## Search found 64 matches

Sat Mar 12, 2016 7:51 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: homework problem 8.101 enthalpy with limiting reagent
Replies: 1
Views: 440

### homework problem 8.101 enthalpy with limiting reagent

A technician carries out the reaction 2 SO2 (g) + O2 (g) --> 2 SO3 (g) at 25 C and 1.00 atm in a constant pressure cylinder. 0.030 mol SO2 and 0.030 mol O2 are initially present in the cylinder. The technician then adds a catalyst to initiate the reaction. (c) Assuming that the reaction goes to comp...
Sat Mar 12, 2016 12:23 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Ea and rate constant
Replies: 3
Views: 501

### Re: Ea and rate constant

an enzyme only lowers the activation energy. since the activation energy is being lowered, the reaction happens faster therefore k (the rate) would increase
Sat Mar 12, 2016 12:21 pm
Forum: General Rate Laws
Topic: rate law
Replies: 1
Views: 309

### rate law

since Rate = -(1/a)d[R]/dt = k[R]^n
if you had a reaction and the coefficient of the reactant (for example NO2) was something other than 1 (such as 2) would the rate law look like this: rate=(-1/2)[NO2]^n
Sat Mar 12, 2016 12:05 pm
Forum: General Rate Laws
Topic: rate of reactants and products course reader page 60
Replies: 1
Views: 320

### rate of reactants and products course reader page 60

on page 60 of the course reader it gives a reaction to prove why rate = -(1/a)d[A]/dt = (1/b)d[B]/dt = 1/cd[C]/dt

2NO2 (g) ---> 2NO(g) + O2 (g)

-d[R]/dt = d[P]/dt
-d[NO2]/dt = d[NO]/dt = 2d[O2]/dt
-(1/2)d[NO2]/dt = (1/2)d[NO]/dt = d[O2]/dt

Where does the 2 in front of d[O2]/dt come from?
Fri Mar 11, 2016 10:00 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: enthalpy and temperature
Replies: 1
Views: 338

### enthalpy and temperature

in the course reader page 36 it states that deltaHrxn plays an important role at low temperature. why is this?
Fri Mar 11, 2016 9:21 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Winter 2014 Final Q1C vaporization term
Replies: 1
Views: 289

### Re: Winter 2014 Final Q1C vaporization term

the 1/2 is in front of mdeltaH because the problem states that only "HALF of his forgetfulness potion has boiled away" so you need to account for that in the mdeltaH (aka boiling) equation
Fri Mar 11, 2016 9:18 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: 2015 Final Q9A
Replies: 1
Views: 363

### Re: 2015 Final Q9A

you would think that the longest carbon chain is the cyclohexane, but remember that you have to include the functional group in the longest carbon chain. so, the cyclohexane becomes the substituent. the cyclohexane also has a chloride on it so there is a substituent on a substituent which is why (3-...
Fri Mar 11, 2016 9:15 pm
Forum: *Alkenes
Topic: Priority
Replies: 1
Views: 340

### Re: Priority

A lot of UA and TAs have told me that too. However, I read a question on chem community asking the same question and "chem mod" answered that double bonds do indeed have priority over triple bonds.
Fri Mar 11, 2016 9:14 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Determining n in nernst equation
Replies: 1
Views: 7326

### Re: Determining n in nernst equation

n is the number of moles of electrons that you "cross" out. so for that reaction you would have to split it into the two half reactions, balance it (balance the elements first, then add H2O to balance the oxygens, then add H+ to balance the hydrogens, then add electrons to balance the char...
Fri Mar 11, 2016 8:53 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: relationship between endothermic/exothermic and q
Replies: 1
Views: 345

### relationship between endothermic/exothermic and q

for exothermic reactions why is q positive and for endothermic reactions why is q negative?
if q is the heat required then shouldn't endothermic reactions have a positive q because endothermic reactions require heat?
Fri Mar 11, 2016 6:28 pm
Forum: *Haloalkanes
Topic: halogens priority and halogen functional group?
Replies: 1
Views: 3648

