Search found 95 matches

by Chanel Mao 3D
Sun Feb 28, 2021 11:33 pm
Forum: Balancing Redox Reactions
Topic: Sapling Week 7/8 #3
Replies: 4
Views: 28

Re: Sapling Week 7/8 #3

Brennan McGurrr 3C wrote:I got the same thing. Maybe double check your superscripts and subscripts when you put it into Sapling. Sometimes it is hard to control all the charges and amounts.

Ohh ok thank you so much
by Chanel Mao 3D
Sun Feb 28, 2021 10:50 pm
Forum: Balancing Redox Reactions
Topic: Sapling Week 7/8 #3
Replies: 4
Views: 28

Sapling Week 7/8 #3

For a particular redox reaction, BrO− is oxidized to BrO−3 and Fe3+ is reduced to Fe2+ . Complete and balance the equation for this reaction in basic solution. The phases are optional. Hi, I'm having a bit of trouble balancing this equation. I first added H2O in order to balance out the oxygen, and ...
by Chanel Mao 3D
Sun Feb 28, 2021 10:16 pm
Forum: Balancing Redox Reactions
Topic: Sapling week 7/8 #3
Replies: 3
Views: 23

Re: Sapling week 7/8 #3

I believe you would need to add 4OH- to both sides so that it will combine with the 4H+ ions to form water. Since this would form 4 molecules of H2O, you would cancel 2 molecules of H2O from both sides of your equation. Hope this helps!
by Chanel Mao 3D
Sun Feb 28, 2021 10:12 pm
Forum: Balancing Redox Reactions
Topic: Sapling #3
Replies: 2
Views: 15

Re: Sapling #3

I believe we use H2O in order to balance the oxygens in MnO2 and MnO-4. When we add H+ in order to balance out the H2Os that were added, we need to add OH- to neutralize the H+. Hope this helps!
by Chanel Mao 3D
Sun Feb 28, 2021 10:09 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Anodes and Cathodes
Replies: 22
Views: 43

Re: Anodes and Cathodes

Substances in the cathode are being reduced and substances in the anode are being oxidized
by Chanel Mao 3D
Sun Feb 28, 2021 9:26 pm
Forum: Balancing Redox Reactions
Topic: Sapling week 7/8 #3
Replies: 5
Views: 44

Re: Sapling week 7/8 #3

For the NO reaction, would it also be possible to use H+ to balance the reaction instead of OH- and H2O? If you were to START balancing the reaction with H+ and then neutralize that with the addition of OH- on both sides, that would work! But, especially because the focus is balancing the "O&q...
by Chanel Mao 3D
Sun Feb 28, 2021 8:39 pm
Forum: Balancing Redox Reactions
Topic: Sapling week 7/8 #3
Replies: 5
Views: 44

Re: Sapling week 7/8 #3

For the NO reaction, would it also be possible to use H+ to balance the reaction instead of OH- and H2O?
by Chanel Mao 3D
Sun Feb 21, 2021 10:06 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: interchanging q rev and deltaH
Replies: 6
Views: 16

Re: interchanging q rev and deltaH

I believe we can use this in isothermal processes.
by Chanel Mao 3D
Sun Feb 21, 2021 10:04 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Sapling 5/6 #7
Replies: 2
Views: 10

Re: Sapling 5/6 #7

Watts is in joules/second, so we would first need to multiply the amount of watts by the time to get just joules (divide by 100 to get kJ). We would then need to find the amount of substance vaporized, which is just the initial mass - final mass of the sample. Then we would convert this number into ...
by Chanel Mao 3D
Sun Feb 21, 2021 9:59 pm
Forum: Balancing Redox Reactions
Topic: Sapling Week 7/8 #1
Replies: 10
Views: 49

Re: Sapling Week 7/8 #1

Since KClO2 is an ionic compound, we know that K+ is the cation. It's also important to remember what charge oxygen normally has in a compound. Once you have determined these things, we can find the charge of the Cl in KClO2. All the charges should add up and cancel in the end, hope this helps!
by Chanel Mao 3D
Sun Feb 21, 2021 9:42 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Trouton's rule
Replies: 4
Views: 11

Re: Trouton's rule

Trouton's rule basically says that the entropy of vaporization for all liquids is around the same value.
by Chanel Mao 3D
Sun Feb 21, 2021 6:44 pm
Forum: Calculating Work of Expansion
Topic: adiabatic processes
Replies: 18
Views: 36

Re: adiabatic processes

I don't think that work is necessarily always equal to 0 in an adiabatic process, but q=0 because there is no heat transferred.
by Chanel Mao 3D
Sun Feb 14, 2021 9:34 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isothermal vs Adiabatic
Replies: 6
Views: 18

