Search found 51 matches
- Sun Mar 18, 2018 8:21 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: State Functions
- Replies: 4
- Views: 448
Re: State Functions
In order to check me answers for this one, I just thought of the ones that included final minus initial.
- Sun Mar 18, 2018 8:17 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Adiabatic Process
- Replies: 4
- Views: 430
Re: Adiabatic Process
An adiabatic process means that heat isn't being transferred, so q equals 0. The internal energy in this case would equal work.
- Sun Mar 18, 2018 8:13 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: how much of catalyst do we need to know? [ENDORSED]
- Replies: 4
- Views: 435
Re: how much of catalyst do we need to know? [ENDORSED]
I think it would be important to know the difference between a catalyst and an intermediate and how to tell that a catalyst needs to start in the reactants and end up in the products.
- Fri Mar 09, 2018 8:03 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Reaction Intermediates
- Replies: 4
- Views: 303
Re: Reaction Intermediates
Will there ever be a situation where there isn't an intermediate and we're still asked to find one? Do we just come to the conclusion that there aren't any?
- Fri Mar 09, 2018 8:00 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Arrhenius Equation [ENDORSED]
- Replies: 7
- Views: 493
Re: Arrhenius Equation [ENDORSED]
When using the Arrhenius Equation, are we always going to use it in the form k=... or are we going to have to know how to re-arrange it and solve?
- Fri Mar 09, 2018 7:35 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Pre-Equilibrium Approach Methodology
- Replies: 2
- Views: 205
Re: Pre-Equilibrium Approach Methodology
Why do we do the pre-equilibrium approach in respect to the excess reactant when there are two reactants?
- Sat Mar 03, 2018 10:35 am
- Forum: Zero Order Reactions
- Topic: zero order slopes
- Replies: 5
- Views: 375
Re: zero order slopes
Can someone explain why the slope is negative for a zero order reaction when we are plotting [A] vs. time?
- Sat Mar 03, 2018 10:19 am
- Forum: Second Order Reactions
- Topic: The graph of second order [ENDORSED]
- Replies: 5
- Views: 535
Re: The graph of second order [ENDORSED]
Yes, the slope of a second order graph is always positive because after integration of the rate law, k ends up being positive. If k were to come out to be negative, you know it is a first order reaction.
- Sat Mar 03, 2018 10:05 am
- Forum: First Order Reactions
- Topic: First Order Graph
- Replies: 11
- Views: 713
Re: First Order Graph
Is it safe to say that the slope for a first order graph is always negative?
- Fri Feb 23, 2018 4:26 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Initial rates
- Replies: 5
- Views: 454
Initial rates
Why is it that when comparing different reaction rates, the reaction rate only depends on the reactants? Why do we just compare the initial rates rather than the rates at the end of the reaction as well?
- Fri Feb 23, 2018 4:10 pm
- Forum: General Rate Laws
- Topic: Rate Constant K [ENDORSED]
- Replies: 4
- Views: 338
Rate Constant K [ENDORSED]
What exactly does it mean when it says that the rate constant K depends on temperature and activation energy??
- Fri Feb 23, 2018 4:02 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: signs
- Replies: 6
- Views: 747
Re: signs
The signs depends on whether or not the rate is for the products or reactants. For products, the rate is positive, and for reactants, the rate is negative.
- Sat Feb 17, 2018 10:29 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidizing & Reducing Agents
- Replies: 6
- Views: 478
Re: Oxidizing & Reducing Agents
When remembering which one is the reducing agent and which one is the oxidizing agent, it's safe to say that the oxidizing agent is one being reduced and the reducing agent is the one being oxidized. This may be confusing at first, but hope it helps.
- Sat Feb 17, 2018 10:18 pm
- Forum: Balancing Redox Reactions
- Topic: process to balance redox reactions
- Replies: 2
- Views: 272
process to balance redox reactions
How does one know when to add H2O, H+ or OH- when balancing redox reactions? and on what side of the reaction to add them to?
- Sat Feb 17, 2018 10:15 pm
- Forum: Balancing Redox Reactions
- Topic: Basic vs Acidic Conditions
- Replies: 2
- Views: 480
Re: Basic vs Acidic Conditions
Are the ways in which one balances a redox reaction in acidic conditions different from the way one balances one in a basic condition? If so, how?
- Thu Feb 15, 2018 1:23 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt Bridge
- Replies: 7
- Views: 443
Re: Salt Bridge
A salt bridge is needed because it allows for the ion transfer, thus keeping the solutions neutral.
- Thu Feb 15, 2018 1:04 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Is spontaneity determined by entropy or free energy?
- Replies: 9
- Views: 751
Re: Is spontaneity determined by entropy or free energy?
As mentioned above, one needs to pay attention to see if the entropy that one is talking about is for the system or the total entropy because whether or not the entropy can determine the spontaneity is based on whether it's the total or for the system.
- Thu Feb 15, 2018 12:53 pm
- Forum: Van't Hoff Equation
- Topic: Van't Hoff
- Replies: 9
- Views: 698
Re: Van't Hoff
Would the above situations be the only ones where this equation is used?
