CHEMISTRY COMMUNITY

Lorie Seuylemezian-2K

Given the instantaneous rate of the reaction. 2.7 x 10^2 andninitial mass of 1.8g confined to a 750ml vessel, what is the rate constant of this reaction. From the previous questions we have they the rate equation is rate=k[h2o][o2]^2

Lorie Seuylemezian-2K

Hey could anyone help me work through question 5 on test 3 i got the n, and the standard e correct but not the last question where you have to find the rate constant

Lorie Seuylemezian-2K

Yes enthaply is a state function!

Lorie Seuylemezian-2K

I agree with the above answer the slow step is the one with the matching rate law

Lorie Seuylemezian-2K

I believe that everything between a 50-79% is a C and then regular percentages above that for B and C

Lorie Seuylemezian-2K

My TA said the same thing about hw problemss I believe it’s material until last Friday’s lecture

Lorie Seuylemezian-2K

You also need time!

Lorie Seuylemezian-2K

I think the best explanation for this is the endorses chem_mod post that you can access in the announcements page!

Lorie Seuylemezian-2K

Got it this makes sense now!

Lorie Seuylemezian-2K

Can someone explain where we get the reaction A= e^-kt * ao

Lorie Seuylemezian-2K

Yes I also agree! You use the coefficients and divide or multiply accordingly

Lorie Seuylemezian-2K

I believe it needs to explicitly show [A]o or else we are unsure what order concentration is given

Lorie Seuylemezian-2K

Does anyone know how much of kinetics (ch 15) will be on the test week 9?

Lorie Seuylemezian-2K

I am having trouble identifying the reducing and oxidizing agent in equations such as 3a in the homework?

Lorie Seuylemezian-2K

No there is a -2 charge on both sides of the equation.
reactants: 2- from s2o3
products: 4- from so4, 10+ from h, 8e-

Lorie Seuylemezian-2K

This is because we multiply the half reactions with a coefficient in order to cancel out the electrons on both sides.

Lorie Seuylemezian-2K

E is cell potential which will not be covered on the midterm.

Lorie Seuylemezian-2K

Yes you can! You don't call it hesss law but the same theory is used to make similar calculations

Lorie Seuylemezian-2K

What equation we use is based on if the equation is reversible or not. If it is reversible we use the equation with R in it and if it is irreversible we use the equation with w=-pextdeltaV

Lorie Seuylemezian-2K

Yes, all of dr. lavelles tests follow the same format, except the midterm is longer than the tests and the final is even longer than that.

Lorie Seuylemezian-2K

Can someone please show me their work with the numbers for this no matter what I do i keep getting the wrong answer?

Lorie Seuylemezian-2K

I believe we the question usually specifies if it is not calcite. (like they do with diamond when carbon is in the question).

Lorie Seuylemezian-2K

On the first quiz there was a question regarding heat exchange and release I had trouble understanding if you use endothermic/exothermic to answer these or just common knowledge such as the sun heats up water during evaporation therefore there is heat exchange.

Lorie Seuylemezian-2K

Can someone help me work through #7 on quiz 1 the one with five steps of enthalpies we must calculate.

Lorie Seuylemezian-2K

Dr. Lavelle continued to explain that the final answer is anything higher than 333k will result in a spontaneous reaction in the forward direction.

Lorie Seuylemezian-2K

I also think this is not possible because if a system exchanges matter the energy will also exchange. Therefore if a system is exchanging matter I think it always classified as a open system.

Lorie Seuylemezian-2K

Does anyone know what the last chapter on the midterm will be?

Lorie Seuylemezian-2K

My TA asked us to move on to chapter 9 he said if you can't do all chapter 9 do half chapter 8 and half chapter 9

Lorie Seuylemezian-2K

After going through the homework I noticed numbers 3-13,25-31, and 47-49 all have to do with calculating work or internal energy. I would suggest studying all the other homework problems specifically for this upcoming test. Can anyone else confirm that these problems aren't going to be tested on? I...

Lorie Seuylemezian-2K

Can someone explain to me how coffee in a thermos is an isolated system? Doesn't heat still escape?

Lorie Seuylemezian-2K

I agree with the responses above that this is just a convention to allow us to do the calculations for solutions.

