Search found 106 matches

by Emma Healy 2J
Sun Feb 28, 2021 5:07 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Metalloids as Conductors
Replies: 1
Views: 5

Re: Metalloids as Conductors

Hi Arezo! I'm wondering this same thing! And are all S block metals conductors or only specific ones? Also, are there any nonmetals that could act as a conductor?
by Emma Healy 2J
Sun Feb 28, 2021 1:11 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Week 7/8 Sapling #12
Replies: 9
Views: 33

Re: Week 7/8 Sapling #12

Hi Samantha! Your work looks correct! I think you just need to convert J to kJ at the end and provide the answer in kJ on Sapling.
by Emma Healy 2J
Sun Feb 28, 2021 1:08 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Sapling HW Week 7/8 #18
Replies: 2
Views: 28

Re: Sapling HW Week 7/8 #18

Hi Adam! I started by writing the unbalanced equation with the reactants on the left side and products on the right. The question states that "rust is caused by iron reacting with oxygen gas in the presence of water to create an oxide layer." So the reactants would be Fe + O2 + H2O. Then i...
by Emma Healy 2J
Sun Feb 28, 2021 1:07 pm
Forum: Balancing Redox Reactions
Topic: Textbook Problem 6K.5 part d
Replies: 1
Views: 11

Textbook Problem 6K.5 part d

Hi! Could someone please walk me through how to solve the textbook problem 6K.5 for part d? It is in basic solution, and I couldn't figure out how to balance the oxygens and hydrogens. Thank you in advance! The question is: Balance each of the following skeletal equations by using oxidation and redu...
by Emma Healy 2J
Sun Feb 28, 2021 1:00 pm
Forum: Balancing Redox Reactions
Topic: Sapling Week 7/8 #18
Replies: 3
Views: 19

Re: Sapling Week 7/8 #18

Hi Scot! I started by writing the unbalanced equation with the reactants on the left side and products on the right. The question states that "rust is caused by iron reacting with oxygen gas in the presence of water to create an oxide layer." So the reactants would be Fe + O2 + H2O. Then i...
by Emma Healy 2J
Sun Feb 28, 2021 12:51 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Eo of Concentration Cell
Replies: 3
Views: 12

Re: Eo of Concentration Cell

Hi Sasha! My understanding is that cell potential E is is sensitive to the concentrations of reactants and products. A galvanic cell typically has different species on both sides, which would have different concentrations. A concentration cell typically has the same species on both sides. If both sp...
by Emma Healy 2J
Sun Feb 21, 2021 11:19 pm
Forum: Administrative Questions and Class Announcements
Topic: Classes for Biochem Majors
Replies: 6
Views: 35

Re: Classes for Biochem Majors

Hi Ethan! I am not a Biochem major, but I know that Wesley Wu, one of the UAs, is also a Biochem major, and he took the 30 series. You could send him or a counselor an email or other students may have an answer for you. Good luck!
by Emma Healy 2J
Sun Feb 21, 2021 11:15 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: fun way to remember anode and cathode
Replies: 16
Views: 60

Re: fun way to remember anode and cathode

Hi Eric! Thank you for sharing this! I've heard of RED CAT before but haven't heard of AN OX, and so I'll definitely use this to help me to remember that anodes participate in oxidation.
by Emma Healy 2J
Sun Feb 21, 2021 11:01 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt Bridge
Replies: 30
Views: 71

Re: Salt Bridge

Hi! A salt bridge helps to maintain electrical neutrality and charge balance with the positive and negatives in the Galvanic cell. It allows ions to pass through to help keep the cell running and neutral and keep the charges flowing within the cell so that they don't build up.
by Emma Healy 2J
Thu Feb 18, 2021 12:31 am
Forum: General Science Questions
Topic: No Lavelle Chem 14C?
Replies: 40
Views: 194

Re: No Lavelle Chem 14C?