- Sun Feb 04, 2018 10:08 pm
- Forum: Van't Hoff Equation
- Topic: Van't Hoff Equation
- Replies: 5
- Views: 1398
Re: Van't Hoff Equation
Would there ever be a time when we are asked to calculate K but not given delta H? If so, then how would we solve for K?
- Sun Feb 04, 2018 9:57 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: pressure and free energy
- Replies: 2
- Views: 189
pressure and free energy
I'm a little confused as to when we use the Gibbs free energy equation that includes pressure? Are we going to be told to use it in a question or do we have to know when to use it by our own knowledge?
- Sun Feb 04, 2018 9:30 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: thermodynamically favored
- Replies: 6
- Views: 935
Re: thermodynamically favored
It refers to the free energy which must be negative in oder to be favored and because of this the entropy is positive and the process is spontaneous.
- Mon Jan 29, 2018 10:02 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Entropy [ENDORSED]
- Replies: 4
- Views: 309
Re: Entropy [ENDORSED]
Yes, it is a state function like enthalpy because it isn't dependent on the path taken to obtain the state it is in.
- Mon Jan 29, 2018 9:52 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Relationship between entropy and volume in liquids
- Replies: 5
- Views: 282
Re: Relationship between entropy and volume in liquids
In lecture, it was mentioned how entropy increases as a solid melts or turns into a liquid, and entropy decreases when a liquid goes to a solid. This would support the above post about the relationship between temperature change and entropy.
- Mon Jan 29, 2018 9:36 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: reversible vs. irreversible [ENDORSED]
- Replies: 2
- Views: 145
reversible vs. irreversible [ENDORSED]
What exactly does it mean to say that a reversible process does more work or the max work??
- Sun Jan 21, 2018 9:46 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Constant Volume vs Constant Pressure
- Replies: 6
- Views: 310
Re: Constant Volume vs Constant Pressure
Based on the above responses, is it safe to say that there is only work done when there is a change in volume???
- Sun Jan 21, 2018 9:24 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: R Constant
- Replies: 2
- Views: 180
Re: R Constant
Yes, as mentioned above depending on the question and what is being asked we would be able to differentiate when to use either or value for R. It is important to remember the units because this will help us distinguish which one to use.
- Sun Jan 21, 2018 9:19 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Difference between Closed and Isolated
- Replies: 10
- Views: 1504
Re: Difference between Closed and Isolated
An isolated system doesn't exchange anything with its surroundings, and a closed system can exchange energy with its surroundings but not matter.
An example of a closed system is a sealed beaker of water, and an example of an isolated system is the combustion of glucose in a bomb calorimeter.
An example of a closed system is a sealed beaker of water, and an example of an isolated system is the combustion of glucose in a bomb calorimeter.
- Sat Jan 13, 2018 6:42 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Intensive vs extensive property
- Replies: 3
- Views: 168
Re: Intensive vs extensive property
An intensive property doesn't depend on the amount of substance where as an extensive property does depend on the amount of substance so yes an intensive property would be more useful to use because it won't change based on the amount of substance.
- Sat Jan 13, 2018 6:28 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Irreversible vs. Reversible Processes
- Replies: 3
- Views: 227
Re: Irreversible vs. Reversible Processes
Is it true that in irreversible processes, the pressure can be considered constant, and in a reversible process, the pressure is constantly changing so the pressure isn't constant??
- Sat Jan 13, 2018 6:14 pm
- Forum: Phase Changes & Related Calculations
- Topic: Why can state properties be added?
- Replies: 11
- Views: 787
Re: Why can state properties be added?
As mentioned above, because state properties don't rely on the path taken to get to their state they can be added and subtracted. They are independent in other words so adding and subtracting them is allowed.
- Thu Dec 07, 2017 5:18 pm
- Forum: Lewis Acids & Bases
- Topic: Lewis Structure in identifying Acid or Base
- Replies: 2
- Views: 254
Lewis Structure in identifying Acid or Base
How do we know whether or not something is an acid or base from drawing the Lewis structure??
- Thu Dec 07, 2017 4:42 pm
- Forum: Conjugate Acids & Bases
- Topic: HW 12.7
- Replies: 3
- Views: 285
Re: HW 12.7
Do we need to be able to name the acids as well as know their molecular formula for the final??
- Tue Nov 28, 2017 8:21 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: polar or nonpolar
- Replies: 1
- Views: 173
polar or nonpolar
How can one find if a molecule is polar or nonpolar when the Lewis structure isn't given? Do we need to draw it out to figure this out??
Re: dentates
In order to find if ligand is bi-, tri-, etc dentate, do we need to draw out the Lewis structures or is there an easier way to do this??
- Fri Nov 24, 2017 10:37 am
- Forum: Ideal Gases
- Topic: Reverse Reaction, Q and K
- Replies: 5
- Views: 659
Re: Reverse Reaction, Q and K
Will there ever be situations in which Q is equal to K and if this is the case, which direction will the reaction proceed??
