Search found 67 matches
- Sat Dec 07, 2019 9:35 pm
- Forum: Administrative Questions and Class Announcements
- Topic: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]
- Replies: 115
- Views: 13318
Re: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]
On question number 21 of the Marshmallow review. Why does iron have a +2 charge if two of the nitrogens on the porphyrin ligand have a +1 charge?
- Wed Dec 04, 2019 7:24 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Polydentate vs Monodentate
- Replies: 1
- Views: 131
Polydentate vs Monodentate
What is the best way or method to determining if a polydentate is monodentate or polydentate?
- Mon Dec 02, 2019 4:11 pm
- Forum: Conjugate Acids & Bases
- Topic: Identifying conjugate acids & bases
- Replies: 3
- Views: 220
Re: Identifying conjugate acids & bases
I thought HCN reacted with H2O to form CN- and H3O^+. So if this is the case, I'd say water is a base because it accepts a proton to form a Hydronium atom. But if it forms a hydroxide ion like you say, then it would be considered an acid, as it would donate one of its hydrogens to form the hydroxide.
- Mon Dec 02, 2019 4:08 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: 6C.17
- Replies: 1
- Views: 131
Re: 6C.17
When I first approached this problem I was a bit confused. When looking in the solutions manual, they took the pKb of both morphine and BrO^- and compared the two. The one with the smaller pKb was the stronger base, which in this case happened to be BrO^- (hypobromite ion).
- Mon Dec 02, 2019 4:05 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Value of Kw?
- Replies: 4
- Views: 624
Re: Value of Kw?
Yes, this is the value that is always used because it is a constant.
- Mon Dec 02, 2019 4:03 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: 6C.21
- Replies: 1
- Views: 188
Re: 6C.21
For part A, trichloroacetic acid is a stronger acid than acetic acid because the CCl3 group bonded to the carboxyl group is more electron withdrawing than the CH3 group bonded to the carboxyl group in acetic acid. For part B, formic acid is a bit stronger than acetic acid because the CH3 group bonde...
- Mon Dec 02, 2019 3:59 pm
- Forum: Lewis Acids & Bases
- Topic: 6A.5
- Replies: 1
- Views: 145
Re: 6A.5
For part A, the bronsted acid is HNO3 because it donates a proton to form NO3^-, and HPO4^2- is the bronsted base because it accepts a proton to become H2PO4^-. For part B, the conjugate acid to HPO4^2- is H2PO4^-, and the conjugate base to HNO3 is NO3^-
- Mon Dec 02, 2019 3:52 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Why water is monodentate
- Replies: 1
- Views: 116
Re: Why water is monodentate
Yes exactly. Only one lone pair will be able to bond at a time
- Tue Nov 26, 2019 3:40 pm
- Forum: Naming
- Topic: Final Exam
- Replies: 3
- Views: 220
Final Exam
Are we expected to memorize that chart in our textbook that provides all the names when naming coordination compounds?
- Tue Nov 26, 2019 3:37 pm
- Forum: Bronsted Acids & Bases
- Topic: Forming a neutralization reaction
- Replies: 2
- Views: 180
Forming a neutralization reaction
For our final, are we going to have to know how to select the correct acid and base for an equation if a question asks us to "write a neutralization reaction that results in the formation of..."?
- Tue Nov 26, 2019 3:27 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Atoms in the same plane
- Replies: 4
- Views: 9244
Re: Atoms in the same plane
I'm pretty sure that to determine whether or not atoms are in the same plane you have to see if there is the presence of a pi bond, which results from either a double or triple bond between atoms. Otherwise, if there is just a single bond/sigma bond, the atoms are free to rotate.
Re: HW 9c.9
The coordination number should be 6. I believe this is because the chloride ligands are monodentate while the ethylene diamine ligands are bidentate.
Re: 9C.3
My best bet is that it is simply put in that order for the chemical formula based off of alphabetical order.
- Tue Nov 19, 2019 9:25 pm
- Forum: General Science Questions
- Topic: Test 2
- Replies: 7
- Views: 588
Re: Test 2
I believe you have to have the shapes memorized.
- Tue Nov 19, 2019 9:24 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Question 2.45
- Replies: 2
- Views: 239
Re: Question 2.45
Yes, you just want to draw the lewis structure that is most stable/least energy.
