CHEMISTRY COMMUNITY

Ananta3G

Lauren Sanchez 3D wrote:I remember hearing about the term amphiprotic. What is the difference between amphiprotic and polyprotic?

polyprotic is the ability of an acid to donate multiple protons (H+) while amphiprotic means a substance can act as an acid and a base.

Ananta3G

Hi! Just wanted to know the difference between the two exactly? Also, to be amphiprotic does that mean you are automatically amphoteric or vise versa?

Ananta3G

Hello! I was just wondering if all chelating ligands are polydentate? Or vise versa? Also, what are the common chelating and/or polydenate ligands that we ought to know? Thanks!

Ananta3G

Hi! In the marshmallow review, question 36 asks about glycine. I don't understand why it is not polyprotic. Can someone explain? Thanks!

Ananta3G

Kinetic energy would be zero if the energy from the electromagnetic radiation was exactly equal to the work function of the metal. E = work function + KE of electrons so if E = work function, kinetic energy would be zero, and the energy of the radiation was just enough to remove the electron and not...

Ananta3G

Hi! Doing sig figs for pH seems like it would not be different than for any other problem. If you are given a concentration of H+ ions and it has 3 sig figs, your pH would also have 3 sig figs. I would not overthink it! Hope this answer helps.

Ananta3G

Hi! I was wondering if there was a general trend about polarity/being charged and acidic? For example, I know that C2H2 is more acidic than C2H4, but why? Thanks a ton!

Ananta3G

Hi! How can you tell if parts of a molecule are in the same plane or a different plane? Is it based on shape? bond angles? polarity? Thanks!

Ananta3G

Hi! Can someone explain how I would describe the shape of hemoglobin? Is it chelating? Is there a polydenate ligand? How do I know? And how does this shape relate to its function? How many O2s can one hemoglobin molecule bind? Thanks!

Ananta3G

Hi! How does one tell if an acid/base is polyprotic? Can someone give me some examples of acids and bases that meet these conditions? Thanks!

Ananta3G

Hi! Can someone help me figure out this problem? The two strands of the nucleic acid DNA are held together by hydrogen bonding between four organic bases. The structure of one of these bases, thymine, is shown below. (a) How many protons can this base accept? (b) Draw the structure of each conjugate...

Ananta3G

Hi! Can someone help me with this question? I got the Lewis Structures. Thank you! Draw the Lewis structure of boric acid, B(OH)3. (a) Is resonance important for its description? (b) The proton transfer equilibrium for boric acid is given in a footnote to Table 6C.1. In that reaction does boric acid...

Ananta3G

Why is the coordination number of the [PtCl2(en)2] 2+ ligand 6? Thanks!

Ananta3G

Hi! In question 9C.5, it asks if the following ligands can be polydendate and if they can, what is the maximum number of places it can bind? How do I go about figuring this this number out? Some of the ligands are H20 and oxalate. Thanks!

Ananta3G

Hi! What is the difference between the "types" or "definitions" of the acids and bases? I feel like the definitions are predicated on the same idea of being an electron donor or receiver so I am a bit confused. Thanks!

Ananta3G

Hi! I have tried reading the textbook and looking at my notes, and I am still a bit confused about how to name coordinate compounds. If someone could give me tips about how to go about it/the general strategy, that would be extremely helpful. Thank you! Hope everyone is having a wonderful break.

Ananta3G

Can someone explain what this question means & how to do it? Thank you! Which of the following ligands can be polydentate? If the ligand can be polydentate, give the maximum number of places on the ligand that can bind simultaneously to a single metal center: (a) HN(CH2CH2NH2)2 (b) CO32 (c) H2O ...

Ananta3G

Hi! Which topics and textbook sections should the week 9 homework be from? The week 10 one? Thanks

Ananta3G

While I don't think we need to know this aspect of the chemo drug because Lavelle did not really mention it, I think it's because the energy cost associated with using cisplatin is a lot lower than using transplatin. Also, I think the structure of cisplatin makes it able to actually bind to the Gs a...

Ananta3G

I think you can just say "bent" no matter if it is AX2E or AX2E2, but if asked to specify the electron geometry, you should state that it is trigonal planar for AX2E and tetrahedral for AX2E2. Hope this answer helps!

Ananta3G

I was a bit confused about why sigma bonds are generally stronger than pi bonds. Thanks!

Ananta3G

Yes, the molecular shape of the molecule will be linear. The electron geometry is trigonal bipyramidal, but that actual bond angle will be 180 degrees because of the molecular shape.

Ananta3G

In question 2.25 in the textbook, it says CH2Cl2 Is polar - why? In the answers, it shows the lewis structure diagram with the Hs next to each other and the Cls next to each other which would cause an uneven distribution of charge so it makes sense that it would be polar, but how would I know to arr...