Re: Isothermal vs Adiabatic

An isothermal process is when the temperature remains constant (delta T = 0), while an adiabatic system has no transfer of heat or mass. Hope this helps!
by Chanel Mao 3D
Sun Feb 14, 2021 9:26 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: G° vs G
Replies: 25
Views: 72

Re: G° vs G

G° is just G in standard temperature and pressure (298K and 1atm)
by Chanel Mao 3D
Sun Feb 14, 2021 9:10 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Sapling #8 Week 5-6
Replies: 4
Views: 16

Re: Sapling #8 Week 5-6

Hi!
I think the order of your temperatures is correct, are you sure you are using the right units for temperature? it should be kelvin for this equation. Hope this helps!
by Chanel Mao 3D
Sun Feb 14, 2021 6:53 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: qrev vs q
Replies: 8
Views: 23

Re: qrev vs q

Maddie Turk Disc 2J wrote:So they are sort of synonymous right? Just Qrev is more specific because it specifies that its reversible expansion?

Yes I believe that is correct, qrev is just specifically referring to heat in a reversible reaction!
by Chanel Mao 3D
Sun Feb 14, 2021 6:49 pm
Forum: Van't Hoff Equation
Topic: Conceptual Van't Hoff Equation
Replies: 3
Views: 19

Re: Conceptual Van't Hoff Equation

Hi Elena! The Van't Hoff Equation basically helps calculate K at different temperatures when there is a given enthalpy change. For problems regarding the Van't Hoff Equation, we would usually need a Temperature 1 and Temperature 2 value as well as a change in enthalpy in order to solve for the K val...
by Chanel Mao 3D
Sun Feb 07, 2021 7:57 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Delta U in relation to q
Replies: 5
Views: 30

Re: Delta U in relation to q

When work = 0, U = q. Since work = -external pressure x change in volume, work would also be 0 if the external pressure was 0.
by Chanel Mao 3D
Sun Feb 07, 2021 7:35 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: sapling question 14
Replies: 3
Views: 17

Re: sapling question 14

Yes, I believe so!
by Chanel Mao 3D
Sun Feb 07, 2021 7:32 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: HW 14
Replies: 8
Views: 36

Re: HW 14

To calculate the work for path A, we need to use the equation w = -nRTln(V2/V1). Next we need to plug in all the values from the problem. To get n, we need to use the PV=nRT equation and solve for n. Hope this helps!
by Chanel Mao 3D
Sun Feb 07, 2021 7:20 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: hw #11
Replies: 5
Views: 35

Re: hw #11

Hi! I'm pretty sure I had the same setup and I got the correct answer! Maybe there was a mistake in solving for Tfinal?
by Chanel Mao 3D
Sun Feb 07, 2021 7:15 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Heat in isothermal expansion
Replies: 5
Views: 19

Re: Heat in isothermal expansion

Adding on to what was already said, an example of this is phase changes. In a phase change, the energy is going into changing the actual phase of a substance, and does not raise the temperature of the substance during this change.
by Chanel Mao 3D
Sun Jan 31, 2021 9:38 pm
Forum: Phase Changes & Related Calculations
Topic: standard form
Replies: 14
Views: 126

Re: standard form

Is there a certain chart though that maybe could be found online or through Lavelle's lectures? Hi! I don't remember Lavelle showing a chart and I can't find a good example of one online, but I think you will be fine if you just remember the standard states for some of the diatomic molecules like H...
by Chanel Mao 3D
Sun Jan 31, 2021 8:58 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated Systems
Replies: 8
Views: 40

Re: Isolated Systems

reva_bajjuri wrote:wait to bomb calorimeters not exchange heat/energy with the surroundings?

A bomb calorimeter is a closed system, so it still allows some heat/energy exchange with its surroundings, even though it is insulated.
by Chanel Mao 3D
Sun Jan 31, 2021 8:46 pm
Forum: Ideal Gases
Topic: justin week 1 worksheet
Replies: 6
Views: 57

Re: justin week 1 worksheet

reva_bajjuri wrote:so just to be clear, a "stoichiometric amount of bromine" means the exact amount of bromine necessary for the reaction to proceed (no excess?)

Hi! Yes you are correct, a stoichiometric amount of bromine will react completely and leave no excess.
by Chanel Mao 3D
Sun Jan 31, 2021 3:43 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: isolated system
Replies: 16
Views: 263

Re: isolated system

Akemi Karamitsos 1E wrote:Is there any way to change the energy of an isolated system?

