## Search found 60 matches

Sun Jan 17, 2021 11:36 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling WK 1, #4
Replies: 3
Views: 23

### Re: Sapling WK 1, #4

Hi! Like others have stated above, we want to start with an ICE table.  (I) The initial pressures of PCl3 and Cl2 will be 0, as the container only consists of PCl5. The initial pressure of PCl5 is given as 0.0750 bar.  (C) Because the system will favor the reverse reaction to reach equilibrium, PCl5...
Sun Jan 17, 2021 11:25 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Autoprotolysis Constant of Water
Replies: 7
Views: 17

### Re: Autoprotolysis Constant of Water

Hi! I agree that this concept is likely an important one to remember, as it serves as the foundation for understanding pH, pOH, acids, bases, etc., as well as the relationships between all these concepts. I would definitely try to remember it for both problem solving and conceptual questions. Hope t...
Sun Jan 17, 2021 11:21 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Endothermic/exothermic reactions and K
Replies: 11
Views: 28

### Re: Endothermic/exothermic reactions and K

Hi! For exothermic reactions, heat is released for the forward reaction; thus, the addition of heat would favor the reverse reaction instead to produce more reactants, and the K value would decrease. For endothermic reactions, heat is absorbed for the forward reaction; thus, the addition of heat wou...
Sun Jan 17, 2021 11:15 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling #10, WK 1
Replies: 8
Views: 63

### Re: Sapling #10, WK 1

Hi! For the final part of this question, we can set up an ICE box.  (I) The initial concentration of N2O4 is unchanged, so we can leave it at 0.373 mol/L; the initial concentration of NO2 needs to account for the additional 1.00 mol added, so that would be 2.04 + 1.00 mol/L.  (C) Because the product...
Sun Jan 17, 2021 11:04 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Autoprotolysis Reaction and Kw
Replies: 3
Views: 12

### Re: Autoprotolysis Reaction and Kw

Hi! Like others have pointed out above, Kw changes with temperature. Because the reaction is endothermic, the forward reaction will absorb heat; an increase in temperature will thus favor the formation of products more, and the equilibrium constant will increase.
Sun Jan 10, 2021 6:45 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium mixture
Replies: 4
Views: 27

### Re: Equilibrium mixture

Hi! Like others have explained above, I believe that the two terms can be used interchangeably; however, the mixture is usually used to describe the whole reaction/system, whereas the concentration is slightly more specific in describing a particular product or reactant.
Sun Jan 10, 2021 6:42 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: How does an inert gas effect a closed system with these certain conditions?
Replies: 5
Views: 42

### Re: How does an inert gas effect a closed system with these certain conditions?

Hi! Like others have said above, the addition of an inert gas to a closed container would likely result in an increase in pressure, but the volume would remain unchanged.
Sun Jan 10, 2021 6:38 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Changes in Q vs K
Replies: 6
Views: 46

### Re: Changes in Q vs K

Hi! Like others have explained above, K does not change in response to changes in pressure because the reaction will simply shift to minimize any change in concentration (as specified in Le Chatelier’s principle). However, in the case of temperature, the reaction will change in the way it favors pro...
Sun Jan 10, 2021 6:34 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Stable Reactants and Products
Replies: 7
Views: 40

### Re: Stable Reactants and Products

Hi! Like others have detailed above, stability can point to whether the reaction will favor forming a reactant or a product. When the equilibrium constant is large, there is a greater proportion of products, suggesting that the products are more stable and the reaction favors the forward direction. ...
Sun Jan 10, 2021 6:19 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K=1
Replies: 8
Views: 49

### Re: K=1

Hi! Like others have mentioned above, when the equilibrium constant is 1, the concentration/pressure of the products and reactants will be equal. To my understanding, this just happens to be rare because there is usually a tendency for reactions to favor one direction over another.
Tue Dec 15, 2020 12:01 pm
Forum: Conjugate Acids & Bases
Topic: Oxyacids
Replies: 8
Views: 48