- Tue Nov 19, 2019 8:08 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Dipole-dipole interacting species
- Replies: 2
- Views: 146
Re: Dipole-dipole interacting species
i'm not completely sure, but I believe the rotating vs stationary polar molecules probably does have to do with whether or not there is just a sigma bond present or if pi bonds are also present.
- Tue Nov 19, 2019 8:07 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Dipole-Dipole and induced dipole
- Replies: 4
- Views: 264
Re: Dipole-Dipole and induced dipole
There is a permanent electric dipole moment pointing along the C-Cl bond, thus it is not induced.
- Tue Nov 19, 2019 8:03 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Why T-shape?
- Replies: 4
- Views: 315
Re: Why T-shape?
The T-shape allows the two lone pairs of electrons to be farthest apart if they occupy two of the three equatorial positions. If they were to occupy axial positions, there would be great repulsion by the electrons.
- Tue Nov 19, 2019 8:00 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E: Question 29
- Replies: 3
- Views: 237
Re: 2E: Question 29
Yes, that is exactly why 1 has a larger dipole moment than 2 in this problem.
- Tue Nov 19, 2019 6:17 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: induced dipole-induced dipole
- Replies: 4
- Views: 275
induced dipole-induced dipole
Typically, when do induced diple-induced dipole interactions occur/arise?
- Wed Nov 13, 2019 3:49 pm
- Forum: DeBroglie Equation
- Topic: Midterm 2019 Question 3A
- Replies: 2
- Views: 370
Midterm 2019 Question 3A
I am unsure why the solutions manual to the midterm is using (9.109 X 10^-34 kg) when using the De Broglie Equation instead of using (9.109 X 10^-31 kg), which is what we've been using on homework problems for questions like these?
- Tue Nov 12, 2019 3:41 pm
- Forum: Dipole Moments
- Topic: Types of Interactions
- Replies: 2
- Views: 246
Re: Types of Interactions
That is probably primarily the interactions we should be studying and focusing on, but it's probably helpful to try and at least understand the various interactions in that section.
- Tue Nov 12, 2019 3:40 pm
- Forum: Bond Lengths & Energies
- Topic: Boiling and Melting points
- Replies: 8
- Views: 442
Re: Boiling and Melting points
I'm not certain but we probably just need to know why certain interactions have higher melting and boiling points than others and potentially be able to determine between two or more interactions which one would likely have the higher melting and/or boiling point.
- Mon Nov 11, 2019 5:04 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Help of 3F.11
- Replies: 5
- Views: 186
Re: Help of 3F.11
An important thing to note is that hydrogen bonds form when an H bonds to either an N, O, or F and there must be lone pairs available for the H to bond to. Thus, this can only be true for d (HNO2).
- Mon Nov 11, 2019 5:02 pm
- Forum: Bond Lengths & Energies
- Topic: 2.25
- Replies: 2
- Views: 147
Re: 2.25
In part B, since the bonds are the same, you have to look at atomic radius size to distinguish which bond is longer. Since phosphorus is larger than nitrogen, the PF bond should be longer than the NF bond.
- Mon Nov 11, 2019 4:43 pm
- Forum: Dipole Moments
- Topic: Dipole moments
- Replies: 2
- Views: 166
Dipole moments
Do nonpolar molecules ever experience dipole moments or is it just for polar molecules?
- Mon Nov 11, 2019 4:40 pm
- Forum: Dipole Moments
- Topic: Textbook question 3F.19 part b
- Replies: 2
- Views: 88
Re: Textbook question 3F.19 part b
H2O contains hydrogen bonding, while C2H5OC2H5 only contains london dispersion forces. Therefore, C2H5OC2H5 contains weaker bonds than H2O and is thus not as tightly held together, allowing for a higher vapor pressure.
- Thu Nov 07, 2019 10:09 am
- Forum: Photoelectric Effect
- Topic: Midterm 1
- Replies: 9
- Views: 699
Re: Midterm 1
I struggled on this question also, but now looking back at it, I think you would calculate the energy per photon required, using the equation E=hv or E=hc/lambda. And once you find that, I believe you would divide the energy that was given to you (in Joules) by the calculated energy you just found (...
- Wed Nov 06, 2019 2:45 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: 1A.11
- Replies: 3
- Views: 320
Re: 1A.11
These series all of have the same energy level such as (n=1 or n=2).
- Wed Nov 06, 2019 2:44 pm
- Forum: Dipole Moments
- Topic: Dipole Moment
- Replies: 3
- Views: 238
Re: Dipole Moment
Well if you take the lewis structure of say a water molecule. The formal charges of the two Hs and the O are all zero, but a dipole moment still exists between the partial negative and partial positive charges.
