CHEMISTRY COMMUNITY

sarahtang4B

On 6N5a, how did the negative on -.0257 disappear? It says when you do 0.06/(2.303x0.0257) that 0.0257 is positive when its supposed to be -? shouldn't the pH end up being negative?

sarahtang4B

can somebody explain in depth how to do both parts of this problem?

sarahtang4B

why is the answer 10^6 and not e^6. Should'nt it be e^6 because we are using ln?

sarahtang4B

What does it mean that the ration is less than 1 but E>0? and how does this relate to delta G=work max=-nFE

sarahtang4B

why did we add 1.00 to -0.60 in part a of this problem?

sarahtang4B

for problem 7D5, Im confused where the solutions manual is getting all the numbers can somebody explain how we get the different values to plug in and why the manual also subtracted 0.59?

sarahtang4B

do we need to memorize this equation?

sarahtang4B

why did we add 1.00 to -0.60 in part a of this problem?

sarahtang4B

for problem 7D5, Im confused where the solutions manual is getting all the numbers can somebody explain how we get the different values to plug in and why the manual also subtracted 0.59?

sarahtang4B

In the solutions manual it says to use a certain equation but I do not remember learning it in class and it's not on the constants and equations page. where did this equation come from?

sarahtang4B

would saying that a positively charged electrolyte flows from the anode to the cathode also be a correct answer?

sarahtang4B

list the following with strongly reducing metal first: Fe, Ag, Au, An, Cu, Ni, Co, Al

Why does it go Al, then Zn, then Fe then Co? why doesn't Zn go after Cu?

sarahtang4B

What does it mean that the ration is less than 1 but E>0? and how does this relate to delta G=work max=-nFE

sarahtang4B

why is the answer 10^6 and not e^6. Should'nt it be e^6 because we are using ln?

sarahtang4B

how do we know which of the redox rxns are the cathode and anode in these two problems? is it because the final concentration has to be less than initial?

sarahtang4B

can somebody explain in depth how to do both parts of this problem?

sarahtang4B

on 6N5b, how did ln(1/[Cl-]^10) turn into ln[Cl-]^10?
then, how did it go from the 10th power to a power of 1?

sarahtang4B

On 6N5a, how did the negative on -.0257 disappear? It says when you do 0.06/(2.303x0.0257) that 0.0257 is positive when its supposed to be -? shouldn't the pH end up being negative?

sarahtang4B

do we need to know how to convert between these two on the final, if so what is the conversion?

sarahtang4B

On problem 6N5, how did the solutions manual get -0.0257ln[H+]=0.06V? Shouldn't it be -0.0129 because you already subtract 0.27 from both sides of equation?

sarahtang4B

On problem 6N3a, why are the e cell 0V for both anode and cathode?

sarahtang4B

On homework problem 6L7c, where did the KOH come from in the cell diagram, do we need to include it?

sarahtang4B

is there a specific order to place the ions in a cell diagram? if so, what is it?

sarahtang4B

How do we know when to include Pt in a cell diagram?

sarahtang4B

Is the more positive e cell always the cathode?

sarahtang4B

For homework 6L1b, do we have to write out both redox equations to find number of moles transferred, if so how do we do it?

sarahtang4B

For 6K5d, how do we balance the separate redox equations? when p4->H2PO2- why do we not add H20 to both sides, how come we just directly add OH-? Then for P4-> PH3, why don't we add 12H20 to the reactant side and 24 H20 to products then 12 OH- to reactants to balance? aren't we usually supposed to d...

sarahtang4B

What is the difference of a rate constant and rate of a reaction?

sarahtang4B

In the homework problems why do we use ln[At]/[A0]=-kt sometimes and other times we use ln[A0]/[At]=kt for first order reactions?
What is the difference?

sarahtang4B

On 7B3b, its a first order reaction so how is it ln(A0/At) = kt and not -kt? I thought it was -kt for first order reactions?

If not, how did we get that equation?

sarahtang4B

When given an experiment with 3 different reactants, once we find the order of one reactant, does it matter that it has to stay constant when you compare other reactions or does it not matter cause we already found the order? On problem 7A17, I noticed the book compares experiment 2 and 3 but reacta...

sarahtang4B

For this approach will the first step always be fast and the second is slow?

sarahtang4B

In lecture today I am confused as to how dr lavelle did the substitution

How did we sub [N2O2] with [NO]^2 ?

sarahtang4B

On problem 6M3, how do we find the number of moles (n) for the G=-nFE equation?

sarahtang4B

On 6L3D, I got a negative voltage of -.83V but I thought we couldn't get negative voltages... did I do something wrong?