### Re: Oxyacids

Hi! Like others have said above, an oxyacid is an acid that contains oxygen, hydrogen, and another element. At least one acidic hydrogen is bonded to an oxygen atom. The more oxygen atoms (or the higher the oxidation number), the stronger the acid.
Tue Dec 15, 2020 11:56 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligands
Replies: 8
Views: 62

### Re: Ligands

Hi! Like others have said above, coordination compounds can definitely have multiple types of ligands, which we list alphabetically in naming.
Sat Dec 12, 2020 4:30 pm
Forum: Bronsted Acids & Bases
Topic: Textbook Problem J.9 part b
Replies: 3
Views: 34

### Re: Textbook Problem J.9 part b

A weak acid will still donate protons. It does not dissociate completely, so there will be some H3PO4 left at equilibrium, but there will also be some of the salt present. if weak acids/bases didn't dissociate at all, they wouldn't be able to participate in an A/B reaction. Hi Zach, I also had this...
Sat Dec 12, 2020 4:22 pm
Forum: Bronsted Acids & Bases
Topic: SO3 lewis acid/bronsted
Replies: 2
Views: 11

### Re: SO3 lewis acid/bronsted

Hi! To my understanding, SO3 is not a Bronsted acid or base, as it cannot donate or accept a proton. You are right that it is a Lewis acid in water because the sulfur accepts an electron pair, but this electron pair should come from the oxygen atom, not H+ (depicted in the attached image). Perhaps y...
Sat Dec 12, 2020 1:08 am
Forum: Bronsted Acids & Bases
Topic: Fundamentals J #9b
Replies: 2
Views: 38

### Fundamentals J #9b

For Fundamentals #9b, I was wondering why the weak acid reactant H3PO4 in the neutralization reaction is written in its dissociated form [3H+(aq) + PO4 3-(aq)], as I thought that only strong acids were supposed to be written out as such. For example, the bromous acid (also a weak acid) in part c is ...
Sun Dec 06, 2020 9:18 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Sapling 5
Replies: 6
Views: 49

### Re: Sapling 5

Hi! Like others have explained above, (en) is the ethylenediamine ligand, or NH2CH2CH2NH2 (you can find this in Table 9C.1), which is a bidentate ligand. To calculate the coordination number, we would consider the number of bonds that the metal (Co) can form with the ligands (en and CO). There are t...
Sun Dec 06, 2020 9:11 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Homework Problem 9C.5
Replies: 3
Views: 43

### Re: Homework Problem 9C.5

Hi! When I did this problem, I drew out the Lewis structures for each ligand, and then determined the number of lone pairs on different atoms. For example, the Lewis structure for (a) HN(CH2CH2NH2)2 reveals three nitrogen atoms with one lone pair each. Because there are three separate lone pairs tha...
Sun Dec 06, 2020 8:58 pm
Forum: Naming
Topic: Textbook Exercise 9C.3
Replies: 4
Views: 42

### Re: Textbook Exercise 9C.3

Hi! Like others have said above, the potassium should be located at the beginning, in front of the brackets, because it is a cation (more specifically, a positively-charged metal) with a 1+ charge. Potassium hexacyanidochromate (III) is a compound, so we name the cation first and then the anion.
Sun Dec 06, 2020 7:23 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Figuring Out monodentate, bidentate, etc
Replies: 5
Views: 38

### Re: Figuring Out monodentate, bidentate, etc

Hi! To my understanding, a monodentate ligand describes a ligand that binds at one site of a central metal atom, donating one electron pair. A bidentate would be a ligand that binds at two sites, donating two electron pairs, and so on. To determine what kind of dentate a ligand is, we can consider t...
Sun Dec 06, 2020 7:18 pm
Forum: Naming
Topic: Sapling Week 9 #1
Replies: 6
Views: 44