### halogens priority and halogen functional group?

if there was one of those questions where it says to circle all the functional groups and there was a halide, would we circle the halide too?

also do halogens have priority in numbering over substituents such as methyl, ethyl, etc.
Fri Mar 11, 2016 1:14 pm
Forum: *Cycloalkanes
Topic: Common name vs. substituent on substituent
Replies: 1
Views: 322

### Common name vs. substituent on substituent

For the name tert-butylcyclohexane, is the IUPAC name dimethylethylcyclohexane or (dimethylethyl)cyclohexane
Thu Mar 10, 2016 5:21 pm
Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
Topic: Winter 2014 final question 7 part F newman projections
Replies: 3
Views: 660

### Winter 2014 final question 7 part F newman projections

For the molecule 3-chloro-4,4,4,-trihydroxy-3-methylbutanenitrile draw the second lowest energy conformation newman diagram, looking down the C2-C3 bond axis. the answer drawn shows the newman projection with C(OH)3 gauche to CN and H, Cl gauche to H and H, and CH3 gauche to CN and H. why can't the ...
Thu Mar 10, 2016 5:16 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Final 2014 question 3A pikachu
Replies: 2
Views: 456

### Final 2014 question 3A pikachu

ash wants to supercharge his pikachu for the upcoming pokemon tournament, use your knowledge of electrochemistry to help him build a galvanic cell that can charge pikachu the following chemicals are available at the local pokemart Zn (s) Cu (s) Fe (s) Pt (s) Zn(NO3)2 (aq) Cu(NO3)2 (aq) Fe(NO3)2 (aq)...
Wed Mar 09, 2016 7:08 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: galvanic/voltaic cell
Replies: 1
Views: 262

### galvanic/voltaic cell

is there a difference between galvanic and voltaic cells or are they the same thing?
Wed Mar 09, 2016 5:00 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: final 2012 question 1A heat and calorimeter
Replies: 1
Views: 256

### final 2012 question 1A heat and calorimeter

Tropinone has structural similarities to the drugs atropine and cocaine. When 1.000g of tropinone is burned in a calorimeter with a heat capacity of 25.950 kJ/C the temperature increases from 25.262C to 25.993C. What is the deltaH of tropinone? In the explanation of the answer how do you know that -...
Wed Mar 09, 2016 4:47 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: q=mcdeltaT vs. q=cdeltaT
Replies: 1
Views: 5778

### q=mcdeltaT vs. q=cdeltaT

Is there a difference between q=mcdeltaT and q=cdeltaT? If so, when is each one used?
Wed Mar 09, 2016 2:16 pm
Forum: *Ethers
Topic: ether priority
Replies: 1
Views: 408

### ether priority

on page 70 of the organic textbook it shows a structure and the name is
4-methoxy-3,4-dimethylcyclohex-1-ene

i know that priority is given to functional groups when numbering, so how come methoxy isn't given the 1?
Mon Mar 07, 2016 8:37 pm
Forum: *Haloalkenes
Topic: Haloalkene naming
Replies: 1
Views: 1003

### Haloalkene naming

For the structure on page 51 of the organic textbook why is
3-chloro-1-fluoro-4,6-dimethylcyclohexa-1,4-diene a better name than
6-chloro-4-fluoro-1,3-dimethylcylohexa-1,4-diene?

I thought 1,3 would be better since it's lower than 4,6
Thu Mar 03, 2016 9:11 pm
Forum: Administrative Questions and Class Announcements
Topic: Video Competition
Replies: 66
Views: 25028

### Re: Video Competition

Ava Mousavi and Franca Park

Enjoy!

Thu Mar 03, 2016 9:05 pm
Forum: *Alkanes
Topic: common names
Replies: 1
Views: 311

### common names

in the course reader it states,

iso: (CH3)2CH--
neo: (CH3)3C--

so what is the molecular formula for tert- and sec-?
Thu Mar 03, 2016 4:51 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Relationship b/w A and k (Arrhenius)
Replies: 1
Views: 328

### Relationship b/w A and k (Arrhenius)

On page 76 of the course reader, it states that as A increases k increases.

