CHEMISTRY COMMUNITY

Belle Calforda3f

how do we know the affect of a catalyst on an overall reaction if its only in one step? and how do we know how many intermediates?

Belle Calforda3f

why is delta s surround negative and system positive?

Belle Calforda3f

ohhhh THANKSSSS

Belle Calforda3f

In 9.13, the problem says 3.00 liters of Nitrogen gas at 18.5 degrees c was compressed suddenly and irreversibly to .500 liters by driving in a piston. The temperature changed to 28.1 degrees c. calculate the total change in entropy. So I know that I need to independently calculate delta s for the c...

Belle Calforda3f

why does delta s surroundings = -q rev/time x t but, delta s = q rev/t

Belle Calforda3f

How do we know which part of the anode is the reduction agent and which part of the cathode is the oxidizing agent?

Belle Calforda3f

do we need to know these to concepts and if so can someone explain them?

Belle Calforda3f

For the question that says H+/H2 and Ni+2/Ni, doesn't both sets have a reducing agent and an oxidizing agent??

Belle Calforda3f

I think a reduction potential chart has to be given.

Belle Calforda3f

when did he say that?

Belle Calforda3f

A catalyst in a different phase than R is heterogeneous.
A catalyst in the same phase as R is homogeneous.

Belle Calforda3f

what is a Daniell cell?

Belle Calforda3f

what is a unique rate and how do you find it?

Belle Calforda3f

for 15.39 b, why does the solutions manual have ".37[a] initial as part of the solution. Where is the .37 coming from?

Belle Calforda3f

would Lavelle ever expect us to derive integrated rate laws greater than second order?

Belle Calforda3f

Taking the integral when solving for the integrated rate law for a second order reaction produces a double negative which turns into a positive. Integrating the integrated rate law for each order will demonstrate this.

Belle Calforda3f

does a half life pertain to a substance in general or an AMOUNT of substance? for ex: does mercury have one half life or do different amounts of mercury have different half lives?

Belle Calforda3f

We will ever use both kinetics and thermodynamics in the same problem?

Belle Calforda3f

using either the integrated rate law or the half life eqn can help you figure out the units for the rate constant without having to memorize anything. If you plug in the units for everything but k, you can figure out what k has to be for the equations to work.

Belle Calforda3f

how does the slow step determine the overall rate? and how do you know how many steps there are?

Belle Calforda3f

on part a of 14.5, I do not get why we add OH when balancing the half reaction.

Belle Calforda3f

what is the difference between Delta G and Delta G "not"

Belle Calforda3f

When can we assume constant pressure?

Belle Calforda3f

when can we use just q=cdeltaT without moles or mass? does this apply to calorimeter problems?

Belle Calforda3f

I understand how to do a problem that asks for the entropy of vaporization of water at room temp, yet I do not really get how water has an entropy of vaporization for room temp. Is water vaporizing at room temp. even if it is not physically boiling?

Belle Calforda3f

your statement is right, but when you wrote the equation the signs are mixed. Your Ta is right with the signs and you are right when you say the ice is gaining heat and the tea is losing heat. But, to show the "release" of heat from the tea it it is -qTea.

Belle Calforda3f

If temperature does not change, can the internal energy change? If not, can someone please explain?

Belle Calforda3f

I just really do not understand delta u: what It means, how to caluculate it, how to know if it equals 0. Can anyone help? thanks

Belle Calforda3f

I am still so confused about work. How does volume affect it?

Belle Calforda3f

what is the conceptual difference of an irreversible and a reversible reaction, and why are most biological reactions irreversible?

Belle Calforda3f

what does kb mean in the Boltzmann equation?

Belle Calforda3f

Gibbs free energy is a representation of spontaneity it the likeliness for which a reaction will occur on its own. So, as entropy can be called "disorder," Gibbs's free energy can be referred to as how spontaneous a reaction is. However, like "disorder," Dr. Lavelle does not love...

Belle Calforda3f

In class Lavelle went over a problem where we subbed 0 for delta g and solved for the other variables. I know it has something to do with equilibrium, but I am really confused about why and how we were just able to put in a 0. Can someone explain? thanks

Belle Calforda3f

sig figs are always important although he does not tend to mark down if they are wrong. If you stick to three, you usually cannot go too wrong.

Belle Calforda3f

The higher the degeneracy, the higher the entropy.

Belle Calforda3f

Although Lavelle said in class that we don't REALLY know haha, it is because matter is neither created nor destroyed.

Belle Calforda3f

The first law of thermodynamics is essentially the law of conservation of mass: matter is neither created nor destroyed. However it is super important to know that as stated by the first law of thermodynamics, the total energy of an isolated system is constant

Belle Calforda3f

regarding q: 8.49 why do we make -P(delta v) = -(delta n)rt negative on both sides?

