Search found 51 matches
- Tue Mar 13, 2018 5:04 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalyst vs Intermedaite
- Replies: 3
- Views: 441
Re: Catalyst vs Intermedaite
Do we put catalysts in the overall rate law or do we leave them out just like we leave intermediates out of the rate law?
- Tue Mar 13, 2018 5:03 pm
- Forum: First Order Reactions
- Topic: Slope of 1st order RXNs
- Replies: 9
- Views: 1250
Re: Slope of 1st order RXNs
The slope would be -k because the amount of reactants is decreasing over time.
- Tue Mar 13, 2018 5:03 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Organic Chem on Final
- Replies: 9
- Views: 1403
Re: Organic Chem on Final
So we would need to know all the functional groups and their line diagrams and how to draw them?
- Thu Mar 08, 2018 12:45 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 2965054
- Wed Mar 07, 2018 9:47 pm
- Forum: General Rate Laws
- Topic: Order of reactants [ENDORSED]
- Replies: 1
- Views: 326
Order of reactants [ENDORSED]
What is useful about knowing the order of the reactants?
- Wed Mar 07, 2018 9:25 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Rate Constant K
- Replies: 3
- Views: 605
Rate Constant K
What are the things that affect the rate constant,k?
- Wed Mar 07, 2018 9:24 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Finding the intermediate(s)
- Replies: 5
- Views: 673
Re: Finding the intermediate(s)
Why do we not include any intermediates in the overall rate law when the intermediates are a part of the slow step?
- Tue Feb 27, 2018 11:27 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Units of Reaction Rate
- Replies: 7
- Views: 898
Re: Units of Reaction Rate
Are there any constants we need to use in this unit?
- Tue Feb 27, 2018 11:26 pm
- Forum: General Rate Laws
- Topic: Will we ever deal with third order reactions?
- Replies: 2
- Views: 318
Re: Will we ever deal with third order reactions?
I remember lavelle saying we won't need to focus in them because they rarely happen. Only 1st and 2nd and 0th
- Tue Feb 27, 2018 11:21 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: What is the order of the reaction? [ENDORSED]
- Replies: 4
- Views: 524
What is the order of the reaction? [ENDORSED]
What does the "order" of a reaction mean? What is the difference between a first, second, third, or zeroth order reaction?
- Mon Feb 19, 2018 7:03 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation Numbers
- Replies: 6
- Views: 832
Re: Oxidation Numbers
Yea O2 has oxidation number of 2- for each oxygen.
- Mon Feb 19, 2018 7:02 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.13 c
- Replies: 2
- Views: 292
Re: 14.13 c
Platinum is added when there is no metal or electrode, it is used because it is chemically inert and rarely reacts. The Cl(aq) is separated because there is a phase change between it and Cl2(g).
- Mon Feb 19, 2018 6:58 pm
- Forum: Balancing Redox Reactions
- Topic: Balanced Redox Reactions
- Replies: 2
- Views: 397
Re: Balanced Redox Reactions
The water is added to balance out the H+ or H3O+ ions in the reaction. It doesn't matter which side you add water. Water is added to balance out the hydrogens in the reaction. Water is there only for an acidic solution and an aqueous solution.
- Tue Feb 13, 2018 5:45 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Reversible
- Replies: 4
- Views: 506
Re: Reversible
When a system is reversible, it can be implied that the system is at equilibrium so yes the deltaS of the system would equal the negative deltaS of the surroundings.
- Tue Feb 13, 2018 5:44 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: What does n represent?
- Replies: 2
- Views: 1919
Re: What does n represent?
n represents the number of moles in the problem. If we are given the mass in grams, we would convert to moles by dividing by the molar mass.
- Tue Feb 13, 2018 5:43 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Practice Test, Question 3A
- Replies: 2
- Views: 334
Re: Practice Test, Question 3A
We would take the given amount of grams and divide by the molar mass of each element to obtain the number of moles of each element then plug it into the equation.
- Mon Feb 05, 2018 11:28 pm
- Forum: Balancing Redox Reactions
- Topic: acronym for reduction
- Replies: 5
- Views: 2324
Re: acronym for reduction
OIL RIG is a good one to memorize the difference between oxidation and reduction. It is an abstract word that is easy to remember.
- Mon Feb 05, 2018 11:27 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Determining reduction or oxidation
- Replies: 4
- Views: 1142
Re: Determining reduction or oxidation
In class we also learned the "LEO" acronym, where loss of electrons is oxidation. That could be a easy way to memorize what oxidation is.
- Mon Feb 05, 2018 11:24 pm
- Forum: Balancing Redox Reactions
- Topic: Salt Bridges?
- Replies: 6
- Views: 617
Re: Salt Bridges?
Is the salt bridge composed of anions or cations?