Aw I'm gonna miss not having Lavelle and Chem Community and the UAs for 14 C : (
by Emma Healy 2J
Wed Feb 17, 2021 10:15 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Textbook 4.43
Replies: 1
Views: 14

Textbook 4.43

Hi! Problem 4.43 in the textbook says if 120 mL of H2 gas at SATP combines with.... Since it says SATP, I thought that meant that it would be at 25 degrees Celsius, but the solutions manual says STP and used 0 degrees Celsius. I'm wondering what the temperature should be?
by Emma Healy 2J
Sun Feb 14, 2021 11:14 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: isochoric / isometric
Replies: 9
Views: 19

Re: isochoric / isometric

Hi! Isochoric means that delta V = 0 and that volume is constant. Isobaric means that delta P = 0 and that pressure is constant. Isothermal means that delta T= 0 and that temperature is constant. I think that isometric is when you have 2 or more compounds that are composed of the same number and spe...
by Emma Healy 2J
Sun Feb 14, 2021 11:04 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Cv vs Cp
Replies: 5
Views: 22

Re: Cv vs Cp

Hi! I'm wondering the same thing and think that this is a great question.
by Emma Healy 2J
Sun Feb 14, 2021 11:03 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: 4H.1 part d
Replies: 3
Views: 22

4H.1 part d

Hi! In the textbook question 4H.1 part d, it asks about which substance has the higher molar entropy at 298 K: 1.0 mol of Ar (g) at 1.00 atm or 1.0 mol Ar (g) at 2.00 atm? I had originally thought that 1.0 mol Ar (g) at 2.00 atm would have a higher molar entropy since the pressure is greater because...
by Emma Healy 2J
Sun Feb 14, 2021 10:55 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 4F.1 part a
Replies: 2
Views: 11

4F.1 part a

Hi! On question 4F.1 part a in the textbook, the answer key shows that delta S = - q / T because heat is leaving the body and releasing energy, but then it showed that the answer was positive. I thought that the answer was supposed to be - 0.341 J/(K * s), but I'm wondering if I'm missing something?
by Emma Healy 2J
Sat Feb 13, 2021 10:31 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D.9
Replies: 1
Views: 19

4D.9

Hi! In the textbook question 4D.9, it asks us about finding the enthalpy density, and I thought it was just a matter of dimensional analysis and converting units, but the answer key used the enthalpies of formation to find the overall enthalpy of the reaction. Were we supposed to get those values in...
by Emma Healy 2J
Sun Feb 07, 2021 10:31 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8812
Views: 1496162

Re: Post All Chemistry Jokes Here

Did you hear that oxygen and potassium went on a date?

Yeah it went OK!
by Emma Healy 2J
Sun Feb 07, 2021 10:25 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Which q equation to use
Replies: 3
Views: 14

Re: Which q equation to use

Hi! I think the first equation you listed may be for a calorimeter and not a molecule, and the mass of the calorimeter is not taken into consideration.
by Emma Healy 2J
Sun Feb 07, 2021 10:22 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Atoms, Linear, Non- Linear Molecules?
Replies: 9
Views: 27

Re: Atoms, Linear, Non- Linear Molecules?

Hi! I think CO2 would be a linear molecule based on the Lewis structure and that Carbon, the central atom, has no lone pairs, which is a factor of its linear shape.

For my Sapling homework, I was given Ar (g) and just assumed that it was an atom.
by Emma Healy 2J
Sun Feb 07, 2021 10:19 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: work and heat (positive or negative?)
Replies: 3
Views: 17

Re: work and heat (positive or negative?)

Hi! What has helped me is thinking about what happens when we work out and how we expend energy when we exercise and do work, thus releasing energy. If you think about the example from lecture with pumping bike tires, it takes a lot of energy to pump them up, and so we release that energy into the s...
by Emma Healy 2J
Sun Feb 07, 2021 12:46 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Positive vs Negative Heat Capacities
Replies: 3
Views: 10

Positive vs Negative Heat Capacities

Hi! Is it possible to have a negative heat capacity? Or does it always have to be a positive value?
by Emma Healy 2J
Sun Jan 31, 2021 11:44 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8812
Views: 1496162

Re: Post All Chemistry Jokes Here

What's a kidney's favorite instrument?


The organ!
by Emma Healy 2J
Sun Jan 31, 2021 11:43 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8812
Views: 1496162

Re: Post All Chemistry Jokes Here

Why are skeletons good at chopping trees?


Because they're lumbar-jacks!
by Emma Healy 2J
Sun Jan 31, 2021 11:42 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8812
Views: 1496162

Re: Post All Chemistry Jokes Here

Never trust an atom...
They make up everything
by Emma Healy 2J
Sun Jan 31, 2021 11:42 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8812
Views: 1496162

Re: Post All Chemistry Jokes Here

What do you call an acid with an attitude?


