CHEMISTRY COMMUNITY

Hanniel U 2B

I believe A is the collision frequency in the correct orientation.

Hanniel U 2B

How is Enthalpy or delta H related to Activation energy, Ea in the Arrhenius equation?

Hanniel U 2B

You should be familiar with the graphs of the rate orders just in case and also Arrhenius equation and just be familiar with labeling them too.

Hanniel U 2B

Are we going to have to identify the slow and fast step or will it be shown on the problems in the final?

Hanniel U 2B

Maria Solis Disc 4C wrote:Internal Energy should always be q+w

Thanks. I see q- w sometimes and that confuses me.

Hanniel U 2B

What is the difference btw delta U= q + w and delta U= q - w?

Hanniel U 2B

I always convert to Kelvin to be safe... There are many instances, such as when you calculate for entropy when you divide two temperatures, and using Celcius here will mess up your ratio and give you an incorrect answer. You also know what to use based on the units and what you need to cancel out.....

Hanniel U 2B

When do you know to convert Celcius to Kelvin?

Hanniel U 2B

Can someone please explain part (c)?

Hanniel U 2B

In the 7th edition textbook, it states "not used" for the equation of half-life of the second order reaction But there are problems, for example, 7b.13 that ask us to calculate the half-life of a second order reaction. I am confused, can someone please clarify this?

Hanniel U 2B

Do we turn in two homework this wee? That is, do we turn in 14 problems this week ?

Hanniel U 2B

Can someone help me understand 7A.13, 7th edition? Why is the rate first order?

Hanniel U 2B

If the Ecell° is positive, the reaction is favorable forward which means has K>1

Hanniel U 2B

Would we be given the standard reduction potential values for the test?

Hanniel U 2B

I usually flip the anode equation. Probably that's why the Cu was flipped. Also, the anode equation is being oxidized.

Hanniel U 2B

I know platinum is used as an oxidation catalyst.

Hanniel U 2B

Calculating the equilibrium constant from Gibbs free energy, calculating the free energy of reaction from formation and using van't Hoff equation.

Hanniel U 2B

How can you identify the species that are being oxidized or reduced?

Hanniel U 2B

The reaction is at equilibrium.

Hanniel U 2B

One thing that I know Gibbs free determines is the spontaneity of a process.

Hanniel U 2B

Are exothermic reactions usually spontaneous because energy is released from the system or is there another way to explain it?

Hanniel U 2B

Use deltaS= nRLnV2/V1 when there is a change in entropy of an ideal gas when there is an isothermal expansion from a volume V1 to V2. Use deltaS= q/t when you are trying to find the change in entropy with given heat energy and temp.

Hanniel U 2B

Yes, I think so. Everything from 4f to 4i. Gibbs free energy is 4j so I don't think we need to study that for the midterm.

Hanniel U 2B

How do I go about this question: Which would have higher molar entropy at T=0, single crystal of BF3 or single crystal of COF2

Hanniel U 2B

Would we be asked to derive equations and formulas relating to thermodynamics on the midterm? Or should we not worry about that?

Hanniel U 2B

1. Start with w: w=-P_{ex}\Delta V 2. Calculate \Delta V \Delta V=1.846L-0.345L=1.501L 3. Convert the given P_{ex} from Torr to atm P_{ex}=750 \textup{ torr } \times \frac{1 \textup{ atm}}{760 \textup{ Torr}}=.99\textup{ atm} 4. Plug into equation for w w=-.99 \times 1.5 =-1.49 \textup{L}\cdot \tex...

Hanniel U 2B

Would q be negative if heat is absorbed?

Hanniel U 2B

Can someone please help me with 4B.5 7th edition?

Hanniel U 2B

I think the example Prof. Lavelle gave in class about why steam burns severely more than liquid is an example of applying enthalpies.

Hanniel U 2B

Positive delta H means an Endothermic reaction because is greater than 0. Negative delta H is an exothermic reaction because heat is released.

Hanniel U 2B

Jordan Lo 2A wrote:Is test 1 the entire outline 2? I could be wrong but I don't remember going over polyprotic acids (last couple exercises in 6th edition) or examples (last bullet points under concepts)

I'm not sure. It would be safe to just go over it and know some information about it.

Hanniel U 2B

Is NH3 amphoteric? I keep getting confused

Hanniel U 2B

What sort of conceptual questions would be asked on test 1? What concepts do we need to know to explain?

Hanniel U 2B

If there a way we can easily identify weak acids and bases or should we just memorize the most common ones?

Hanniel U 2B

Can some please explain how to apply Le Chatelier's Principle?

Hanniel U 2B

Does anyone know what would be covered on test 1 next week?

Hanniel U 2B

Can someone please help me with 5G.11 7th edition?

Hanniel U 2B

If you are asking about the percentage of X2 molecules that has decomposed at equilibrium, It is the difference between the diatomics at the start and when it reaches equilibrium which is 11-5=6. Divide that by the diatomics at the start = (6/11)*100= 54.5%. I'm not sure but that's how I answered it.

Hanniel U 2B

Albert_Luu3K wrote:NaOH is a strong base because it fully dissociates in water. That means there are more OH- ions floating in solution making it more basic.