However, using the Arrhenius equation, if you increase A, k decreases.

What is the correct relationship? I'm confused.
Wed Mar 02, 2016 10:30 am
Forum: *Haloalkanes
Topic: Halogens vs Substituents
Replies: 1
Views: 725

### Re: Halogens vs Substituents

It would be alphabetical. The only time halogens have higher priority than carbon substituents is when you are deciding whether the molecule is Z or E when dealing with a double bond.
Wed Mar 02, 2016 10:28 am
Forum: *Free Energy of Activation vs Activation Energy
Topic: Temp. and Activation Energy
Replies: 1
Views: 310

### Re: Temp. and Activation Energy

Temperature and activation energy are independent of each other. However, temperature affects rate. So, if temperature increases, it can more easily surpass the activation energy. If temperature decreases, it'll be harder to surpass the activation energy. Temperature does not higher or lower the act...
Mon Feb 29, 2016 10:29 pm
Forum: *Alcohols
Topic: Functional Group Distinction
Replies: 1
Views: 390

### Re: Functional Group Distinction

Dr. Lavelle said in lecture that we will not be dealing with molecules with more than one functional group (such as alcohol mixed with a ketone, etc).

But functional groups have priority over double bonds which have priority over substituents.
Mon Feb 29, 2016 10:27 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Rate limiting step
Replies: 2
Views: 512

### Re: Rate limiting step

The rate limiting step is usually the first step as the reaction goes from something stable to something very unstable (making of a carbocation). If you look at the free energy diagram for electrophilic addition it has 2 "humps." the first one will have a very high hump (high deltaG) compa...
Thu Feb 18, 2016 8:31 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: ARRHENIUS EQUATION
Replies: 1
Views: 1686

### ARRHENIUS EQUATION

how do you get this equation? where did it come from? where is it derived from?
$ln(\frac{k'}{k})= \frac{E{a}}{R}(\frac{1}{T}-\frac{1}{T'})$
Thu Feb 18, 2016 6:23 pm
Forum: Second Order Reactions
Topic: quiz 2 practice winter 2014
Replies: 2
Views: 511

### quiz 2 practice winter 2014

or the reaction A-->products, the following data were collected. Time (s) 0 1.00 2.00 3.00 4.00 [A]t, M 1.00 0.430 0.270 0.200 0.160 1/[A]t 1.00 2.33 3.70 5 6.25 What is the half life for this reaction? (Hint: Draw a graph.) For this question why do you ignore [A] when drawing the graph? how do you ...
Wed Feb 10, 2016 1:11 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Delta U and Pressure
Replies: 3
Views: 659

### Re: Delta U and Pressure

think about it conceptually. say you have a gas and you decrease the temperature. the particle movement is going to slow down and decrease thereby decreasing the internal energy of the gas (a lot of movement and translational/positional energy ---> less movement and energy). aka the deltaU is going ...
Wed Feb 10, 2016 11:10 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: entropy and temperature
Replies: 2
Views: 293

### Re: entropy and temperature

I understand that. But conceptually, shouldn't entropy increase if temperature is increasing since an increase in temperature means more particle movement therefore more disorder?
Wed Feb 10, 2016 10:43 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: entropy and temperature
Replies: 2
Views: 293

### entropy and temperature

Due to the equation deltaS=q/T, it would make sense that has temperature increases, entropy decreases. However, how does this make sense because if temperature is increased doesn't that cause more particle movement therefore more "randomness" aka more entropy?
Tue Feb 09, 2016 10:05 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Delta U and Pressure
Replies: 3
Views: 659

### Re: Delta U and Pressure

I don't think the answer is implying that there is a relationship between pressure and deltaU, but emphasizing the fact that if delta U decreases, temperature decreases. therefore, by looking at PV=nRT, temperature and pressure are in a direct relationship. so, since temperature decreases, pressure ...
Tue Feb 09, 2016 10:02 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy
Replies: 1
Views: 280

