Search found 32 matches

by Belicia Tang 1B
Wed Mar 08, 2017 3:51 pm
Forum: *Aldehydes
Topic: Ketones vs. Aldehydes
Replies: 1
Views: 658

Ketones vs. Aldehydes

Hi, I am confused as to why ketones cannot occur at the end of a chain. Wouldn't the molecule C(CH3)2O (acetone) be an example of a ketone that occurs at the end of a chain (or rather, the ketone itself is the chain...)? Nothing else can bond to the two CH3's attached to the central C.
by Belicia Tang 1B
Sun Mar 05, 2017 11:32 am
Forum: *Cycloalkanes
Topic: Cycloalkanes vs Aromatic compounds
Replies: 1
Views: 2046

Cycloalkanes vs Aromatic compounds

Generally, is the term "aromatic compound" an umbrella term for all ring/cyclic structures? In other words, would something like a cycloalkane fall under the category of an aromatic compound? Or would it be categorized as an aliphatic compound, since it is a type of alkane?



Thanks!
by Belicia Tang 1B
Sat Mar 04, 2017 8:40 am
Forum: Administrative Questions and Class Announcements
Topic: Quiz 3 Winter 2017
Replies: 183
Views: 15893

Transition states

I have a quick question regarding transition states– when drawing a transition state diagram, must you include partial charges? Thanks!
by Belicia Tang 1B
Sat Feb 25, 2017 7:17 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7606
Views: 1018939

Re: Post All Chemistry Jokes Here

Did you know that you can cool yourself to -273.15˚C and still be 0k?
by Belicia Tang 1B
Tue Feb 14, 2017 1:55 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 2014 midterm #8
Replies: 4
Views: 421

Re: 2014 midterm #8

I was confused as to which reaction to flip, because I thought that usually you will flip the reaction with the lower reduction potential, which in this case, would be the second one. Flipping the first equation will give us a negative standard potential, which means the reaction is unfavorable.
by Belicia Tang 1B
Tue Feb 14, 2017 1:54 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: HW 14.85
Replies: 1
Views: 403

HW 14.85

How would Volta have ordered the following metals, if he put the most strongly reducing metal first: Fe, Ag, Au, Zn, Cu, Ni, Co, Al? According to the solution manual, the order of increasing reduction potential is: Al<Zn<Fe<Ni<Co<Cu<Ag<Au based on the table of standard reduction potentials. I unders...
by Belicia Tang 1B
Tue Feb 14, 2017 12:12 am
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Typo in HW 14.57?
Replies: 1
Views: 387

Typo in HW 14.57?

Hi,

According to the solutions manual, the standard cell potential of the reaction 2H20(l) -> O2(g) + 4 H+(aq) + 4e- is -0.42 V. However, according to the table of cell potentials, the same reaction is -0.83 V. Which one is correct?





Thanks!
by Belicia Tang 1B
Mon Feb 13, 2017 11:51 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: HW 14.55
Replies: 4
Views: 635

Re: HW 14.55

I have the same question. How did you know to use 2H20(l) -> O2(g) + 4 H+(aq) + 4e- as the anode reaction? Is it because the NiSO4 (aq) is in water?



Thanks!
by Belicia Tang 1B
Mon Feb 13, 2017 9:37 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Winter 2016 Midterm Q1A
Replies: 2
Views: 391

Re: Winter 2016 Midterm Q1A

I found Q1A to be particularly tricky. When we have a complicated molecule like this, would the simplest way to go about solving the problem be to break all the bonds and form all of them again?

If someone could show how they got the answer, I would really appreciate it!
by Belicia Tang 1B
Sun Feb 05, 2017 12:32 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell potential vs. Standard Reduction Potential
Replies: 1
Views: 200

Cell potential vs. Standard Reduction Potential

Hi,

I am just clarifying-- do the terms "cell potential" and "standard reduction potential" both refer to "E"? Except s.r.p. refers to E at standard conditions of 1atm and 25 degrees C?


Thanks.
by Belicia Tang 1B
Mon Jan 23, 2017 2:18 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Reversible vs. Irreversible Processes?
Replies: 1
Views: 256

Reversible vs. Irreversible Processes?