A mean-oh acid!
by Emma Healy 2J
Thu Jan 28, 2021 2:41 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Combustion of nitrogen for enthalpy of combustion reactions
Replies: 2
Views: 21

Combustion of nitrogen for enthalpy of combustion reactions

Hi! I was looking at enthalpy of combustion problems and am wondering if the equation for the combustion of Nitrogen is just N2 + 2 O2 --> 2 NO2 ? or would it be N2 + O2 --> 2 NO ?

Also for a reaction like CxHxOxNx + O2 → CO2 + H20 + N2
would it yield N2 or NO2?
by Emma Healy 2J
Sat Jan 23, 2021 11:37 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Table 5G2 - K vs Kc
Replies: 4
Views: 20

Table 5G2 - K vs Kc

Hi! For table 5G2 in the textbook, I'm wondering if the K without a subscript is supposed to be Kp? It is clear that the other K value that is listed is Kc.
by Emma Healy 2J
Sat Jan 23, 2021 11:34 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: standard states
Replies: 6
Views: 72

standard states

Hi! Are we supposed to know the standard states of molecules? Or just some of the most common ones? Or will they be given to us?
by Emma Healy 2J
Sat Jan 23, 2021 11:33 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp and aqueous solutions
Replies: 1
Views: 36

Kp and aqueous solutions

Hi! I know that for Kc equilibrium expressions we leave out solids and liquids, and we keep aqueous states and gases in the expression. I also know that when determining which direction a reaction will shift due to a change in pressure, we look at the amount of moles of gas on both sides and do not ...
by Emma Healy 2J
Fri Jan 22, 2021 5:33 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Method 2 and Resonance Structures
Replies: 2
Views: 23

Method 2 and Resonance Structures

Hi! When we're using method 2 or the bond enthalpies to find the overall enthalpy for the reaction, and we're looking at which bonds are breaking and forming, what should we do if we have resonance structures?
by Emma Healy 2J
Fri Jan 22, 2021 5:30 pm
Forum: Phase Changes & Related Calculations
Topic: Carbon (graphite form)
Replies: 6
Views: 42

Carbon (graphite form)

Hi! What should we know about Carbon in the graphite form?
by Emma Healy 2J
Sun Jan 17, 2021 10:00 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6E.1 Textbook problem
Replies: 1
Views: 19

Re: 6E.1 Textbook problem

Hi Jazlyn! I solved this problem the same way that you did. Since H2SO4 is a strong acid, I assumed that it would fully dissociate, and the concentration of [H30+] would be 0.15 M. The you should be able to do pH=-log(H3O+), which would be = -log(0.15)= 0.82. Dr. Lavelle also mentioned this in his l...
by Emma Healy 2J
Sun Jan 17, 2021 9:52 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pH of Salts
Replies: 1
Views: 9

Re: pH of Salts

Hi! This is a great question! I'm wondering if neutralization would occur?
by Emma Healy 2J
Sun Jan 17, 2021 9:48 pm
Forum: Calculating Work of Expansion
Topic: Sapling Week 3/4 no. 14
Replies: 4
Views: 63

Re: Sapling Week 3/4 no. 14

Hi Shana! I am not sure how to do this problem either, but Dr. Lavelle has not lectured on this topic yet, so I'm hoping that our lectures this week will help us to be able to solve it. It's not due for a little while, so it's good that we have more time to work on it.
by Emma Healy 2J
Sun Jan 17, 2021 9:45 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Week 2 #5
Replies: 1
Views: 32

Re: Sapling Week 2 #5

Hi Jaylin! I started by converting pH to pOH and then found the concentration for [OH-] using 10^(-pOH). I then assumed that the concentration of [OH-] was at equilibrium and used that concentration of [OH-] to fill out my ICE table. In the ice table here, I used [OH-] = 3.673*10-5. We just don't kn...
by Emma Healy 2J
Sun Jan 17, 2021 9:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Week 2 #5
Replies: 2
Views: 46

Re: Sapling Week 2 #5

Hi Margia! I also started by converting pH to pOH and then got a similar concentration for [OH-]. I just assumed that the concentration of [OH-] was at equilibrium and used that concentration of [OH-] to fill out my ICE table. We just don't know the initial concentration of the amine, so I used the ...
by Emma Healy 2J
Sun Jan 10, 2021 1:33 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook problem 5G.3b
Replies: 1
Views: 7

Re: Textbook problem 5G.3b

Hi! I think you're right! It seems like it should be 5 N2(g) for the products.
by Emma Healy 2J
Sun Jan 10, 2021 1:18 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Chemical Equilibrium Part 4 Post-Module Assessment #15
Replies: 2
Views: 14

