Search found 23 matches

Sat Mar 18, 2017 3:06 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Catalysts in Net Reaction
Replies: 1
Views: 1368

Catalysts in Net Reaction

When there is a catalyst in the reaction, we know that it's in the reactants and in the products because it is not consumed by the reaction. Do we include it in our net reaction when writing it? So as my net reaction, would I write: (enzyme) + reactants ---> (enzyme) + products OR reactants -----> p...
Thu Mar 02, 2017 2:38 pm
Forum: *Alkanes
Topic: "R" in Reference to Alkane to Alkyl Naming
Replies: 1
Views: 308

"R" in Reference to Alkane to Alkyl Naming

What exactly does "R" mean? I'm really confused about this, all I know is that when 1H is removed from an alkane, it becomes and Alkyl group.
Wed Feb 22, 2017 11:26 pm
Forum: General Rate Laws
Topic: Equilibrium Constant K
Replies: 1
Views: 331

Equilibrium Constant K

I know that equilibrium constant K=Products/Reactants. We also are told that K=k/k'. k is defined as the forward reaction's reactants and k' is defined as the reverse equation's reactants. We are given the example: A + B <---> C + D. The rate of the forward reaction is k[A][B] and the rate of the re...
Wed Feb 22, 2017 2:13 pm
Forum: General Rate Laws
Topic: Differential Rate Law Versus Integrated Rate Law
Replies: 1
Views: 355

Differential Rate Law Versus Integrated Rate Law

In what scenario do we use each law? I know that there are different orders that you must approach either of these with precaution, but how do you know when to use the differential rate law versus the integrated one? Do they find different characteristics?
Wed Feb 15, 2017 1:23 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Enthalpy Predictions
Replies: 1
Views: 352

Enthalpy Predictions

When predicting the sign of dS(sys), when do you know when it should be positive or negative?
I'm doing question 2 of the Winter 2014 final and it asks us to predict the dS(sys) without doing any calculations. The equation we're predicting dS of is 2CO(g) + O2(g) --> 2CO2(g).
Tue Feb 14, 2017 7:04 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Common Bond Enthalpies
Replies: 1
Views: 353

Common Bond Enthalpies

Going through Winter Midterm 2016, Question 1... The bond enthalpies aren't given, but they're used. Are we expected to memorize bond enthalpies of common bonds, like C-O, O-H, C-C.... ?
Mon Feb 13, 2017 5:29 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Standard Molar Entropy
Replies: 1
Views: 537

Standard Molar Entropy

What are characteristics for high/low molar entropy? Entropy is disorder, yes. So does symmetry of a molecule signify low entropy? Do larger elements in a molecule signify higher molar entropy because of the larger amount of electrons and nuclear subparticles? Please explain, I'm really stuck on the...
Mon Feb 13, 2017 2:06 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Stability of Molecules
Replies: 1
Views: 315

Stability of Molecules

I'm looking at one of the Integrated Exercises of Chapter 9 and I wanted to know what steps do you need to do in order to find out what molecule was more stable: Fe3O4 or Fe2O3.

Is there any general rule for molecule stability? Or do we need to calculate it using some formula?
Thu Feb 09, 2017 8:05 pm
Forum: Calculating Work of Expansion
Topic: Reversible Vs. Irreversible
Replies: 1
Views: 329

Reversible Vs. Irreversible

I understand that some equations only apply to either reversible or irreversible equations, but I'm not sure that I have the concept of a "reversible" or "irreversible" reaction. Is it just that reversible means that it can undo? Like, the products and can turn back into reactant...
Sun Jan 22, 2017 12:19 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Ideal Gas Law
Replies: 2
Views: 333

Ideal Gas Law

I understand that the ideal gas law is PV=nRT... what does it tell us? When do we use it?
Sun Jan 22, 2017 12:17 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Homework Chapter 8 Problem 8.27
Replies: 1
Views: 373

Homework Chapter 8 Problem 8.27

The problem reads, "Calculate the work for each of the following processes beginning with a gas sample in a piston assembu woth T=303K, P=1.79 atm, V=4.29L : (a.) irreversible expansion against a constant external pressure of 1.00 atm to a final volume of 6.52L (b.) isothermal, reversible expan...
Sun Jan 22, 2017 12:04 pm
Forum: Phase Changes & Related Calculations
Topic: Expected Conversions [ENDORSED]
Replies: 2
Views: 385

