CHEMISTRY COMMUNITY

Midori Hupfeld 3D

I think Lyndon said that you can use either. I think it would be useful to just know the coordination compound formula though in case it isn't given as oxalato.

Midori Hupfeld 3D

I think it is just because it is an acid, and acids always have the hydrogen connected to the oxygen if there is oxygen in the molecule.

Midori Hupfeld 3D

I rounded to 0.09 moles because of the 100 kJ and got the question correct, so I think for future reference, just keep rounding to the lowest amount of sig figs given in the problem.

Midori Hupfeld 3D

In a cis molecule, two of the same atoms are on one side, and the other two same atoms are on the other side. For example, cisplatin has two NH3 molecules on one side of the platinum, and chlorines on the other side. In a trans molecule, the atoms are diagonal from each other around the central atom.

Midori Hupfeld 3D

he most important part of this problem is remembering that CaO, a strong base, produces 2 moles of OH-. Convert these masses of HCl and CaO into moles of H+ and OH- respectively. It is basically like a limiting reactant problem, so whichever produces more H+ or OH- is in excess, and we want to find ...

Midori Hupfeld 3D

Rain can become acidic because it is water, H2O, and if it reacts with sulfur dioxide SO2, or carbon dioxide CO2 in the air, then it produces strong acids H2SO3 and H2CO3, respectively.

Midori Hupfeld 3D

First, remember to say the strengths of the intermolecular forces between compounds, because it is not the actual intramolecular bonds. Also, NH3 has the greater boiling point, because it actually has hydrogen bonding (remember that you can form hydrogen bonds only on Hydrogens that are bonded to N,...

Midori Hupfeld 3D

The reason you do this is because the number of photons can be calculated with units J/(J/photon), which gives you units photons. So, the energy you calculated in the first part is the work function, which is the amount of energy (PER PHOTON) needed to eject an electron from the metal. So the units ...

Midori Hupfeld 3D

I think it is because they are completely ionized in the solution, so it is completely dissociated into hydrogen ions and the other element.

Midori Hupfeld 3D

The final will be cumulative so prepare everything, but I'd guess the the things we learned after the midterm will be emphasized as we have not been tested on everything yet.

Midori Hupfeld 3D

The metal hydroxides are alkaline, and they release OH- ions in the solution.

Midori Hupfeld 3D

There is a chart on Dr. Lavelle's website that shows all the important names! Use the ones on the left hand column because they are more common and easier to memorize, also they mean the same thing!

Midori Hupfeld 3D

Do we know how to tell the difference between a square planar complex and a tetrahedral complex from the formula?

Midori Hupfeld 3D

How do you know when to use brackets and when to use parentheses when you're writing out a coordinate compound?

Midori Hupfeld 3D

Do acids always have a hydrogen ion in them?

Midori Hupfeld 3D

No you draw it like a normal double bond and just label them one as sigma and the other as pi.

Midori Hupfeld 3D

How do we know whether a molecule will be cis or trans? The Lewis Structure will obviously be different for each, which affects whether the molecule will be polar or non polar by having its dipole moments cancel or not. For example, in Dr. Lavelle's lecture, the example about cis-dichloroethene vers...

Midori Hupfeld 3D

I'm pretty sure it means the same thing, use whichever term you like!

Midori Hupfeld 3D

The reason some are 106 and 107 is because they are just a bit less than 109.5 (tetrahedral), and it is due to the electron repulsion caused by lone pairs.

Midori Hupfeld 3D

They have their dipoles in different areas, so dimethylpropane is spherical, which makes the bonds less strong compared to pentane which has rod-shaped dipoles. The rod shaped dipoles are closer together which makes the bonds stronger.

Midori Hupfeld 3D

I think you just view one of the central atoms and create the VSEPR model from that.

Midori Hupfeld 3D

The shape determines how close the dipole interactions will be, drawing the atoms closer, which makes the bonds shorter, which makes the bonds stronger.

Midori Hupfeld 3D

I have heard that we get our midterms back in Wednesday's lecture this week.

Midori Hupfeld 3D

As others are saying it depends on the molecule, but row 3 and beyond can have more than 8. I know that phosphorous can have up to 10, and so on, but any molecule in the d block can technically have up to 18. However that is rare.

Midori Hupfeld 3D

Take into consideration if the atom obeys the octet rule (or if it is an exception) and formal charge.

Midori Hupfeld 3D

For pentane versus dimethylpropane, they have the same number of electrons, but the shape is what makes it closer. Rod-shaped molecules have their 2 dipoles closer to each other if you look at the drawing Dr. Lavelle showed in class, while the spherical shaped one has one dipole-dipole interaction t...

Midori Hupfeld 3D

I don't think we quite have to worry about shape yet. So, unless Dr. Lavelle says so in lecture, radicals' electrons can be drawn in whatever way you like!

Midori Hupfeld 3D

Technically, the equation for formal charge is just for you to check whether the structure you drew is the best and most stable structure. Unless it asks you for the formal charge, I guess you do not really need to solve it. However, it is recommended to check for formal charge.

Midori Hupfeld 3D

No, I think we only need to know through row 4!

Midori Hupfeld 3D

And, we learned that radicals are also an exception to the octet because they have an odd number of electrons (unpaired electrons).