Chemical Equilibrium Part 4 Post-Module Assessment #15

Hi! How many moles are there of reactants and products in this question? I was thinking that there were 6 moles of reactants and 6 moles of products, not including solids or aqueous. Unless the aqueous should be included for determining the number of moles on each side? 15. The photosynthesis reacti...
by Emma Healy 2J
Sun Jan 10, 2021 1:09 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Counting Moles
Replies: 11
Views: 67

Counting Moles

Hi! When finding the effect of increasing or decreasing partial pressure by determining how many moles are on each side of the chemical equation or how many moles there are of reactants and products, are aqueous molecules included? or just gases? For example, 2A (aq) + 1B (g) <--> 2C (g), would ther...
by Emma Healy 2J
Sat Jan 09, 2021 5:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chemical Equilibrium Part 3 Post-Module Assessment #20
Replies: 3
Views: 25

Re: Chemical Equilibrium Part 3 Post-Module Assessment #20

Okay! I tried doing that, but I still got the incorrect concentration for SO3.
by Emma Healy 2J
Sat Jan 09, 2021 5:53 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Changing K
Replies: 4
Views: 27

Changing K

Hi! So Dr. Lavelle has been talking about how temperature is the only thing that changes k but doubling the stoichiometric coefficients for a reaction will square the k value, so technically changing the temperature isn't the only way to change the k value?
by Emma Healy 2J
Fri Jan 08, 2021 10:03 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chemical Equilibrium Part 3 Post-Module Assessment #20
Replies: 3
Views: 25

Chemical Equilibrium Part 3 Post-Module Assessment #20

Hi! On the Chemical Equilibrium Part 3 Post-Module Assessment, this is problem #20: A vial of SO2 (0.522 mol.L-1) and O2 (0.633 mol.L-1) react and reach equilibrium. Calculate the equilibrium concentrations of the products and reactants given that KC = 5.66 x 10-10 for this reaction: 2 SO2 (g) + O2 ...
by Emma Healy 2J
Wed Jan 06, 2021 5:21 pm
Forum: Administrative Questions and Class Announcements
Topic: Question about sapling homework
Replies: 5
Views: 57

Re: Question about sapling homework

Hi! No, we don't lose points, and there is no penalty for using hints! If you give up on the question, it will mark the question wrong though and deduct points.
by Emma Healy 2J
Wed Dec 16, 2020 9:06 pm
Forum: Naming
Topic: Resources for Help With Naming
Replies: 2
Views: 12

Re: Resources for Help With Naming

Hi Amanda! I hope that you're doing well! I found this website to be helpful for me! I can look and see if I can find others. Naming can definitely be a challenge.

http://www.chemistry.wustl.edu/~edudev/ ... _comp.html
by Emma Healy 2J
Wed Dec 16, 2020 9:02 pm
Forum: Lewis Structures
Topic: Maximum electrons in expanded octet
Replies: 2
Views: 36

Maximum electrons in expanded octet

Hi! I'm just wondering what the maximum number of electrons would be in an expanded octet for an element like Iodine?
by Emma Healy 2J
Wed Dec 16, 2020 9:00 pm
Forum: Administrative Questions and Class Announcements
Topic: Brooke's Week 10 Workshop KEY
Replies: 1
Views: 84

Re: Brooke's Week 10 Workshop KEY

Thank you so much Brooke for positing this and for all of your time and help this quarter! I appreciate you so much and am looking forward to your sessions in 14B! Happy Holidays!
by Emma Healy 2J
Wed Dec 16, 2020 8:58 pm
Forum: Student Social/Study Group
Topic: HUGE THANK YOU to Dr. Lavelle, the UAs, TAs!
Replies: 14
Views: 322

Re: HUGE THANK YOU to Dr. Lavelle, the UAs, TAs!

Thank you so much Dr. Lavelle and to all of the TAs and UAs! I am so grateful for all of the time, help, dedication, and commitment! I appreciate you all so much and am looking forward to seeing you all in 14B! Happy Holidays! : )
by Emma Healy 2J
Wed Dec 16, 2020 8:55 pm
Forum: Administrative Questions and Class Announcements
Topic: TA Review: Acids and Bases - Kat [ENDORSED]
Replies: 1
Views: 128

Re: TA Review: Acids and Bases - Kat [ENDORSED]

Thank you so much for posting your slides! They are so helpful!
by Emma Healy 2J
Wed Dec 16, 2020 8:54 pm
Forum: Administrative Questions and Class Announcements
Topic: Chemistry Community posts after this quarter [ENDORSED]
Replies: 7
Views: 61

