CHEMISTRY COMMUNITY

Amanda Mac 1C

How do you find total degeneracy? And what does that tell you about the system?

Amanda Mac 1C

Can someone tell me the difference between S (like in the Boltzmann equation) and delta S besides the fact that delta S is the change in entropy? How would we find S?

Amanda Mac 1C

Does a large value for oxidation power mean a more positive reduction potential or is it the other way around?

Amanda Mac 1C

In order to make iced-tea a 50g ice cube at 0C is added to 500mL of tea at 20C. What is the final temperature of the iced tea once it has reached thermal equilibrium. Assume that no heat is transferred to or from the surroundings. The density of water (and iced tea) is 1g/mL over the range 0C-20C. C...

Amanda Mac 1C

For question 6A on the midterm, are answers A and B both correct? If so, could someone explain why A is valid?

Amanda Mac 1C

On the midterm for question 2B, I know that the entropy would be positive but can someone explain the actual reasoning behind that?

Amanda Mac 1C

A 1st order reaction is allowed to proceed for 2 hours. Then it is determined that at this time that 76.6% of the initial concentration of reactants remain. Determine what chemical reaction is occurring and at what temperature the reaction is occurring. (There is a table included in the test if you ...

Amanda Mac 1C

In a 2nd order reaction, a reactant has a known half-life of 3 minutes and an initial concentration of 5M. How much time will it take for the concentration of this reactant to drop to 2M? Could someone explain each step to solve this problem?

Amanda Mac 1C

Could someone explain the uni- bi- molecular concept again? Does unimolecular have to be first order and bimolecular, second order?

Amanda Mac 1C

If a reaction has multiple mechanisms which means multiple slow steps, would the rate determining step be the whole mechanism or just the slow step of that particular mechanism depending on the rates given?

Amanda Mac 1C

I'm still a little unclear about the pre-equilibirum approach so could anyone explain this simply?

Amanda Mac 1C

When looking at energy diagrams, how would you know which peak is the rate-determining step? Is it the highest peak because that's the highest activation energy?

Amanda Mac 1C

So my TA mentioned that one element could be involved in multiple functional groups at the same time. Is there an example of this?

Amanda Mac 1C

Could someone explain steady state approximation and in what scenarios it would be used?

Amanda Mac 1C

If you're given and end reaction and told to find the individual steps, how would you know what compound to use as the intermediate? Or would you be given that information already?

Amanda Mac 1C

In a second order reaction, if one reactant alone is doubled does that mean the rate is quadrupled? What happens if two reactants in a second order reaction are both doubled?

Amanda Mac 1C

So I know that the rate constant and equilibrium constant both depend on the concentrations, but what is the relationship between the two besides that? If we have one, can we calculate the other?

Amanda Mac 1C

What information does the order of a reaction give us? Can someone give me a rundown of the context?

Amanda Mac 1C

I believe it's used as a standard to compare electron transfer. Since we can not measure electron transfer of one cell, we compare the electron transfer of all cells through half-reactions with respect to the standard hydrogen electrode.

Amanda Mac 1C

Can someone explain why max potential is when there is very little current flow?

Amanda Mac 1C

Oxidizing agents are being reduced and reducing agents are being oxidized because if the substance is being reduced, that must mean its gaining electrons from somewhere which means it's causing another substance to lose electrons. This is why the one being reduced is called an oxidizing agent. Just ...

Amanda Mac 1C

Why are endothermic reactions not favorable at high temperatures?

Amanda Mac 1C

When you have expansion in a vacuum, is it always free expansion and no work is being performed?

Amanda Mac 1C

To my knowledge, the only monoatomic gases that are stable in ideal conditions are the noble gases.

Amanda Mac 1C

W is the number of ways of achieving a given energy state, aka the number of possible microstates. Consider two elements with the same energy in a flask, the microstates could be AB on one side, BA on one side, A on the left and B on the right, or B on the left and A on the right. This makes W=4 bec...

Amanda Mac 1C

In the example during lecture (at what temp is Br(l) to Br(g) spontaneous at 1 atm), why do we ask the question at what temp is deltaG negative? And then why do we find the temperature when deltaG=0 later on if we're trying to make deltaG negative?

Amanda Mac 1C

I think that in terms of entropy, a perfect crystal has entropy=0 because all the molecules are lined up perfectly. All the molecules are uniform and no matter how you arrange the molecules, they'll still fit perfectly. Since this is true, there is no "disorder" and this foundation makes u...

Amanda Mac 1C

The units are Joules per Kelvin (J/K).

Amanda Mac 1C

Would the difference between using the average bond enthalpies to calculate enthalpy of reaction and using specific bond enthalpies be significant? Or would they give nearly the same result in calculation?

Amanda Mac 1C

How do you differentiate between whether work is done ON a system or BY the system?

Amanda Mac 1C

Enthalpy is a way to measure energy in a thermodynamic system, it's the total heat content of a system or the internal energy of the system plus the product of pressure and volume. It's also a state function which means it does not depend on the pathway. When a reaction occurs, heat is either releas...

Amanda Mac 1C

We know that the products are all in the liquid state, so now we consider the states of the reactants needed to make those products. For example, we get liquid H2O from O2 and H2. Both of these diatomic elements are in the gaseous state because elements like to be in the most stable phase at 1 atm a...

Amanda Mac 1C

I know that the Specific Heat Capacity is the one used in calculations because it's intensive, but would there be any occasion we would use the Heat Capacity for calculations instead?

