## Search found 35 matches

Mon Mar 13, 2017 3:59 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell potential equals zero?
Replies: 1
Views: 708

### Cell potential equals zero?

When does the standard cell potential equal zero? Is it when it is an electrolyte concentration cell reaction? Furthermore, what is an electrolyte concentration cell reaction?
Sun Mar 12, 2017 10:45 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: winter 2015 final 5A
Replies: 1
Views: 221

### winter 2015 final 5A

In a neuron (a nerve cell), the concentration of K ions inside the cell is about 20–30 times as great as that outside. What potential difference between the inside and the outside of the cell would you expect to measure if the difference is due only to the imbalance of potassium ions? The solution s...
Sun Mar 12, 2017 10:37 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Winter 2016 final 4B
Replies: 4
Views: 571

### Winter 2016 final 4B

Given:
Step 1: ClO+O2->ClO2+O
Step 2: ClO+O->ClO2
How do I go about finding the rate law for step 2? I think we are suppose to get rid of the oxygen in the final rate law because it is an intermediate but how do I do so? Thanks in advance.
Sun Mar 12, 2017 2:32 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Winter 2016 final 2a
Replies: 1
Views: 213

### Winter 2016 final 2a

The equation given is PCl3+Cl2->PCl5 and the standard gibbs free is given for PCl5 as -305 kJ/mol and PCl3 is -267.8 kJ/mol. The part I am confused about is when the explanation says to calculate delta G of the reaction using only the gibbs free for PCl5 and PCl3. Why is the gibbs free energy of Cl2...
Sun Mar 12, 2017 12:41 pm
Forum: *Alcohols
Topic: Determining phenol functional groups
Replies: 3
Views: 969

### Determining phenol functional groups

Can a phenol functional group also be considered an alcohol functional group because the phenol is a hydroxy attached to a benzene ring?
Sat Mar 11, 2017 7:46 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: winter 2015 final 7B
Replies: 2
Views: 256

### winter 2015 final 7B

The question asks for the reverse activation energy. The explanation says that because it is an exothermic reaction, it will have a reverse activation energy of delta enthalpy+the forward activation energy. How did they get this equation and will we need to know this on the final?
Mon Mar 06, 2017 12:03 pm
Forum: *Identifying Primary, Secondary, Tertiary, Quaternary Carbons, Hydrogens, Nitrogens
Topic: Clarification on sec
Replies: 1
Views: 503

### Clarification on sec

On page 23 of the green organic book, there is an example of 1-sec-butyl-4-methylcyclohexane. Is it possible to also write the compound as
1-(2-butyl)-4-methylcyclohexane? I thought that since the butyl substituent is attached to cyclohexane at its second carbon, I can write 2-butyl.
Sun Mar 05, 2017 7:30 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Self test 4.4A
Replies: 2
Views: 297

### Self test 4.4A

Can someone explain part c? I thought the answer was step two but the answer is step one.
Sat Mar 04, 2017 11:28 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Effect of catalyst on fast versus slow step [ENDORSED]
Replies: 1
Views: 309

### Effect of catalyst on fast versus slow step[ENDORSED]

Lets say there are 3 transition states in a reaction, if a catalyst is added to the slowest step, what is its effect on the overall rate reaction versus when a catalyst is added to the fastest step.
Sat Mar 04, 2017 2:25 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Quiz 3 question 7
Replies: 1
Views: 243

### Quiz 3 question 7

The questions asks for the product of the reaction of 2-butene with Cl2 and the answer is 2,3-dichlorobutane.

