## Search found 43 matches

Sat Mar 12, 2016 10:49 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneity
Replies: 1
Views: 396

### Re: Spontaneity

If K>1, then it is spontaneous. Also if E is positive, then the reaction is also spontaneous.
Sat Mar 12, 2016 10:47 pm
Forum: *Cycloalkanes
Topic: Z vs E for cycloalkane with one substituent
Replies: 1
Views: 525

### Re: Z vs E for cycloalkane with one substituent

Here the Z is actually referring to the double bond in the cycloalkene. When the ring gets large enough, such as in this case there are 8 carbons, then the double bond can actually bend inward. https://en.wikipedia.org/wiki/Cyclooctene There's a picture on wiki that shows you how it bends.
Sat Mar 12, 2016 10:34 pm
Forum: *Ethers
Topic: Ether priority
Replies: 1
Views: 756

### Re: Ether priority

The are the same level. Basically just treat ether as a substituent.
Tue Mar 08, 2016 11:24 pm
Topic: Two step electrophilic addition reaction
Replies: 3
Views: 595

### Re: Two step electrophilic addition reaction

Christine Wang 3D wrote:Is electrophilic addition always 2 steps?

Yes I believe so.
Tue Mar 08, 2016 11:20 pm
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: Final 2013 Q6A
Replies: 1
Views: 384

### Re: Final 2013 Q6A

Because we want the lowest single number possible, not the lowest sum. That's why we want the 1 in 1556 as opposed to the 2 in 2344.
Tue Mar 08, 2016 11:17 pm
Forum: Balancing Redox Reactions
Topic: Finding n for redox reaction (2013 Final Question 4A)
Replies: 1
Views: 378

### Re: 2013 Final Question 4A

There are 2 Fe going to Fe2+. 2* (2-0)=4.That makes four.
Sun Mar 06, 2016 6:04 pm
Forum: *Alcohols
Topic: Priority between two functional groups?
Replies: 1
Views: 458

### Re: Priority between two functional groups?

carboxylic acid always has the highest priority.

And I believe professor Lavelle said in class that we don't need to know the priority of different function groups.
Sun Mar 06, 2016 5:02 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Gibbs Free Energy of Formation
Replies: 1
Views: 384

### Gibbs Free Energy of Formation

In home work problem 14.33, they told us that the standard gibbs free energy of formation of Tl3+ is 215 kJ/mol. Why is the formation reaction Tl3+ + 3e- --> Tl and not the other way around? How would you know this?
Thu Mar 03, 2016 11:38 am
Forum: *Alkanes
Topic: Winter 2016 Quiz#3 Prep(pg43)
Replies: 2
Views: 362

### Re: Winter 2016 Quiz#3 Prep(pg43)

We would rather break the carbon chain down to more simpler substituents than one big substituent.
In the incorrect naming, you will end up with a tert-butyl as apposed to a ethyl and two methyl given in the correct answer.
Wed Mar 02, 2016 9:09 pm
Forum: *Cycloalkanes
Topic: Quiz Preparation Pg. 43, Number 5
Replies: 1
Views: 366

### Re: Quiz Preparation Pg. 43, Number 5

The answer is wrong. Yours is correct.
Wed Mar 02, 2016 9:07 pm
Forum: *Identifying Primary, Secondary, Tertiary, Quaternary Carbons, Hydrogens, Nitrogens
Topic: Sec and tert - Alphabetical order
Replies: 2
Views: 579

### Re: Sec and tert - Alphabetical order

Wendy_Xie wrote:In this case I won't use the common names but the IUPAC naming instead. This should solve such problems.

But I believe sec and tert are common names themselves?
Wed Mar 02, 2016 11:56 am
Forum: *Identifying Primary, Secondary, Tertiary, Quaternary Carbons, Hydrogens, Nitrogens
Topic: Sec and tert - Alphabetical order
Replies: 2
Views: 579

### Sec and tert - Alphabetical order

I understand that sec and tert are not considered when putting the substituents in alphabetical order. But what if there is a cyclobutane attached to a sec-butyl, a tert-butyl, and a butyl at the same time? Which substituents would come first?

The is question 6D on the 2012 final.
Tue Mar 01, 2016 10:41 pm
Forum: *Cycloalkanes
Topic: Quiz 3 Prep pg 43 question 5
Replies: 3
Views: 577

### Re: Quiz 3 Prep pg 43 question 5

Cindy Chen_2I wrote:You give priority to the I because it has a larger atomic number.

