CHEMISTRY COMMUNITY

Vana Mirzakhani 3I

Can we include OH- in our cell diagrams? Thank you.

Vana Mirzakhani 3I

What is the difference between ΔG and ∆Go? is there a difference between the following equations: ΔG=w and ∆Go=w? Thank you.

Vana Mirzakhani 3I

When solving bond enthalpies, what role do coefficients play? How do coefficients affect how we solve bond enthalpy problems? Thank you.

Vana Mirzakhani 3I

They most probably used Cp = (5/2)*R because this HW problem had specific heat at constant pressure (not constant volume).

Vana Mirzakhani 3I

For phase changes, we usually solve in mols since the equation includes n(change in)Hfusion or n(change in)Hvaporization. The "n" in these equations represent number of mols.

Vana Mirzakhani 3I

E cell does not become multiplied by any coefficient, it remains the same.

Vana Mirzakhani 3I

atm is the unit most commonly used.

Vana Mirzakhani 3I

Any constant in general does not have units because it is a ratio.

Vana Mirzakhani 3I

A catalyst only speeds up a reaction rate, but has no direct effect on the equilibrium constant.

Vana Mirzakhani 3I

K is your forward rate and k' is your reverse rate, so yes, there are differences among the two.

Vana Mirzakhani 3I

When drawing a cell diagram, do we include H20(l) at all? If we do include it in our diagram, are there any exceptions as to when we do or do not include them? Thank you.

Vana Mirzakhani 3I

Why is it that in the 7th edition HW 4A.11, the answer key solved the problem in K but the book gave us the variables in degrees C? There was no conversion between degrees C and K, the answer key just solved it using the the numbers as given. Thank you.

Vana Mirzakhani 3I

What are the differences and similarities between heat (q) in a reaction and heat (q) in a calorimeter? Thank you.

Vana Mirzakhani 3I

What criteria allows us to solve problems using just equilibrium constants or the quadratic formula? Thank you.

Vana Mirzakhani 3I

In the 7th edition homework problem 5I.33, why do we not use an ICE chart to solve?

Vana Mirzakhani 3I

When solving certain homework questions, such as 5I.19 (7th edition), how do we solve when given a certain percentage of a compound exists at equilibrium? Thank you

Vana Mirzakhani 3I

In an ICE chart, how do we know when to put coefficients for our "-x" or "+x"'s in the "C" row? Thank you.

Vana Mirzakhani 3I

When making an ice chart, when do you know to add or subtract in the "C" row? Thank you.

Vana Mirzakhani 3I

Do coefficients affect oxidation numbers? Thank you.

Vana Mirzakhani 3I

When we are given an equation with coefficients and multiple products, how do we write the differential rate law? Thank you.

Vana Mirzakhani 3I

When writing differential rate laws and we are given coefficients in our equation, how do we go about writing the rate law? How does having coefficients present affect rate law? Thank you.

Vana Mirzakhani 3I

Does anyone know how to solve homework 7B.3 part C step by step from the 7th edition textbook? I am having difficulty understanding how to solve when given a concentration from the products instead of the reactants. Thank you.

Vana Mirzakhani 3I

Does change in U = internal energy or does just U by itself = internal energy? I am confused as to which symbol is the correct one to represent internal energy? Thank you.

Vana Mirzakhani 3I

Put simply, Q is calculated when the reaction is not at equilibrium.

Vana Mirzakhani 3I

Yes, both are solved in the same way. Once both values are found, compare both to see if Q=K, which means the solution is at equilibrium.

Vana Mirzakhani 3I

pH=-log[H3O+] or pH=-log[H+]
Please note that anything with brackets means "concentration of".

Vana Mirzakhani 3I

Simply put, anything with OH- is a base and anything with H30+ or H+ is an acid.

Vana Mirzakhani 3I

ICE tables may be used for both cases. They are also helpful in comparing Q with K to check equilibrium.

Vana Mirzakhani 3I

Hi Ashley! Thank you so much for your thorough advice!

Vana Mirzakhani 3I

May someone please explain the ratios for the ice boxes that we do? How does "-x" work with ratios? Thank you.

Vana Mirzakhani 3I

Does anyone remember the Q and K bar graph Dr. Lavelle explained in his slides? May someone please explain the bar graph and its patterns. Thank you.

Vana Mirzakhani 3I

When solving HW problem 5I.13, it asked to see which is more "thermodynamically stable"? What is meant by thermodynamic stability? What determines its stability? Thank you.

Vana Mirzakhani 3I

I know some are already expected of us to know. Overall, my TA said its highly recommended that you do know them.

Vana Mirzakhani 3I

Yes, we always write the molecular geometry because it gives a more accurate shape name than electronic geometry.

Vana Mirzakhani 3I

I believe it will be appropriate to say so if electronegative difference exists, resulting in polarity.