### Re: Enthalpy

you can do it either way. it just depends on what the problem is asking you. if the problem gives you deltaH's to work with than you use (final-initial), if the problem gives you bond enthalpies than find bonds broken and bonds formed. reminder that using bond enthalpies is less accurate than using ...
Tue Feb 09, 2016 9:56 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy concepts
Replies: 3
Views: 554

### Re: Entropy concepts

fluorine has a big mass. the bigger the mass/volume a gas has, the greater the number of possible positions
Tue Feb 09, 2016 9:54 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: state function
Replies: 2
Views: 408

### state function

are all state functions extensive properties?
Tue Feb 09, 2016 6:58 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: 2014 Midterm #8
Replies: 4
Views: 666

### Re: 2014 Midterm #8

HF has to be on the reactant side because recall from Chem14A that Ka= [H+][A-]/[HA] meaning that HF has to be on the bottom and since K=[P]/[R] HF must be a reactant
Tue Feb 09, 2016 5:47 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Midterm 2014 Q7: galvanic cell
Replies: 1
Views: 306

### Midterm 2014 Q7: galvanic cell

A galvanic cell is constructed utilizing the following standard cell potentials NO3^- (aq) + 2H^+ +e- ---> NO2(g) + H2O (l) E(knot) = +0.80V Zn^2+ (aq) + 2e- ---> Zn(s) E(knot) = -0.76V Write the balanced overall cell reaction I see that both half reactions are written as reductions. How do you know...
Tue Feb 09, 2016 5:11 pm
Forum: Phase Changes & Related Calculations
Topic: Charmander vs. Squirtle problem
Replies: 1
Views: 443

### Charmander vs. Squirtle problem

C. Charmander attacks with fire containing 50.0x10^9 J of thermal energy. What volume of water (in liters) at 25.0C must squirtle counterattack with to absorb the energy of the attack resulting in an amazing showcase of steam at 100.0C" In the solutions, it used the equation q(fire) =q(water) =...
Tue Feb 09, 2016 2:30 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 0.02569 with ln
Replies: 1
Views: 436

### 0.02569 with ln

for the nernst equation, the equation is simplified to E = E (knot) - 0.0259/n lnQ , but everytime time i plug in (8.314)(298)/(964853) for RT/F I Keep getting 0.0025678 what am i doing wrong?
Sun Feb 07, 2016 11:08 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: thermodynamically more stable?
Replies: 1
Views: 429

### thermodynamically more stable?

Which is the thermodynamically more stable iron oxide in air, Fe3O4(s) or Fe2O3(s)? Justify your selection. The solutions manual says that this question can be "best answered by considering the reaction gather interconverts the two compounds" 4Fe3O2 (s) + O2 (g) ---> 6Fe2O3 (s) Then, delta...
Sun Feb 07, 2016 10:57 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: higher entropy cis or trans
Replies: 8
Views: 1198

### higher entropy cis or trans

Considering positional disorder, would you expect a crystal of octahedral cis-MX2Y4 to have the same, higher, or lower residual entropy than the corresponding trans isomer? Explain your conclusion The solutions manual says that for the cis compound there will be 12 different orientations while for t...
Sun Feb 07, 2016 9:13 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: balancing equations 9.55
Replies: 1
Views: 274

### balancing equations 9.55

Write a balanced chemical equation for the formation of NH3 (g). Determined H from data in Appendix 2A. I balanced the equation like this: N2+3H2=2NH3 and then calculated deltaH=2(-46.11kJ/mol)=-92.22kJ/mol. However, the solutions manual balanced it like this: 1/2N+3/2H=NH3 and calculated deltaH=-46...
Thu Feb 04, 2016 11:52 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: calculationg Ph using nernst HW 14.39
Replies: 3
Views: 617

### Re: calculationg Ph using nernst HW 14.39

2.303 is just a conversion factor. ln of a number = 2.303log of that number (see page 54 in the course reader for reference at the top of the page) in my opinion, i wouldn't go through the trouble to convert ln to log, especially if your calculator has an "e^x" button. I would keep the equ...
Thu Feb 04, 2016 11:39 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Example14.3
Replies: 1
Views: 268