Ananta3G

Hello! How does one figure out the bond angle of a certain molecular geometrical shape? I know you can find it based on what kind of shape it is ie linear = 180 degrees, but how do you know when it is slightly more or less than the typical/definitional bond angle given by the general shape? ie somet...

Ananta3G

Hi! I know there have been a few posts about what is on test two but I just wanted to clear it up. Are the topics polarizability/polarizing power, types of bonds/adding bonds, VESPR, and anything else? Thanks!

Ananta3G

Hi! For the a and b shapes, SCl4 and ICl3, how do I classify the molecular shapes/figure out what they are?

Ananta3G

Hi! So I understand that molecular shape is determined by the number of atoms the central atom is bonded to, I'm a little unsure of how you differentiate between for example, something that is planar or pyramidal, but both have 3 bonding pairs. Does it have to do with electronegativity? Or something...

Ananta3G

The class is graded on a straight scale out of 500 points ie if you get 465 points out of 500, you can get an A. Make sure to do the HW and post on chemistry community as those grades are good cushions to improve. Good luck! :)

Ananta3G

If you already have the Lewis Dot Drawing of the molecules correctly completed, you can just count the number of electrons around the atom by counting up each electron of the lone pair as one electron and each bonded pair as one electron as well ie 1 for a single bond, 2 for a double bond, etc. and ...

Ananta3G

Van Der Waals Interactions are small, intermolecular attractions caused by the electrical interactions between electrons and protons of near by molecules. They are super weak and on & off. They are, however, interchangeably known as dipole-dipole "moments" because it is the movement of...

Ananta3G

Hi! Can someone explain the answer to this question in a bit of detail? Thank you! Given that the length of a C–O single bond is 1.43 Å and a C=O double bond is 1.21 Å, comment on the length of the C–O bonds in carbonate.

Good luck everyone!

Ananta3G

Hi! These ones can be a bit tricky. Cu is an element with an exception where having a fully filled 3d shell is more stable so instead of the original electron configuration being [Ar] 3d9 4s2, it is [Ar] 3d10 4s1. Thus, when you make Cu+ you take away the electron in the 4s1 position leaving us with...

Ananta3G

How do you do this: Use the covalent radii in Fig. 2D.11 to calculate the bond lengths in the following molecules. Account for the trends in your calculated values: (a) CF4 (b) SiF4 (c) SnF4. Thank you!

Ananta3G

Can someone summarize/explain why certain elements can have incomplete octets and why some can have extended (overfilled) octets? I know there are exceptions, I am just unsure of which ones follow which exceptions and why. So if someone could summarize them, that would be AMAZING. Thank you!

Ananta3G

What is the answer to this question: An excited hydrogen atom emits a light with frequency 1.14x10^14 Hz to reach energy level n = 4. In what energy level did it begin?

Ananta3G

Hi! I am having a bit of trouble doing 1A.15 in the textbook. I know I need to use -hR/n^2, find the change in E, and that n initial is equal to 2 because the wavelength, 102.6 nm is in the ultraviolet spectrum. I am unsure of how to put it all together. Here is the question: In the ultraviolet spec...

Ananta3G

Hello! So I was doing this problem and I have two questions from it. One: what exactly is a radical and how can I tell it from the number of electrons/structure of the molecule and two: for the 3rd molecule, ClONO2, I drew it so that 2 of the 3 Os were double bounded together but the correct answer ...

Ananta3G

Also, the reason the electronegativity is so great ie more than 2 is because an ion bond is usually between a metal and a nonmetal.

Ananta3G

I am confused about what numbers to plug in where in the formal charge equation, especially what "1/2B" stands for in the equation. If someone could give an example for how to use the equation, that example would be spectacular. Thanks!

Ananta3G

If I am understanding the topic/your question correctly, the equation, En=hR/n^2, is the equation used to find the energy emitted by an H atom when an electron makes a transition from one quantum level to another. The equation does use the Rydberg Constant: 3.29 x 10^15 Hz. The equation in the textb...

Ananta3G

Hi! I am a little confused about how or when one would know to use a double or triple bond instead of a single bond. Thanks!

Ananta3G

Hi, for question 1E.17, it asks you to: predict the type of orbital (1s, 2p, 3d, 4f, etc.) from which an electron will be removed to form the +1 ion: (a) Ge; (b) Mn; (c) Ba; (d) Au. I was wondering if there was a better way to do it other than just writing out all the orbital and seeing where the co...

Ananta3G

Yes, the number of valence electrons increases as you go across a period which connects to the other trends that a) ionization energy increases as you cross a period from left to right because the outer shell is more and more stable because they are filling the octets of valence electrons and thus t...

