only equation you would focus on is the equation of the incoming light ...
by kim 2I
Mon Oct 21, 2019 7:48 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 6
Views: 47

Re: Electron Affinity

Electron affinity of an element is the energy released when an electron is added to a gas-phase atom. In terms of the periodic table, the highest electron affinities can be found toward the right side of the periodic table (especially the upper right near oxygen, sulfur, and the halogens).
by kim 2I
Mon Oct 21, 2019 7:44 pm
Forum: Trends in The Periodic Table
Topic: Atomic Radius
Replies: 3
Views: 29

Re: Atomic Radius

An atomic radius is defined as half the distance between the centers of neighboring atoms. This inclues both ionic and covalent radii as well. A covalent radius is specifically referring to two atoms joined by a chemical bond while an ionic radius refers to the distance between neighboring ions in a...
by kim 2I
Thu Oct 17, 2019 3:46 pm
Forum: Quantum Numbers and The H-Atom
Topic: Ryberg's Constant
Replies: 7
Views: 71

Re: Ryberg's Constant

I would rely more on what Dr. Lavelle has used in class/has provided for us on the constants sheet (R = 3.28984 × 10^15 Hz or 1/s). The Rydberg's constant on Google has a different unit (1/m) and would possibly interfere with the calculations Dr. Lavelle has taught us.
by kim 2I
Thu Oct 17, 2019 3:35 pm
Forum: Photoelectric Effect
Topic: Unit of measurements for E=hv
Replies: 6
Views: 43

Re: Unit of measurements for E=hv

The equation E=hv has the basic units of Joules, but if you think back to the photoelectric effect and the incoming light, the units also refer to the amount of energy per photon. Keeping this in the back of your mind will help you make any conversions that are necessary to figure out how many photo...
by kim 2I
Thu Oct 17, 2019 3:31 pm
Forum: DeBroglie Equation
Topic: DeBroglie Equation Use
Replies: 5
Views: 30

Re: DeBroglie Equation Use

De Brogile's wave equation can be used for any particle with momentum that has wave-like properties with a wavelength. The equation wavelength=h(planck's constant)/(momentum, or the particle's mass times speed) is usually used to find the wavelength of a traveling particle or electron.
by kim 2I
Thu Oct 17, 2019 3:25 pm
Forum: Properties of Light
Topic: EM Spectrum
Replies: 3
Views: 37

Re: EM Spectrum

I don't think it's necessary to memorize every specific wavelength and its regions for the exams, but I would recommend knowing just in general that infrared radiation has the longest wavelengths and that UV radiation has the shortest wavelengths. Also, since Lavelle mentioned that visible light is ...
by kim 2I
Thu Oct 17, 2019 3:21 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisengberg Uncertainty Equation Meaning
Replies: 7
Views: 38

Re: Heisengberg Uncertainty Equation Meaning

The Heisenberg uncertainty principle states that if the location of a particle is known with an uncertainty (delta X), then the momentum of the particle (p) can be also known within the uncertainty of delta p. The equation is usually used to find the minimum uncertainty in the speed (delta v) or the...
by kim 2I
Tue Oct 08, 2019 5:48 pm
Forum: Significant Figures
Topic: Do we use molar mass ?
Replies: 8
Views: 67

Re: Do we use molar mass ?

Are you referring to the molar mass of a compound that is given to you in the problem, or are you referring to the molar masses you use for calculations off the periodic table? If it's the molar mass of a compound that is given in the problem, then I would think you'd take its sig figs into account ...
by kim 2I
Tue Oct 08, 2019 5:42 pm
Forum: Empirical & Molecular Formulas
Topic: Formula Units
Replies: 10
Views: 103

Re: Formula Units

From what I know, formula units can be interchangably used with the number of molecules or atoms, so using Avogadro's number should work for any question asking for a compound's formula units. Something to keep in mind is that formula units usually refer to ionic compounds while molecules refer to m...
by kim 2I
Tue Oct 08, 2019 5:30 pm
Forum: Limiting Reactant Calculations
Topic: Test 1
Replies: 11
Views: 162

Re: Test 1

For extra practice, you could do the examples that are embedded in the readings of the fundamental chapters. However, the listed problems on Outline 1 should be sufficient to prepare you for the test. My TA said that there will be around 7 calculation-based problems for us to answer, so concepts mig...
by kim 2I
Mon Oct 07, 2019 6:02 pm
Forum: Significant Figures
Topic: Homework
Replies: 4
Views: 59

Re: Homework

For week 2, Lavelle gives us the option to complete 5 homework problems from Outline 1 (Fundamentals) or from Outline 2 (The Quantum World). Since the quiz is on Fundamentals/Review material, he told us that doing 5 different homework problems from Outline 1 is acceptable to assist us in studying. H...
by kim 2I
Mon Oct 07, 2019 5:55 pm
Forum: Molarity, Solutions, Dilutions
Topic: Dilutions
Replies: 3
Views: 50

Re: Dilutions

By definition, molarity is the moles of solute divided by the total volume of the solution in liters, so on the test, converting all mL to L before any calculation would be the right thing to do. If the problem gives the a volume in mL, then it would be okay to convert the volume answer found in L b...
by kim 2I
Tue Oct 01, 2019 8:39 pm
Forum: Empirical & Molecular Formulas
Topic: Rounding [ENDORSED]
Replies: 12
Views: 135

Re: Rounding [ENDORSED]

Another thing about rounding at the end of your calculation is that is your last digit is 5, make sure you round to the nearest even number. For example: If you need only 2 sig figs and your answer is 1.35, then your answer would be 1.4. If you had 1.65, then your answer would be 1.6. *Remember that...
by kim 2I
Tue Oct 01, 2019 8:26 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Question on E17c
Replies: 2
Views: 29

Re: Question on E17c

Yep! The answer you got is correct since you do the same calculations for both Fe and Ru. You divide 7.36 x 10^27 atoms of Fe (or in this, Ru as well) by avogadro's number in order to convert the given number of atoms into moles.
by kim 2I
Tue Oct 01, 2019 4:42 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Balancing Equations [ENDORSED]
Replies: 25
Views: 507

Re: Balancing Equations [ENDORSED]

An easy way for me to determine what number to multiple a decimal by to get a whole number is to divide 1 by the decimal. For example: If there are 2.5 mols of C, do 1/0.5 = 2. You should multiply the 2.5 mols by 2 to get a whole number (5). If it's a more difficult value, maybe like 2.125 mols of ...
by kim 2I
Tue Oct 01, 2019 4:33 pm
Forum: Significant Figures
Topic: Sig Figs for Tests/Quizzes
Replies: 7
Views: 82

Re: Sig Figs for Tests/Quizzes

It's probably best to not worry about sig figs until the end of all of your calculations. Since you'd want the most accurate answer at the end, it's better to have as many decimal places when using the calculated values to find your answer. It'd be unnecessary to worry about sig figs through each st...
by kim 2I
Tue Oct 01, 2019 4:26 pm
Forum: SI Units, Unit Conversions
Topic: formula units [ENDORSED]
Replies: 69
Views: 23252

Re: formula units [ENDORSED]

Usually answers should be written in the same unit as the unit presented in the question. Since the unit difference was only a conversion (L to mL), I think both answers would be acceptable as long as the numerical value is correct.

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