Re: Chemistry Community posts after this quarter [ENDORSED]

Hi! I think we can still see our posts after this quarter ends because Chemistry Community has posts from 2011 and possibly earlier until now!
by Emma Healy 2J
Sat Dec 12, 2020 10:50 pm
Forum: Hybridization
Topic: Pi Bonds and Hybrid Orbitals
Replies: 1
Views: 26

Re: Pi Bonds and Hybrid Orbitals

This is a great question! I have been wondering the same thing.
by Emma Healy 2J
Mon Dec 07, 2020 12:03 am
Forum: Biological Examples
Topic: Oxidation States
Replies: 4
Views: 36

Re: Oxidation States

For example, if you had [Fe(CN)6]^4-, you know that the overall charge is -4. CN has an oxidation state of -1 and -1x6=-6. Using algebra, x+(-6)=-4, x=2. So Fe would have to have an oxidation state of +2.
by Emma Healy 2J
Sun Dec 06, 2020 11:59 pm
Forum: Biological Examples
Topic: Oxidation States
Replies: 4
Views: 36

Re: Oxidation States

For finding oxidation states, I would look at the charges that you know and use algebra to find the oxidation state of the metal.
by Emma Healy 2J
Sun Dec 06, 2020 11:58 pm
Forum: Student Social/Study Group
Topic: 14BL
Replies: 2
Views: 13

Re: 14BL

I also enrolled in Chem 14BL and Chem 14B for next quarter and am wondering the same thing!
by Emma Healy 2J
Sun Dec 06, 2020 11:57 pm
Forum: Administrative Questions and Class Announcements
Topic: TA review sessions [ENDORSED]
Replies: 4
Views: 75

TA review sessions [ENDORSED]

I saw that each TA has 2 review sessions where they will be discussing the same topic in each. Will both sessions be the same? Will the material they discuss in each session be the same? Or will each of their 2 sessions be different?
by Emma Healy 2J
Sun Dec 06, 2020 11:55 pm
Forum: Hybridization
Topic: un-hybridized orbitals / orthogonal
Replies: 1
Views: 11

un-hybridized orbitals / orthogonal

Are un-hybridized orbitals considered orthogonal? And why or why not?
by Emma Healy 2J
Sun Dec 06, 2020 11:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: flat plane vs 3D
Replies: 2
Views: 20

flat plane vs 3D

Would a tetrahedral be considered the first 3D shape? Would molecules with 2 and 3 regions of electron density be considered flat?
by Emma Healy 2J
Sun Nov 29, 2020 11:45 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Easiest Way to Memorize Shape Names
Replies: 9
Views: 90

Re: Easiest Way to Memorize Shape Names

I think just doing a lot of practice problems is beneficial in memorizing the shapes and bond angles and becoming more familiar with the molecules. I also think that being able to visualize the 3D shape of the molecule is helpful. One of the UA's shared this website with us: http://intro.chem.okstat...
by Emma Healy 2J
Sun Nov 29, 2020 11:43 pm
Forum: Resonance Structures
Topic: Resonance Structure Confusion
Replies: 5
Views: 38

Re: Resonance Structure Confusion

An example of a resonance structure would be O3 because there is one single bond between an O and another O and one double bond between an O and another O. The electrons are delocalized and are shared in the molecule, and the single and double bonds could rotate between atoms and keep the same struc...
by Emma Healy 2J
Sun Nov 29, 2020 11:40 pm
Forum: Resonance Structures
Topic: Resonance Structure Confusion
Replies: 5
Views: 38

Re: Resonance Structure Confusion

They are not considered resonance structures because the structures and number of single, double, and triple bonds were changing for each one, and the electrons were not delocalized between the atoms.
by Emma Healy 2J
Sun Nov 29, 2020 11:35 pm
Forum: Hybridization
Topic: Determining the number of sigma and pi bonds
Replies: 8
Views: 57

Re: Determining the number of sigma and pi bonds

Yes, I counted all of the sigma bonds first for every bond and then all of the pi bonds after for the molecules.
by Emma Healy 2J
Sun Nov 29, 2020 11:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Tetrahedral molecular shape
Replies: 10
Views: 100