### Re: Sapling Week 9 #1

Hi! Like others mentioned, Toolbox 9C.1 in the textbook and Table 9C.1 are pretty helpful for this question. But this is how I approached the problem: We would start with the part inside the brackets, [Co(NH3)5Cl]. There are three separate components: Co, NH3, and Cl. We know that Co is the transiti...
Sun Nov 29, 2020 6:20 pm
Forum: Hybridization
Topic: Sapling #11
Replies: 19
Views: 115

### Re: Sapling #11

Hi! Like others have explained above, quickly determining the hybridization primarily consists of counting the number of regions of electron density. Even in a complex structure like the one above, this holds true; we can see that each phosphorous has one lone pair and three bonds. This adds up to p...
Sun Nov 29, 2020 6:15 pm
Forum: Hybridization
Topic: Sapling #18
Replies: 10
Views: 100

### Re: Sapling #18

Hi! For all atoms to exist on the same plane, we would be essentially be able to connect them all on a 2-D plane (ex: they all could lie on the same sheet of paper). To answer the Sapling problem, we would need to consider whether there are an even or odd number of atoms. When there is an even numbe...
Sun Nov 29, 2020 6:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sapling Week 7/8 HW #12
Replies: 8
Views: 82

### Re: Sapling Week 7/8 HW #12

Hi! Like others have explained above, I started by determining the formula of the molecule. I multiplied the mass percentages with the molar mass to determine the number of moles of each element, yielding a formula of CH4O. From here, I drew the structure, keeping in mind that carbon is the most ele...
Sun Nov 29, 2020 6:03 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sapling #20
Replies: 5
Views: 64

### Re: Sapling #20

Hi! Like Olivia mentioned above, I would also examine the charge of the molecule or ion. In this question, we want the formal charges of the atom to have a sum of -3, as the ion has a charge of -3. Thus, the structure that would give an overall formal charge of -3 would be if arsenic had one double ...
Sun Nov 29, 2020 5:58 pm
Forum: Hybridization
Topic: hybridization of phosphorus (Sapling Q.11)
Replies: 21
Views: 96

### Re: hybridization of phosphorus (Sapling Q.11)

Hi! This is another part of Sapling Q.11. I understood how your answers applied to the other diagram, but this diagram threw me for a loop. If any of you have advice on how to better understand and complete these questions it would be much appreciated! Thank you! Hi! Like others have detailed above...
Sun Nov 22, 2020 5:05 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sapling Week 7 & 8 HW Question 6
Replies: 6
Views: 56

### Re: Sapling Week 7 & 8 HW Question 6

Hi! Like others have said above, I believe the molecule you are missing is XeF2, which has Xe in the middle and F on either side of Xe, and the lone pairs are distributed fairly evenly.
Sun Nov 22, 2020 5:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar bonds
Replies: 8
Views: 40

### Re: Polar bonds

Hi, going off of this, I understand how to determine the polarity of a molecule but I am a little confused how to determine if an individual bond is polar or non-polar. Is it simply a large difference in electronegativity between the two atoms? Hi! I agree with the response above. To my understandi...
Sun Nov 22, 2020 4:57 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Memorizing Shape Names
Replies: 12
Views: 70

### Re: Memorizing Shape Names

Hi! Personally, I don’t have any specific mnemonics to remember the names of the different shapes (other than looking at the prefixes), but I usually memorize them simply by drawing them all out on a blank sheet of paper without my notes. Hope this helps!
Sun Nov 22, 2020 4:51 pm
Forum: Hybridization
Topic: Pi and Sigma Bonds
Replies: 10
Views: 85

### Re: Pi and Sigma Bonds

Hi! Like others have said above, I believe you are correct. Sigma bonds and pi bonds are found in covalent bonds, with single bonds having only a sigma bond. For double bonds and beyond, both sigma and pi bonds are present.
Sun Nov 22, 2020 4:47 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: shape
Replies: 6
Views: 48

