CHEMISTRY COMMUNITY

nshahwan 1L

Is there any point in which Enot and Ecell would be the same value?

nshahwan 1L

605395381 wrote:they will probably have us download and print the finals

But what if I don't have a printer? Like that seems really problematic

nshahwan 1L

Im not saying this would happen, but I am really afraid that my laptop will malfunction or my wifi will go out or something during the final. Do y'all think if something bad like that happens we will still be able to turn it in someway else?

nshahwan 1L

KBELTRAMI_1E wrote:Does anyone know how to scan from an at home wireless printer?

There are also a lot of apps you can download to scan with your phone not just notes.

nshahwan 1L

I'm a little confused on how you specifically determine if it is first order or not. Could someone explain with an example because sometimes in the book it just says it is first order and doesn't say how to get that.

nshahwan 1L

On test 2 someone explained to me that on one of the questions you had to know your solubility rules but I don't remember any of that so does anyone have a good source where I could learn them?

nshahwan 1L

In the electrochem readings, it defines Gibbs free energy as non expansion work. Is that relevant?

nshahwan 1L

In the book for calculating Gibbs it always uses n=2. Im confused on how they got that because in one of the problems the solution uses n=6. I think I must have missed it in the reading or something but how do you figure out what n is?

nshahwan 1L

On page 549 the difference between Ecell and E standard cell is explained but the book gets really wordy and confusing. It says it is important to know so could someone explain to me the difference?

nshahwan 1L

I am confused on part d of this question could someone explain how to do it? Basically the way I do these question I usually get the correct answer, but then the solutions shows something different in the balancing or it combines certain elements and I am just confused on when to do that.

nshahwan 1L

This is a more general question, but does anyone have any advice on what they would do if the question does not give enough information to use any formulas? I usually get very stuck when I am missing a variable that PV=nRT doesn't help with, and I was wondering if there were any strategies anyone ha...

nshahwan 1L

Should there be any specific examples of salts that are in salt bridges that we should be aware of?

nshahwan 1L

i guess also how would you go about solving a problem where you aren't given any entropies in the first place? Like this obviously depends on the information given in the question, but i feel like I often don't have enough information to find both. Thank you so much for the explanations tho they wer...

nshahwan 1L

ok thanks for the simpler clarification!

nshahwan 1L

thank you so much for all the great explanations!!

nshahwan 1L

How would you define gibbs free energy in laymens terms?

nshahwan 1L

can someone explain how you find surrounding again? I just want a clearer and simpler explanation than the book.

nshahwan 1L

how do you know when to put water in the half reaction when balancing?

nshahwan 1L

can someone re explain what a salt bridge does?

nshahwan 1L

Yes any electrochem we do in week 8 should be on it

nshahwan 1L

Thanks so much!

nshahwan 1L

4C.9 (a) Calculate the heat that must be supplied to a copper kettle of mass 500.0 g containing 400.0 g of water to raise its temperature from 22 . 0 °C to the boiling point of water, 100 . 0 °C . (b) What percentage of the heat is used to raise the temperature of the water? (See Table 4A.2.) 4C.11 ...

nshahwan 1L

How do you know if you are supposed to add the enthalpy of phase change to the heat or not? For example in 4C.9 you do not, but in 4C.11 you do

nshahwan 1L

Would we be given any problems like this on the midterm? Only asking because it uses radius and distance for volume instead of just volume in leters

nshahwan 1L

On the midterm, will we be given the formulas for heat capacity monatomic ideal gases? For example, will we be given the formula for a monatomic ideal gas heat capacity at constant volume/pressure (4C.3)

nshahwan 1L

Would we ever have to calculate/know the amount of that force? Thanks!!

nshahwan 1L

Thank you so much this helped a lot!!

nshahwan 1L

Ok thanks so much!

nshahwan 1L

where did you get that internal energy is equal to 2/3nRT?