- Thu Feb 01, 2018 8:38 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: The value of Cp
- Replies: 8
- Views: 1504
Re: The value of Cp
So we only use the C value when there is a constant pressure value and use the R constant value when the pressure isnt constant?
- Thu Feb 01, 2018 8:36 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Problem 9.13
- Replies: 4
- Views: 576
Re: Problem 9.13
Yea i was also wondering why the heat capacity wasn't needed. Would we be wrong if we used the heat capacity?
- Thu Feb 01, 2018 8:31 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Change of Entropy for V and T
- Replies: 2
- Views: 338
Re: Change of Entropy for V and T
In the ideal gas law, pressure is the inverse of volume so you flip the pressure values in order to find the change in entropy.
- Sat Jan 27, 2018 2:18 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Constant Volume and Constant Pressure
- Replies: 3
- Views: 798
Re: Constant Volume and Constant Pressure
What equation would we use if the volume or pressure was not constant to find entropy?
- Sat Jan 27, 2018 2:15 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Degeneracy
- Replies: 3
- Views: 494
Re: Degeneracy
What are the equations for degeneracy? In what context would we solve for degeneracy?
- Sat Jan 27, 2018 1:26 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Entropy of gas vs liquid vs solid
- Replies: 7
- Views: 8649
Re: Entropy of gas vs liquid vs solid
What does it mean when there are more possible states a gas can occupy?
- Thu Jan 18, 2018 10:48 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Reaction Enthalpy v. Enthalpy of Formation
- Replies: 4
- Views: 284
Re: Reaction Enthalpy v. Enthalpy of Formation
What is the difference between the two?
- Thu Jan 18, 2018 10:47 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Constant pressure/volume
- Replies: 2
- Views: 226
Re: Constant pressure/volume
When would we need to use these values of 5/2R and 3/2R? Could you give some context?
- Thu Jan 18, 2018 10:45 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calorimeter
- Replies: 5
- Views: 565
Re: Calorimeter
When would we use the equation q=C (delta)T in a calorimeter problem?
- Sun Jan 14, 2018 4:04 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Bomb Calorimetry
- Replies: 4
- Views: 1821
Re: Bomb Calorimetry
Are the calculations for coffee cup calorimetry problems different than bomb calorimeter problems? What are the biggest differences, if any?
- Sun Jan 14, 2018 4:03 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Delta H and Delta U
- Replies: 3
- Views: 212
Re: Delta H and Delta U
How are the equations for delta h and delta u different? Are there differenet variables in each equation?
- Sun Jan 14, 2018 4:02 pm
- Forum: Phase Changes & Related Calculations
- Topic: Endo and Exothermic Ways to Remember
- Replies: 28
- Views: 11403
Re: Endo and Exothermic Ways to Remember
The Ex- in exothermic is like the ex- in exit, so heat is leaving the system into the surroundings. Once you know that exothermic is when heat leaves the system, that means endothermic is when heat enters or is absorbed by the system.
- Sun Dec 03, 2017 4:59 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Why is Kw value typically used at 25 degrees C [ENDORSED]
- Replies: 6
- Views: 2037
Re: Why is Kw value typically used at 25 degrees C [ENDORSED]
Does only changing the temperature affect the Kw value? Does anything else affect the Kw value?
- Sun Dec 03, 2017 4:57 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: pH and pOH
- Replies: 10
- Views: 1367
Re: pH and pOH
If the ph or pOH is 7, is the solution considered neutral, neither acidic nor neutral?
- Wed Nov 29, 2017 10:06 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Weaks vs. Strong acids
- Replies: 3
- Views: 639
Re: Weaks vs. Strong acids
A strong acid completely dissociates when put in water, where the H+ is ionized in the water. A weak acid does not completely ionize in water. Only a small amount of the molecule becomes aqueous in the water. Only a small amount of H+ is ionized.
- Wed Nov 29, 2017 10:04 pm
- Forum: Properties & Structures of Inorganic & Organic Bases
- Topic: Weak Bases
- Replies: 4
- Views: 1134
Re: Weak Bases
How do you determine just by looking at a molecule that it is a weak base?
- Mon Nov 20, 2017 2:40 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: KP versus KC
- Replies: 3
- Views: 495
Re: KP versus KC
They represent the same thing. Normally we would just call it k. It is up to you to figure out if we are trying to find concentrations or pressure. But the equilibrium constant is the same in both cases.
- Mon Nov 20, 2017 2:38 pm
- Forum: Ideal Gases
- Topic: PV=nRT [ENDORSED]
- Replies: 4
- Views: 585
Re: PV=nRT [ENDORSED]
what are the units for each variable? Are there different units for pressure? How do we convert them to atm?
- Sun Nov 12, 2017 4:35 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Isoelectronic [ENDORSED]
- Replies: 4
- Views: 1536
Re: Isoelectronic [ENDORSED]
Are elements isoelectronic if they have the same number of valence electrons but different structure?