Oh I'm sorry they say the workbook gave the wrong answer, so your answer is correct as it is.
Mon Feb 29, 2016 11:42 pm
Topic: Two step electrophilic addition reaction
Replies: 3
Views: 595

### Re: Two step electrophilic addition reaction

The H will tend to bond onto the more "Hydrogen-rich" carbon.
I think they say they will explain why in 14C or D.
Mon Feb 29, 2016 11:40 pm
Forum: *Alkanes
Topic: Identifying substituents in the molecular formula
Replies: 3
Views: 507

### Re: Identifying substituents in the molecular formula

Usually if you see (CH2)x, it's in the middle of a chain because the C is attached to 2H and a 2 other Cs on the main chain.
If you see a (RCH3), it's usually the end of a chain because the C is already connected to 3H and a C on the left, so it cannot be attached to anything else.
Mon Feb 29, 2016 7:38 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: Naming a Compound with Geometric Isomerization
Replies: 1
Views: 386

### Re: Naming a Compound with Geometric Isomerization

(Z)-1,3-dibromo-2-chloroprop-1-ene
you can leave out the 1 before "ene"
Mon Feb 29, 2016 7:30 pm
Forum: *Alcohols
Topic: Naming priority between double bond and functional group
Replies: 4
Views: 9818

### Naming priority between double bond and functional group

Do we prioritize function groups over double bonds in naming?

Because according to question 2.40 (c) of the Intro to Organic Chem, the OH group gets the priority over the double bond. I'm not sure but I think I heard somewhere that we're supposed to prioritize the double bond?
Mon Feb 29, 2016 7:09 pm
Forum: *Cycloalkanes
Topic: Quiz 3 Prep pg 43 question 5
Replies: 3
Views: 577

### Re: Quiz 3 Prep pg 43 question 5

You give the lower number to the first alphabetical substituent only when the two substituents are connected by the same kind of atom. For example, in 1-ethyl-2-methylcyclopentane, you give the one to the alphabetically first substituent because they are both connected by a C atom (when you go down ...
Mon Feb 29, 2016 7:05 pm
Forum: *Cycloalkanes
Topic: Quiz 3 Prep pg 43 question 5
Replies: 3
Views: 577

### Re: Quiz 3 Prep pg 43 question 5

You give priority to the I because it has a larger atomic number.
Mon Feb 29, 2016 7:02 pm
Forum: *Alkanes
Topic: Naming in General
Replies: 2
Views: 451

### Re: Naming in General

No, you just look at the root.
Mon Feb 29, 2016 6:53 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: Another possible constitutionl isomer?
Replies: 4
Views: 595

### Re: Another possible constitutionl isomer?

No it's still the same thing because one side of the double bond is attached to two Hs. So there would be no cis or trans in this case.
Basically you're just rotating the molecule.
Mon Feb 29, 2016 6:49 pm
Forum: *Alkanes
Topic: Naming Structures
Replies: 1
Views: 341

### Re: Naming Structures

Comma separates two numbers and hyphen separates letters and numbers
Sun Feb 28, 2016 12:09 am
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: Another possible constitutionl isomer?
Replies: 4
Views: 595

### Re: Another possible constitutionl isomer?

What you draw is the same isomer as the one right next to it.
If you try to name it, you'll see that they're both named 2-Methyl-1-butene
Sun Feb 28, 2016 12:02 am
Forum: *Alkanes
Topic: Tert- and Sec- Prefixes
Replies: 2
Views: 375

### Re: Tert- and Sec- Prefixes

you don't want to count the Cs on the main chain when doing common naming
you kind of just ignore the main chain part and focus on the side chain
Sat Feb 27, 2016 11:59 pm
Forum: *Alkenes
Topic: Hmwk 1.25
Replies: 4
Views: 554

### Re: Hmwk 1.25

it's 7 because there are 2 on the left of the double bond + 2 connected by the double bond + 3 on the right of the double bond
Mon Feb 22, 2016 11:02 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: Reaction Profile
Replies: 1
Views: 359

### Reaction Profile

Could someone list out the differences between reaction profiles when they have 1) potential energy 2) standard enthalpy and 3) Gibbs free energy as their Y-axis?
Mon Feb 22, 2016 10:54 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: Organic Chem. Book: Q 4.30 Activation Energy and temperature
Replies: 2
Views: 554

### Re: Organic Chem. Book: Q 4.30 Activation Energy and tempera

On page 154 of Intro to Organic Chem, they also mentioned in the third to last paragraph that generally reactions with activation energy lower than 80 kJ/mol can occur at room temperature.
Sun Feb 21, 2016 8:22 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: A as pre-exponential factor
Replies: 2
Views: 477

### Re: A as pre-exponential factor

"A" would not be given if it cancels out. For example, when they ask you to calculate the relationship between two "k" at two different temperature, with the activation energy given, you can get the answer by using ln(k 1 /k 2 )= E a /R*(1/T 2 -1/T 1 ). And yes, I believe in real...
Sun Feb 21, 2016 8:14 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Transition States
Replies: 1
Views: 344

### Re: Transition States

The transition state is when bonds are partially formed but intermediates are molecules of which bonds are already formed.