- Wed Nov 06, 2019 11:14 am
- Forum: DeBroglie Equation
- Topic: Midterm Problem help
- Replies: 2
- Views: 246
Re: Midterm Problem help
This is what I did to solve the problem but I keep getting an answer of 3.77 X 10^14 instead of 6.78 X 10^14 and I don't know why.
- Wed Nov 06, 2019 9:37 am
- Forum: DeBroglie Equation
- Topic: Midterm Problem help
- Replies: 2
- Views: 246
Midterm Problem help
Hi, can someone please go step by step through this problem and show calculations. I keep using De Broglie's formula and getting the wrong answer: A newly designed laser pointer with a certain frequency is pointed at a sodium metal surface. An electron is ejected from the metal surface with waveleng...
- Tue Nov 05, 2019 4:23 pm
- Forum: Einstein Equation
- Topic: Rydberg Equation
- Replies: 1
- Views: 298
Rydberg Equation
When using the Rydberg Equation to find out the initial and final (n) values of energy for an electron during the emission of energy, is the equation: v=R[(1/n initial)^2-(1/n final)^2] or the opposite?
- Tue Nov 05, 2019 2:42 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Molecular Spectroscopy
- Replies: 1
- Views: 867
Re: Molecular Spectroscopy
I believe it just examines the absorption and emission patterns of molecules as opposed to just an atom.
- Mon Nov 04, 2019 5:41 pm
- Forum: Ionic & Covalent Bonds
- Topic: Names and chemical formulas
- Replies: 5
- Views: 448
Re: Names and chemical formulas
It is probably helpful to know them, but I feel that we will probably be given the formulas for solving problems. I'm not 100% sure though.
- Sun Nov 03, 2019 10:33 am
- Forum: Lewis Structures
- Topic: Bonds
- Replies: 4
- Views: 154
Bonds
When drawing Lewis Structures, how do we know when to use a double bond or triple bond vs just a single bond?
- Mon Oct 28, 2019 10:14 pm
- Forum: Trends in The Periodic Table
- Topic: Elemental Classification?
- Replies: 2
- Views: 159
Re: Elemental Classification?
I identify metalloids as the elements that fall into the diagonal zigzag on the right side of the periodic table. Metals are to the left of the zigzag, except for Hydrogen, and nonmetals are to the right of the zigzag.
- Mon Oct 28, 2019 4:06 pm
- Forum: Lewis Structures
- Topic: Homework problem 2C.3
- Replies: 5
- Views: 160
Homework problem 2C.3
On this homework problem, we are asked to draw lewis structures for ion like the periodate ion and the hydrogen phosphate ion, but the problem doesn't provide you with any formula for these ions. So, I'm wondering whether or not we are expected to just know the formulas of these ions?
- Mon Oct 28, 2019 3:51 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: hm
- Replies: 1
- Views: 127
Re: hm
When writing electron configurations it is okay to write [He]2s^2 2p^2 for carbon for instance, but conceptually you just need to know that electrons, when filling up the s, p, d, and f blocks do not want to be in the same orbital if possible. Thus, just think of the electrons as filling up the p-bl...
- Mon Oct 28, 2019 3:44 pm
- Forum: Photoelectric Effect
- Topic: Problem 1.31a
- Replies: 1
- Views: 205
Re: Problem 1.31a
In order to figure out which laser to use, you must solve for the energies of both the red ruby laser and the violet laser using the equation E=hc/lambda. Next you must convert the work function given in eV to joules. Once you have calculated all of these things, you look to see which of the two ene...
- Mon Oct 28, 2019 3:35 pm
- Forum: Trends in The Periodic Table
- Topic: Question 2B.9
- Replies: 3
- Views: 285
Re: Question 2B.9
I just placed the potassium atoms floating outside of/around the central phosphorous atom and then bracketed each atom to show the individual charges.
- Wed Oct 23, 2019 9:13 am
- Forum: Trends in The Periodic Table
- Topic: Ionization Energy [ENDORSED]
- Replies: 3
- Views: 182
Ionization Energy [ENDORSED]
I understand why Ionization Energy decreases down a group, but why does it increase across a period?