Hi, I am having trouble understanding what makes a process reversible vs irreversible. According to the textbook, a reversible process is one that can take place in EITHER direction. That is, a process that can be reversed by an infinitely small change in external pressure. An irreversible process i...
by Belicia Tang 1B
Sat Jan 21, 2017 8:12 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: HW Problem 8.67 Part A
Replies: 2
Views: 292

HW Problem 8.67 Part A

This question asks us to find the enthalpy of reaction of the formation of H20 (l). The chemical reaction is: H2(g) + 1/2 O2(g) –> H20(l) The solution manual solved this problem using the method of BOND ENTHALPIES. However, couldn't you also solve it using heat of formations? If you did it with heat...
by Belicia Tang 1B
Sat Jan 21, 2017 6:05 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy
Replies: 2
Views: 285

Re: Entropy

Hey guys! So from what I understand, enthalpy and entropy are the two factors you must consider in determining whether a reaction is favorable or not. Exothermic reactions (delta H is negative) are favorable. However, just knowing that delta H is negative does not guarantee that the reaction will oc...
by Belicia Tang 1B
Wed Jan 11, 2017 8:21 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Units for Standard Enthalpy of Reaction
Replies: 1
Views: 262

Units for Standard Enthalpy of Reaction

Just to clarify, the units for standard enthalpy of reaction and standard enthalpy of formation are BOTH kJ/mole, right? Oftentimes, when stating the standard enthalpy of reaction, the textbook omits the "per mole" part, so I was just wondering if the "per mole" was implicit.
by Belicia Tang 1B
Wed Jan 11, 2017 5:49 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Cha. 8 HW Problem #57
Replies: 7
Views: 687

Cha. 8 HW Problem #57

What does the symbol "delta H subscript c" stand for in this problem? At first I thought it was heat of combustion, but the reaction does not involve oxygen:

C2H2(g) + 2H2(g) –> C2H6(g)




Thanks!
by Belicia Tang 1B
Wed Nov 30, 2016 3:57 pm
Forum: Identifying Acidic & Basic Salts
Topic: 12.65 (e) and (f)
Replies: 4
Views: 957

Re: 12.65 (e) and (f)

I have the same question. I'm not sure why exactly there are 6 water molecules surrounding the cation. Also, is the charge of each individual water molecule neutral? Or does it take on the charge of the entire complex (so in part e, the charge of the complex is 3+, so is each water molecule also 3+?)
by Belicia Tang 1B
Fri Nov 25, 2016 9:38 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Homework problem 12.53b
Replies: 1
Views: 342

Homework problem 12.53b

Suggest an explanation for the different strengths of: acetic acid (CH3COOH) and formic acid (CH2O2) The difference between the two is the part bonded to the COOH. In acetic acid, you have CH3 bonded to COOH, whereas in formic acid, only H is bonded to COOH. According to the solution manual, "t...
by Belicia Tang 1B
Mon Nov 21, 2016 8:26 pm
Forum: Lewis Acids & Bases
Topic: Homework 12.9 [ENDORSED]
Replies: 5
Views: 709

Re: Homework 12.9 [ENDORSED]

@Pauline Tze

Here's the ionic equation:

NH4(+) + I(-) + K(+) + NH2(-) --> K(+) + I(-) + 2NH3

Net Ionic:

NH4(+) + NH2(-) --> 2NH3
by Belicia Tang 1B
Thu Nov 03, 2016 10:22 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Bond order of B2 molecule
Replies: 1
Views: 17480

Bond order of B2 molecule

Hey guys, So the bond order of B2 is equal to 1, which you can get by drawing the molecular orbital diagram and performing the equation Bond Order = .5 * (# of bonding electrons - # of antibonding electrons). However, when you draw the Lewis structure of B2, you get a triple bond. I always thought b...
by Belicia Tang 1B
Mon Oct 31, 2016 9:44 pm
Forum: Lewis Structures
Topic: Fall 2012 Midterm Question 7b
Replies: 2
Views: 389

Re: Fall 2012 Midterm Question 7b

But Fluorine is the most electronegative element on the periodic table... O is less EN than F



EDIT: My mistake!! Why did I think it was fluorine? I'm dumb lol sorry about that, your explanation makes a lot more sense now!
by Belicia Tang 1B
Mon Oct 31, 2016 9:26 pm
Forum: Lewis Structures
Topic: Fall 2012 Midterm Question 7b
Replies: 2
Views: 389

Fall 2012 Midterm Question 7b

Draw the lowest energy Lewis structure of ClO4- According to the book, the lowest energy structure has 3 double bonded O's and 1 single bonded O. Why can't all the O's be double bonded to the Cl central atom? If you did that, the formal charges for all the O's would be 0, while Cl would have a forma...
by Belicia Tang 1B
Mon Oct 31, 2016 9:18 pm
Forum: Lewis Structures
Topic: Fall 2013 Midterm Q7.
Replies: 2
Views: 419

Re: Fall 2013 Midterm Q7.