Thus, the transition state would be the peak on the energy vs reaction progress plot. The intermediate would be the valley in between the peaks.
Sun Feb 14, 2016 9:36 pm
Forum: General Rate Laws
Topic: Slopes of the orders
Replies: 2
Views: 372

### Re: Slopes of the orders

And I was assuming you mean when we plot concentration against time. If the reaction is a zero-order reaction, the slope of rate against time can also be 0.
Sun Feb 14, 2016 9:33 pm
Forum: General Rate Laws
Topic: Slopes of the orders
Replies: 2
Views: 372

### Re: Slopes of the orders

The slope would be 0 when the concentration of something remain constant. So that would either mean this reaction is not occurring or that the system has reached equilibrium.
Sat Feb 06, 2016 11:40 pm
Forum: Balancing Redox Reactions
Topic: Clarification on Oxidizing and Reduction Agents
Replies: 2
Views: 358

### Re: Clarification on Oxidizing and Reduction Agents

Yes, the oxidizing agent is oxidizing others and thus undergoing reduction itself.
Thus the reduction agent would be reducing another and undergoing oxidation itself.
Sat Feb 06, 2016 11:38 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: standard cell potentials
Replies: 2
Views: 426

### Re: standard cell potentials

Both will give you the correct answer!
Just remember to plug in both reduction potentials for the equation E cathode - E anode
Don't plug in oxidation potential for the anode side, or you will undo the negative in the equation.

Use which ever you're most comfortable with!
Sat Feb 06, 2016 11:29 pm
Forum: Balancing Redox Reactions
Topic: Oxidation and Reduction
Replies: 2
Views: 322

### Re: Oxidation and Reduction

Oxidation --> losing electrons
Reduction --> gaining electrons
Tue Feb 02, 2016 11:46 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Chapter 14 Homework Problem 14.13(b)
Replies: 1
Views: 340

### Re: Chapter 14 Homework Problem 14.13(b)

Though I2 is a solid, it is not a conductor. That's why we need Pt here as an electrode. And since Pt is an inert electrode, it will not be involved in the reaction. My TA said he thinks the order of I2 and I- doesn't matter but he was not entirely sure.

Hope that helps :)
Sun Jan 31, 2016 10:22 pm
Forum: Van't Hoff Equation
Topic: Difference between K and K sub c?
Replies: 4
Views: 1718

### Re: Difference between K and K sub c?

Then why does the textbook specifically stated in section 11.11 (Not entirely sure this is the correct section because I have the fifth edition) that we must use K, not Kc for the van't Hoff equation?
Sun Jan 31, 2016 10:16 pm
Forum: Van't Hoff Equation
Topic: Van't Hoff Equation
Replies: 1
Views: 412

### Re: Van't Hoff Equation

I think he actually subtracted ln K1 from ln K2 on p.44 of the course reader

ln K2 - ln K1 = ln (K2/K1)
= (-delta H)/R* (1/T2-1/T1)
Mon Jan 25, 2016 10:33 am
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Determining Residual Entropy in Crystal Form
Replies: 7
Views: 1370

### Re: Determining Residual Entropy in Crystal Form

Thank you!!
Sat Jan 23, 2016 6:17 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Determining Residual Entropy in Crystal Form
Replies: 7
Views: 1370

### Determining Residual Entropy in Crystal Form

How would you approach this problem?

If SO2F2 adopts a disordered arrangement in its crystal form, what would its residual molar entropy be?
Sat Jan 16, 2016 9:44 pm
Forum: Phase Changes & Related Calculations
Topic: Homework Problem 8.21
Replies: 6
Views: 3283

### Re: Homework Problem 8.21

Oh haha sorry. It should be 20*0.39*(100-T) = 50.7*4.18*(T-22)
you get 24.8 degree for the answer.

Sorry again for the confusion.
Mon Jan 11, 2016 11:36 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Reaction Enthalpy (Course Reader)
Replies: 3
Views: 357

### Re: Standard Reaction Enthalpy (Course Reader)

Are you referring to the " ?
They just mean same as above.

So the whole thing should read:
Standard State for a gas...
Standard State for SOLN...
Standard State for Pure...
Standard State for an element...
Mon Jan 11, 2016 11:32 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Homework Problem 8.51
Replies: 2
Views: 342

### Re: Homework Problem 8.51

Because the standard enthalpy of formation of an element in its most stable form (in this case N2) is zero. (See course reader p.19)
That's why you can leave it out.
Mon Jan 11, 2016 11:24 pm
Forum: Phase Changes & Related Calculations
Topic: Homework Problem 8.21
Replies: 6
Views: 3283

### Re: Homework Problem 8.21

should be something like this:
heat released = heat absorbed
20 (mass)*0.39 (specific heat of Cu) *(100-T) (change in temperature) = 50.7 (mass)* 1 (specific heat of H2O) *(T-22)(change in temperature)

Try to solve for T. I got 32.4 degree Celsius as the final temperature.