Ananta3G

I recommend maybe writing all the equations down at the top of the sheet and then substituting/combining the equations as you see fit.

Ananta3G

In other words, adding another electron to an already half full orbital of electrons, it causes electron-electron repulsion which makes it easier for an electron to be removed or for the ionization energy to be much lower.

Ananta3G

Hey! I am having a bit of trouble understanding the difference between wave functions, orbitals, subshells, and shells. Which one is contained in the others? Are some bigger than others? What is a good organizational way to remember them? I just feel like I don't have a grasp on how all of them fit ...

Ananta3G

The equation gives you an answer in meters so you would need to convert the velocity from mph to m/s first. Then, in order for Planck's constant's units, J/Hz to cancel out the other units, you need to convert the mass to Kg, otherwise you would have one mass in ounce but a unit that uses Kg which w...

Ananta3G

Do the rules we learned about the different quantum values work for all atoms? Or just the ones with 1 e-? I know Lavelle mentioned it, but I am unsure where the "1 e-" fits in? Thanks!

Ananta3G

Hi in this question (1D.11), it asks " How many orbitals are in subshells with l equal to (a) 0; (b) 2; (c) 1; (d) 3?" What is l and how would I approach this problem? Thank you!

Ananta3G

Hello! So the way to approach this problem is as follows: You know that a 32 watt lamp can generate 32 J per second because 1 watt is equivalent to 1 joule/s. Thus, in 2 seconds, the lamp will emit 64 J of energy. Next, you need to find out how much energy is emitted per photon by using the wave len...

Ananta3G

Hi! This question is a little tricky with its wording, but here is how I reasoned it: Electromagnetic radiation is just another way of saying energy or in this case, we can take it to mean waves of light. Thus, for the first answer, the speed is always a constant so it does not change meaning that (...

Ananta3G

Hi! I understand I need to use the wavelength to get E for this problem, but I am unsure how to proceed after that step. Thank you! In the ultraviolet spectrum of atomic hydrogen, a line is observed at 102.6 nm. Determine the values of n for the initial and final energy levels of the electron during...

Ananta3G

Hi! While I understand that the photoelectric effect proves that light does not always act as a wave because changing the intensity did not make the electrons come off the metal, I wonder what the exact line of reasoning and logic is because I feel like I am missing a few steps in my understanding. ...

Ananta3G

This question is just testing if you understand that a) the stoichiometric coefficients before each product or reactant in the balanced equation tells you molar ratios and b) the limiting reactant controls how much product is formed. First, if there are 12 mol of of CIO2 and the reactants are in a 6...

Ananta3G

Yes! Both replies were so helpful, thank you so much. I can assume the product with nitrogen in it is N2, right? because it is a gas?

Ananta3G

A stimulant in coffee and tea is caffeine, a substance of molar mass 194 g/mol. When 0.376 g of caffeine was burned, 0.682 g of carbon dioxide, 0.174 g of water, and 0.110 g of nitrogen were formed. Determine the empirical and molecular formulas of caffeine, and write the equation for its combustion...

Ananta3G

Also, sometimes you might be given some information that could lead you to the threshold energy easily. For example, in the problem Lavelle showed in class today, the problem gave us the "energy needed to remove the electron" which is technically the threshold energy. Additionally, however...

Ananta3G

Hi! I am at a loss about how to do this problem: Sodium bromide, NaBr, which is used to produce AgBr for use in photographic film, can itself be prepared as follows: Fe+Br2→FeBr2 FeBr2+Br2→Fe3Br8 FeBr2+Na2CO3→NaBr+CO2+Fe3O4 What mass of iron, in kilograms, is needed to produce 2.50 t of NaBr? Note t...

Ananta3G

Hello! I am in a similar boat as you are & I found that the D section in the Fundamentals in the textbook was a really helpful read for brushing up on naming so definitely look into those pages & maybe do some of the exercises there. Some other tips to remember: Ionic compounds are named by ...

Ananta3G

The camel stores the fat tristearin, C57H110O6, in its hump. As well as being a source of energy, the fat is also a source of water because,when it is used, the reaction 2C57H110O6(s)+163O2(g)→114CO2(g)+110H2O(l)2 takes place. (a) What mass of water is available from 1.00 pound (454 g) of this fat? ...

Ananta3G

Hi! Just remember in general for sig figs, zeroes after the decimal are significant if they are trailing (the last number). Thus, the first zero in your answer 0.0981 is not significant so having the .0001 at the end allows you to have 3 sig figs which you need to have because in 10.0, both zeroes a...

Ananta3G

I am generally unsure which equation to use to solve this problem. I understand that I should find out how many moles of sodium carbonate there are in the solution and then the molarity of it, but I am a bit lost about how to go from there. Here the the question: A student prepared a solution of sod...

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