Vana Mirzakhani 3I

Also, to add on, bases are alkaline and as long they are so, a "soapy" feel of bases will result

Vana Mirzakhani 3I

Thank you so much for having taken the time to create a review packet for us Lyndon! Appreciate it!

Vana Mirzakhani 3I

Coordination # = number of ligands bonded to central atom
Oxidation # = charge on central atom

Vana Mirzakhani 3I

Yes, and just in case if you will need a kind reminder of which problems, here they are:

7th Edition Unit 5
Focus 9C.1 and 9C.2 Problems 9C: 1,3,5,7,9

7th Edition Unit 6
Fundamentals J Problems 1,7,9,11,13,17,23

Vana Mirzakhani 3I

Can you find coordination numbers with 2 central atoms? if so, how? If not, why not? Thank you.

Vana Mirzakhani 3I

To add on, as atomic size increases, surface area of the atom also increases, leading to a higher melting point for CHI3 rather than CHF3.

Vana Mirzakhani 3I

You will need to write the molecular geometry only.

Vana Mirzakhani 3I

Are lewis structures only used for covalent bonds or are they also used for ionic bonds as well? Thank you.

Vana Mirzakhani 3I

What is exactly meant by the term magnitude in the definition of a dipole? Thank you.

Vana Mirzakhani 3I

Hey Brian, thank you so much for your help!

Vana Mirzakhani 3I

On the 2.59 homework, how do we write the composition of bonds and hybridization of lone pairs for H2C=CHCHO when you have a double bond with one pi and one sigma bond? I am having difficulty understanding, for example, how to reach one of the answers of sigma (C2sp^2,O2sp^2) pi(C2p, O2p). Also, how...

Vana Mirzakhani 3I

For unit 4 HW, question 2F.1, when we are asked to write the relative orientations of the hybrid orbitals, may we just write their molecular geometry (tetrahedral or linear or t-shape)? Is saying, for example, tetrahedral, the same as tetrahedron? Is there a difference between relative orientation a...

Vana Mirzakhani 3I

A: What's the formula for water?
B: H I J K L M N O
A: That's wrong!
B: Nope, the formula is H to O

Vana Mirzakhani 3I

Sigma bonds can be rotated because they interact end to end with one electron bonded end to end. Because this electron is bonded end to end makes it possible for the sigma bond to rotate without breaking. On the other hand, pi bonds interact side to side with one electron bonded side to side, making...

Vana Mirzakhani 3I

Lone pairs have great repulsion strength from one another, always trying to move as far apart as possible while keeping an equally distributed distance from the central atom.

Vana Mirzakhani 3I

How would you label/draw hybridization if you had BF3?

Vana Mirzakhani 3I

How come for trigonal planar geometry and for tetrahedral geometry if the number of bonded electrons (coordination number) is 2, the molecular geometry is bent but for trigonal bipyramidal when the number of bonded electrons is 2, the molecular geometry is linear - not bent? Thank you in advance!

Vana Mirzakhani 3I

This past Saturday we received an email mentioning how we are done with outline 3 and will be starting outline 4 throughout this week in hopes of not having lecture next week. I would assume we are ahead enough where no lecture will be needed next week. Good luck with travel plans!

Vana Mirzakhani 3I

If the molecule is polar, then yes, triple and double bonds have more polarity than a single bond. Also, a triple bond has more polarity than a double bound, if you were to compare the two together. Hope this helps!

Vana Mirzakhani 3I

Is it possible to have a coordination number that's 1? Why or why not? Thank you.

Vana Mirzakhani 3I

When trying to draw the structure of NH3, will this structure have that triangular shaped wedge at any given time? I ask so because I know that the central atom, N, ends up with a lone pair, but am not sure if that triangular shaped wedge would be appropriate. Thank you.

Vana Mirzakhani 3I

When drawing the shape of a compound, what do the dashed signs ("||||||") between elements and the dark triangular signs (▲) mean? Thank you.

Vana Mirzakhani 3I

To add on, spherical shaped molecules have lower boiling points, usually 10°C, and rod shaped molecules have higher boiling points, usually 36°C.

Vana Mirzakhani 3I

I was interested in knowing if H2S is polar or nonpolar? Why? Also, is it dipole or not? Why? The differences among the two have been confusing me. Thank you!

Vana Mirzakhani 3I

When dealing with a limited number of valence electrons, you turn to double bonds to add more flexibility when wanting to achieve octets. For example, when given the compound ONF, first we find its valence electrons. O has 6, N has 5, F has 7, all of which total to 18. Now you know your limited numb...

Vana Mirzakhani 3I

From the best of my knowledge, I know that if that element is either in or after row 3, it may have more than an octet. Also, if an element is usually past the atomic number of 20, it may have more than an octet as well. Hope this helps.

Vana Mirzakhani 3I

The HW question gives K3P compound and asks for Lewis Structure to be written? Would anyone know why the final answer is spaced out in such a way? Also, would anyone know why only P has brackets around it, but not K? Thank you in advance!

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