Expected Conversions[ENDORSED]

In many questions in the textbook, we need to convert units (such as torr to atm, Celcius to Kelvins, etc)... Are we expected to remember the conversions of these units? Or will we be provided the information?
Thu Jan 12, 2017 8:30 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: State Property/Function
Replies: 3
Views: 356

State Property/Function

What is being referred to as "state"? Is it the (physical) state of a substance? And I understand that a "state function" is "a property whose value does not depend on the path taken to get that specific value", but what does that mean exactly? Examples please!
Fri Dec 02, 2016 1:50 am
Forum: Bronsted Acids & Bases
Topic: Strong Acids [ENDORSED]
Replies: 1
Views: 486

Strong Acids[ENDORSED]

Why are most of the halogens strong acids? The more electronegative, the stronger the pull of the electrons, then the shorter the bond. The shorter the bond, the weaker the acid due to the lower amount of disassociation. Shouldn't they be weak acids?
Tue Nov 29, 2016 9:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Composition and ICE tables
Replies: 1
Views: 398

Equilibrium Composition and ICE tables

So, I know that the equilibrium constant, Kc, is the ratio between products and reactants of an equation at equilibria... but why is it important? Like, what's the relevance of it, what is equilibrium composition, and why is equilibrium composition important at all?
Sat Nov 12, 2016 9:37 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Cis- versus Trans-
Replies: 2
Views: 422

Cis- versus Trans-

I know that these prefixes have some relevance in the biological significance of coordination compounds, but why? Why is it crucial that two of the same element/atom are side by side versus opposite in a molecule?
Sat Nov 12, 2016 9:01 pm
Forum: Ideal Gases
Topic: Partial Pressure
Replies: 1
Views: 283

Partial Pressure

Why is pressure relevant when talking about gasses in equilibrium?
Thu Oct 27, 2016 9:03 pm
Forum: Hybridization
Topic: Defining Sigma and Pi Bonds [ENDORSED]
Replies: 1
Views: 321

Defining Sigma and Pi Bonds[ENDORSED]

Alright, so I have a general understanding that sigma bonds represent a single bond and have been told that pi bonds are just double bonds... but the reading is countering that explanation. I can't imagine what they look like, and don't understand what they are...Some one help?
Sat Oct 22, 2016 10:09 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Wanted Formal Charge
Replies: 2
Views: 463

Wanted Formal Charge

Why do we want the formal charge to equal zero? And why do we find the formal charge of each molecule in an atom?
Mon Oct 10, 2016 10:00 am
Forum: General Science Questions
Topic: Unit Conversions
Replies: 2
Views: 907

Unit Conversions

What are some essential conversions we should know?
I mean stuff like joules, hertz, etc.
I know some simple things like 1nm=10^-9m, but otherwise I'm completely lost. Help?
Sun Oct 09, 2016 7:25 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Wavefunction/Orbital concept
Replies: 1
Views: 318

Wavefunction/Orbital concept

So, to my understanding, a wave function is used to describe where an electron is in an atom at a certain point in time. During the lecture, I heard him say that an orbital IS a wave function. I don't understand the differentiation between a wave function, orbital, and energy level. Someone please c...
Mon Oct 03, 2016 8:18 pm
Forum: Properties of Light
Topic: Light as a Particle vs Light as a Wave
Replies: 2
Views: 421

Light as a Particle vs Light as a Wave

So, I understand that light has both qualities of a "wave" and a "particle... But when is it acting as one versus the other? Or does it act as both simultaneously... In addition, if it is a "particle", is that when it's considered a photon? And is a wave just a stream of pho...
Sun Oct 02, 2016 10:03 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Terminology Clarfication [ENDORSED]
Replies: 7
Views: 1090

Re: Terminology Clarfication[ENDORSED]

After what I've read, the roman numerals are based on the "stock system" in order to help name compounds with multivalent metals. They supposedly tell the charge of that certain metal- copper (II) has a charge of 2+ (I believe). In relation to that, bother copper and copper (II) have a 2+ ...