Re: Tetrahedral molecular shape

I would also add that if each of the bond angles were 90 degrees, then the molecule would be flat and not 3D. Since there are repulsion forces between bonding pairs of electrons and the atoms are maximizing the distance, the structure is 3D, thus making the bond angles 109.5, which is greater than 90.
by Emma Healy 2J
Sun Nov 29, 2020 11:25 pm
Forum: Sigma & Pi Bonds
Topic: Textbook Problem 2F.3
Replies: 1
Views: 11

Re: Textbook Problem 2F.3

Hi! H2S has 2 single bonds, so it has 2 sigma bonds and 0 pi bonds. SO2 has 2 double bonds, and each double bond has 1 sigma bond and 1 pi bond, so there are 2 sigma bonds and 2 pi bonds in total for SO2.
by Emma Healy 2J
Sun Nov 29, 2020 11:22 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape Names and Degrees
Replies: 4
Views: 29

Re: Shape Names and Degrees

Hi! I think we do need to memorize bond angles and make sure that we know that one of them is 109.5 degrees. I think just doing a lot of practice problems is beneficial in memorizing the shapes and bond angles and becoming more familiar with the molecules. I also think that being able to visualize t...
by Emma Healy 2J
Thu Nov 19, 2020 10:33 pm
Forum: Dipole Moments
Topic: 3F:5
Replies: 3
Views: 38

3F:5

3F.5 Suggest, giving reasons, which substance in each of the following pairs is likely to have the higher normal melting point (Lewis structures may help your arguments): CHI3 or CHF3. I thought that CHF3 would have a higher melting point because F is very electronegative and has a higher ionization...
by Emma Healy 2J
Thu Nov 19, 2020 11:43 am
Forum: Lewis Structures
Topic: Textbook Q 2.C.5
Replies: 3
Views: 27

Re: Textbook Q 2.C.5

I had this same question. I think that O is more electronegative than Cl, and so it has a higher electron pulling power and really wants the full octet. Since O is more electronegative than Cl, it can handle having the negative formal charge.
by Emma Healy 2J
Wed Nov 18, 2020 9:59 pm
Forum: Trends in The Periodic Table
Topic: Trend for effective nuclear charge
Replies: 3
Views: 37

Trend for effective nuclear charge

Is there a trend for effective nuclear charge?
by Emma Healy 2J
Tue Nov 17, 2020 11:35 pm
Forum: Bond Lengths & Energies
Topic: Energy bullet point on outline
Replies: 1
Views: 14

Energy bullet point on outline

What does this bullet mean on the outline about the quantum world? Describe the factors affecting the energy of an electron in a many-electron atom.
by Emma Healy 2J
Tue Nov 17, 2020 10:58 pm
Forum: Quantum Numbers and The H-Atom
Topic: n=6,l=5
Replies: 6
Views: 99

n=6,l=5

If n=6, would l=5 be a valid answer? I know that l can be 0,...n-1 and that l=0 corresponds to s, l=1 corresponds to p, l=2 corresponds to d, l=3 corresponds to f. Based on this, l=5 would not correspond to s, p, d, or f. So would l=5 be valid because it fits for n=6-1=5?
by Emma Healy 2J
Tue Nov 17, 2020 10:38 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodes in the d orbital
Replies: 4
Views: 52

Nodes in the d orbital

How many nodes does the d orbital have? I think the p orbital just has 1 node and the s orbital has 0 nodes.
by Emma Healy 2J
Mon Nov 16, 2020 12:00 am
Forum: Bond Lengths & Energies
Topic: Bond energy equation
Replies: 3
Views: 30

Bond energy equation

In the bond energy equation, what grows faster? The numerator or radius (denominator)?
by Emma Healy 2J
Sun Nov 15, 2020 11:59 pm
Forum: Dipole Moments
Topic: London Dispersion Forces
Replies: 8
Views: 94

London Dispersion Forces

Why do all molecules experience London Dispersion Forces?
by Emma Healy 2J
Sun Nov 15, 2020 11:56 pm
Forum: Lewis Structures
Topic: Resonance Structures
Replies: 2
Views: 9

Resonance Structures

Some molecules can have a resonance structure with one double bond, two double bonds, or three double bonds, and so do you count all of them as resonance structures even if the molecule with two or three double bonds is not as stable as the molecule with one rotating double bond?
by Emma Healy 2J
Sun Nov 15, 2020 9:45 pm
Forum: Trends in The Periodic Table
Topic: Ion Trends
Replies: 18
Views: 131