I don't think so, because the amount of energy in an isolated system is constant.
by Chanel Mao 3D
Sun Jan 31, 2021 3:38 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Question 2
Replies: 6
Views: 48

Re: Sapling Question 2

Hi! First we need to note that the chemical reaction for a weak acid is: HA(aq) + H20 (l) <-> A-(aq) + H3O+(aq), Ka = [HA]/[A-][H3O+] = .00474 Next, we need to set up our ICE table: HA <-> A- H3O+ I .159 0 0 C -X +X +X E .159-X X X Once you solve for X, put X/.159 to find the percent ionization. Ho...
by Chanel Mao 3D
Sun Jan 24, 2021 6:16 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Inert Gases and Le Chatelier's Principle
Replies: 6
Views: 16

Re: Inert Gases and Le Chatelier's Principle

Hi!
If the reaction is at constant volume, then the addition of an inert gas would not change the equilibrium because it won't change the partial pressures of any of the other gases. Hope this helps!
by Chanel Mao 3D
Sun Jan 24, 2021 6:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Question 2
Replies: 6
Views: 48

Re: Sapling Question 2

Hi! First we need to note that the chemical reaction for a weak acid is: HA(aq) + H20 (l) <-> A-(aq) + H3O+(aq), Ka = [HA]/[A-][H3O+] = .00474 Next, we need to set up our ICE table: HA <-> A- H3O+ I .159 0 0 C -X +X +X E .159-X X X Once you solve for X, put X/.159 to find the percent ionization. Hop...
by Chanel Mao 3D
Sun Jan 24, 2021 5:55 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Strong vs weak acids/bases
Replies: 6
Views: 23

Re: Strong vs weak acids/bases

We need to use ICE tables for weak acids/bases, because weak acids and bases don't completely dissociate and therefore we cannot just assume the concentration of a weak acid or base. Because strong acids and bases completely dissociate, we do not need to use an ICE table to figure out the concentrat...
by Chanel Mao 3D
Sun Jan 24, 2021 5:49 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook 5I 23
Replies: 2
Views: 14

Re: Textbook 5I 23

Hi! I also got Kc=3.91, and I solved this problem using an ICE table: CO + 3H2 <-> CH4 + H2O I .2 .3 0 0 C -X -3X +X +X E .1522 .1566 .0478 .0478 and I plugged in the values for the Kc equation: Kc = (.0478)^2/((.1522)(.1566)^3) = 3.909. I'm also wondering if I made an error, but I wouldn't worry ab...
by Chanel Mao 3D
Sun Jan 24, 2021 5:33 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Method 3 Help
Replies: 3
Views: 18

Re: Method 3 Help

Hi! Just to preface, there are some liquids and solids (like H2O(l) and graphite(s)) that are already in their standard forms even though they are not gases, and we would still use their standard reaction enthalpies when solving an equation. If something is a liquid or solid and is not in their stan...
by Chanel Mao 3D
Sun Jan 24, 2021 5:22 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Using mean bond enthalpies for enthalpy of a reaction
Replies: 2
Views: 25

Re: Using mean bond enthalpies for enthalpy of a reaction

Hi! I feel like lewis structures are necessary in understanding which bonds need to be broke/formed. Although example 4E.2 (I'm assuming this is what you are referring to bc I can't find an example 4E.3) doesn't explicitly state which bonds need to be broken, you can find that out by comparing the b...
by Chanel Mao 3D
Mon Jan 18, 2021 12:16 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Inert Gas and Pressure
Replies: 5
Views: 31

Re: Inert Gas and Pressure

Hi! Pressure changes because total pressure = the sum of all the partial pressures in a container, which includes the partial pressure of the inert gas. Hope this helps!
by Chanel Mao 3D
Mon Jan 18, 2021 12:08 am
Forum: Phase Changes & Related Calculations
Topic: Usage of Ph with acids and bases
Replies: 6
Views: 27

Re: Usage of Ph with acids and bases

Hi! pH is just an easier way to understand the concentration of H+ ions, since pH gives a scale from 0 - 14. pH also means -log[H+]. I'm not sure if this fully answered your question, but I hope this helped!
by Chanel Mao 3D
Sun Jan 17, 2021 10:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Making the Assumption that Change x is Small
Replies: 4
Views: 24

Re: Making the Assumption that Change x is Small

In terms of double checking the % ionization, I also heard that if the % ionization is less than 5%, we can technically ignore the change!
by Chanel Mao 3D
Sun Jan 17, 2021 10:41 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Remembering Le Chatelier's Principle
Replies: 6
Views: 50

Re: Remembering Le Chatelier's Principle

I used to forget Le Chatelier's and how it affects endothermic/exothermic reactions, but it's important to remember that the addition of heat will favor the endothermic side of the reaction. It's also good to keep in mind that with gases, and increase in pressure favors the side with less moles. Hop...
by Chanel Mao 3D
Sun Jan 10, 2021 11:12 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling #6
Replies: 2
Views: 25