Amanda Mac 1C

Could some please clarify why there are plateaus in a heating curve when there is a phase change? Heat is being added so why isn't there a china in temperature represented until the next phase is reached?

Amanda Mac 1C

For example, if there is a positive charge on the central atom, and a negative charge on one bonded atom does that mean those charges cancel each other regardless of another atom attached to the central atom without a pull on it?

Amanda Mac 1C

If a compound has a linear shape, how do you determine polarity or non-polarity? Is there a sure fire method?

Amanda Mac 1C

Why does CO2 have a greater ionic character than CS2?

Amanda Mac 1C

I know that longer bonds mean weaker bonds and more acidity. In the course reader it says that H2O is less acidic than H2Te because H2O has a shorter bond since it's in period 2 and Te is in period 5. Does H2Te have a weaker bond because Te is not as electronegative as O?

Amanda Mac 1C

Determine whether the following statements are true or false:
a. When chemical equilibrium is reached, the composition of the reaction mixture remains constant.
b. If we make a reaction go faster, we can increase the amount of product at equilibrium.

Amanda Mac 1C

A. One number that gives us information about the relative concentrations of reactant and product.

Amanda Mac 1C

I think the (III) refers to the Cobalt and not the chloride. So your formula is correct, just take out the subscript 3 on the Cl.

Amanda Mac 1C

I believe that's usually true but there are exceptions. For example a bidentate ligand such as ethylenediamine can bind to a metal such as Ni^2+ to form a five-membered ring with is a chelate ring. But complexes that contain polydentate ligands are called chelate complexes. Polydentate ligands are s...

Amanda Mac 1C

Will we need to know how to name complex coordinate compounds or just be able to recognize them? If yes, is there any simple way to remember all the IUPAC prefixes and rules?

Amanda Mac 1C

My logic with how to place the atoms was that C likes to have four bonds, Oxygen likes to have two, and Hydrogen likes to have one bond (this is what I learned as the HONC guideline in high school chemistry). With this in mind, if you put the two O's and the H around the C, then the number of bonds ...

Amanda Mac 1C

How would you know the Al atom in aluminum chloride is a Lewis Acid? I read somewhere else that if you calculate the formal charge and it's positive, then it's a Lewis acid because it wants to accept electrons. But when I calculated the formal charge for Al, I got 0 so how would you know if Al was a...

Amanda Mac 1C

If you're given B2^+, B2, B2^-, and B2^2- how would you know how to order them from shortest bond length to longest bond length using the molecular orbital theory?

Amanda Mac 1C

Tetrahedral named molecules do not have lone pairs on the central atom which means there are four electron density regions and all four of those regions are occupied by atoms. In trigonal pyramidal molecules, there is one lone pair on the central atom which means only 3 out of the 4 regions are occu...

Amanda Mac 1C

Yes, you're correct. The electron configuration would be 1s^2 2s^2 2p^6 3s^2 3p^6 3d^8 because of the absence of 4s^2 due to the 2+ charge.

Amanda Mac 1C

Yes, that is correct. All material up until October 25th will be covered so basically Fundamentals up until the end of Chapter 3.

Amanda Mac 1C

The VSEPR name of CH4 is tetrahedral where there are all bonded pairs. Trigonal pyramidal would be three bonded pairs and one lone pair of electrons such as NH3. A lewis structure is a representation of the structure but I do not think they have names if that's what you're asking. Hope this helped!

Amanda Mac 1C

We talked about the different ways to draw SO4^2- and worked out how the structure with double bonds was more stable than the structure with only single bonds. But are both technically correct Lewis structures?

Amanda Mac 1C

I know formal charge indicates the gain or loss of electrons while forming covalent bonds but does that mean it indicates the gain/loss of electrons in the molecule as a whole or each atom separately?

Amanda Mac 1C

Sodium vapor lamps, used for public lighting, emit yellow light of wavelength 589 nm. How much energy is emitted by (a) an excited sodium atom when it generates a photon (b) 5.00 mg of sodium atoms emitting light at this wavelength (c) 1.00 mol of sodium atoms emitting light at this wavelength So fo...

Amanda Mac 1C

Should we know how to do Shrodinger Equation problems for the upcoming test? Or do we just need the De Broglie Equation and the Heisenberg Uncertainty principle?

Amanda Mac 1C

Hi! From what I know, if the work function (threshold energy to remove electrons) is equal to the energy of the photon then no electrons are ejected which means there’s no excess energy and kinetic energy equals 0. I believe that the problems will usually tell you that no electrons were ejected or t...

Amanda Mac 1C

For series problems on tests like Lyman, Balmer, etc. do we need to know the exact wavelengths each series corresponds to or do we just need to remember what n-levels they are associated with?

Amanda Mac 1C

How I approached F13 was to find the mass percent composition first. So 4.14g P/27.8g solid * 100 comes out to be 14.89% which means Cl makes up 85.11% of the compound. With this you can assume, 100 grams and find the moles and then the atomic ratio from there. Finding empirical formulas almost alwa...

Amanda Mac 1C

The decay of teeth can be slowed by the use of fluoridated toothpaste. The fluoride ions convert the hydroxyapatite, Ca5(PO4)3OH, in tooth enamel into fluorapatite, Ca5(PO4)3F. If all the hydroxyapatite is converted into fluorapatite, by what percentage does this conversion increase the mass of the...

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