Search found 38 matches

by Reine Nakamura 1C
Wed Mar 09, 2016 7:26 pm
Forum: Student Social/Study Group
Topic: Switch 14C discussions
Replies: 2
Views: 750

Re: Switch 14C discussions

Hi! What lecture are you in? And where is the discussion held?
by Reine Nakamura 1C
Wed Mar 09, 2016 1:10 am
Forum: *Alcohols
Topic: Difference between hydroxy and alcohol?
Replies: 1
Views: 1732

Difference between hydroxy and alcohol?

What is the difference between hydroxy and an alcohol? It seems that both are an -OH group branched off of a C parent chain.. If we were given a line structure and asked to name it, how would we know which to use?
by Reine Nakamura 1C
Tue Mar 08, 2016 12:27 am
Forum: Administrative Questions and Class Announcements
Topic: Winter 2016 Final Exam Review and Information
Replies: 25
Views: 16935

Re: Winter 2016 Final Exam Review and Information

Will we be responsible for organic naming topics such as when to use -dial (pg. 59) or carbaldehyde (pg. 60)? And do we need to know things such as haloalkanes (pg. 50)? Or is the material strictly what is covered in the course reader?
by Reine Nakamura 1C
Mon Feb 29, 2016 6:47 pm
Forum: *Cycloalkenes
Topic: Numbering Priority
Replies: 1
Views: 313

Re: Numbering Priority

For 1.16, I believe that you put the 2 on the isopropyl and the 1, 1 on the dimethyl because 2 and 1,1 is not as large as 1 and 2,2. A student asked a similar question, so this might help explain the numbering process more clearly. Remember that you are trying to have the smallest numbers for the su...
by Reine Nakamura 1C
Mon Feb 29, 2016 6:39 pm
Forum: *Alkanes
Topic: Quiz 3 Preparation
Replies: 34
Views: 11511

Re: Quiz 3 Preparation

I thought priority was only considered when evaluating geometric isomers... in halogenated compounds the halogens are treated as substituents and are organized alphabetically. Double and triple bonds are still given priority. I believe the correct answer should be 1-bromo-3-iodo because all halogen...
by Reine Nakamura 1C
Mon Feb 29, 2016 4:59 pm
Forum: *Alkanes
Topic: Quiz 3 Preparation
Replies: 34
Views: 11511

Re: Quiz 3 Preparation

For the question #2 on page 43, it states to name the compound CH3CH(CH3)CH(CH2CH3)C(CH3)3. I have named the compound 3-ethyl-2,2,4-trimethyl pentane but the answer says its 2,2,4-trimethyl-3-ethyl pentane. Why? For this question, I would say that your answer is correct because when putting the sub...
by Reine Nakamura 1C
Mon Feb 29, 2016 4:40 pm
Forum: *Alkenes
Topic: HW Question 1.12 Numbering the structure
Replies: 2
Views: 414

Re: HW Question 1.12 Numbering the structure

I think you're asking about 1.21?? For structures with -diene, you'll number it so that the double bond has the lowest number. Numbering double bonds takes precedence over numbering substituents (pg. 12 in the O chem book).
by Reine Nakamura 1C
Sun Feb 28, 2016 1:46 pm
Forum: *Alkynes
Topic: Homework 1.5c
Replies: 2
Views: 855

Re: Homework 1.5c

Screen Shot 2016-02-28 at 1.43.25 PM.png
I wondered the same thing! It helps to draw in where the C atoms are and fill in the H atoms so that each C has 4 bonds... By doing this, it's easier to see that the formula is C2H2n-2, and in this case, C3H4.
by Reine Nakamura 1C
Sat Feb 27, 2016 12:56 am
Forum: *Alkanes
Topic: Common Names
Replies: 1
Views: 270

Common Names

For isobutane, I understand where the iso prefix comes from, however why is it but-? I wrote in my notes that the IUPAC name would be 2-methylpropane, which makes more sense as the longest chain of carbons seems be 3. When we use common names, are we looking for number of carbons overall (in which c...
by Reine Nakamura 1C
Tue Feb 16, 2016 3:25 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Course Reader page 75
Replies: 2
Views: 489

