CHEMISTRY COMMUNITY

Courtney_Koenig_3K

Since there is no material left to cover, I was wondering if there is going to be a lecture on Friday.

Courtney_Koenig_3K

In the front of the course reader it says the final exam is worth 160 points, but all of the previous finals have been 170 points. Does anyone know if it's worth 160 points or 170?

Courtney_Koenig_3K

In lecture Dr. Lavelle talks about an example where a HBr molecule is broken and attached to a hydrocarbon. In the example he always attaches the H+ ion first to the hydrocarbon and then the Br- to the hydrocarbon. Does the order that the ions are attached matter? And if it does, then why is the H+ ...

Courtney_Koenig_3K

Do we have to know how to draw any graphs for quiz 2?

Courtney_Koenig_3K

In the course reader it says to make only one reactant's concentration variable and the other's constant. Then it says that n (order) is determined by the plot. (Ln([A])=1st order, 1/[A]=2nd order, and [A]=zero order) How would we find the plot to determine the order? or would we be given the plot a...

Courtney_Koenig_3K

When balancing redox reactions, H2O and OH- are always used to balance the O and H in the RXN. Why isn't H+ used to balance the RXN?

Courtney_Koenig_3K

I know for an exothermic system delta H is negative, but if the question is asking for the quantity of that heat, would the quantity be positive?

For example, if delta H= -1500kJ/mol, would we say that 1500kJ/mol is removed from the system?

Courtney_Koenig_3K

If a question asks how much heat is removed from a system, would the answer always be positive?
I found delta H and it was negative, so I don't know if I keep it as a negative, or make it a positive cause it is asking for how much heat and not the change in heat.

Courtney_Koenig_3K

I think that since it says the reaction is an isothermal reaction, any energy that is lost from doing work is replaced in the form of heat from the surroundings. Since delta S(sys)= delta H(sys)/T, as T decreases, delta S(sys) increases to become positive.

Courtney_Koenig_3K

Thank you so much it makes so much sense now.

Courtney_Koenig_3K

In the course reader it says that delta U= 3/2 nR(delta T)=0. Is this just for when the system is at equilibrium so all the heat lost is replaced (delta T=0)? If not then why is this equation true?

Courtney_Koenig_3K

Can someone please explain what degeneracy is? I don't understand what it is or why it is related to entropy.

Courtney_Koenig_3K

What do Qv and Qp stand for and how do you find the Qv and Qp?

Courtney_Koenig_3K

Why are there so many methods to finding enthalpy and how do I know which method should be used?

Courtney_Koenig_3K

During lecture Dr. Lavelle keeps saying that the moles of the titrate is equal to the moles of the sample. Why is this true?

Courtney_Koenig_3K

In the course reader there is a note on page 156 that says if [H3O]+ < 10^(-7) then solution is considered neutral because we know that autorpotolysis generates 10^-7 mol/L H3O+. Can someone please explain what this means.

Courtney_Koenig_3K

When we make the ice box, if there are two products/reactants we say that they have the same change in concentration. For example 2NO<=>N2+O2. The change in N2 and O2 would both be x, but why do they have the same change in concentration?

Courtney_Koenig_3K

In the 1st practice quiz for quiz 3 in the workbook, number 3 has (en)2 in the chemical formula. The answer gives it the name bisethylenediamine. Why is it named like this?

Courtney_Koenig_3K

In the p orbitals, px and py are pi bonds and pz is sigma bonds. Why are there two pi bonds and one sigma bond, and why is it the pz orbital that has the only sigma bond?

Courtney_Koenig_3K

In the Wednesday lecture he showed us that the Carbon atom had its valence electrons placed in these orbitals: two electrons in the s orbital, one electron in the px and py orbitals, and an empty pz orbital. Why can't the H electrons just fill the empty pz orbital and the rest of the px and py ones?

Courtney_Koenig_3K

Which elements are predicted to have the following ground-state electron configurations. d) [Rn]7s^2 6d^2 In the periodic table in the textbook both thorium and rutherfordium have this configuration, but the solutions manual says that the answer is thorium. How do I know which one it is if they have...

Courtney_Koenig_3K

Thank you. That makes sense.

Courtney_Koenig_3K

Thank you for explaining it. I found the picture and it makes sense now.

Courtney_Koenig_3K

On the second practice quiz for quiz #1 in the workbook #8 asks what is the wavelength of the radiation emitted when an electron transitions from n=4 to n=3? For my answer I got -1875 nm, but the answer is 1875 nm. Why is it positive? Here is my work: E=-hR/(4)^2= -1.3624x10^-19 E=-hR/(3)^2= -2.4220...

Courtney_Koenig_3K

Could someone please explain to me the answer to Chapter 1 homework question 1.11 Q. 1.11: In the spectrum of atomic hydrogen, several lines are generally classified together as belonging to a series (for example, Balmer series, Lymann series, Paschen series), as shown in Figs. 1.10 and 2.1. What is...

Courtney_Koenig_3K

What is the chemical formula for coffee? Co(Fe)2 If H2O is the formula for water, what is the formula for ice? H2O cubed Why did the chemist sole and heel his shoes with silicone rubber? To reduce his carbon footprint. What happened to the man who was stopped for having NaCl and a nine-volt in his c...

CHEMISTRY COMMUNITY

Search found 26 matches

Lecture on Friday

Final Exam points

HBr example from lecture

Re: Quiz 2 Winter 2017

Determining 1st, 2nd, or 3rd Order

OH- H+ and H2O in balancing redox reactions

Re: signs of delta H

signs of delta H

Re: Practice Quiz 1 #9

Re: Qv and Qp in delta U equations [ENDORSED]

Ideal gas.

Degeneracy

Qv and Qp in delta U equations [ENDORSED]

Methods of Determining Enthalpy

Moles in sample and titrate

Autorpotolysis Note(pg 156 Course Reader)

Ice Box Change in Concentrations

(en)2 naming

sigma and pi bonds in p orbital

Hybridization question

Ch. 2 Textbook Question 45d. [ENDORSED]

Re: Practice Quiz #8

Re: Atomic Spectra question 1.11 [ENDORSED]

Practice Quiz #8

Atomic Spectra question 1.11 [ENDORSED]

Re: Chemistry Jokes