CHEMISTRY COMMUNITY

Leela_Mohan3L

A salt of a weak acid contains a strong conjugate base as its anion. This strong conjugate base is good at pulling a proton off H2O and thus OH- ions will be produced, making the solution basic. A salt of a weak base contains a strong conjugate acid, which is good at giving protons to H2O. This will...

Leela_Mohan3L

Ligands are lewis bases that donate an electron pair to a transition metal cation (lewis acid) and form a coordinate covalent bond with it. Multiple ligands can bond to the same transition metal cation, which forms a coordination complex. In terms of which ligands you need to know about, refer to &q...

Leela_Mohan3L

I think its because the bromide ion is the anion of a strong acid, not a weak acid. Thus, it is ineffective at pulling a proton off water. This leaves the solution as neutral? In general, strong acids have weak conjugate bases.

I'm not completely sure though so someone correct me if I'm wrong.

Leela_Mohan3L

Thank you! Does the compound in number 31 have a net charge? [Ni (NH3)5 NO2]^+2 Because the Nickel has a 3+ charge and the NO2 has a 1- charge, it brings it to a net charge of 2+. NH3 has no charge. I hope this helps. Please correct me if I made a mistake. Thanks That's what I was thinking as well....

Leela_Mohan3L

Thank you! Does the compound in number 31 have a net charge?

Leela_Mohan3L

I read something about the CH3 functional group having "electron donating properties," which destabilizes the conjugate base anion, but I don't really understand how that works.

Leela_Mohan3L

How do you go about doing #3 in the acid/base section?

Leela_Mohan3L

Specifically, how do you determine whether the shape is tetrahedral or square planar. How do you know how many lone pairs are on the transition metal cation in the center?

Leela_Mohan3L

The shape of the ligand (or rather, where each atom is placed) does affect whether a molecule is mono/bi/tridentate! For example, if you had a ring-shaped ligand that had a binding site on one end and another binding site on the complete opposite end, then the molecule is monodentate (This is becau...

Leela_Mohan3L

I know that it has to do with the amount of ligands with lone pairs, but does the shape of the ligand matter as well when determining whether it is bidentate or tridentate?

Leela_Mohan3L

The concentration of HCl is reduced to 12% of its initial value by dilution. By what amount does the pH of the solution change.

Leela_Mohan3L

The dipole direction goes towards the more electronegative atom. For example, if you have HF, the dipole would be pointing towards fluorine since it is more electronegative than Hydrogen. Thus, the Hydrogen would be delta positive and the Fluorine would be delta negative.

Leela_Mohan3L

Molecular shape takes into account the atoms that are bonded to the central atom, whereas electron geometry takes into account the atoms bonded to the central atom as well as lone pairs around the central atom. Let's use the lewis structure of H2O as an example. The molecular geometry for an H2O mol...

Leela_Mohan3L

The intermolecular forces between molecules are what determine the state of something. Generally, the stronger the intermolecular forces, the more likely something will be a solid at room temperature or have a higher boiling point.

Leela_Mohan3L

We will be going into that probably some time next week.

Leela_Mohan3L

What determines the strength of dipole dipole forces?

Leela_Mohan3L

Why do more electrons make an atom/molecule more polarizable though? I get how the size of the atom relates to polarizability but not how the amount of electrons are related to it.

Leela_Mohan3L

If the mass composition doesn't add up to 100% then that is an indication that there is another element present in the compound. Depending on the problem, you would be able to tell which element is missing. Ex: if the problem was asking you to find the molecular formula of a compound that was burned...

Leela_Mohan3L

Ionization energy increases from left to right because the amount of protons is increasing, and thus the nuclear charge increases. As a result, the electrons are more attracted to the nucleus, which makes them more difficult to remove. Electronegativity increases from left to right for the same reas...

Leela_Mohan3L

Would we be expected to know how to draw complex lewis structures (like Glycine H2C(NH2)COOH) on the midterm?

Leela_Mohan3L

Would we be expected to know how to draw complex lewis structures (like Glycine H2C(NH2)COOH) on the midterm?

Leela_Mohan3L

O has an even amount of valence electrons (6) while Cl has an odd amount of valence electrons (7). Thus, Cl is the radical since it has an odd amount of valence electrons.

Leela_Mohan3L

O has an even amount of valence electrons (6) while Cl has an odd amount of valence electrons (7). Thus, Cl is the radical since it has an odd amount of valence electrons.