- Wed Oct 23, 2019 9:11 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Exceptions to Electron Configurations
- Replies: 3
- Views: 118
Exceptions to Electron Configurations
What is the reasoning behind why the elements of Cr and Cu have different electron configurations than the rest of the elements in the 3d block? For instance why is Cr's electron configuration: [Ar]3d^5 4s^1 instead of [Ar]3d^4 4s^2?
- Mon Oct 21, 2019 10:22 pm
- Forum: Trends in The Periodic Table
- Topic: Ionization Energies Trend
- Replies: 5
- Views: 220
Re: Ionization Energies Trend
As you move from left to right across a period the nuclear charge of an atom increases, which trumps the shielding effect. Thus, ionization energy tends to increase across a period due to this increase in charge across a period.
- Mon Oct 21, 2019 3:22 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Format
- Replies: 11
- Views: 516
Re: Midterm Format
I am not exactly sure what units will be covered on the midterm, but anything we have learned or have gone over/will go over in class before the midterm I would say is fair game for a test question. From what I've heard, the midterm is similar in structure to our test, but with multiple different pa...
- Mon Oct 21, 2019 3:12 pm
- Forum: *Shrodinger Equation
- Topic: Week 4 Homework
- Replies: 3
- Views: 134
Re: Week 4 Homework
I believe we can turn in quantum problems, especially since this Monday's lecture was still over quantum material. In addition, if he starts on a new focus topic, we can probably also submit problems under that.
- Thu Oct 17, 2019 8:48 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: electron configurations
- Replies: 3
- Views: 189
electron configurations
How do you determine what orbital an electron would be removed from to form a +1 ion for an element?
- Wed Oct 16, 2019 10:01 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: subshell calculations
- Replies: 2
- Views: 131
subshell calculations
How do you calculate the number of subshells present when given an n-value (for instance, n=6)?
- Wed Oct 16, 2019 9:26 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: uncertainty
- Replies: 3
- Views: 131
Re: uncertainty
To calculate uncertainty, you would use Heisenberg's Indeterminacy Equation, which is delta p (indeterminacy in momentum)* delta x (indeterminacy in position)= h (planck's constant)/4pi. This equation is used because there is a limit on the accuracy to which momentum and position of a particle can b...
- Tue Oct 15, 2019 10:26 am
- Forum: SI Units, Unit Conversions
- Topic: Conversion
- Replies: 2
- Views: 134
Re: Conversion
In order to convert a number from meters to nanometers, you would utilize dimensional analysis and divide the number in meters by 10^-9 because that is the conversion factor. So you would divide (2.26*10^-46 m)/(1*10^-9) to convert from meters to nm. The good thing about conversionn/unit factors is ...
- Tue Oct 15, 2019 10:20 am
- Forum: Photoelectric Effect
- Topic: HW 1B.5
- Replies: 8
- Views: 370
Re: HW 1B.5
I believe they multiplied that number by 10^3 because of the fact that it is keV, thus to get from keV to just eV you would need to multiply that number by 10^3.
- Mon Oct 14, 2019 9:22 pm
- Forum: Properties of Electrons
- Topic: calculating frequency
- Replies: 3
- Views: 263
calculating frequency
Say you are asked to calculate the frequency of a photon emitted by a hydrogen atom after making a transition from a higher energy level to a lower energy level. Well when using the Rydberg equation you would get a negative energy because energy is being emitted. But my question is could you get a n...
- Mon Oct 14, 2019 9:15 pm
- Forum: Properties of Electrons
- Topic: atomic spectroscopy
- Replies: 5
- Views: 414
atomic spectroscopy
Can someone please help me answer this question: Can atomic spectroscopy be used to identify elements? If so why is it possible?
- Mon Oct 14, 2019 8:47 pm
- Forum: Properties of Electrons
- Topic: ER spectrum
- Replies: 1
- Views: 154
ER spectrum
So I'm working on the quantum modules on the class website, and I need help with this question: The meter was defined in 1963 as 1,650,763.73 wavelengths of radiation emitted by krypton-86 (it has since been redefined). What is the wavelength of this krypton-86 radiation? To what region of the elect...
- Sat Oct 12, 2019 2:07 am
- Forum: Properties of Electrons
- Topic: Mass of Electron in De Broglie Equation
- Replies: 4
- Views: 169
Re: Mass of Electron in De Broglie Equation
The mass of ann electron is given on the formula sheet. So if you just pull out the formula sheet it should be there. It's probably helpful to learn, but I wouldn't worry too much because with all of our exams we are supposed to be given a formula sheet.