Midori Hupfeld 3D

Also Hydrogen and Helium, as well as boron and the rest of column 3 can have incomplete octets. Hydrogen and helium can only hold 2 electrons because they only have an s shell.

Midori Hupfeld 3D

Covalent character happens in ionic bonds, and it is just if the one ion is so highly charged that it causes the bonding to act somewhat like a covalent bond I guess (they share electrons, but unequally). Polarizing power affects this, which is affected by atomic radius. A larger atomic radius allow...

Midori Hupfeld 3D

It is basically just asking you to determine which structure is more stable.

Midori Hupfeld 3D

Typically the chemical formula is written such that the order of elements shows what bonds with what element. So for hydrogen phosphate, the formula is HO4P-2 so hydrogen bonds with oxygen, and the oxygens pair with phosphorous.

Midori Hupfeld 3D

l can be 0, 1, 2, ..., n-1 where l=0 is the s orbital, l=1 is the p orbital, l=2 is the d orbital, and l=3 is the f orbital and so on. This just means how many subshells there are.

Midori Hupfeld 3D

How do we determine which atom will be the center of the structure if there is more than two different atoms? For example in 2B.11 in the homework.

Midori Hupfeld 3D

Can someone explain why we separate the different elements or molecules when drawing the lewis structure?

Midori Hupfeld 3D

The rule for increasing electronegativity is that it increases across a period and up a group. Since the noble gases don't apply to this rule (they have completely full shells), fluorine is the uppermost and rightmost element on the periodic table.

Midori Hupfeld 3D

Double bonds are shorter than single bonds because they have more electrons, so the attraction between the positive nucleus and the negative electrons grow greater. The length between the nucleus and the valence electrons gets shorter as there is more attraction.

Midori Hupfeld 3D

No, wave functions just describe things with wavelike properties. Orbitals are the shells that contain electrons in an atom. n, l, and m are quantum numbers that describe the orbitals whether that's shape or size, etc.

Midori Hupfeld 3D

Velocity is speed with direction, so they cannot be used interchangeably if you need to convey direction or not. The speed of light is a constant and I don't think that you can really determine the direction of light.

Midori Hupfeld 3D

In lecture, we found what the possible n, l, and ml values could be. Will there ever be a situation where we have to determine the specific value for a quantum number? If so, how do we know?

Midori Hupfeld 3D

a) This is false because the Zeffe of electrons is affected by the total number of electrons because electrons in lower energy orbitals shield the outermost electrons from the positive nucleus. This allows them to offset the attraction to the nucleus. b) True c) False, the electrons are less able to...

Midori Hupfeld 3D

Can someone explain how to approach 1B #25? I looked at the solution and it rearranged an inequality equation that does not look like the one we discussed in lecture. It says that the uncertainty in momentum times the uncertainty in velocity is equal to 1/2 times h with a line through the top.

Midori Hupfeld 3D

When the electron transitions to a lower level, the electron emits energy as a photon, so yes, it does decrease so to say. It becomes more negative. I think the frequency must decrease as well because it is directly proportional to the change in energy. The equation E=hv (h=constant and v=frequency)...

Midori Hupfeld 3D

You have to calculate how much of the reactant is used up in the reaction by converting it from the product produced. Then you subtract the amount of the reactant that was used up from the amount of that reactant that you had to begin with.

Midori Hupfeld 3D

Energy is directly proportional to frequency, the equation is energy= Planck's constant times frequency. However, it is inversely proportional to wavelength in that a lower energy is given off by larger wavelength, and a higher energy is given off by a smaller wavelength.

Midori Hupfeld 3D

You have to convert the milligrams of sodium to grams and then divide by the molar mass of sodium to get the moles of sodium. Then, you take the answer you found in part a, which is the energy of one sodium atom, and multiply it to the molar mass of sodium to find the energy of the atoms in 5.00 mg ...

Midori Hupfeld 3D

When writing out a chemical reaction, we have to label each compound or molecule as solid, liquid, gaseous, or aqueous. My question is, what state are acids in? Are all acids in the same state?

Midori Hupfeld 3D

I noticed in the solutions manual for parts a & b on E9 that the answer has no units. Is there a reason for this?

Midori Hupfeld 3D

I was just wondering if someone could explain the example Dr. Lavelle proposed in class? I don't really understand what he means by very small objects can accept energy in discrete amounts and how that relates to water being poured from a bucket. Is it saying that just because it appears to be conti...

Midori Hupfeld 3D

I'm pretty sure you should just individually calculate the molar ratios and then solve for mass. I'm not sure what you mean by combine the reactions, but it sounds like you will be manipulating the formulas too much. They're probably separate for a reason.

Midori Hupfeld 3D

If you're finding the empirical formula I think I would multiply 2.44 by 5 because it is not close enough to say it's 2.5 and just multiply by 2.

Midori Hupfeld 3D

I round at the end, so just take the exact number from the periodic table, which is usually to two decimal places, except for hydrogen- I always use 1.008.

Midori Hupfeld 3D

I just multiply the non whole number by whatever makes it whole, for example if the number if 1.2, multiply it by 5, if it is 1.3, multiply by 3, etc. However, if you come across a situation where there is more than one non whole number, just keep multiplying by whole numbers (go up by 1 each time i...

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