Is there a reason why the two chlorines bond with the two carbons that have the double bond?
Sat Mar 04, 2017 2:20 pm
Forum: *Nucleophiles
Topic: QUIZ 3 question 6 [ENDORSED]
Replies: 1
Views: 256

### QUIZ 3 question 6[ENDORSED]

Why are both of the structures nucleophiles? One structure is a 1,3,5-cyclohexene(i could be wrong in naming this) and the other is CH3OCH3.
Thu Mar 02, 2017 11:34 pm
Forum: *Alkanes
Topic: Line structures
Replies: 1
Views: 204

### Line structures

Can someone explain line structures when there are horizontal lines that vary in length? What is the purpose of these and how do I learn how to draw them? (For reference, I'm asking because the self-test 1.2B asks a question about the line structure for propyne.)
Thu Feb 16, 2017 11:28 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Homework question 15.19
Replies: 2
Views: 345

### Re: Homework question 15.19

Why do we look at experiment 1 where the initial rate is 8.7? I thought we would look at the initial rate in experiment 2 because the initial concentration changes from experiment 2 to 3.
Tue Feb 14, 2017 9:43 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.15c
Replies: 1
Views: 177

### 14.15c

Write the half-reactions and devise a galvanic cell (write a cell diagram) to study each of the following reactions: (c) Cd(s)+2 Ni(OH)3(s)->Cd(OH)2(s)+2 Ni(OH)2(s), the reaction in the nickel–cadmium cell My question is why is the cell diagram written as Cd(s)|Cd(OH)2(s)|KOH(aq)||Ni(OH)3(s)|Ni(OH)2...
Mon Feb 13, 2017 11:22 am
Forum: Balancing Redox Reactions
Topic: 2016 midterm #6a
Replies: 1
Views: 279

### 2016 midterm #6a

Identify the elements undergoing changes in oxidation state and indicate the initial and final oxidation numbers for these elements.
H(plus one charge)+Cr2O7(minus two charge)+C5H5OH->Cr3(plus three charge)+C2H4O+H2O

I understand how Cr is reduced from 6+ to 3+ but how is C oxidized from 2- to 1-?
Mon Feb 13, 2017 10:54 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 2014 midterm #8
Replies: 1
Views: 246

### 2014 midterm #8

The question asks to solve for Ka of HF given the standard cell potentials: F2+2H(plus one charge) +2e->2HF E knot=3.03 V F2+2e->2F(minus one charge) E knot=2.87 V I understand how to use the formula to solve for K but I don't understand how the cathode and anode are determined. In the solution, HF ...
Sat Jan 28, 2017 11:36 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: 2013 midterm Q5 [ENDORSED]
Replies: 1
Views: 226

### 2013 midterm Q5[ENDORSED]

Arrange the following in order of increasing standard molar entropy: CHF3(g), CF4(g), CH3F(g), CH2F2(g) The answer says it is CH3F<CH2F2<CHF3<CF4 But why does CF4 have the largest molar entropy when its carbon atom is surrounded by 4 fluorine atoms? Shouldn't that indicate its number of possible pos...
Sat Jan 28, 2017 12:00 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: HW 9.35
Replies: 1
Views: 290

### Re: HW 9.35

Both do have one mole but container A has monatomic molecules while container c has diatomic molecules. The number of particles is greater in in container A because each particle is counted as an individual atom while diatomic molecules need two particles to create a molecule.
Thu Jan 26, 2017 1:33 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.33 part a
Replies: 1
Views: 182

### 9.33 part a

Without performing any calculations, predict whether there is an increase or a decrease in entropy for each of the following processes: (a) Cl2(g)+H2O(l)->HCl(aq)+HClO(aq) The solution manual says entropy decreases because the number of moles of gas is less on the product side but why do they only l...
Fri Jan 20, 2017 9:59 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 8.111 part c [ENDORSED]
Replies: 1
Views: 227

### 8.111 part c[ENDORSED]

Part A gives us the formula 2H2S(g)+O2(g)->2S(s)+2H2O(l) and we know from part b of the equation that the enthalpy for 60 kg of sulfur is -4.96x10^5 kJ. Part c asks would the reactor need to be cooled or heated to maintain a constant temperature? Specifically, my question is what exactly is a reactor?
Tue Jan 17, 2017 10:31 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 8.19 heat capacity
Replies: 2
Views: 250

### 8.19 heat capacity

How or where do I find the heat capacity for copper?
Tue Jan 17, 2017 11:33 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 8.87 Heat Capacity
Replies: 1
Views: 254