Re: Sapling #6

Hi! For this question, you do not need to take the temperature into account when finding the reaction quotient.
by Chanel Mao 3D
Sun Jan 10, 2021 5:45 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Question on #19 from focus topic 3
Replies: 3
Views: 21

Re: Question on #19 from focus topic 3

The reaction quotient is calculated the same way as K, so you would put the concentration of H2 ((1.23 x 10^-3)/3) over the concentration of AsH3 ((5.55 x 10^-4)/3). We leave out the concentration of As since it is a solid. Hope this helps!
by Chanel Mao 3D
Sun Jan 10, 2021 5:39 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Chemical Equilibrium Module 2 #29
Replies: 1
Views: 25

Re: Chemical Equilibrium Module 2 #29

First, we need to calculate 18.3% of 1.84 x 10^-4 moles (3.37 x 10^-5) in order to get the moles of BrCl gas at equilibrium. Because the reaction vessel is 1L, the concentration of BrCl is also 3.37 x 10^-5. Since there is a 2:1 ratio between BrCl and Br2/Cl2, we know that there is 1.68 x 10^-5 mole...
by Chanel Mao 3D
Sun Jan 10, 2021 5:14 pm
Forum: Ideal Gases
Topic: partial pressures
Replies: 14
Views: 94

Re: partial pressures

Partial pressures are basically the pressure of each gas if it were to occupy the container just by itself (the total pressure of a container of mixed gases is the sum of all the partial pressures of each gas). Since concentration is moles/liters, you can technically put moles of gas over liters. Ho...
by Chanel Mao 3D
Sun Jan 10, 2021 5:11 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Left vs. Right
Replies: 29
Views: 129

Re: Left vs. Right

The two statements are basically the same, but saying that a reaction shifts to the left/right might be misleading because the reaction doesn't physically shift. Hope this helps!
by Chanel Mao 3D
Sat Dec 12, 2020 4:00 pm
Forum: Naming
Topic: Textbook problem 9C.3
Replies: 4
Views: 46

Re: Textbook problem 9C.3

* Sorry, I meant to say coordination sphere instead of coordination compound
by Chanel Mao 3D
Sat Dec 12, 2020 3:58 pm
Forum: Naming
Topic: Textbook problem 9C.3
Replies: 4
Views: 46

Re: Textbook problem 9C.3

Hi! To determine the number of atoms that appear outside the brackets, we would have to look at the overall charge of the coordination compound (everything inside the brackets). In part a, hexacyanido has a charge of 6- (1- for every cyanido), and chromate has a 3+ charge, which brings the total cha...
by Chanel Mao 3D
Sat Dec 12, 2020 3:53 pm
Forum: Trends in The Periodic Table
Topic: Ionization period trend
Replies: 2
Views: 27

Re: Ionization period trend

Hi! You are correct in that the general trend shows higher ionization energies for elements towards the right. Elements like Be/B and N/O are exceptions to this trend because of their electron configurations and their overall stability after we take away an electron. For example, the electron config...
by Chanel Mao 3D
Sat Dec 12, 2020 3:46 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Why isn't HF a strong acid?
Replies: 23
Views: 150

Re: Why isn't HF a strong acid?

Hi! When looking at HF, we have to take into account the bond length between the two atoms. Since the bond between H and F is relatively short, it will be harder for the bond to break when placed into a solution. Because of this, the ions will not dissociate as easily, which is why HF is not conside...
by Chanel Mao 3D
Sat Dec 12, 2020 3:43 pm
Forum: Naming
Topic: Bis, Tris, Tetrakis
Replies: 4
Views: 52

Re: Bis, Tris, Tetrakis

Hi!
I think that might just be a mistake, because even if we were to take into account the bis, tris, tetras, etc. prefixes (which I'm pretty sure we don't), diaqua would still be placed before bisoxalato because of the a in aqua.
by Chanel Mao 3D
Sat Dec 12, 2020 3:38 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Textboo 6C.21 (b)
Replies: 2
Views: 47

Textboo 6C.21 (b)

6C.21 Suggest an explanation for the different strengths of acetic acid and formic acid. The textbook states that formic acid is stronger than acetic acid. Can someone explain why the single H atom in formic acid (HCOOH) accounts for higher acidity strength than the CH3 group in acetic acid (CH3COOH)?
by Chanel Mao 3D
Sun Dec 06, 2020 3:45 pm
Forum: Administrative Questions and Class Announcements
Topic: Table 9C.1
Replies: 1
Views: 19

Re: Table 9C.1

Hi! I believe it is highly recommended that we memorize Table 9C.1.
by Chanel Mao 3D
Sun Dec 06, 2020 3:41 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: chelating ligands [ENDORSED]
Replies: 31
Views: 7401

Re: chelating ligands [ENDORSED]

Lorena_Morales_3D wrote:Hi!