sarahtang4B

When we have a block of ice added into water is it always q(ice)= -q(water)

then when we have water at 25 degrees added to water at 90 degrees is it still q(cooler water)= -q(hot water)

I noticed my TA was just doing q(ice)=q(water) and some homework problems do it with the above equation.

sarahtang4B

On homework 4D15 how do we know we have to write the balanced equations whereas on 4D17, why don't we have to write the equations?
Also, how do we write the balanced equations?

sarahtang4B

What equations are used in Constant P and what equations are used in constant V?
also, what can we assume when we have these conditions?
I know at constant V, then w=0, what other things can we assume from these conditions?

sarahtang4B

On the constants and formulas are we expected to memorize some equations like change in internal energy=q+w? and Ccalorimeter=q/delta T? etc.
I noticed these constants weren't on the constants and formula page of our first test will these be given on the midterm?

sarahtang4B

On homework 4C3 part a and b, why do we have to multiply the specific heat(C) by 5/2 and 3/2 respectively?
and how do we calc the enthalpy for part b?

sarahtang4B

How does a reversible reaction do more work?

sarahtang4B

Whats an irreversible and reversible expansion?
im confused with these two definitions.

sarahtang4B

on homework 5J5 b, why does the reactant change when there are same # of mols of both sides of equation?

sarahtang4B

On question 5I13, how do we determine what is more thermodynamically more stable ?
How does K value tell us what is more stable?

sarahtang4B

Are we given the Kb and pH values of acids and bases on the test?
on the homework problem 6D13, how do we do it without any kB and pH values?

sarahtang4B

On 7th edition problem 6B11, I'm confused how to do it, for a)ii) why do you multiply by 55ml/5ml?

sarahtang4B

On 6B9 on the homework 7th edition I get a negative pH for 0.176 after doing -log[H3O+], do we just convert it to negative or am I doing something wrong with calculating?

sarahtang4B

What are all the strong acids and bases we should know for Test1

sarahtang4B

How do we know when we need to use ICE tables to calculate pH?
on the homework, some questions use ice tables even with a strong acid.. I thought we could just take -log[H3O+] if its a strong acid or base?
when can we just use that equation and when do we need to use an ICE table too?

sarahtang4B

when asked to calculate pH of 0.15M H2SO4 at 25celsius, why do we need to create an ice table if this is a strong acid??

Can't we just use pH=-log[H3O+]???

sarahtang4B

On homework 6D3 (7th edition), do we know the H3O+ conc. and ClO2- conc. are the same because it a strong acid dissociating?
Also, why do we only include 1sf when we get Ka but have 2sf with the pKa answer?

sarahtang4B

When we calculate pOH for Ba(OH)2, why do we multiply the concentration by two?

Is it because there's two OH?

sarahtang4B

What are the rules for sig figs when doing calculations for pH? do we always keep 2 digits after the decimal?

sarahtang4B

On problem 6A19 part c of 7th edition, the solutions manual says the concentration given is 3.1e-3 when the textbook gives the concentration as just 3.1 mol per liter.

Which concentration do we use? am I just missing a step in solving??

sarahtang4B

Increasing the pressure on a reaction involving reacting gases increases the rate of reaction. Changing the pressure on a reaction that involves only solids or liquids has no effect on the rate. If you increase the pressure of a gas, you squeeze it into a smaller volume. In order for any reaction to...

sarahtang4B

They are both the reactant quotients but Q tells you if a reaction will shift forward or backward and K represents equilibrium

sarahtang4B

Can you determine if reaction is spontaneous with the K value?

sarahtang4B

on our homework it asks to use Ksp to calculate E^o of half reactions, we never covered this in class, are we supposed to learn by ourselves?

sarahtang4B

On 7th edition homework question 6C17, the solutions manual says to compare PKb value so smaller value means a stronger base so on the final are we given these values?
If not, how do we determine is BrO- or C17H19O3N is stronger?

sarahtang4B

Predict which would have a higher boiling point, NH3 or PH3, and explain.
Discuss the forces involved.

sarahtang4B

I-, Cl-, S2-, P3-

Li+, Ca2+, Cs+, Ba2+
out of these ions, would Cl- and Cs+ have the greatest ionic character?
and which would have greatest covalent character?

sarahtang4B

what specifically makes thymine a base?

sarahtang4B

Which pair of atoms are most tightly bound and why?
C=C C=0 C=N

sarahtang4B

Do we expect ozone to have two bond lengths that are the same or different and why.

and

between oxygen and ozone, which would have the strongest bond and why

sarahtang4B

Predict which would have a higher boiling point, NH3 or PH3, and explain.
Discuss the forces involved.
and
How do the forces relate to boiling point?

sarahtang4B

Discuss the forces present in H2S and H2Se, explain why H2Se has a higher boiling point.