Ion Trends

What are some of the ion trends that we should know? And could someone please explain the ionic radius trend?
by Emma Healy 2J
Sun Nov 15, 2020 9:44 pm
Forum: Bond Lengths & Energies
Topic: Hydrogen Bond Length
Replies: 3
Views: 13

Hydrogen Bond Length

If two molecules have multiple Hydrogen bonds, do they all have to be the same length?
by Emma Healy 2J
Tue Nov 10, 2020 6:59 pm
Forum: Electronegativity
Topic: Electronegativity Difference for Covalent and Ionic Bonds
Replies: 6
Views: 37

Electronegativity Difference for Covalent and Ionic Bonds

So if the electronegativity difference is > 2, then there is an ionic bond like NaCl. If the electronegativity difference is < 1.5, then there would be a covalent bond (C-F). What would happen if the value falls between 1.5 and 2?
by Emma Healy 2J
Sun Nov 08, 2020 11:54 pm
Forum: Lewis Structures
Topic: Shape
Replies: 3
Views: 12

Shape

Does it matter where you put each atom when creating a Lewis structure as long as the formal charges are okay and the correct number of electrons are used?
by Emma Healy 2J
Sun Nov 08, 2020 11:52 pm
Forum: Electronegativity
Topic: Fluorine and Helium
Replies: 6
Views: 48

Fluorine and Helium

Knowing that Fluorine is the most electronegative element and that it's not in the very top right corner of the periodic table, would Helium be considered an exception to the trend since it is in the very top right corner?
by Emma Healy 2J
Sun Nov 08, 2020 11:51 pm
Forum: Electronegativity
Topic: Fluorine
Replies: 7
Views: 43

Re: Fluorine

Knowing that Fluorine is the most electronegative element and that it's not in the very top right corner of the periodic table, would Helium be considered an exception to the trend since it is in the very top right corner?
by Emma Healy 2J
Sun Nov 08, 2020 11:46 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: bigger cation and how that affects polarization
Replies: 2
Views: 27

bigger cation and how that affects polarization

If you have a bigger cation, then the charge density is lower, and it has a lower pulling ability and lower polarizing power. What does this mean about the polarizing ability? And how is it affected?
by Emma Healy 2J
Sun Nov 08, 2020 11:43 pm
Forum: Lewis Structures
Topic: expanded/smaller octets
Replies: 6
Views: 25

Re: expanded/smaller octets

Yes, I believe that only atoms with a d-orbital can have an expanded octet.
by Emma Healy 2J
Sun Nov 08, 2020 7:21 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8812
Views: 1496162

Re: Post All Chemistry Jokes Here

Are you a CATion? Because you're always so PAWsitive!
by Emma Healy 2J
Sun Nov 01, 2020 11:16 pm
Forum: SI Units, Unit Conversions
Topic: Memorizing SI Units
Replies: 14
Views: 116

Re: Memorizing SI Units

Hi Amanda! I am not sure which ones we should have memorized, and I have this same question too. I did find picometers on the formula sheet, which is given as 1 pm = 10^-12 m. I think an acronym could be really helpful if someone has one!
by Emma Healy 2J
Sun Nov 01, 2020 8:36 pm
Forum: Trends in The Periodic Table
Topic: Radius trends for elements like Carbon
Replies: 4
Views: 37

Radius trends for elements like Carbon

Would Carbon and other elements in the same column gain or lose an electron? And how does it affect its radius and the radii trends?
by Emma Healy 2J
Sun Nov 01, 2020 7:36 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: S and P orbitals and shielding
Replies: 2
Views: 13

S and P orbitals and shielding

Hi! Does the 3s orbital shield the 3p orbital? Or instead of n=3, it could be n=2 or n=1.
by Emma Healy 2J
Fri Oct 30, 2020 4:13 pm
Forum: Quantum Numbers and The H-Atom
Topic: M(l) Quantum Number
Replies: 5
Views: 55

Re: M(l) Quantum Number

Yes, okay thank you!
by Emma Healy 2J
Fri Oct 30, 2020 4:09 pm
Forum: Quantum Numbers and The H-Atom
Topic: M(l) Quantum Number
Replies: 5
Views: 55

M(l) Quantum Number

Hi! If we were looking at the 2p orbital, then n=2 and l=1, then m(l) could equal -1, 0, or 1, thus being 3 possible quantum values. If we made our own arbitrary scale, like p(x)=-1, p(y)=0, and p(z)=1, we could say that m(l) = -1 if we wanted the quantum number for p(x)? Or does that matter? I know...
by Emma Healy 2J
Tue Oct 27, 2020 11:45 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum Numbers
Replies: 3
Views: 56