Re: Course Reader page 75

Just to add on to the previous response, in my TA's office hours today, they said that because k, k', etc are all constants, you can denote that by just putting k... So in some ways it's similar to calculus where you combine any constants after finding an indefinite integral and write it as C.
by Reine Nakamura 1C
Tue Feb 16, 2016 12:48 am
Forum: Second Order Reactions
Topic: Question 51 in the homework [ENDORSED]
Replies: 4
Views: 1020

Re: Question 51 in the homework [ENDORSED]

It's a second order reaction because the overall order of the reaction is the sum of the orders for [NO] and [Br2]. In this case both are first order, making the overall order 2.
by Reine Nakamura 1C
Mon Feb 08, 2016 6:12 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: W for BH2F
Replies: 3
Views: 1695

Re: W for BH2F

For problems dealing with S=k B lnW, I find it useful to draw the Lewis structures for the molecules to determine W. If you draw out BH 2 F, you'll see that is a trigonal planar molecule with B in the middle, and the 2 H atoms and the 1 F atom around it. In this case, the F atom is different from th...
by Reine Nakamura 1C
Mon Feb 08, 2016 5:48 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: log(Q) vs. ln(Q) in the nernst equation
Replies: 3
Views: 946

Re: log(Q) vs. ln(Q) in the nernst equation

I was wondering the same exact thing... I believe they used logQ because the question specified that T=25^{\circ}C[/tex]. Therefore, you can use the equation E=E^{\circ}-\frac{{0.05916V}}{n}logQ[/tex] to save some time. This presents (RT/F) as a constant, rather than having to plug in the correspond...
by Reine Nakamura 1C
Sun Jan 31, 2016 12:10 am
Forum: Balancing Redox Reactions
Topic: Identifying Which Half-Reaction to Reverse
Replies: 3
Views: 471

Re: Identifying Which Half-Reaction to Reverse

I think that statement mainly applies to the redox reactions having to do with batteries, since batteries never have a negative voltage. However, in the example on page 52 in the course reader, the is -0.54 V, showing that negative cell potentials are possible in certain cases.
by Reine Nakamura 1C
Thu Jan 28, 2016 1:22 am
Forum: Balancing Redox Reactions
Topic: Quick question
Replies: 2
Views: 393

Re: Quick question

Just to add-on a little, youolook at both the moles and charges of the respective atoms/molecules to help you balance/see if you need to balance the equation. For example in the course reader on pg 37 you have 8H+ + MnO4- + 5Fe2+ ---> Mn2+ + 5Fe3+ + 4H2O To calculate the charge on each side, you eit...
by Reine Nakamura 1C
Sun Jan 24, 2016 3:37 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Homework 8.67d
Replies: 2
Views: 341

Re: Homework 8.67d

You can determine resonance by drawing out the Lewis structure for benzene. There you will see that benzene has 2 resonance structures because you can change the location of the double bonds within the carbon ring. This would change the solution for this problem because if you calculate the standard...
by Reine Nakamura 1C
Mon Jan 18, 2016 10:12 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Sig Figs in 8.21
Replies: 2
Views: 338

Re: Sig Figs in 8.21

My best guess is that the answer key has 2 sig figs because the specific heat for copper is 0.38 (2 sig figs). Therefore, when you multiply everything out, you would go off of the smallest number of sig figs which is 2.
by Reine Nakamura 1C
Mon Jan 18, 2016 12:44 pm
Forum: Phase Changes & Related Calculations
Topic: Systems
Replies: 4
Views: 439

Re: Systems

Are you referring to problem 8.17 by any chance? If heat is absorbed, this means q has a positive value. If the system undergoes change at a constant temperature, then delta U (change in internal energy) is 0. If q is +, then work must be - in order for q+w=delta U to be true. When work is -, this m...
by Reine Nakamura 1C
Mon Jan 18, 2016 12:24 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Homework Problem 8.73
Replies: 4
Views: 883

Re: Homework Problem 8.73

Yes, by calculating the energy of the bonds broken and bonds formed, you can determine the enthalpy change for the reaction (calculate the value and see if it's exothermic or endothermic) And as far as calculating bond enthalpies, Tables 8.6 and 8.7 on pages 300 and 301 have the values for various b...
by Reine Nakamura 1C
Mon Jan 18, 2016 11:57 am
Forum: Phase Changes & Related Calculations
Topic: Enthalpy
Replies: 3
Views: 477