### Re: shape

Hi! Like others have mentioned, I would start by drawing the Lewis structure, and then look at the bonding/lone electron pairs, which should correspond to a specific molecular shape, specified by the VSEPR model/formulas. Hope this helps!
Sun Nov 15, 2020 8:57 pm
Forum: Bond Lengths & Energies
Topic: Hydrogen Bonds
Replies: 16
Views: 119

### Re: Hydrogen Bonds

So to clarify, in conclusion, a hydrogen bond only exist between H and an N, O, or F molecule? H bonds are polar correct? Because the H is attracted to a more electronegative atom? Hi! I believe that hydrogen bonds exist between a hydrogen atom (covalently bonded specifically to F/O/N within the mo...
Sun Nov 15, 2020 8:48 pm
Forum: Dipole Moments
Topic: Hydrogen Bonding
Replies: 3
Views: 9

### Re: Hydrogen Bonding

Hi! In the case of hydrogen bonding, electrons are not considered to be shared, as hydrogen “bonding” refers to an intermolecular force. Rather, there is a force of attraction between the partial positive hydrogen and the partial negative charge of another highly electronegative atom in a separate m...
Sun Nov 15, 2020 7:03 pm
Forum: Resonance Structures
Topic: Formal Charge vs. Oxidation number vs. Bond Length
Replies: 3
Views: 17

### Re: Formal Charge vs. Oxidation number vs. Bond Length

Hi Linette! I’m not too sure, but I believe that we can use oxidation states to evaluate which Lewis structures are consistent with general oxidation state rules (oxygen usually has an oxidation state of -2 in compounds, monatomic ions have oxidation states equal to their ionic charges, etc.). If th...
Sun Nov 15, 2020 6:50 pm
Forum: Lewis Structures
Topic: Sapling weeks 5/6 Question 4
Replies: 6
Views: 78

### Re: Sapling weeks 5/6 Question 4

Hi! I believe the question is simply asking how closely the expected values match the observed ones. If the bond has “ample” character of the expected, then it would show bond lengths only somewhat similar to the specified observed; if the bond has “overwhelming” character of the expected, then it w...
Sun Nov 15, 2020 6:35 pm
Forum: Ionic & Covalent Bonds
Topic: Hydrogen Bonding
Replies: 13
Views: 65

### Re: Hydrogen Bonding

Hi! To my understanding, it is the combination of electronegativity and size that allow N, O, and F specifically to form hydrogen bonds. F, O, and N are some of the elements with the greatest electronegativity, and they are also unique in that they have relatively small sizes compared to other also-...
Sun Nov 08, 2020 8:28 pm
Forum: Trends in The Periodic Table
Topic: Tips for learning the trends in the Periodic table
Replies: 11
Views: 69

### Re: Tips for learning the trends in the Periodic table

Hi! Like others have mentioned above, I personally try to understand the concepts to apply when looking at the periodic table, but for memorization, I just stick to general directions on the period table. For example, as you move upwards and to the right on the periodic table, the atomic radius beco...
Sun Nov 08, 2020 8:25 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Effective Nuclear Charges Between Orbitals
Replies: 3
Views: 39

### Re: Effective Nuclear Charges Between Orbitals

Hi! I believe that electrons in 3d would have a greater effective nuclear charge than electrons in the 4s orbital, because as electrons exist in energy levels farther away from the nucleus, the greater distance reduces the attraction. So in the case of scandium, the electron in 3d should experience ...
Sun Nov 08, 2020 8:22 pm
Forum: Quantum Numbers and The H-Atom
Topic: ml and number of possible electrons
Replies: 6
Views: 51

### Re: ml and number of possible electrons

Hi! I believe you are right. When ms is not specified, there will be two possible electrons with the same ml quantum number, as ms refers to the electron spin (either up or down).
Sun Nov 08, 2020 8:19 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 4s before 3d Orbital
Replies: 11
Views: 88

### Re: 4s before 3d Orbital

Hi! Like other people have said, I believe that this means that the electrons fill up the 4s orbital before the 3d orbital because 4s has lower energy than 3d. Hope this helps!
Sun Nov 08, 2020 7:10 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: The orbitals
Replies: 8
Views: 67