- Fri Nov 24, 2017 10:32 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equilibrium constant
- Replies: 4
- Views: 196
Re: Equilibrium constant
With this, does that mean we completely disregard the solids and liquids when calculating the K constant? The gaseous reactants and products are the only ones used??
- Sun Nov 19, 2017 10:06 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Defining a Ligand
- Replies: 3
- Views: 240
Re: Defining a Ligand
Can someone further explain the relationship between ligands and coordination spheres and how they relate to the coordination number??
- Sun Nov 19, 2017 10:00 am
- Forum: Hybridization
- Topic: Difference between sigma and pi bonds?
- Replies: 6
- Views: 1517
Re: Difference between sigma and pi bonds?
sigma bonds allow bound atoms to rotate which allows them to have electron density with cylindrical symmetry around the internuclear axis, while pi bonds don't allow for rotation of bound atoms which explains the electron density on each side of internuclear axis
- Thu Nov 09, 2017 9:48 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: delta v
- Replies: 4
- Views: 410
Re: delta v
Do we always have to multiply by 2 in order to find the delta v for these problems??
- Thu Nov 09, 2017 9:33 am
- Forum: DeBroglie Equation
- Topic: DE BROGLIE [ENDORSED]
- Replies: 3
- Views: 240
DE BROGLIE [ENDORSED]
How do we find the mass of atom given the molar mass of the element in order to use the de broglie equation??
- Sat Nov 04, 2017 11:15 am
- Forum: Ionic & Covalent Bonds
- Topic: Ionic or Covalent?
- Replies: 4
- Views: 350
Re: Ionic or Covalent?
Is there any way to tell if a bond is ionic or covalent without having to calculate the electronegativity difference?
- Sat Nov 04, 2017 11:01 am
- Forum: Lewis Structures
- Topic: Expanded Octet
- Replies: 3
- Views: 197
Re: Expanded Octet
Given the information above, why is it that expanded octet structures have lower energy than regular octet structures? Is it because of it having a d-orbital?
- Fri Oct 27, 2017 10:34 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: anion vs. cation [ENDORSED]
- Replies: 2
- Views: 302
anion vs. cation [ENDORSED]
Other than the removing and addition of electrons, are there any other differences between anions and cations?
- Fri Oct 27, 2017 9:25 pm
- Forum: Lewis Structures
- Topic: Lewis Structures- resonance [ENDORSED]
- Replies: 4
- Views: 316
Lewis Structures- resonance [ENDORSED]
Lewis structures with resonance, for example nitrate, when asked to draw the lewis structure would we be able to draw any of the three possible structures that we went over in class and still have the correct answer or is there one preferred over the others?
- Fri Oct 20, 2017 8:04 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: quantum numbers
- Replies: 2
- Views: 189
quantum numbers
During lecture today, it was mentioned that the rows of the periodic table correspond to quantum numbers. What exactly does this mean?
Thanks!
Thanks!
- Fri Oct 20, 2017 8:04 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: quantum numbers [ENDORSED]
- Replies: 5
- Views: 554
quantum numbers [ENDORSED]
During lecture today, it was mentioned that the rows of the periodic table correspond to quantum numbers. What exactly does this mean?
Thanks!
Thanks!
- Fri Oct 20, 2017 7:52 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: p-orbital [ENDORSED]
- Replies: 2
- Views: 222
p-orbital [ENDORSED]
I'm not sure if I'm wording this correctly, but when writing the electron configurations, do we have to include the x, y, and z for like the p-orbital or can we simply just write it all as p?
- Thu Oct 12, 2017 1:48 pm
- Forum: Properties of Light
- Topic: Clarification on C=λv
- Replies: 10
- Views: 1912
Re: Clarification on C=λv
Is it safe to say that electromagnetic radiation and wavelength are inversely proportional, while frequency and electromagnetic radiation are directly related, based on the responses above?
- Thu Oct 12, 2017 12:43 pm
- Forum: Properties of Light
- Topic: 1.27
- Replies: 1
- Views: 181
1.27
Can someone please help with this question:
A lamp rated at 32W emits violet light of wavelength 420 nm. How many photons of violet light can the lamp generate in 2.0 s? How many moles of photons are emitted in that time interval?
Thanks!
A lamp rated at 32W emits violet light of wavelength 420 nm. How many photons of violet light can the lamp generate in 2.0 s? How many moles of photons are emitted in that time interval?
Thanks!
- Thu Oct 05, 2017 8:48 pm
- Forum: Significant Figures
- Topic: Number of sig figs in answer
- Replies: 8
- Views: 811
Re: Number of sig figs in answer
Yes, I agree. It's always good to save the rounding and finding the sig figs for the end. Doing it like this allows for the answer to be more accurate.
- Thu Oct 05, 2017 8:35 pm
- Forum: Balancing Chemical Reactions
- Topic: Order of steps
- Replies: 6
- Views: 727
Re: Order of steps
Honestly, when balancing equations I usually go with the first one that comes in the order of the equation and from there I balance the rest. I might need to go back and fix ones that I already balanced, but this usually works.