Hope the following picture helps!
by Belicia Tang 1B
Fri Oct 28, 2016 12:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Do we need to know exact bond angles?
Replies: 3
Views: 433

Do we need to know exact bond angles?

If I recall correctly, in Wednesday's lecture, Dr. Lavelle said we don't need to memorize the exact bond angles. Is this correct? (b/c in the textbook problems a lot of questions ask us to predict bond angles based on molecular geometry...)




Thanks!
by Belicia Tang 1B
Fri Oct 21, 2016 12:11 am
Forum: Lewis Structures
Topic: Question 3.67 part B?
Replies: 2
Views: 323

Re: Question 3.67 part B?

I have the same question! If you calculate the formal charge of Cl in the molecule w/ double bonds, it ends up being 0, while the one w/ single bonds is +2. You would think that the lower formal charge molecule should be stabler... Any thoughts from anyone else?
by Belicia Tang 1B
Sat Oct 15, 2016 8:27 pm
Forum: Ionic & Covalent Bonds
Topic: Question on Ionic vs Covalent bonds
Replies: 2
Views: 432

Question on Ionic vs Covalent bonds

In high school, I learned that ionic bonds are bonds formed btwn metals and nonmetals, while covalent bonds are those formed btwn nonmetals. In the textbook/course reader, it says that if the lowest energy can be achieved by the complete transfer of one/more electrons, then an ionic compound is form...
by Belicia Tang 1B
Thu Oct 13, 2016 1:41 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Textbook Question 2.37 part b [ENDORSED]
Replies: 3
Views: 454

Textbook Question 2.37 part b [ENDORSED]

True or False: Electrons in an s-orbital are more effective than those in other orbitals at shielding other electrons from the nuclear charge b/c an electron in an s-orbital can penetrate to the nucleus of the atom. What does "penetrate to the nucleus of the atom" mean? Does this refer to ...
by Belicia Tang 1B
Thu Oct 06, 2016 8:55 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Question on #7 on Heisenberg Uncertainty module (pre/post assessment question) [ENDORSED]
Replies: 1
Views: 472

Question on #7 on Heisenberg Uncertainty module (pre/post assessment question) [ENDORSED]

#7. The hydrogen atom has a radius of approximately 0.05 nm. Assume that we know the position of an electron to an accuracy of 1% of the Hydrogen radius, calculate the uncertainty in the speed of the electron using the Heisenberg uncertainty principle. What confused me was figuring out the uncertain...
by Belicia Tang 1B
Mon Oct 03, 2016 4:11 pm
Forum: Significant Figures
Topic: Significant figures in textbook Ex. 1.7 (p. 18) [ENDORSED]
Replies: 2
Views: 396

Significant figures in textbook Ex. 1.7 (p. 18) [ENDORSED]

In the final step calculation, there is a 2 in the denominator, so since that is only 1 sig fig, shouldn't the answer only be 1 sig fig, instead of 2?
by Belicia Tang 1B
Mon Oct 03, 2016 4:05 pm
Forum: Significant Figures
Topic: Significant Figures in E21
Replies: 2
Views: 356

Re: Significant Figures in E21

IMG_7136.jpg
E21 (sol manual)



I noticed that too. I think there should be 4 sig figs in the answer... not sure why they would truncate to 3.
by Belicia Tang 1B
Sat Oct 01, 2016 4:15 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectroscopy-- CONCEPTUAL CLARIFICATION
Replies: 1
Views: 255

Atomic Spectroscopy-- CONCEPTUAL CLARIFICATION

Hi! I just wanted to double check that my concept of atomic spectroscopy is correct. Energy of the light shown onto the hydrogen sample, which causes the electron to be excited (not ejected-- this isn't photoelectric effect) to a higher energy level, is the same as: - the energy difference between n...
by Belicia Tang 1B
Sun Sep 25, 2016 2:09 pm
Forum: Properties of Light
Topic: Midterm question Q2F [ENDORSED]
Replies: 3
Views: 598

Re: Midterm question Q2F [ENDORSED]

Also note that this question is based on the implication that the frequency of light shown onto the metal surface is SUFFICIENT to eject electrons. If the frequency is not high enough in the first place, increasing or decreasing the intensity of the light (aka changing number of photons) will NOT ca...

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