Can somebody help me understand how to do this, I am confused how to know which one gets a higher boiling point because of forces.

sarahtang4B

Discuss the forces present in H2S and H2Se, explain why H2Se has a higher boiling point.

Can somebody help me understand how to do this, I am confused how to know which one gets a higher boiling point because of forces.

sarahtang4B

How do lone pairs of electrons affect the polarity of a molecule?

sarahtang4B

What is a chelating complex and a heme complex?

sarahtang4B

Do we need to know hybridizations of lone electrons such as on the NH3, if so how is it found?

sarahtang4B

So then would Cl- and Cs+ have greatest ionic character?

sarahtang4B

When does amine get spelled with one m rather than ammine with two m?
Is there no difference? Or is there a difference

sarahtang4B

when naming a compound when do you use iron and ferrum,ferrate. why do some compounds use iron instead of ferrate.

sarahtang4B

Order these anions in order from least to most polarizable: I-, Cl-, S2-, P3-

Order these cations in order from least to most polarizing power: Li+, Ca2+, Cs+, Ba2+

and then which ion pairs would have bonds with greatest ionic and greatest covalent character and why?

sarahtang4B

Would BF3 or ClF3 have a net dipole and how does vsepr explain it?

sarahtang4B

What does polarizability mean and polarizing power?

sarahtang4B

Order these anions in order from least to most polarizable: I-, Cl-, S2-, P3-

Order these cations in order from least to most polarizing power: Li+, Ca2+, Cs+, Ba2+

and why?

sarahtang4B

Would NH3 have a lower boiling point compared to CH4 because NH3 has a lone pair of electrons?

sarahtang4B

is naming a compound pentaaquathiocyanato the same as pentaaquathiocyano?

also the book uses chlorido instead of chloro... are these two ligands the same?

sarahtang4B

In 7th edition homework question 9C3d how do we write sodium bisoxalato(diaqua)ferrate(III), and does the order of how the molecules are written matter?
Also, why is the aqua written as OH2 and is attached to the Fe instead of the bioxalato attached to the Fe.

sarahtang4B

on homework question 9C1 on 7th edition, how do we determine oxidation number of a metal in a complex ion such as [Co(CN)5 (OH2)]^-2 and [Co(NH3)5 (SO4)]+

sarahtang4B

For homework question 2.F.15 it asks: noting that the bond angle of an sp3 hybridized atom is 109.5 and that of an sp2 hybridized Atom is 129 do you expect bond angle between two hybrid orbitals to increase or decrease as s-character of the hybrids is increased. What is the s-character and how do we...

sarahtang4B

How do we know that C5H5N is polar?

sarahtang4B

On homework 2.E.19 how do we draw the structure of (CH3)2Be?
Will we be required to know how to draw the lewis structure to determine shape and bond angles? or will test 3 have easier lewis structures than this to determine shapes.

sarahtang4B

Why does Xenon trioxide form double bonds with oxygen and have one lone pair instead of single bonds and a lone pair?

sarahtang4B

Why does hybridization occur?

sarahtang4B

Do coordination spheres only occur in transition metals and why is there a coordination sphere surrounding the complex. What is the significance of having the sphere?

sarahtang4B

What is a coordinate covalent bond? how do you define it?

sarahtang4B

How do you define a ligand and what is it? still confused..

sarahtang4B

Can somebody explain how Cisplatin works in chemotherapy again and why trans doesn't?

sarahtang4B

If the molecular shape is determined with how many atoms there are then what is the difference of trigonal pyramidal and t shaped?

sarahtang4B

For test 3, which outlines are covered?

sarahtang4B

Can somebody explain again why a double bond has one sigma and one pi bond and why a triple bond has one sigma and 2 pi bonds?

sarahtang4B

If the shape of a molecule is determined by the number of bounded atoms, then what is the difference of t shaped and trigonal pyramidal?

sarahtang4B

Pi bonds are usually weaker than sigma bonds. Quantum mechanics says this is because the orbital paths are parallel so there is much less overlap between the p-orbitals. Pi bonds happen when two atomic orbitals are in contact through two areas of overlap.

sarahtang4B

you have to draw all the possible resonance structures to show all the possible bond formations

sarahtang4B

how does the bond length affect the melting and boiling points for H20 and H2S?

sarahtang4B

What does localized vs delocalized electrons mean?

sarahtang4B

on homework question 2.d.5 it asks if CO2 or CS2 is more covalent and on the periodic table these elements are all relatively close to each other so how we we know which is more ionic without being given a chart with their electronegativities?

sarahtang4B

when forming double bonds and oxygen is present, is it typically the oxygen that forms the double bond?

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