Does that mean strong acids also fully dissociate in water?

Hanniel U 2B

"Not all amphoteric substances are amphiprotic. Although an amphiprotic species must be amphoteric, the converse is not true. For example, the metal oxide ZnO contains no hydrogen and cannot donate a proton. Instead, it is a Lewis acid whose Zn atom accepts an electron pair from the base OH−.&q...

Hanniel U 2B

Does that mean atoms after row three can? Does this relate to the atomic number?

Hanniel U 2B

Because it is T-shaped and T-shaped molecules have sp^3d hybridization.

Hanniel U 2B

I think we have to give both answers during the test. But make sure to clearly differentiate and state your answers when including resonance structures.

Hanniel U 2B

I found this online. I hope it helps!

Hanniel U 2B

Because the electron domain of the central atom is 4 and not 2. Someone correct me if I'm wrong.

Hanniel U 2B

On test 3, would we be asked to name molecular shapes like seesaw, t-shaped, and square planar?

Hanniel U 2B

Van der Waals forces are also known as Dispersion/ induced dipole-induced dipole/ and London interactions. All of these terms describe intermolecular attractions that are always present and attractive. They arise due to fluctuating electron distributions, which results in fluctuating dipoles. These...

Hanniel U 2B

Sigma and pi bonds are chemical covalent bonds. Sigma bond has been referred to as the strongest type of covalent bond.

Hanniel U 2B

Can someone please give an overview of van der Waals forces?

Hanniel U 2B

I was also confused about that. At first, I even thought the molecule would be linear as a whole. But it makes sense that it is Tetrahedral. It is still confusing though.

Hanniel U 2B

Molecular geometry usually includes the lone pair on the central atom. I call this the parent shape. While Molecular shape just describes the shape excluding the lone pair on the central atom. Make sure to differentiate both if or when asked to name shape. An example I like to use is SO2. The molecu...

Hanniel U 2B

Just to be on the safe side, I identify each shape as the parent shape and molecular shape. For example, S02 has a parent shape that is trigonal planar because of its lone pair on S but the molecular shape for S02 is bent or angular.

Hanniel U 2B

The electronegativity difference between S and F is greater than 0.5, that's why it is Polar.

Hanniel U 2B

During lecture today, C2H4 had a sp^2 hybridization. But when it was expanded, it was 2sp^2 and 2p. I am confused about that.

Hanniel U 2B

I was wondering; would Tuesday discussion sessions still take place or not?

Hanniel U 2B

Is the VSEPR group the names of the shapes of the Lewis structure? I'm so confused.

Hanniel U 2B

I know Professor Lavelle mentioned this but do we have to know the bond angles or we just have to guess what it is less than? Also, I'm guessing we have to memorize all the names of shapes right?

Hanniel U 2B

I don't think there is a grading scale. The total number of points you could get is 500. So just add up all your points at the end of the quarter.

Hanniel U 2B

This is a good video:
https://youtu.be/dNPs-cr_6Bk

Hanniel U 2B

The first four elements on the periodic table are elements with octet exceptions.

Hanniel U 2B

The octet rule is basically a guideline for bonding which says that elements (with atomic number below 20) should have 4 bonding pairs of electrons (8 e- total - the noble gas configuration). The first 4 elements do not follow this guideline as they do not need 8 e- to reach a noble gas configurati...

Hanniel U 2B

d orbitals can hold up to 10 electrons.

Hanniel U 2B

Can someone please explain the octet rule and why the first 4 atoms on the periodic table don't have it. Thanks !

Hanniel U 2B

Valence electrons are the outer electrons that are involved in bonding and they hold the highest energy. That's why electrons in the s and p orbitals are valance electrons.

Hanniel U 2B

What kind of questions would be on the test relating to Atomic Spectra?

Hanniel U 2B

From what I know, the test will cover the Photoelectric effect, De Broglie wavelength, Heisenberg uncertainty, Atomic spectra, and Quantum numbers.

Hanniel U 2B

Also, p=mv. So wavelenght=h/p which is also wavelenght= h/mv.

Hanniel U 2B

It depends. Sometimes you would have to use kg*m^2*s^-2 instead of J*s to cancel out and get the right units at the end of your calculations.

Hanniel U 2B

I just want to clarify. Do we have to know and are we gonna use the schrodinger's equation or not?

Hanniel U 2B

Thanks!

Hanniel U 2B

I don't think you have to worry about the f-orbitals for now. They are more complicated in shape. Just be familiar with s, p and d.

Hanniel U 2B

Electromagnetic radiation is a form of energy that is produced by oscillating electric and magnetic disturbance, or by the movement of electrically charged particles traveling through a vacuum. Electron radiation is released as photons, which are bundles of light energy that travel at the speed of l...

Hanniel U 2B

Does photon have to be greater than work function for photoelectric effect to work?

Hanniel U 2B

I think we need to. There will be problems were we we need to state the spectrum given the answer we get. There was a similar problem like that on the homework.

Hanniel U 2B

Okay but during the post assessment, I answered that it cannot have two limiting reactants but the answer was wrong. That's why I'm confused.

Hanniel U 2B

I watched the video but I'm still not sure. Can a chemical equation have two limiting reagents ?

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