Lorie Seuylemezian-2K

This makes sense now, thank you all for the responses! I was having trouble grasping the concept earlier.

Lorie Seuylemezian-2K

Can someone explain to me why heat capacity increases as molecular complexity increases?

Lorie Seuylemezian-2K

Can someone explain how a sample's temp remains constant during phase transitions?

Lorie Seuylemezian-2K

Can someone help me figure out for the bond enthalpies method why the reactants have positive enthalpies and the products negative?

Lorie Seuylemezian-2K

I use the prefixes, Ex->exiting heat, en-> entering heat or needing heat.

Lorie Seuylemezian-2K

Can someone please explain this principle to me and how we are supposed to apply it?

Lorie Seuylemezian-2K

Could someone help me name and draw the Lewis structure for the test problem [HgF2(OH2)2]+

Lorie Seuylemezian-2K

Yes I agree with the post above! Only use the equilibrium arrow when you are working with weak acids and bases.

Lorie Seuylemezian-2K

Always remember to keep it consistent! If one reactant is decreasing by X then all of them should be decreasing and visa versa!

Lorie Seuylemezian-2K

Thank you so much! I just wasn't understanding why we originally count out of 17 but now I get it!

Lorie Seuylemezian-2K

Can someone help me out with part C of 11.7, I don’t really understand why the answer book is out of 17?

Lorie Seuylemezian-2K

Is the single sigma bond always the "center" bond?

Lorie Seuylemezian-2K

I believe you name it based on the exact type that the ligand is acting as in the specific polydentate.

Lorie Seuylemezian-2K

In my opinion knowing the trend is the easiest way to remember the electronegativity of different elements. An easy trick for that is just learning the atomic radius trend and knowing that everything else is the opposite! The only exception there is for the last group of elements because their valen...

Lorie Seuylemezian-2K

I believe they are different things. Molecular shape is the 3D structure of a molecule which includes the bond angles and the orientation of the different atoms. On the other hand molecular geometry is the name of the shape for example trigonal planar or tetrahedral.

Lorie Seuylemezian-2K

Does anyone know if the homework from week 7 is from chapter 4 or chapter 17?

Lorie Seuylemezian-2K

Personally, I️ think memorizing what type of shape a certain number atom molecule is and the angles associated with that is the quickest way to learn! But once you know it for a single 3 atom molecule you know it for all 3 atom molecules!

Lorie Seuylemezian-2K

I️ agree with this tip! It helps to prevent errors in calculation which can ruin your Lewis structure

Lorie Seuylemezian-2K

The homework for this week is ch 4! However I’m not sure how the discussions on Friday turn in the homework!

Lorie Seuylemezian-2K

Determining whether or not electrons are paired can be done using an Aufbau diagram if every electron has a pair for example 2 arrows on every line than all electrons are paired! An easy trick is if the number of electrons in each sub shell is at the maximum then all electrons are paired.

Lorie Seuylemezian-2K

5s has a lower energy until there are 2 electrons in that orbital. Once there are 2 electrics 4d has a lower energy!

Lorie Seuylemezian-2K

Can someone help me work through chapter 2 section 63?

Lorie Seuylemezian-2K

Can anyone explain how we determine the bonding when it comes to exceptions to the octet rule ad drawing lewis structures.

Lorie Seuylemezian-2K

There is no scientific reason why we fill the px orbital first. Theoretically, it could fill any on of them however we start with px for simplicity.

Lorie Seuylemezian-2K

Is there a reason for this exception? (the difference in stability)

Lorie Seuylemezian-2K

This helps so much! Thank you, Is there any combustion where we know the oxygen because in the homework there were sceniors where we did not approach the problem this way.

Lorie Seuylemezian-2K

What is the smallest wavelength that can be detected?

Lorie Seuylemezian-2K

I also solved the problem and got 150 pm, I think the back of the book is a typo as the solutions manual agrees with our answer.

Lorie Seuylemezian-2K

Can someone help me work through the compound X question on Test 1. It was the second to last question on the test?

Lorie Seuylemezian-2K

Can someone explain step by step how to do step B

Lorie Seuylemezian-2K

Hello!
I just wanted to ask if the 0 after the number 0.0450 counts as a significant figure? Is this 5 or 4 sig figs?

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