Perhaps someone else has already asked this but I was wondering, what exactly is a chelating ligand? :(


Hi! Chelating ligands are basically polydentate ligands that can attach to two or more positions to a metal atom. Hope this helps!
by Chanel Mao 3D
Sun Dec 06, 2020 3:24 pm
Forum: Naming
Topic: Sapling #9 question 1
Replies: 11
Views: 195

Re: Sapling #9 question 1

I have been having trouble naming the coordination compounds. Does anyone have any tips? Hi! I would just recommend doing a lot of practice problems in order to get used to the different prefixes, suffixes, and ligand names, but I generally just remember to (1) list ligands in alphabetical order, n...
by Chanel Mao 3D
Sun Dec 06, 2020 3:07 pm
Forum: Administrative Questions and Class Announcements
Topic: Lectures not loading
Replies: 6
Views: 76

Re: Lectures not loading

Hi, I had the same problem earlier! Have you tried using a different web browser? I went on chrome and the lectures played fine after that! Hope this helps!
by Chanel Mao 3D
Sun Dec 06, 2020 3:03 pm
Forum: Naming
Topic: Sapling 1
Replies: 34
Views: 181

Re: Sapling 1

So why would this be cobaltate and not cobalt at the end Hi! This would actually just be cobalt at the end instead of cobaltate. You only add the -ate at the end of the metal if the net charge of the complex is negative. Also, don't forget to add the oxidation number in parenthesis after the metal!...
by Chanel Mao 3D
Sun Nov 29, 2020 8:28 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: ions
Replies: 8
Views: 86

Re: ions

If the negative/positive ion affects the number of lone pairs an atom has, then it can change the VSEPR shape of the molecule. Otherwise it doesn't really affect VSEPR theory. Hope this helps!
by Chanel Mao 3D
Sun Nov 29, 2020 8:25 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Resonance Structure Definition
Replies: 9
Views: 81

Re: Resonance Structure Definition

Hi! In resonance structures you are basically only moving/changing where the electrons are - the atoms themselves stay in a fixed position. In resonance structures, the overall formal charge of the molecule should stay the same, but FC for individual atoms can change. Hope this helped! So in other ...
by Chanel Mao 3D
Sun Nov 29, 2020 8:11 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Resonance Structure Definition
Replies: 9
Views: 81

Re: Resonance Structure Definition

Hi!
In resonance structures you are basically only moving/changing where the electrons are - the atoms themselves stay in a fixed position. In resonance structures, the overall formal charge of the molecule should stay the same, but FC for individual atoms can change. Hope this helped!
by Chanel Mao 3D
Sun Nov 29, 2020 8:06 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity
Replies: 17
Views: 75

Re: Polarity

Catherine Bubser 2C wrote:Would this mean certain geometries are always polar/ nonpolar?

Hi! Yes you are correct! Certain geometries like trigonal pyramidal and bent shapes will always be polar, even if the bonds themselves are nonpolar.
by Chanel Mao 3D
Sun Nov 29, 2020 7:56 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: How do bonds affect shapes?
Replies: 11
Views: 90

Re: How do bonds affect shapes?

Hi!
In addition to the number of atoms surrounding the central atom, it is also important to take into account the number of lone pairs (if any) surrounding a central atom. double/triple bonds do not affect the molecular shape of a molecule. Hope this helps!
by Chanel Mao 3D
Sun Nov 22, 2020 9:29 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity from Lewis Structures
Replies: 6
Views: 30

Re: Polarity from Lewis Structures

Hi! We can infer a molecule's molecular shape by looking at its lewis structure and how many bonds/lone pairs the molecules have. From there, we can determine the polarity of the structure from its molecular geometry. If a molecule has lone pairs, that's a good sign that the structure might be polar...
by Chanel Mao 3D
Sun Nov 22, 2020 9:14 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pairs and Bonding Pairs
Replies: 6
Views: 39

Re: Lone Pairs and Bonding Pairs

Hi! SF2 would have a bent shape due to the two lone pairs. A similar example would be H2O, which is bent (polar) and has two lone pairs attached to the oxygen.
by Chanel Mao 3D
Sun Nov 22, 2020 9:12 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: repulsion strength
Replies: 10
Views: 76

Re: repulsion strength

Just to clarify, lone pair electrons have more repulsions so therefore that angle is wider, correct? In that case, we just have to know that concept? Or is there certain angle degree that is associated with lone pair repulsion? Hi! Yes you are correct, lone pair repulsion is greater than bonding pa...
by Chanel Mao 3D
Sun Nov 22, 2020 4:06 pm
Forum: Octet Exceptions
Topic: Octet Exceptions Question
Replies: 5
Views: 69

Re: Octet Exceptions Question

Expanded octets can have more than 4 bonds! You can look at phosphorous pentachloride as an example (it has 5 bonds). However, even expanded octets don't typically go beyond 5 bonds (Z=10), so don't draw an unlimited number of bonds just because the atom has d-orbitals! Good to know! Can anyone exp...
by Chanel Mao 3D
Sun Nov 22, 2020 3:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity of BrF3
Replies: 6
Views: 52

Re: Polarity of BrF3

Hi!