nshahwan 1L

Thanks for the replies. Also I think they will tell us if it is reversible but I am not sure. For example if it is isothermic should we assume it to be reversible?

nshahwan 1L

Could someone explain how the small change is made to reverse a process? Like I understand a very small part of a variable is changed (like pressure) but how would that be done?

nshahwan 1L

This page explains the isothermal expansion of an ideal gas and I don't really understand it in the books language. Could someone explain it in other words or perhaps an example?

nshahwan 1L

when does internal energy not equal work?

nshahwan 1L

This is just for clarification but would the expansion work of the piston and cylinder on p245 be when the piston is retracting? Also could someone more clearly define what it means to be the force opposing expansion?

nshahwan 1L

Im having a little trouble understanding the language of when work should be positive or negative. What is the difference between work done on a system and work done by a system? Could someone explain using examples?

nshahwan 1L

I noticed this on the formula sheet thank you for letting me know!

nshahwan 1L

Thank you all so much! I found a much better explanation of this rule in chapter 6 as well.

nshahwan 1L

oh ok thanks so much!

nshahwan 1L

thank you all so much this helped a lot!

nshahwan 1L

Could someone explain how to do part b? Because it is asking for Kb and pKb is it an acid or a base?

nshahwan 1L

Can someone explain how you get the first to columns? Like why did they just multiply 1.5 by 10^-14

nshahwan 1L

6A.21 The value of K w for water at body temperature (37 °C) is 2 .1 × 10 − 14 . (a) What is the molar concentration of H 3 O + ions at 37 °C? (b) What is the molar concentration of OH − in neutral water at 37 °C?

I am confused on what should be the difference for part a vs part b?

nshahwan 1L

Could someone explain the first paragraph on p431 of the textbook??

nshahwan 1L

In example 5J.2, it justifies picking 0.0144... over 81.7... for the x value because partial pressures must be positive. However, both of these values are positive. How would you know which positive value to pick?

nshahwan 1L

When using an ice box, should you always use the approximation method where x additions are removed first? In other words, how can you tell when or when not to use the quadratic equation? Toolbox 5I.1 explains this, but I don't understand it in their words.

nshahwan 1L

Could someone explain the Gibbs free-energy curve shown in figure 5I.3 in the book. The book explains it but I don't quite have a grasp of it.

nshahwan 1L

Could someone more clearly explain how to change the units to bar? Example 5I.1 show it but it is not very clear and I am confused

nshahwan 1L

would there be any case when the reactants would not be -x in the ice box?

nshahwan 1L

what is the difference between partial pressure and total pressure? Could someone explain this using an example

nshahwan 1L

how should we know to use K_p or K_c? Like when is it appropriate to use each one. I am asking because the example problem in class for K_c was an equation of only gases.

nshahwan 1L

thank you this helped

nshahwan 1L

could someone conceptually explain it?

nshahwan 1L

Would we ever have to calculate anything with the formula he gave us in class? also, would it be correct to say the higher the charge, the more polarizable the anion

nshahwan 1L

6C.21 Suggest an explanation for the different strengths of (a) acetic acid and trichloroacetic acid; (b) acetic acid and formic acid.
Am i supposed to know the formulas for things like formic acid?

nshahwan 1L

6C.17 Which is the stronger base, the hypobromite ion, BrO−, or morphine, C 17 H 19 O 3 N ? Justify your answer.
The book's justification is because of pKb, but how would we know that? Are we supposed to be able to calculate it?

nshahwan 1L

Im having trouble balancing part d of this question could someone help? J.7 Select an acid and a base for a neutralization reaction that results in the formation of (a) potassium bromide; (b) zinc nitrite; (c) calcium cyanide, Ca(CN) 2 ; (d) potassium phosphate. Write the balanced equation for each ...

nshahwan 1L

Ok so this is just clarification.
heme complex + protein = myoglobin
4 myoglobin = hemoglobin
Also is one heme complex monodentate, but the myoglobin as a whole is tetradentate??