Re: Enthalpy

The specific heat (or specific heat capacity) and heat capacity for a substance are related, yet not quite the same. The specific heat capacity is the "heat required to raise 1 g of a substance by 1 degree Celsius." This is 'specific' in that it is referring to 1 g. Heat capacity is simply...
by Reine Nakamura 1C
Thu Jan 14, 2016 8:03 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Homework Problem 8.73
Replies: 4
Views: 883

Re: Homework Problem 8.73

For these problems, it helps me to draw out the Lewis structures for both the products and reactants... If you draw out the C2H2 you see that there is indeed a triple bond between the 2 carbons and a single bond between each carbon and a hydrogen. Since there is a coefficient of 3 in front of the C2...
by Reine Nakamura 1C
Thu Jan 14, 2016 7:27 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Enthalpy of Formation Question (63)
Replies: 1
Views: 557

Re: Standard Enthalpy of Formation Question (63)

Hi! So for this problem the answer key had a slight typo, and it calculated the sum of the enthalpies of formation for the products using 417.5 kJ for K2S(aq) instead of 471.5 kJ. This error caused the standard enthalpy of formation to be 15.28 kJ when the correct answer is what you got, -38.72 kJ. ...
by Reine Nakamura 1C
Sat Jan 09, 2016 9:55 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.63C
Replies: 1
Views: 269

Re: 8.63C

Yes! I just did the calculations and got -38.72 kJ as the answer. When you use the 417.5 kJ/mol value, it makes the sum of the standard enthalpy of formation of all the products have a smaller negative value than that of the reactants. Therefore when you subtract the two negatives, it results in a +...
by Reine Nakamura 1C
Sat Dec 05, 2015 2:54 pm
Forum: *Titrations & Titration Calculations
Topic: Determining Sig Figs for a Weak Acid/Strong Base Titration
Replies: 1
Views: 1454

Determining Sig Figs for a Weak Acid/Strong Base Titration

Referring to the Fall 2010 Final, Question 7B: Can someone explain why you use 3 significant figures for your molar concentrations in the ICE box (ex: 2.86x10^-2), even though you divide 1.0x10^-3 moles CH3COOH (2 sig figs) by 0.0350 L (3 sig figs)? For dividing, you use the smallest number of signi...
by Reine Nakamura 1C
Sat Dec 05, 2015 2:45 pm
Forum: *Titrations & Titration Calculations
Topic: Page 225 Question 7B in the course reader
Replies: 2
Views: 440

Re: Page 225 Question 7B in the course reader

After neutralization, 1.0x10^-3 moles of CH3COOH have given off a proton to the strong base NaOH and formed 1.0x10^-3 moles of CH3CO2-. By subtracting 1.0x10^-3 moles from the initial 2.5x10^.3 moles of CH3COOH, you are left with 1.5x10^-3 moles in the weak acid form.
by Reine Nakamura 1C
Tue Dec 01, 2015 8:28 pm
Forum: *Titrations & Titration Calculations
Topic: Titrant
Replies: 3
Views: 1105

Re: Titrant

I'm pretty sure titrants are always strong acids or bases, because they completely ionize in solution. This way, you know the concentration of the titrant and can determine moles of H30+ or OH- (depending on if it's a strong acid or base). From there, you can use this value to calculate the pH of th...
by Reine Nakamura 1C
Mon Nov 30, 2015 10:12 pm
Forum: *Titrations & Titration Calculations
Topic: Henderson-Hasselbach Equation
Replies: 4
Views: 645

Re: Henderson-Hasselbach Equation

Today, Professor Lavelle also mentioned that if you are given the percentages of both HA and A- at a certain pH, you know the ratio of A-/HA and can use the Henderson-Hasselbach equation to calculate the pKa... So this equation can be manipulated to solve for various values, and is not just used to ...
by Reine Nakamura 1C
Mon Nov 23, 2015 1:55 am
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Strong Acid or Weak Acid?
Replies: 2
Views: 460

Re: Strong Acid or Weak Acid?