### Re: The orbitals

Hi! I believe that of all the information we are responsible for regarding orbitals, we especially need to be familiar with information like the number of orbitals in s/p/d/f, the location of the spdf blocks on the periodic table, etc.  As for 2s, the 2 refers to the 2nd energy level, and the s refe...
Sun Nov 01, 2020 9:39 pm
Forum: Photoelectric Effect
Topic: N initial vs. N final
Replies: 7
Views: 91

### Re: N initial vs. N final

Hi! Yes, it depends on whether the electron is emitting or absorbing energy; if it is emitting energy, the electron will drop energy levels, and if it is absorbing energy, the opposite will be true. To identify the initial energy state, consider whether we know if we are referring to the Lyman or Ba...
Sun Nov 01, 2020 9:36 pm
Forum: DeBroglie Equation
Topic: Sapling Week 2-4 HW Question 24
Replies: 11
Views: 127

### Re: Sapling Week 2-4 HW Question 24

Hi! I think that the bottom two in the right column would not be compatible—in order for the wave patterns to be compatible, they should be continuous and consistent in amplitude and wavelength. I try to imagine copy-pasting the graphs side by side to see if it would create a function resembling a s...
Sun Nov 01, 2020 9:32 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Sapling #24
Replies: 16
Views: 73

### Re: Sapling #24

Hi! I believe that for the wave patterns to be compatible, they must be continuous and consistent in amplitude/wavelength. Personally, I imagined copy-pasting the graph side by side; if this would create a continuous and consistent function resembling a sin function, it would be compatible.
Sun Nov 01, 2020 9:28 pm
Forum: Electron Configurations for Multi-Electron Atoms
Replies: 6
Views: 51

Hi! I believe that the ionic radius simply refers to the distance between the nucleus and outermost electrons. For ionic compounds made up of two or more different kinds of ions, this definition should still hold true.
Sun Nov 01, 2020 9:23 pm
Forum: Trends in The Periodic Table
Topic: Tips for remembering
Replies: 14
Views: 106

### Re: Tips for remembering

Hi! Personally, I just memorize the trend directionally; as you move to the right and upwards on the periodic table, the atomic radius decreases. The opposite is true for electron affinity and ionization energy.
Sun Oct 25, 2020 1:54 am
Forum: DeBroglie Equation
Topic: Textbook Question 1B.15
Replies: 6
Views: 73

### Re: Textbook Question 1B.15

Hi! I think the question is just asking for the energy work function, given that the frequency is 2.50 x 10^16 Hz. To solve for the energy, you would probably just use E = hv.
Sun Oct 25, 2020 1:46 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Amplitude
Replies: 16
Views: 85

### Re: Amplitude

Hi! I don’t believe that amplitude is related to frequency or wavelength. To my understanding, increasing amplitude simply means increasing intensity.
Sun Oct 25, 2020 1:44 am
Forum: Photoelectric Effect
Topic: Photoelectric Effect Problem
Replies: 6
Views: 67

### Re: Photoelectric Effect Problem

Hi! I’m not entirely sure because I used a different approach than the ones described above, but I got the same answer as Xinyu^. These were my steps: 1. Convert the work function from eV to joules (1.7624x10^-19 J). 2. Use the wavelength of the incident light to solve for the frequency of the incom...
Sun Oct 25, 2020 1:25 am
Forum: Einstein Equation
Topic: Textbook Problem 1A.3
Replies: 9
Views: 55

### Re: Textbook Problem 1A.3

^ Hi! I believe the correct answer should be C because frequency in EM radiation refers to the number of cycles that occur within a given amount of time. If the frequency decreases, there are fewer cycles taking place in this interval of time and the waves broaden. Thus, the extent of change that ha...
Sun Oct 25, 2020 1:19 am
Forum: Properties of Light
Topic: Textbook Question 1A.5
Replies: 5
Views: 36