nshahwan 1L

Can the oxidation number of the metal ever be above (IV)? I have never seen it higher so I'm just curious.

nshahwan 1L

Can someone explain how to do sig figs for pH I'm confused??

nshahwan 1L

Can someone explain when the Kinetic energy would be 0 in a question? I'm confused because in some questions it is zero and in others it is not and I don't know how to tell when it is?

nshahwan 1L

so for :N=N: the sigma bond would be (N2sp;N2sp) but for the pi bonds, would both of them be (N2p²;N2p²) or would it be (N2p;N2p) for both of them??

nshahwan 1L

Ok so for lone pairs, do we just look at the regions of electron density and determine they hybridization for just that atom? For example, if I was given a N with 3 regions of electron density (one region being composed of a lone pair), would I write N= 2sp²?

nshahwan 1L

Could anyone explain conjugate acids and bases in words? I understand how to identify them in an equation, but is there any way to describe them in words?

nshahwan 1L

This is just a clarification question, but when looking at a molecule and determining the points of hydrogen bonding, we are supposed to count each lone pair as well as each hydrogen bonded to NO or F correct?

nshahwan 1L

When naming we write the ligands in alphabetical order. When we write out the formula from a name, should we write the substances in alphabetical order or does it not matter?

nshahwan 1L

Will we ever have to calculate Ka for weak acids?? Or will they always be given? Also, should we know how to calculate pKa?(its simple but It sort of relates to if we have to calculate Ka in the first place or if it will be given)

nshahwan 1L

also, should we know an example of a coordination compound for each usual coordination number? Like an example for the coordination number 2, because 2 is a less common coordination number.

nshahwan 1L

Would it be correct to say that coordination number is synonymous with regions of electron density? Or is it different because it specifically refers to the places in which coordinate covalent bonds are formed?

nshahwan 1L

Regarding the email Dr. Lavelle sent, should we be expected to memorize everything on the pdf in preparation for the final? Everything as in all the neutral and anionic ligands listed as well as the names of the example coordination compounds at the bottom?

nshahwan 1L

Ok so I understand what a substitution reaction is, however would we need to know which ions cause a less complete reaction? The example in the book is [Fe ( OH 2 ) 6 ] 2+ ( aq ) + Cl − ( aq ) → [ FeCl ( OH 2 ) 5 ] + ( aq ) + H 2 O ( l ). Also, could anyone explain why certain ions do not completely...

nshahwan 1L

Is there any specific way to tell the difference between each force when assigning the IMFs to molecules. Like for dipole-dipole, besides it being polar is there anything in a molecule that would tell you it was that? Also for IMFs, are there ever any exceptions?

nshahwan 1L

Can someone explain part b to me?
2E.3 Draw the structures and name the shapes of the following molecules: (a) HCN; (b) CH₂F₂ .

nshahwan 1L

How can you tell if something is linear or not?

nshahwan 1L

should we know how to draw a resonance hybrid??

nshahwan 1L

2B.11 Draw the complete Lewis structure for each of the following compounds: (a) formaldehyde, HCHO, which as its aqueous solution, “formalin,” is used to preserve biological specimens; (b) methanol, C H 3 OH , the toxic compound also called wood alcohol; (c) glycine, H 2 C(N H 2 )COOH , the simples...

nshahwan 1L

How can you tell if the bond is ionic enough to write the lewis structure in that way? For example in 2B.9:2B.9 Draw the complete Lewis structure for each of the following compounds: (a) ammonium chloride; (b) potassium phosphide; (c) sodium hypochlorite. Also, should we know the nomenclature for th...

nshahwan 1L

2A.23 On the basis of the expected charges on the monatomic ions, give the chemical formula of each of the following compounds: (a) magnesium arsenide; (b) indium(III) sulfide; (c) aluminum hydride; (d) hydrogen telluride; (e) bismuth(III) fluoride. Should I know how to do this? we never went over i...