BrF3 is polar because there are two sets of lone pairs on the Br, making its molecular geometry trigonal pyramidal (which is polar). Hope this helped!
by Chanel Mao 3D
Sun Nov 15, 2020 7:51 pm
Forum: Dipole Moments
Topic: Sapling W 5/6 #17
Replies: 10
Views: 115

Re: Sapling W 5/6 #17

Im stuck on this problem too and I'm not really understanding the concept. Would it be better to draw the lewis structure or label which of the atoms is more electronegative Hi! It would be better to draw the lewis structure and it would help if you knew the molecular geometry of each molecule. Sin...
by Chanel Mao 3D
Sun Nov 15, 2020 7:00 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Textbook 1E.23
Replies: 4
Views: 47

Re: Textbook 1E.23

Hi! The p sub-level has 3 orbitals, and 2 electrons can fit in each orbital. According to Hund's rule, you have to fill each orbital with one electron before you start pairing the electrons. Since Ga has one electron in the 2p state, it would only have 1 unpaired electron. Ge would have two unpaired...
by Chanel Mao 3D
Sun Nov 15, 2020 6:48 pm
Forum: Lewis Structures
Topic: textbook problem 2C #9
Replies: 1
Views: 9

Re: textbook problem 2C #9

Hi! I think this has to do with formal charges. If we were to use double bonds to connect the Xe to the two F atoms, both F atoms would have a +1 charge. Additionally, there are 22 valence electrons total, so if you were to use double bonds, you would have a few valence electrons left over. Hope thi...
by Chanel Mao 3D
Sun Nov 15, 2020 6:44 pm
Forum: Ionic & Covalent Bonds
Topic: bond lengths
Replies: 9
Views: 82

Re: bond lengths

A double bond is shorter than a single bond because the additional bonding electrons create a stronger attraction to the nucleus, which pulls the two atoms closer together. Since the bond length can be classified as the distance between the nuclei of two atoms, a double bond would be shorter than a ...
by Chanel Mao 3D
Sun Nov 15, 2020 6:41 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Textbook 1E.23
Replies: 4
Views: 47

Re: Textbook 1E.23

Hi! Correct me if I'm wrong, but I think you have confused unpaired electrons with valence electrons. Since Ga, Ge, As, Se, and Br are all p-block elements, the number of unpaired electrons for each element respectively is 1,2,3,2,1. If you are looking for the number of valence electrons for each el...
by Chanel Mao 3D
Sun Nov 15, 2020 6:34 pm
Forum: Coordinate Covalent Bonds
Topic: Covalent Bond Character
Replies: 7
Views: 64

Re: Covalent Bond Character

Hi! In a covalent bond, the electrons are shared (unlike ionic bonds in which oppositely charged ions attract each other). However, in an ionic bond, the positively charged ion pulls and slightly the distorts the negatively charged ion. Sometimes the two ions overlap - the place where they overlap r...
by Chanel Mao 3D
Wed Nov 11, 2020 1:57 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 4s and 3d Orbitals
Replies: 1
Views: 16

4s and 3d Orbitals

Hi!

Can someone explain why the 4s orbital is still filled before the 3d orbital even though the 4s orbital is higher in energy (for elements after Calcium)?
by Chanel Mao 3D
Sun Nov 08, 2020 11:14 pm
Forum: Lewis Structures
Topic: Resonance Structures
Replies: 3
Views: 46

Re: Resonance Structures

Resonance Lewis Structures mean that there are multiple possibilities for where to put single/double/triple bonds, so you would have to draw out each possibility and indicate resonance by putting a double-sided arrow between each possible structure. Hope this helped!
by Chanel Mao 3D
Sun Nov 08, 2020 11:02 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Explaining Electron Configuration
Replies: 4
Views: 15

Re: Explaining Electron Configuration

Hi! Electron configuration basically just tells how many electrons an atom has, and where those electrons are located. To find an element's electron configuration, we would need to look at the periodic table and take into account the number of electrons that particular atom has (don't forget to fact...
by Chanel Mao 3D
Sun Nov 08, 2020 10:51 pm
Forum: Resonance Structures
Topic: formal charge
Replies: 5
Views: 15