### Re: Textbook Question 1A.5

Hi! I’m not sure about memorizing all the specific wavelengths/frequencies, but I think it would probably be helpful to know at least the order of the EM spectrum, and perhaps a general estimate of wavelengths in the context of the Lyman and Balmer series.
Sun Oct 18, 2020 3:24 pm
Forum: Photoelectric Effect
Topic: Light Intensity
Replies: 23
Views: 109

### Re: Light Intensity

Hi! Yes, I believe that it was only the brightness (intensity) of the light that was increasing, not the actual frequency/wavelength.
Sun Oct 18, 2020 3:22 pm
Forum: DeBroglie Equation
Topic: Names of equations
Replies: 8
Views: 39

### Re: Names of equations

Hi! I’m not sure that we need to memorize the names of the equations—I believe they are given. However, it’s probably a good move to be familiar enough with each one to be able to quickly identify and apply them if the question asks for a specific one.
Sun Oct 18, 2020 3:18 pm
Forum: Einstein Equation
Topic: m vs nm
Replies: 66
Views: 453

### Re: m vs nm

Hi! I believe either is fine, unless the question specifically asks for one over the other. As others have said, though, I think many of the test questions will be multiple choice, so it might not be an issue at all.
Sun Oct 18, 2020 3:16 pm
Forum: Student Social/Study Group
Topic: How are you studying?
Replies: 203
Views: 1291

### Re: How are you studying?

Hi! I was planning on taking notes as I watched the lectures and then annotating my notes after all the lectures to see which parts I am least familiar with. (Unfortunately, my iPad deleted all my notes so now I have no lecture notes to review.) I think that doing practice problems is the most effec...
Sun Oct 18, 2020 3:11 pm
Forum: Properties of Light
Topic: Energy from shorter wavelength
Replies: 5
Views: 47

### Re: Energy from shorter wavelength

Hi! To my understanding, the higher energy of a shorter wavelength refers to the energy of the photon :)
Fri Oct 09, 2020 11:31 pm
Forum: SI Units, Unit Conversions
Topic: Kg to g
Replies: 13
Views: 138

### Re: Kg to g

Hi! In order to calculate between kilograms and grams by hand, you can multiply by the conversion factor of 1 kg/1000 g or 1000 g/1 kg. You can think about it in terms of canceling out units. So to go from kg to g, we would multiply by (1000 g/1 kg); to go from g to kg, we would multiply by (1 kg/10...
Fri Oct 09, 2020 12:39 am
Forum: Balancing Chemical Reactions
Topic: Naming compounds
Replies: 21
Views: 192

### Re: Naming compounds

Hi! I don’t think we are required to know how to name and identify compounds for exams just yet (based on what Dr. Lavelle mentioned before), but it would probably be helpful to brush up on some basic nomenclature anyway :)
Fri Oct 09, 2020 12:34 am
Forum: Limiting Reactant Calculations
Topic: Limiting reactants in all chemical rxns?
Replies: 18
Views: 148

### Re: Limiting reactants in all chemical rxns?

Hi! I think it would be extremely improbable for a chemical reaction to not have a limiting reactant. To do so would require having exact quantities of reactants that perfectly align with the stoichiometric ratios in a given equation, and reaching this point of precision is pretty unlikely. As such,...
Fri Oct 09, 2020 12:30 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Moles vs molecules
Replies: 14
Views: 152

### Re: Moles vs molecules

Hi! Molecules are atoms that are bound together in a group. A mole is essentially a unit representing set quantity of anything (6.022x10^23 “things”).
Fri Oct 09, 2020 12:15 am
Forum: SI Units, Unit Conversions
Topic: Sig figs and molar mass
Replies: 18
Views: 101

### Re: Sig figs and molar mass

Hi! Like others, I’ve been using as many decimal points as detailed in the period table posted on the class website. I assume that that is the periodic table we use for this class, so I stick to those values.