Search found 22 matches

by mhuang 1E
Sun Mar 18, 2018 12:07 am
Forum: General Rate Laws
Topic: 15.85 Drawing structures for activated complex
Replies: 3
Views: 371

15.85 Drawing structures for activated complex

Could someone explain how to draw structures for the activated complex and what is the activated complex?
by mhuang 1E
Sat Mar 17, 2018 11:37 pm
Forum: General Rate Laws
Topic: rate law
Replies: 6
Views: 468

Re: rate law

Do you mean when:
A+B--> C+C
rate law = Rate= k[A][B]
or
A+A+B-->C+C
rate law = Rate = k[A]^2[B]

The product isn't part of the rate.
by mhuang 1E
Wed Mar 14, 2018 2:43 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 15.63
Replies: 4
Views: 204

Re: 15.63

I think there was a typo in the solutions manual in that the setup is:
lnk(k'/k)=E/R((1/T)-(1/T'))
ln(k'/k)=(38kJ/mol)/(.008314kJ/K*mol)((1/298K)-(1/310K)) = .59
(k'/k)= 1.8
k=1.5x10^10 L/mol*s
Solve for k'
k'=2.7 x 10^10 L/mol*s
by mhuang 1E
Tue Feb 27, 2018 9:15 pm
Forum: General Rate Laws
Topic: Orders and units
Replies: 3
Views: 138

Re: Orders and units

Each different order type has different units because as Harrison replied on my previous post: "Zero - rate of reaction is equal to rate constant k 1st order - depends on only ONE reactant concentration 2nd order - depends on two different reactants or one reactant squared" So, that would ...
by mhuang 1E
Tue Feb 27, 2018 9:07 pm
Forum: Zero Order Reactions
Topic: Homework question 15.17
Replies: 3
Views: 390

Re: Homework question 15.17

For this question, I tried solving for the order of [C] and got stuck. The solutions manual says that "C is independent of the rate." What does this mean? This means that C is a zero order reaction: it doesn't depend (or is affected) by the rate. When you compare experiments 1 and 4, you ...
by mhuang 1E
Mon Feb 26, 2018 10:17 pm
Forum: General Rate Laws
Topic: Order of reactions?
Replies: 3
Views: 119

Order of reactions?

Could someone clarify what exactly is zero, first and second order reactions?
by mhuang 1E
Tue Feb 20, 2018 7:03 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagram
Replies: 2
Views: 84

Re: Cell Diagram

Thank you! For 19(a) and 19(c), I was confused on when to only add Pt(s) on one side of the cell diagram and when to add Pt(s) on both sides of the cell diagram.
by mhuang 1E
Tue Feb 20, 2018 6:27 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagram
Replies: 2
Views: 84

Cell Diagram

When do we include inert solids such as Pt(s) in our cell diagrams and in 15(c), why does the cell diagram include KOH on the anode side and Ni(s) on the cathode side?
by mhuang 1E
Tue Feb 13, 2018 11:14 pm
Forum: Administrative Questions and Class Announcements
Topic: Chem Community Posts
Replies: 5
Views: 350

Re: Chem Community Posts

Are the posts counted weekly or is it cumulative throughout the quarter and then counted towards the end?
by mhuang 1E
Tue Feb 13, 2018 11:11 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 9.37d
Replies: 1
Views: 2805

9.37d

For clarification, I was wondering why the moles of solid products are mored than moles of solid reactants?
by mhuang 1E
Thu Jan 25, 2018 12:34 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.101e
Replies: 2
Views: 122

Re: 8.101e

To add on, if the standard reaction enthalpy for a certain rxn is negative, that means that the rxn is exothermic (indicating that heat is released, or that energy leaves the system.) To contrast, if the standard reaction enthalpy for the rxn is positive, that means that the rxn is endothermic (indi...
by mhuang 1E
Wed Jan 24, 2018 10:06 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 8.49 [ENDORSED]
Replies: 4
Views: 202

Re: 8.49 [ENDORSED]