Re: formal charge

Hi! Yes you are correct, the formal charges of the atoms should add up the the formal charge of the molecule as a whole. Also I may be wrong, but I think it's more common for certain elements to have certain charges in ionic compounds (like NaCl) - this isn't necessarily true for molecules that are ...
by Chanel Mao 3D
Sun Nov 01, 2020 11:09 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Sapling HW Spectral Lines/Energy Levels
Replies: 4
Views: 57

Re: Sapling HW Spectral Lines/Energy Levels

Hi! Since you know that n=7 -> n=1 has the highest energy emitted, you would need to find the change in energy with the Rydberg Equation (which should be on the equation sheet). After that, you would use the equation lamda=(h*c)/E to get the wavelength in meters. You would then need to multiply this...
by Chanel Mao 3D
Sun Nov 01, 2020 11:01 pm
Forum: Quantum Numbers and The H-Atom
Topic: Sapling #21
Replies: 4
Views: 55

Re: Sapling #21

Hi!

Because n=5 and l=3, we are dealing with electrons in the 5F orbital. In this orbital, m can be -3,-2,-1,0,1,2, or 3 (basically 7 different orientations). Because there is a maximum of 2 electrons in each shell, there can be 14 electrons when n=5 and l=3. Hope this helps!
by Chanel Mao 3D
Sun Nov 01, 2020 10:56 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Sapling HW #8
Replies: 4
Views: 33

Re: Sapling HW #8

Hi! Since it is a "blue" line, you know that you are dealing with visible light. Therefore, the line would be from the Balmer series, because the Balmer series is associated with light in the visible range, while the Lyman series is associated with light from the UV range. If you are deali...
by Chanel Mao 3D
Sun Nov 01, 2020 10:51 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbital energy
Replies: 5
Views: 46

Re: Orbital energy

Hi!

I think you are right about the higher values of n, and I also think it's the same for multi-electron systems! Also yes, as you go up values of n, the electrostatic attraction between the nucleus and electrons decreases! Hope this helps!
by Chanel Mao 3D
Thu Oct 29, 2020 10:39 pm
Forum: Quantum Numbers and The H-Atom
Topic: UA Worksheets Question and ml
Replies: 3
Views: 45

Re: UA Worksheets Question and ml

Hi! I believe you are correct! Since the 2py orbital has a nodal xz plane, the probability of finding an electron there would be zero. Hope this helps!
by Chanel Mao 3D
Sun Oct 25, 2020 4:32 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Diffraction
Replies: 4
Views: 32

Re: Diffraction

Hi!
I'm pretty sure diffraction refers to both, since it is essentially what happens when waves interact with other obstacles, including other waves. Hope this helps!
by Chanel Mao 3D
Sun Oct 25, 2020 4:21 pm
Forum: Limiting Reactant Calculations
Topic: using the molar ratio to find LR?
Replies: 3
Views: 52

Re: using the molar ratio to find LR?

Hi,
I think you can do whichever is easiest for you, but keeping the mols in terms of the reactant saves some time. However, if the answer asks for mols of product you can just convert the mols of reactant directly to the mols of product. Hope this helped!
by Chanel Mao 3D
Sun Oct 25, 2020 4:14 pm
Forum: Limiting Reactant Calculations
Topic: Textbook G.25
Replies: 4
Views: 76

Re: Textbook G.25

To provide further clarification, your answer states that there is less than 1 molecule left, or really closer to 1 millionth of a molecule left. Molecules are indivisible (ignoring fission), so this small of a number indicates that there is no molecule remaining. That makes a lot of sense, thank y...
by Chanel Mao 3D
Sun Oct 25, 2020 4:12 pm
Forum: Limiting Reactant Calculations
Topic: Textbook G.25
Replies: 4
Views: 76

Re: Textbook G.25

Charlene D 3I wrote:Hi Chanel,
This confused me as well. I think the textbook said "no substance" because the answer you got is very small and therefore insignificant and has no effect on a patient.
i hope this helped.


Oh okay, thank you!!
by Chanel Mao 3D
Sun Oct 25, 2020 4:07 pm
Forum: Limiting Reactant Calculations
Topic: Textbook G.25
Replies: 4
Views: 76

Textbook G.25

To explore this question, suppose that you prepare a solution of a supposedly active sub-stance, X, with a molar concentration of 0.10 mol/L. Dilute 10. mL of that solution by doubling the volume, doubling it again, and so on, for 90 doublings in all. How many molecules of X will be present in 10. m...
by Chanel Mao 3D
Fri Oct 23, 2020 12:03 pm
Forum: DeBroglie Equation
Topic: De Broglie Equation v. Speed of Light Equation
Replies: 14
Views: 105

Re: De Broglie Equation v. Speed of Light Equation

Hi! The speed of light equations are used when you want to find the wavelength/frequency of a photon, so you can't use it for other objects. You can instead use DeBroglie's equation to find the wavelength! Also, sometimes the question asks if an object's wavelength is detectable/not detectable, whic...
by Chanel Mao 3D
Thu Oct 22, 2020 7:21 pm
Forum: General Science Questions
Topic: Using Equations for Problems
Replies: 3
Views: 44