Belle Calforda3f

If work and delta u are not gonna be tested computationally, does anyone have any idea what sort of concept questions will be asked?

Belle Calforda3f

In question 8.13, why is 947 kj absorbed written as a negative q value?

Belle Calforda3f

I thought the value for R was .0821, where is the answer book getting 8.314 J/KxMOL?

Belle Calforda3f

What are the two equations that are used for reversible and irreversible reactions and how do you differentiate between the processes if not told in the problem?

Belle Calforda3f

When doing problems that involve phase changes, for example changing ice to steam, how do you solve them if given two temperatures one for ice and one for steam and multiple molar heat capacities rather than one temperature?

Belle Calforda3f

regarding homework problem 8.1, why is mercury in a thermometer a closed system rather than isolated?

Belle Calforda3f

All of my questions about this are coming from the week 9 review sheet number 8. With that being said, I am particularly confused about why the stoichiometric coefficients doubling would cause an increase or a decrease and I am also confused about what happens when the concentrations of A and B are ...

Belle Calforda3f

For number 1 on the week nine sheet, I am confused because the problem says that the equilibrium concentration for SO2 is X, but it has a coefficient of 2 so it should be adding 2X. Also, the solutions key shows the addition of 2x for both so2 and o2 even though o2 does not have a coefficient. At fi...

Belle Calforda3f

why would C have a radical on it rather than an N, in a c-n bond?

Belle Calforda3f

yes I believe it is the same. I think he used deprotonization to emphasize the facte that bronzed acids and bases involve the donation and acceptance of protons.

Belle Calforda3f

Even if we don't "have" to memorize strong acids and bases, I'm sure it will help with comfortability on final problems.

Belle Calforda3f

Equilibrium arrows are used for weak acids and weak bases because they do not dissociate completely. Likewise, only weak acids and weak bases have conjugate acids and conjugate bases because they do not dissociate completely.

Belle Calforda3f

Are weak acids and bases the only acids and bases that have conjugates because they do not ionize completely? Or do strong acids and bases have conjugates as well?

Belle Calforda3f

The "ate" ending is added if the overall compound is an anion(a negatively charged ion)

Belle Calforda3f

Delocalized bonds are not constricted to one nucleus as localized bonds are. Resonance structures are a good example of delocalized bonding because as we learned, resonance structures exhibit single/double or single/triple etc character throughout the molecule even though each lewis structure shows ...

Belle Calforda3f

Do we use the kw value because water is amphoteric and can act as a base or an acid or is there another reason? Also why does water and kw allow us to figure out ph and Poh?

Belle Calforda3f

while lewis and bronsted acids and bases are reversed in roles- Lewis acids accept while bronzed acids donate- the main difference is that Lewis acids and bases involve the donation and acceptance of electrons while bronzed acids and bases are talking about protons.

Belle Calforda3f

not sure how to post a question, but how do we know when to use cyano or cyanido for cn? Also, how do we know which is attached, the C or the N, for example of Cyanide?

Belle Calforda3f

How do we know if we should use the new IUPAC names or the old ones when naming coordination compounds?

Belle Calforda3f

I am nor familiar with coordination compounds/complexes/bonds. Can someone please differentiate and define these?

Belle Calforda3f

Why do we say bonds are less than 109 degrees or less than 120 degrees? I don't understand why it is "less than"

Belle Calforda3f

Can someone explain why for example: [kr]4d105s2 has no unpaired electrons?

Belle Calforda3f

Could someone please explain effective nuclear charge?

Belle Calforda3f

Since 0 correlates to the S orbitals, 1- p orbitals, 2-d orbitals, and 3- f orbitals, we know that if l = 3 we are referring to the f block. Since the f block has 14 electrons and 7 different orbitals we know there can be 7 subshells. If you memorize what 0,1,2,and 3 correlate to in regards to angul...

Belle Calforda3f

The (x,y,and z) of px,py, and pz simply distinguish which axis the electrons lie on. If you took AP chem in high school you likely were taught to write use the notation: 1s^2,2p^6 for example rather than 1s^2,2px^2,2py^2,2pz^2. I was confused and asked Professor Lavelle in class and he said either f...

Belle Calforda3f

No the equation given in the book also is only useful for hydrogen related purposes.

Belle Calforda3f

The Rydberg equation given in the text book is a derivation of the formula given by Dr. Lavelle. He said we can use it if we understand the way it was created.

Belle Calforda3f

I believe they said we will get a chart to use on the test. However, I don't think it will say for example that the Balmer Series is visible light.

Belle Calforda3f

Take notes on your own first and then use lectures and discussions as clarifications! Also, use youtube for catchy phrases to help remember how to approach questions. For example, for empirical formulas I use.. "% to mass, mass to mole, divide by smole(smallest mole), and multiply to whole."

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