Quantum Numbers

Can the first 3 quantum numbers be the same?
by Emma Healy 2J
Sun Oct 25, 2020 10:49 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg Equation
Replies: 2
Views: 29

Re: Rydberg Equation

Hi! I am wondering the same thing, but I think that n1 is n final and n2 is n initial, because it should always be final - initial.
by Emma Healy 2J
Sun Oct 25, 2020 10:46 pm
Forum: Properties of Electrons
Topic: Work Function
Replies: 3
Views: 40

Work Function

Is there a way to find work function? Or does it just need to be given?
by Emma Healy 2J
Sun Oct 25, 2020 10:44 pm
Forum: Properties of Electrons
Topic: Kinetic energy for electrons
Replies: 3
Views: 43

Kinetic energy for electrons

When would the kinetic energy be 0 for an electron when using:
KE(electron)=E(photon)- Work Function
by Emma Healy 2J
Sun Oct 25, 2020 10:37 pm
Forum: Limiting Reactant Calculations
Topic: Multi-Step Limiting Reactant
Replies: 1
Views: 26

Multi-Step Limiting Reactant

Hi! To find the limiting reactant for a multi-step reaction, would we just use the molar ratios and convert the moles from one reaction to the other? Or will each chemical equation have its own limiting reactant?
by Emma Healy 2J
Sun Oct 25, 2020 10:35 pm
Forum: Limiting Reactant Calculations
Topic: Excess reactant affecting limiting reactant
Replies: 7
Views: 105

Excess reactant affecting limiting reactant

Hi! If the excess reactant is given, does that mean there is no limiting reactant? Or if oxygen is in excess, then would the other reactant be the limiting reactant?
by Emma Healy 2J
Sun Oct 18, 2020 11:19 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student [ENDORSED]
Replies: 231
Views: 118114

Re: Advice from a Medical Student [ENDORSED]

Thank you so much for sharing all of this information! This is all so helpful! I am so grateful for all of the UAs and all of the extra resources in this class; it's pretty amazing. Best of luck in your future!
by Emma Healy 2J
Sun Oct 18, 2020 8:55 pm
Forum: Limiting Reactant Calculations
Topic: 2 Limiting Reactants
Replies: 3
Views: 25

Re: 2 Limiting Reactants

Then if the reactants are consumed at the exact same time, how would it be labeled?
by Emma Healy 2J
Sun Oct 18, 2020 8:42 pm
Forum: Limiting Reactant Calculations
Topic: 2 Limiting Reactants
Replies: 3
Views: 25

2 Limiting Reactants

Is it possible to have 2 limiting reactants in a reaction?
by Emma Healy 2J
Sun Oct 18, 2020 8:33 pm
Forum: Limiting Reactant Calculations
Topic: M5 - excess reactant
Replies: 2
Views: 38

M5 - excess reactant

For M5 in the textbook, why is BrF3 the excess reactant and not the limiting reactant?
by Emma Healy 2J
Sun Oct 18, 2020 5:00 pm
Forum: SI Units, Unit Conversions
Topic: (M1)(V1)=(M2)(V2) with L vs mL
Replies: 5
Views: 40

(M1)(V1)=(M2)(V2) with L vs mL

Hi! When I'm using the equation (M1)(V1)=(M2)(V2) and am given M1=0.2, V1=250 mL, and V2=500 mL, do I have to covert mL to Liters when solving for M2 because the units for volume will cancel?
by Emma Healy 2J
Sat Oct 17, 2020 12:58 am
Forum: Administrative Questions and Class Announcements
Topic: Exam Format
Replies: 1
Views: 27

Exam Format

Hi! So in the past, the exams have been free response, and you had the opportunity to get some points back if you did the problem correctly but miscalculated something and got an incorrect final answer? Since our exams will be multiple choice, we no longer will be able to get some points back for co...
by Emma Healy 2J
Sat Oct 17, 2020 12:53 am
Forum: Administrative Questions and Class Announcements
Topic: Where can I buy a webcam for a reasonable price?
Replies: 60
Views: 1183

Re: Where can I buy a webcam for a reasonable price?

Yes, that was what my TA said today! We can just use a phone, laptop, iPad, or second device to login to the zoom meeting so that they can see our hands.
by Emma Healy 2J
Mon Oct 12, 2020 11:11 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8812
Views: 1496162

Re: Post All Chemistry Jokes Here

Haha good one!

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