Just a quick clarification, HCl is aqueous, because it is dissolved in H2O (the solvent). Only when H2O is present (as the base that accepts the protons to form the hydronium ion, H3O+) does HCl act as an acid. If it were in the gas phase, this reaction would not occur and HCl would not dissociate.
by Reine Nakamura 1C
Mon Nov 23, 2015 1:46 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Homework Question 12.51 A
Replies: 5
Views: 779

Re: Homework Question 12.51 A

I was pretty confused on this problem at first too... I's recommend checking out section 12.9 in the book. The concluding statement says, "Acid strengths of binary acids across a period correlate with electron affinities; acid strengths down a group correlate with bond strength" (pg. 482)....
by Reine Nakamura 1C
Sun Nov 15, 2015 3:05 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Question on a step in 11.61?
Replies: 2
Views: 495

Re: Question on a step in 11.61?

Sorry I misread your question! But I got (4.92 + or - 4.84)/1.21 as well... So I'm guessing the solutions manual just had a typo and switched 4.84 to 4.48
by Reine Nakamura 1C
Sun Nov 08, 2015 12:38 am
Forum: Hybridization
Topic: D orbital vs S orbital
Replies: 2
Views: 452

Re: D orbital vs S orbital

Chromium takes away from the s orbital instead of the d because it's ground state electron configuration is [Ar] 3d^5 4s^1. Therefore, the outermost electron is in the 4s orbital, and this is the one that is removed first.
by Reine Nakamura 1C
Sun Nov 01, 2015 1:56 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: H-F Diagram
Replies: 4
Views: 1416

Re: H-F Diagram

In the review session on Friday, a few students asked about heteronuclear diatomic molecules with atoms in different periods (such as HF). Professor Lavelle said that although the book asks for it, we haven't learned it and he preferred not to cover it... So I wouldn't worry too much as I don't thin...
by Reine Nakamura 1C
Mon Oct 26, 2015 1:36 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Angular Bond Angles
Replies: 1
Views: 824

Re: Angular Bond Angles

Yes! When the molecule has 1 lone pair and 2 shared, it has 3 regions of electron density, making the arrangement trigonal planar. You can think of taking a trigonal planar molecule and replacing one atom with a lone pair. Since trigonal planar is 120, the lone pair will cause the bond angles to be ...
by Reine Nakamura 1C
Sun Oct 25, 2015 8:17 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles for Angular, T-shaped, etc.
Replies: 4
Views: 716

Re: Bond Angles for Angular, T-shaped, etc.

For T-shaped, would the bond angles be slightly less than 90 because of the 2 lone pairs pushing down on those that are bonded?
by Reine Nakamura 1C
Mon Oct 19, 2015 10:19 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configurations for 3.9
Replies: 3
Views: 569

Re: Electron Configurations for 3.9

Because Co2+ and Fe2+ are ions with a positive charge, you start with the electron configuration of the neutral atom and remove 2 electrons. When electrons fill the 4s subshell and begin to occupy the 3d subshell, the 3d subshell has a lower energy than the 4s. Therefore, when you go to remove 2 ele...
by Reine Nakamura 1C
Wed Oct 14, 2015 10:36 pm
Forum: Trends in The Periodic Table
Topic: 2nd Ionization Energy
Replies: 2
Views: 529

Re: 2nd Ionization Energy

I would recommend checking out Figure 2.26 on page 55 in the textbook and reading the little paragraph next to it... Helped me a lot! It shows that for Group 2 elements, such as Mg, they have similar second and first ionization energies as both electrons are in the 3s subshell rather than in a noble...
by Reine Nakamura 1C
Tue Oct 06, 2015 9:32 pm
Forum: Properties of Light
Topic: Homework 1.15 - Electron emission
Replies: 2
Views: 514

Re: Homework 1.15 - Electron emission

I think you are correct in that n initial is 3 and n final=1. Because the energy is being emitted, it will release a photon and drop from a higher energy state (n=3) to a lower energy state/its ground state (n=1). Because energy is being emitted the change in energy ΔE would be equal to the -E final...
by Reine Nakamura 1C
Wed Sep 30, 2015 6:21 pm
Forum: SI Units, Unit Conversions
Topic: Units for Plank's Constant [ENDORSED]
Replies: 3
Views: 713

Re: Units for Plank's Constant [ENDORSED]

The units for the Joule are kg*m^2/s^2, so you had all the right exponents, just the s^2 belongs in the denominator. When you calculate wavelength using λ= h/mv, the m^2 on top cancels out with one m (from velocity, v) on the bottom. Also, the kg on top cancels out with the kg (from mass, m) on the ...

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