From what I read on another post, it's said that if the temperature is not explicitly statedg, we can assume that the reaction is occurring at standard temperature, which is 25C (room temp) or 298K.
by mhuang 1E
Tue Jan 23, 2018 11:56 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.73 part C
Replies: 3
Views: 130

Re: 8.73 part C

I was also confused on how the enthalpy of the rxn would be 0 from the solutions manual. How does 1 C-C bond, 4 C-H bonds, and 1 H-H bond equal to 1 C-C bond, and 6 C-H bonds from the products?
by mhuang 1E
Tue Jan 23, 2018 10:35 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.49
Replies: 1
Views: 111

Re: 8.49

Because we're dealing with gases, use the ideal gas law: PV=nRT.
work=-p(delta v)=-(delta n)RT= -(1mol OF2)(8.314 JK^-1mol-^-1)(298K)=-2.48KJ
(Use 298K because we assume the rxn occurs at room temp.)
Because we are finding the change of internal energy:
(delta U)= q+ w= -318 KJ-2.48 KJ= -320KJ
by mhuang 1E
Tue Jan 23, 2018 6:37 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law Details
Replies: 2
Views: 97

Re: Hess's Law Details

Also, though final equations can have fractions has coefficients, we typically use whole numbers instead, just so that it's easier to calculate and work with.
by mhuang 1E
Tue Jan 23, 2018 6:34 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 887784

Re: Post All Chemistry Jokes Here

I'd tell a chemistry joke, but I know I wouldn't get a rxn.
by mhuang 1E
Mon Jan 15, 2018 11:44 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: HW Question 8.9
Replies: 5
Views: 498

Re: HW Question 8.9

To add on, could someone expand what is the ideal gas constant?
by mhuang 1E
Fri Dec 01, 2017 12:33 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.41
Replies: 1
Views: 152

11.41

I had a question regarding finding the number of moles for the mols of NH3 formed in the rxn: NH4(NH2CO2)(S) ⇋ 2NH3(g) + O2(g). The solutions manual uses the moles fo CO2 to find the number of mols for NH3 (2 mol of NH3 formed per mol of CO2; number of mol for NH3= 2x3.95x10^-4 = 7.90 x10^-4). But, ...
by mhuang 1E
Mon Oct 23, 2017 12:16 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Values of m1 orbitals [ENDORSED]
Replies: 1
Views: 559

Values of m1 orbitals [ENDORSED]

I was wondering if anyone could elaborate on how to find how many (and what) values of m1 are allowed for an electron for a specific sub-shell. For example, on #2.19b, it asks for the values of m1 for a 6d subshell. A d-orbital would have 5 orbitals and thus have 5 values for m1(-3,-2,-1,0,1,2,3). S...
by mhuang 1E
Wed Oct 18, 2017 12:52 am
Forum: DeBroglie Equation
Topic: CHAPTER 1 QUESTION 33!!!
Replies: 8
Views: 395

Re: CHAPTER 1 QUESTION 33!!!

I also have a question on #33, but not related to what is above. I am wondering how, in part a, you get the mass? The answer in the book says that the mass is 9.1*10^-31, but that is not given in the question and I am unsure how you would figure that out. The mass of the electron is given in the ba...
by mhuang 1E
Thu Oct 12, 2017 11:23 pm
Forum: Properties of Light
Topic: Speed of Light Constant
Replies: 18
Views: 665

Speed of Light Constant

For the problems given in the book, the textbook uses the constant c= 2.998 x 10^8 m/s, while the module examples use 3.00 x 10^8 m/s. For the problems assigned, should we use what is given in the textbook, or what is used in the module?
by mhuang 1E
Wed Oct 04, 2017 11:43 pm
Forum: Significant Figures
Topic: F5: Problem deciding significant figures
Replies: 2
Views: 200

F5: Problem deciding significant figures

Hi! I'm having some problem deciding/knowing how many significant figures to use for each problem. For example, in F5, the solutions manual shows that the mass percentage composition for C is 52.15%, while the mass percentage composition for H is 9.3787%. Could anyone explain why the answer for H ca...

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