Search found 22 matches

by Marc Farah 3D
Sat Mar 18, 2017 11:00 pm
Forum: *Electrophilic Addition
Topic: Reaction step naming
Replies: 3
Views: 866

Reaction step naming

Are electrophilic addition reactions always two step?
Does S2N mean the reaction goes from 2 molecules in the reactants to 2 molecules in the products?
by Marc Farah 3D
Fri Mar 10, 2017 3:07 pm
Forum: *Cycloalkenes
Topic: Numbering carbon atoms
Replies: 1
Views: 680

Numbering carbon atoms

For numbering the carbon atoms for cycloalkanes. Why do we not find the longest chain and start with that as opposed to just counting the ring structure
by Marc Farah 3D
Sat Mar 04, 2017 5:35 pm
Forum: *Complex Reaction Coordinate Diagrams
Topic: Naming compounds
Replies: 1
Views: 633

Naming compounds

What is the rule on numbering the Carbon atoms? How do we know which Carbon to label as number 1?
by Marc Farah 3D
Fri Feb 24, 2017 6:10 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Electrophiles
Replies: 3
Views: 491


Why are elements like Florine and Chlorine which have so many electrons considered electrophiles? Shouldn't they be attracted to positive species?
by Marc Farah 3D
Sun Feb 19, 2017 9:24 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Differential Rate Law
Replies: 1
Views: 356

Re: Differential Rate Law

In certain cases you can use the product concentrations but it is not always accurate because sometimes the product that gets formed cant go back to reactants lile gas going into the surroundings. So it is more reliable to use the inital reactants concentration.
by Marc Farah 3D
Mon Feb 13, 2017 2:14 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: electrodes
Replies: 1
Views: 276


What do we do when we are given a redox reaction and there is no solid metal conductor for one of the half reactions? How do electrons get transferred in that case?
by Marc Farah 3D
Mon Feb 13, 2017 2:10 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Gibbs free energy
Replies: 2
Views: 417

Gibbs free energy

Why is it so that the work maximum is equal to delta G?
by Marc Farah 3D
Mon Feb 13, 2017 2:09 pm
Forum: General Rate Laws
Topic: Overall Rate Law
Replies: 1
Views: 360

Re: Overall Rate Law

Yes the overall rate law is the same as the slowest rate because the slowest rate of the reaction is the rate determining step so that will be what the overall rate of the reaction is dependent on
by Marc Farah 3D
Wed Feb 01, 2017 1:35 pm
Forum: Balancing Redox Reactions
Topic: Balancing reactions
Replies: 4
Views: 506

Balancing reactions

When we balance half reactions, and double the reaction, why do we not double the E(not)? Why is it kept constant but when flipped it, we must change the E to negative?
by Marc Farah 3D
Fri Jan 27, 2017 7:39 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs equilibrium
Replies: 1
Views: 274

Gibbs equilibrium

Are equilibrium conditions when delta G = 0 or when delta G (not) =0? Why? Also why is the system not at equilibrium if Gr doesn't equal Gp?
by Marc Farah 3D
Fri Jan 20, 2017 1:58 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Work of Expansion [ENDORSED]
Replies: 2
Views: 446

Work of Expansion [ENDORSED]

For Work of expansion, why must we measure the changes in energy for in very small steps? And therefore having to use an integral for the infinitesimal changes in volume? When do we use w=-pV as opposed to the integral equation for w?
by Marc Farah 3D
Sun Jan 15, 2017 11:22 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Clarification on units
Replies: 1
Views: 307

Re: Clarification on units

You use KJ's when the question asks for enthalpy. However KJ/mol is used when dealing with standard enthalpy of formation. The reason is that standard enthalpy of formation is calculated per one mole of that product.
by Marc Farah 3D
Wed Nov 30, 2016 1:36 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Calculating pH
Replies: 1
Views: 353

Calculating pH

In the course reader it says if H30+ is less than 10^-7, then the solution is considered neutral becausee we know that as a result of autoprotolysis there are 10^-7 mol L^-1 H30+. What exactly does this mean?
by Marc Farah 3D
Wed Nov 30, 2016 1:30 pm
Forum: *Indicators
Topic: Importance of Indicators
Replies: 2
Views: 3236

Importance of Indicators

What is the key aspect we need to know about indicators in titration problems?
by Marc Farah 3D
Thu Nov 10, 2016 4:09 pm
Forum: *Molecular Orbital Theory Applied To Transition Metals
Topic: Drawing MO Diagrams
Replies: 3
Views: 3550

Drawing MO Diagrams

When we are asked to draw the molecular orbital theory for a molecule with two different elements, I know we have to draw the orbitals for one element lower than the others but why and which one do we choose? Also what are the important ideas we have to pay attention to when we have two different el...
by Marc Farah 3D
Mon Oct 31, 2016 2:32 pm
Forum: Resonance Structures
Topic: Stable Lewis Structures
Replies: 3
Views: 610

Re: Stable Lewis Structures

I believe it is best to draw the most stable Lewis Structure. So in this case, check the formal charges on each atom to see which structure is most stable and preferred.
by Marc Farah 3D
Sat Oct 29, 2016 11:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape for Sulfur Tetrafluoride
Replies: 1
Views: 512

Re: Shape for Sulfur Tetrafluoride

When determining the shape first look at how many regions of electron density there are around the central atom. In this case even though S has 4 bonds, it also has a lone pair so 5 total regions of electron density. Making it a trigonal bipyrmidal. However the lone pair creates a strong repulsion w...
by Marc Farah 3D
Thu Oct 20, 2016 6:12 pm
Forum: Lewis Structures
Topic: Drawing Lewis Structures [ENDORSED]
Replies: 2
Views: 474

Drawing Lewis Structures [ENDORSED]

How do we know which element to put as the central atom when drawing lewis structures? Is it the one with the lowest electron affinity or electronegativity?
by Marc Farah 3D
Thu Oct 20, 2016 6:05 pm
Forum: Lewis Structures
Topic: Forming double bonds [ENDORSED]
Replies: 1
Views: 270

Re: Forming double bonds [ENDORSED]

I believe it is because the atom doesn't have any more valence electron to share evenly 1 to 1. So the atom with the lone pair will just share both of it's electrons with the other atom forming a bond. It cannot just give it one of its electrons and hold on to the other one because then a bond doesn...
by Marc Farah 3D
Fri Oct 14, 2016 2:45 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic Bonds of Octet Outliers
Replies: 3
Views: 548

Re: Ionic Bonds of Octet Outliers

Unlike covalent bonding where they share their electrons, in ionic bonding, the elements with high electronegativty like Oxygen and Flourine pull the electrons from He, Li, Be. So oxygen for example would satisfy the octet rule becoming an anion while the metal would become a cation.
by Marc Farah 3D
Wed Oct 05, 2016 10:04 pm
Forum: *Shrodinger Equation
Topic: Slight Confusion about Orbitals
Replies: 2
Views: 406

Re: Slight Confusion about Orbitals

From what I believe, the orbitals tell us roughly the movement of the electrons around the nucleus. They move in wave like form along those dimensions. However they may not be exactly moving on those orbitals because it is hard to determine exactly where they are at a certain time, but they tell us ...
by Marc Farah 3D
Mon Sep 26, 2016 11:23 pm
Forum: Student Social/Study Group
Topic: Chemistry Jokes
Replies: 31
Views: 5279

Re: Chemistry Jokes

1) A photon checks into a hotel and is asked if he needs any help with his luggage. He says, "No, I'm traveling light."

2) If you're not part of the solution, you're part of the precipitate.

3) If the Silver Surfer and Iron Man team up, they'd be alloys.

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