Re: Using Equations for Problems

Hi, I've also noticed that as well! I've done problems where the DeBroglie equation was needed in conjunction with Photoelectric effect problems. In the equation E(photon) = work function + kinetic energy of the electron, sometimes the problem doesn't give you the kinetic energy ((1/2)mv^2). To find...
by Chanel Mao 3D
Sun Oct 18, 2020 8:05 pm
Forum: Administrative Questions and Class Announcements
Topic: Respondus
Replies: 4
Views: 35

Re: Respondus

Hi!

I think that's all we're expected to have, I know that my discussion section is doing a practice exam using respondus just to make sure everything works. But you can also contact your TA just to double check!
by Chanel Mao 3D
Sun Oct 18, 2020 8:00 pm
Forum: Photoelectric Effect
Topic: Questions from Discussion
Replies: 2
Views: 32

Re: Questions from Discussion

Hi! You can first calculate the work function (Energy of the photon - the kinetic energy of the electron), which should be 5.51*10^-19 J/photon. Then, you divide the total energy (6.22*10^-17 J) by the calculated work function (5.51*10^-19 J/photon) to get the number of photons. Since one photon has...
by Chanel Mao 3D
Sun Oct 18, 2020 7:54 pm
Forum: Properties of Light
Topic: Kinetic Energy of Electron
Replies: 4
Views: 45

Re: Kinetic Energy of Electron

Hi!

I'm not sure if this is what you meant, but you can also calculate the kinetic energy of an electron when you subtract the work function from the energy of the photon. Hope this helped!
by Chanel Mao 3D
Sat Oct 17, 2020 9:41 pm
Forum: Properties of Electrons
Topic: Electrons ejected
Replies: 7
Views: 58

Re: Electrons ejected

Hi!

Yes, if the photons have enough energy to eject electrons, increasing the intensity could also increase the amount of electrons that can be ejected. Since one photon is capable of ejecting one electron, more electrons can be ejected if you increase the amount of photons.
by Chanel Mao 3D
Wed Oct 14, 2020 9:58 am
Forum: Properties of Electrons
Topic: Discussion 2D Question 2
Replies: 3
Views: 54

Re: Discussion 2D Question 2

Hi!

Yes, I believe you are correct. Since one photon can only eject one electron, the maximum number of electrons that can be ejected is equal to the number of photons emitted.
by Chanel Mao 3D
Wed Oct 07, 2020 5:46 pm
Forum: Empirical & Molecular Formulas
Topic: Sapling Question Number 9
Replies: 12
Views: 220

Re: Sapling Question Number 9

Hi! The 0.1034 moles of H is because there are 2 moles of Hydrogen atoms in one molecule of H2O, so yes you would multiply the 0.0516 moles of H2O by 2. Since both CO2 and H2O have Oxygen in them, we would need to calculate the grams of Carbon and Hydrogen (0.6194g and 0.1040g respectively), add the...
by Chanel Mao 3D
Wed Oct 07, 2020 5:33 pm
Forum: Balancing Chemical Reactions
Topic: Textbook Problem L 35
Replies: 5
Views: 51

Re: Textbook Problem L 35

Hi! I'm pretty sure t stands for metric ton
by Chanel Mao 3D
Wed Oct 07, 2020 5:09 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: G13 Question
Replies: 7
Views: 110

Re: G13 Question

Hi Charlene! You are correct that the number of moles of NH4NO3 stay the same before and after the reaction, but in this problem you are finding the moles of Nitrogen atoms as opposed to the moles of NH4NO3. Therefore you would have to multiply the moles of NH4NO3 by 2 (there are two moles of Nitrog...
by Chanel Mao 3D
Wed Oct 07, 2020 4:13 pm
Forum: Empirical & Molecular Formulas
Topic: Rounding EF to Integers
Replies: 6
Views: 64

Re: Rounding EF to Integers

Hi!

Just to clarify, an empirical formula refers to the simplest integers ratio of atoms present in a molecule, so yes, I would say that it is necessary to make the empirical formula integers only. Hope this helps! Let me know if you have any more questions!
by Chanel Mao 3D
Wed Oct 07, 2020 10:53 am
Forum: Molarity, Solutions, Dilutions
Topic: G. 23
Replies: 5
Views: 60

G. 23

Hi! I'm having some trouble working out problem G. 23 in the textbook: In medicine it is sometimes necessary to prepare solutions with a specific concentration of a given ion. A lab technician has made up 100.0 mL of a solution containing 0.50 g of NaCl and 0.30 g of KCl, as well as glucose and othe...

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