- Wed Oct 09, 2019 5:50 pm
- Forum: Properties of Electrons
- Topic: electron energy [ENDORSED]
- Replies: 7
- Views: 535
Re: electron energy [ENDORSED]
When moving up energy levels, an electron absorbs energy (gains/increases in energy). If an electron falls down an energy level, it emits energy as a photon (loses energy).
- Mon Oct 07, 2019 9:45 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 1
- Replies: 1
- Views: 97
Re: Test 1
We are supposed to be provided with a formula sheet, but I would recommend learning the units just in case.
- Mon Oct 07, 2019 8:59 pm
- Forum: Properties of Light
- Topic: Photons
- Replies: 7
- Views: 333
Re: Photons
By increasing intensity, more electrons may be emitted, but that does not mean that their energies have increased. Frequecy would need to increase for this to happen.
- Mon Oct 07, 2019 8:55 pm
- Forum: Balancing Chemical Reactions
- Topic: Fundamentals H.11
- Replies: 3
- Views: 150
Re: Fundamentals H.11
No, you would not carry the two over to the next equation because this is a completely new equation. Thus, recommend writing the new equation out without any stoichiometric coefficients initially and then balance if needed.
- Mon Oct 07, 2019 8:53 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Dilution Calculatons
- Replies: 2
- Views: 127
Re: Dilution Calculatons
So what you want to do first is find the molarity of NH4NO3 after it has been diluted by using the equation (MiVi=MfVf). Thus, the diluted NH4NO3 solution concentration= (.2M x 1L)/4L=.05M. Next, you are going to find the number of moles present of NH4NO3 using only 100 mL. To find this, you would m...
- Fri Oct 04, 2019 9:31 pm
- Forum: Empirical & Molecular Formulas
- Topic: Homework Problem L39
- Replies: 2
- Views: 269
Homework Problem L39
So I just worked out this homework problem without any problems, but my question is that on part B of the question it asks me to write the name of the oxide produced from a chemical reaction after finding the empirical formula. So my question is do we have to know how to name different oxides just b...
- Wed Oct 02, 2019 3:45 pm
- Forum: SI Units, Unit Conversions
- Topic: rounding of the elements. [ENDORSED]
- Replies: 6
- Views: 218
rounding of the elements. [ENDORSED]
So when I normally solve homework problems involving the molar mass of elements of compounds, I use all of the numbers given for each element (without rounding initially) to solve for a problem. But in the solution manual, sometimes I will get a different answer that is only off by a few decimal poi...
- Mon Sep 30, 2019 3:29 pm
- Forum: Empirical & Molecular Formulas
- Topic: Fundamentals L.39
- Replies: 2
- Views: 89
Re: Fundamentals L.39
When looking at the solution manual, I believe you must find the moles of tin and oxygen in their elemental form, which is why 16.00 g of oxygen is used as opposed to 32.00. And then with those moles, you would take the smaller of the two mole values and divide both by whatever the smallest number w...
- Mon Sep 30, 2019 3:17 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Homework problem E23
- Replies: 5
- Views: 253
Re: Homework problem E23
When given the correct balanced equation, I just look at the stoichiometric coefficients of whatever element(s) or compound(s) I am making a ratio for because those coefficients give the correct number of moles for that element or compound.
- Sun Sep 29, 2019 8:26 pm
- Forum: Significant Figures
- Topic: Rounding the elements
- Replies: 12
- Views: 875
Re: Rounding the elements
Yeah, I personally try to use all of the digits given to me on the periodic table for an element/elements (specifically Lavelle's periodic table), and then I use as many steps as needed to solve the equation, without rounding whatsoever, until the very end, in which I will then round my answer as ne...
- Sat Sep 28, 2019 4:27 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: HW Question: G5 (Part A)
- Replies: 3
- Views: 134
Re: HW Question: G5 (Part A)
So in the solutions manual for homework problems, what is the equation that was used with this: "V=(2.15*10^-3 mol Na+(1 mol NaCO3))/(0.07967 mol*L^-1 Na2CO3)(2 mol Na+)?
- Sat Sep 28, 2019 4:00 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: mass of solute
- Replies: 3
- Views: 83
mass of solute
I need help understanding part of the solving explanation on example problem G.2 in our chem textbook. The question states "Very dilute solutions of CuSO4 are used to control algal growth in fish tanks. Suppose you are investigating the optimum concentration that will control the algae but not ...