nshahwan 1L

1E.5 Which of the following statements are true for many-electron atoms? If false, explain why. (a) The effective nuclear charge Z e ff e is independent of the number of electrons present in an atom. (b) Electrons in an s-orbital are more effective than those in other orbitals at shielding other ele...

nshahwan 1L

1E.1 Which of the following increase when an electron in a lithium atom undergoes a transition from the 1s-orbital to a 2p-orbital? (a) Energy of the electron. (b) Value of n. (c) Value of l. (d) Radius of the atom. Which answers would be different for a hydrogen atom and in what way would they be d...

nshahwan 1L

1D.19 How many orbitals are present in the (a) 4p-subshell; (b) 3d-subshell; (c) 1s-subshell; (d) 4f-subshell of an atom?
I just want to confirm if I have this right in my head:
subshells = 4f,3d,3p,1s,etc...
orbitals = number of spots to put the paired electrons in?

nshahwan 1L

1D.1 Which of the following increase when the electron in a hydrogen atom undergoes a transition from the 1s-orbital to a 2p-orbital? (a) Energy of the electron. (b) Value of n. (c) Value of l. (d) Radius of the atom. Could someone explain this one to me? I'm more confused with the quantum number pa...

nshahwan 1L

also for part d ((d) What kind of electromagnetic radiation was used?) would we need to know something like this for the midterm?

nshahwan 1L

Im confused as well. Why would we use E=hv for this one?

nshahwan 1L

I understand how to do this, but could someone explain why you divide the energy of the photon from the given watts?

nshahwan 1L

1A.15 In the ultraviolet spectrum of atomic hydrogen, a line is observed at 102.6 nm. Determine the values of n for the initial and final energy levels of the electron during the emission of energy that leads to this spectral line. Also how do you find the initial and final n for this problem? Would...

nshahwan 1L

1A.11 In the spectrum of atomic hydrogen, several lines are generally classified together as belonging to a series (for example, Balmer series or Lyman series, as shown in Fig. 1A.10). What is common to the lines within a series that makes grouping them together logical?
Could someone explain this?

nshahwan 1L

The Pauli Exclusion Principle states that no two electrons can share the same combination of four quantum numbers. The electrons in an orbital must have opposite spins in order for their quantum numbers to differ. Since their n, l, and ml are the same, their ms (which refers to the spin of the elec...

nshahwan 1L

Figure 1A.10 in the text is a good visual of them

nshahwan 1L

Don't stress too much! there are tons of resources available! I find that talking to other people in the class helps a lot.

nshahwan 1L

2px: 2 level; p orbital; x-axis

nshahwan 1L

They aren't overwhelmingly significant I would say, but they give visual to the direction and overall shape of an atomic orbital.

nshahwan 1L

is it better to use 2.998 or 3?

nshahwan 1L

Read the textbook and find other people in the class! Office hours help too!

nshahwan 1L

Should we have to indicate x, y, z in answers?

nshahwan 1L

Can someone explain this one I just want to make sure I'mg getting it right. Which of the following happens when the frequency of electromagnetic radiation decreases? a) The speed of the radiation decreases b) The wavelength of radiation decreases c) The extent of the change in the electrical field ...

nshahwan 1L

I was looking for more resources for review and these are all super helpful!

nshahwan 1L

Thanks this was a helpful review.

nshahwan 1L

Example G2 on page F55 is a good example of this problem.

nshahwan 1L

I am not entirely sure, but I think you could use the moles of people, or include the conversion you did in part a in your answer. You would need the moles of people in order to convert to seconds because you have to cancel the moles of peas to have an answer in time units.

nshahwan 1L

When calculating mass percentage composition, what should I round the numbers to? I did problem F5 and my percentages for C₇H₁₅NO₃ did not add up to 100% because of the places I rounded to.

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