Leela_Mohan3L

An atom will lose electrons from the subshell with a higher energy. Thus, if an atom has electrons in the 3d and 4s shells, it will lose electrons from the 4s subshell when being ionized because the 4s subshell has a higher energy.

Leela_Mohan3L

All of these atoms have the same amount of electrons, so you can look at the number of protons as an indicator of atomic radius. When going across a period, more protons --> smaller atomic radius. This is because the amount of protons increases the nuclear charge which increases the attraction of th...

Leela_Mohan3L

This is because carbon has an empty 2p orbital that can be filled with an electron. A half filled 2p subshell is more stable than a partially filled 2p subshell. Nitrogen, on the other hand, does not have an empty orbital to accomodate an electron and thus has a lower affinity for electrons.

Leela_Mohan3L

On his website there is a document titled "Solution Manual Errors" and that question is listed in there. So when doing problems like this you would use the method that Dr. Lavelle taught us!

Leela_Mohan3L

The Lyman series refers to the wavelengths of light that are absorbed by hydrogen in the Ultraviolet spectrum . The principal quantum number for this series is n=1, meaning that whenever one of the specific wavelengths in this series is absorbed by hydrogen, an electron will jump from the n=1 energy...

Leela_Mohan3L

Copper (I) has a +1 charge, so in order to get this charge you have to remove one electron. Copper (II) has a +2 charge, so you have to remove two electrons.

Leela_Mohan3L

The mass of an electron is provided on the formula sheet that's on Dr. Lavelle's website, and it will be given to us on the test!

Leela_Mohan3L

I think he said something about how the word "uncertainty" makes it seem like we don't know anything about the particle's momentum or position, when in reality we can approximate it.

Leela_Mohan3L

When would you use λ = c/v to find wavelength and when would you use λ = hc/E to find wavelength? Are they both referring to the wavelength of a photon?

Leela_Mohan3L

There is a way to modify this equation to make it work for one electron ions, however I believe we will only have to know the equation for Hydrogen atoms.

Leela_Mohan3L

Threshold energy is the amount of energy required to remove an electron from an atom of a certain material. The electron will only be removed if the light source has enough energy to overcome this threshold energy.

Hope that helps!

Leela_Mohan3L

Yes they will be, according to past students.

Leela_Mohan3L

Hi Adrienne. According to the photoelectric effect, light is made up of photons. When you have light with a long wavelength, the photons in that light do not have sufficient energy to remove an electron from an atom of a metal. When you increase the amplitude of this light wave (aka the intensity of...

Leela_Mohan3L

In this problem, you can determine the molecular formula of caffeine by finding the grams of Carbon, Hydrogen, and Nitrogen that are present. Once you add these masses up, you'll see that they do not equal the total mass of the initial hydrogen compound and therefore there has to be another element ...

Leela_Mohan3L

If you have water being poured from a bucket with a large opening into a cup that sits on top of a scale, the reading on the scale will gradually increase as the amount of water in the cup increases. However, if you decrease the opening of that bucket so much so that only one molecule of H20 can com...

Leela_Mohan3L

Question: Practitioners of the branch of alternative medicine known as homeopathy claim that very dilute solutions of substances can have an effect. Is the claim plausible? To explore this question, suppose that you prepare a solution of a supposedly active substance, X, with a molarity of 0.10 mol/...

Leela_Mohan3L

This makes a lot of sense, thank you! So in general, if we aren't sure what elements are included in an unknown compound, we should calculate the masses of each individual element and then add them up in order to verify that they equal the mass of the initial unknown compound? I hope my question mak...

Leela_Mohan3L

Question: A stimulant in coffee and tea is caffeine, a substance of molar mass 194 g mol 1. 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 it...

Leela_Mohan3L

Calcium sulfide is an ionic compound. You know this because it consists of a cation (calcium) and an anion (sulfide). Calcium as a 2+ charge and sulfide has a 2- charge. An ionic compound must have a net charge of 0, therefore you get CaS.

Leela_Mohan3L

Question: The psychoactive drug methamphetamine which is sold as the prescription medication Desoxyn C10H15N, undergoes a series of reactions in the body; the net result of these reactions is the oxidation of solid methamphetamine by oxygen gas to produce carbon dioxide gas, liquid water, and an aqu...

Leela_Mohan3L

I began this problem by multiplying 1.00 mol of Ag by Avogadro's number to get 6.022x10^23 atoms of Ag. Then I multiplied that by 2(144 pm)--144 pm is the radius of the atom, so to get the total length of the atom you have to double it. The end result was 1.73x10^26 pm, which is equal to 1.73x10^11 ...

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