### 8.87 Heat Capacity

Where can I find the heat capacity value for H2O as a solid ? The solution manual says the q(heat capacity) equation for H2O solid should be 42.30g(2.03)(0+5.04)=432.95 J where 2.03 is the heat capacity but I have no idea where this value came from.
Fri Dec 02, 2016 4:31 pm
Forum: *Titrations & Titration Calculations
Topic: Half way stoichiometric point
Replies: 1
Views: 293

### Half way stoichiometric point

Why is the pH at the half way stoichiometric point equal to the pKa?
Sun Nov 20, 2016 8:23 pm
Forum: Conjugate Acids & Bases
Topic: What does a conjugate acid/base do? [ENDORSED]
Replies: 4
Views: 908

### What does a conjugate acid/base do?[ENDORSED]

I understand that in a equation, acid+base<->conjugate acid+conjugate base, the acid by the Bronsted definition, donates a proton to the base, but what does the conjugate bases or conjugate acids do? Do they follow the Lewis or Bronsted definitions of an acid or base? I can't see the relationship.
Fri Nov 11, 2016 3:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chapter 11.29 HW
Replies: 1
Views: 305

### Chapter 11.29 HW

If Q =1.0 for the reaction N2(g)+O2(g)->2 NO(g) at 25 C, will the reaction have a tendency to form products or reactants, or will it be at equilibrium?
In the solution manual, K is calculated by referring to Appendix 2A, but it that the only way to solve this problem?
Thu Nov 10, 2016 3:28 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ideal gas law
Replies: 2
Views: 316

### Ideal gas law

What does each variable in the ideal gas law(PV=nRT) stand for and is there a constant value for it (for example, is there a value for R or T we must know to solve the problem?
Mon Nov 07, 2016 12:01 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Oxidation State
Replies: 3
Views: 282

### Oxidation State

What exactly does the oxidation state mean?
Tue Nov 01, 2016 10:19 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone pairs in polarity
Replies: 1
Views: 277

### Lone pairs in polarity

Do lone pairs affect the polarity of an atom? How so?
Sun Oct 30, 2016 9:53 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: bond angles
Replies: 1
Views: 233

### bond angles

What are the bond angles for seesaw, t-shaped, square pyramidal. and square planar? Specifically, is there a pattern or conceptual method to know the bond angles?
Sun Oct 30, 2016 9:35 pm
Forum: Octet Exceptions
Topic: Ground state
Replies: 2
Views: 331

### Ground state

If the ground state electron configuration for Fe^3+ is [Ar]3d^5, what is the electron configuration for vanadium, which is isoelectric to Fe^3+?

And another question I have is whether all isoelectric atoms have the same electron configurations?
Thu Oct 27, 2016 7:07 pm
Forum: Sigma & Pi Bonds
Topic: Anti bonding orbitals
Replies: 1
Views: 229

### Anti bonding orbitals

What exactly are anti bonding orbitals and how are they written?
Thu Oct 20, 2016 6:23 am
Forum: Ionic & Covalent Bonds
Topic: NH4Cl question 3.39
Replies: 1
Views: 237

### NH4Cl question 3.39

Why is it that NH4 is drawn in brackets while Cl is outside of the brackets and how do you know when to draw the lewis structure this way?
Fri Oct 14, 2016 5:24 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Question 2.19 part b and c [ENDORSED]
Replies: 6
Views: 688

### Re: Question 2.19 part b and c[ENDORSED]

What exactly does it mean when m sub l is -2, -1, 0, 1, 2 compared to when m sub l is -1, 0, 1 for when l=1?
Wed Oct 05, 2016 9:03 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Relationship between momentum and position
Replies: 1
Views: 221

### Relationship between momentum and position

For clarification, is the reason why position and momentum can not be know at the same time because light from an ejected electron affects both simultaneously?
Mon Sep 26, 2016 8:51 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactant Question M19
Replies: 3
Views: 441

### Re: Limiting Reactant Question M19

I believe we can not subtract the total moles of the three compounds/element from the given caffeine mass because moles and masses are different units. Instead, we can subtract the total mass of C, H, and N from the given caffeine mass to find the mass of oxygen. We know to find oxygen because the p...