- Sun Nov 12, 2017 4:17 pm
- Forum: Lewis Structures
- Topic: Shape
- Replies: 5
- Views: 569
Re: Shape
I was wondering what the difference between molecular structure and the molecular shape.
- Sun Nov 05, 2017 11:28 am
- Forum: Octet Exceptions
- Topic: Octets
- Replies: 8
- Views: 1072
Re: Octets
Could someone explain why some elements do not need a full octet?
- Sun Nov 05, 2017 11:27 am
- Forum: Ionic & Covalent Bonds
- Topic: How to easily tell between Ionic and Covalent bonds?
- Replies: 8
- Views: 1508
Re: How to easily tell between Ionic and Covalent bonds?
Will the values of electronegativity be given to us if we are asked to compare which elements are more electronegative or which are ionic and covalent bonds?
- Sun Oct 29, 2017 10:09 pm
- Forum: Ionic & Covalent Bonds
- Topic: Study Habits [ENDORSED]
- Replies: 8
- Views: 1167
Re: Study Habits [ENDORSED]
Mr. Andersen videos are very helpful. But Lavelle honestly has the best tools for you to study and succeed in his class. I would recommend doing all the homework problems and going to peer learning sessions to master the material.
- Sun Oct 29, 2017 10:06 pm
- Forum: Ionic & Covalent Bonds
- Topic: Homework 3.5 part c [ENDORSED]
- Replies: 3
- Views: 525
Homework 3.5 part c [ENDORSED]
What is the ground state electron configuration of Ga^3+?
Could someone please advise?
Could someone please advise?
- Mon Oct 23, 2017 2:22 pm
- Forum: Trends in The Periodic Table
- Topic: 1st and 2nd ionization energy? [ENDORSED]
- Replies: 7
- Views: 9976
Re: 1st and 2nd ionization energy? [ENDORSED]
The ionization energy to remove the second electron of an atom will always be higher than the ionization energy to remove the first electron because the pull from the nucleus gets stronger and stronger as you begin to remove the electron shells.
- Mon Oct 23, 2017 2:18 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Chromium and Copper Electron Configuration Exceptions [ENDORSED]
- Replies: 5
- Views: 1316
Re: Chromium and Copper Electron Configuration Exceptions [ENDORSED]
The d-orbitals for Chromium and Copper are only half-filled and fully-filled. Instead of writing Chromium as [Ar]3d^44s^2, you would write the electron configuration as [Ar]3d^54s^1 to fill the d-orbital with five electrons rather than four. The same goes for copper, instead of 9 electrons in the d-...
- Sun Oct 15, 2017 11:40 pm
- Forum: Photoelectric Effect
- Topic: Wavelike properties [ENDORSED]
- Replies: 4
- Views: 468
Re: Wavelike properties [ENDORSED]
How do we know if the wavelength is measurable? If the answer comes out to be a wavelength of 10^-24, is it measurable?
- Sun Oct 15, 2017 4:12 pm
- Forum: DeBroglie Equation
- Topic: question on how to determine if something has wavelike properties.
- Replies: 6
- Views: 1866
Re: question on how to determine if something has wavelike properties.
I was confused because I remember watching one of Dr. Lavelle's modules and him saying that large objects like baseballs and cars do not have wave-like properties. Only small masses with high velocities have wave-like properties. Could someone please clarify? How do you know if something has measura...
- Tue Oct 10, 2017 9:41 pm
- Forum: Properties of Electrons
- Topic: electrons
- Replies: 2
- Views: 548
Re: electrons
Due to the conservation of energy, the energy is not irrelevant and just disappear. It may heat up the metal or take another form. Energy is neither created or destroyed.
- Tue Oct 10, 2017 9:34 pm
- Forum: Einstein Equation
- Topic: Where does Planck's Constant Come From
- Replies: 5
- Views: 714
Re: Where does Planck's Constant Come From
This is a good question as I was wondering the same thing. Based off the reading from the textbook, I can make an educated guess that he conducted an experiment about the photoelectric effect to come up with the constant value. He proposed in his experiment that energy travels in packets.
- Thu Oct 05, 2017 3:42 pm
- Forum: SI Units, Unit Conversions
- Topic: Sig Figs
- Replies: 12
- Views: 3224
Re: Sig Figs
Also, when you are doing the problem, you should keep the number of sig figs the same throughout the work of the problem until you get an answer. Once you have your final answer, you may adjust it accordingly to the number of sig figs in the number specifically listed in the question.
- Thu Oct 05, 2017 3:36 pm
- Forum: SI Units, Unit Conversions
- Topic: Base Units
- Replies: 6
- Views: 766
Re: Base Units
It really all just depends on the problem and what it asks you to find. If the question is asking for the amount of product that can be prodced in grams, and you end up with moles of the product, you should multiply that amount by the molar mass to get the answer in terms of grams.