### Re: Example14.3

it's because of the 2 moles of electrons! anytime you use the equations deltaG = -nFE, n refers to the moles of electrons that you cancel out after balancing the redox reactions
Thu Jan 28, 2016 11:33 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: entropy change: order
Replies: 2
Views: 356

### entropy change: order

for the reaction 4KClO3(s) ---> 3KClO4(s) + KCl(s)

Why are the four moles of solid product more ordered than the four moles of solid reactants?
Thu Jan 28, 2016 10:21 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: internal energy state function
Replies: 1
Views: 336

### internal energy state function

How does it make sense that internal energy is a state function when it is made up of heat and work which are both not state functions?
Thu Jan 28, 2016 9:58 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: q = deltaH
Replies: 1
Views: 483

### q = deltaH

sorry if this is a stupid question, but when can we assume q = deltaH? such as the problem in practice quiz #2: "How many grams of water can be heated from 25.0C to 100.0C by the heat released from converting 49.7g of PbO to Pb?" The converting reaction is: PbO (s) + C(s) -> Pb (s) + CO (g...
Thu Jan 28, 2016 9:45 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Winter 2015 quiz #10 change in entropy
Replies: 1
Views: 409

### Winter 2015 quiz #10 change in entropy

Calculate the change in entropy of a bucket of water after 200J of energy is reversibly transferred to the water at 20 degrees C I know that you have to use the equation deltaS = qrev/T but why is the answer positive? if energy is being transferred wouldn't that mean the energy is leaving meaning th...
Wed Jan 27, 2016 9:53 pm
Forum: Calculating Work of Expansion
Topic: Work on a system vs. work by a system
Replies: 2
Views: 682

### Work on a system vs. work by a system

Can someone explain the difference between work done on a system and work done by a system? If you were given data such as question 8.7 in which it states, "The internal energy of a system increased by 982 J when it absorbed 492 J of heat. Was work done by or on the system?," how would you...
Wed Jan 20, 2016 12:48 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy: cooling of hot metal
Replies: 2
Views: 615

### Entropy: cooling of hot metal

The textbook states that "the cooling of a hot metal is accompanied by an increase in entropy as energy spreads into the cooler surroundings." Can someone explain this statement? Since the hot metal, which has a lot of disorder due to the vibrational motion of its particles, wouldn't entro...
Sat Dec 05, 2015 8:52 pm
Forum: Identifying Acidic & Basic Salts
Topic: Salts: Solubility of Ionic Compounds in Water
Replies: 1
Views: 449

### Salts: Solubility of Ionic Compounds in Water

In page 153 of the course reader it states guidelines for predicting the solubility of ionic compounds in water. Why is this information important? What does the fact that a salt is soluble mean? Why is it important to know which salts are soluble and insoluble?
Tue Dec 01, 2015 2:24 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 12.57 homework
Replies: 1
Views: 417

### 12.57 homework

(a) When the pH of 0.10 m HClO2(aq) was measured,
it was found to be 1.2. What are the values of Ka and pKa of chlorous acid?

the equation sets out to be
HClO2 + H2O --> H3O+ + ClO2-

the solution manual says that you can assume that [H3O+] = [ClO2-]

why is this?
Mon Nov 30, 2015 8:06 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Value of Kw question
Replies: 2
Views: 10443

### Re: Value of Kw question

In water we assume that the concentration of [H3O+] = [OH-] (such as when Kw = 1.0 x 10^-14, [H3O+] = 1.0 x 10^-7 and [OH-] = 1.0 x 10^-7) so Kw = 2.1 x 10^-14 = [H3O+][OH-] but since [H3O+] = [OH-] Kw = 2.1 x 10^-14 = x^2 so x = square root 2.1 x 10^-14 Then, you get the pH by taking the -log of x....
Thu Nov 19, 2015 12:02 am
Forum: Naming
Topic: Writing chemical formulas
Replies: 1
Views: 738

### Re: Writing chemical formulas

From potassium tetracyanonickelate (II), you know that nickel has a charge of +2. You also know that cyanide has a charge of -1 (from memorization). Since there are 4 cyanides, the charge is -4. Thus the total charge of everything in the brackets is 2+(-4)= -2. Remember that the metal outside of the...
Wed Nov 04, 2015 12:42 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron configuration: filling in the d orbital
Replies: 3
Views: 1123

### Re: Electron configuration: filling in the d orbital

does this rule apply to ions then?
"Write the ground-state electron-configuration for Fe3+"
Tue Nov 03, 2015 7:00 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron configuration: filling in the d orbital
Replies: 3
Views: 1123

### Electron configuration: filling in the d orbital

I know that Cu and Cr have exceptions when writing their electron configuration in which the electrons in the p-orbital go to the d-orbital to make the atom more stable. However, what if, for example, if I'm writing the electron configuration for Mn which is [Ar]3d5 4s2, should i move the electrons ...
Mon Nov 02, 2015 4:56 pm
Forum: Administrative Questions and Class Announcements
Topic: Video Recording of my Chem 14A Review Session Fall 2015
Replies: 5
Views: 9782

### Re: Video Recording of my Chem 14A Review Session Fall 2015

I'm having technical difficulty. I downloaded the plug in but it still won't load. it says plug in failure
Sat Oct 31, 2015 4:22 pm
Forum: Resonance Structures
Topic: Energy of Resonance Structures
Replies: 1
Views: 1571

### Energy of Resonance Structures

The book states, "low-energy structures contribute more to the resonance mixture than high-energy structures." I am confused by this statement, because I thought all the structures in a resonance hybrid have the same energy? Thus, they all contribute to the resonance hybrid equally? Can so...
Wed Oct 28, 2015 7:47 pm
Forum: Dipole Moments
Topic: CClF3 dipole moment
Replies: 1
Views: 2014

### CClF3 dipole moment

In my discussion, we discussed how CClF3 is a polar molecule because the dipole moment goes from C to Cl because Cl has a bigger atomic radius and it's going to pull more electrons, thus it is more negative. But shouldn't the dipole moment go from C to F since F is more electronegative?
Wed Oct 28, 2015 7:40 pm
Forum: Administrative Questions and Class Announcements
Topic: About course selection for next quarter
Replies: 1
Views: 490

### Re: About course selection for next quarter

no you do not have to take 14b and 14bl together
Wed Oct 28, 2015 5:57 pm
Forum: Ionic & Covalent Bonds
Topic: Workbook Quiz 2 Prep: #9 Which has 2 unpaired electrons?
Replies: 1
Views: 439

### Workbook Quiz 2 Prep: #9 Which has 2 unpaired electrons?

A. OF+
B. NO+
C. CO+

The answer is A, but I do not understand how to do this problem. I drew the Lewis structures for all of these species, but I don't think that helps. Do I have to do the electron configuration in order to do this problem?
Wed Oct 14, 2015 11:26 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: #43 e) homework question: electron configuration tungsten
Replies: 1
Views: 581

### #43 e) homework question: electron configuration tungsten

The electron config. for tungsten is [Xe]4f14 5d4 6s2

I understand that the f block needs to included, but why is it 4f if tungsten is in the 6th group?
Wed Oct 14, 2015 11:24 pm
Forum: Empirical & Molecular Formulas
Topic: Self quiz #9
Replies: 1
Views: 349

### Re: Self quiz #9

2.38 is very close to 2.4
if you multiply 2.4 by 5 you will get 12, which is better than the 7.14 you got from multiplying by 3

hope that helps
Tue Sep 29, 2015 1:24 pm
Forum: Limiting Reactant Calculations
Topic: Question #M9 a) Write the net ionic equation
Replies: 2
Views: 2783

### Question #M9 a) Write the net ionic equation

Question: Copper (II) nitrate reacts with sodium hydroxide to produce copper (II) hydroxide.

Answer: Cu[sup]2+ + 2OH[sup]- ---> Cu(OH)[sub]2

How are net ionic equations formed? I forget!

(Franca Park Discussion 3I)