Search found 61 matches
- Wed Mar 13, 2019 9:18 pm
- Forum: *Enzyme Kinetics
- Topic: Catalysts
- Replies: 18
- Views: 2535
Re: Catalysts
Is there any case where there must be a catalyst for a reaction to occur?
- Wed Mar 13, 2019 9:16 pm
- Forum: Experimental Details
- Topic: Pre Equilibruim Approach
- Replies: 6
- Views: 1721
Re: Pre Equilibruim Approach
Do you need the observed rate to be given for this approach?
- Wed Mar 13, 2019 9:13 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: NO as a catalyst for O2 to O3
- Replies: 1
- Views: 294
NO as a catalyst for O2 to O3
In this environmental example Dr. Lavelle explained in class today, must NO always be present for the reaction from oxygen to ozone to occur, or is it just that it makes it happen more often/easily?
- Wed Mar 06, 2019 9:02 pm
- Forum: First Order Reactions
- Topic: order
- Replies: 5
- Views: 581
Re: order
Is it possible to know the order based on the balanced chemical equation? What other information would you need?
- Wed Mar 06, 2019 9:00 pm
- Forum: Zero Order Reactions
- Topic: General Meaning of "Zero Order" Reactions
- Replies: 7
- Views: 743
Re: General Meaning of "Zero Order" Reactions
Celine Cheng 1H wrote:If the reaction rate is dependent on a catalyst, does that mean the substrate has to be in high concentration as well?
Dr. Lavelle said to assume the catalyst/enzyme is saturated with substrate (meaning it is already working at maximum capacity) so adding substrate doesn't change the rate.
- Wed Mar 06, 2019 8:58 pm
- Forum: General Rate Laws
- Topic: Negative sign for reactant rate
- Replies: 2
- Views: 292
Negative sign for reactant rate
Is the purpose of the negative sign just to make sure all the rates are positive? Can you assume that all initial reactant rates are negative and therefore become positive after adding the negative sign?
- Wed Feb 27, 2019 8:32 pm
- Forum: Balancing Redox Reactions
- Topic: oxidizing agent and reducing agent
- Replies: 15
- Views: 1375
Re: oxidizing agent and reducing agent
The reactant of the reduction half reaction is the oxidizing agent. The reactant of the oxidation half reaction is the reducing agent.
- Wed Feb 27, 2019 8:30 pm
- Forum: Balancing Redox Reactions
- Topic: 14.13 6th edition [ENDORSED]
- Replies: 2
- Views: 4793
Re: 14.13 6th edition [ENDORSED]
Does it matter if we use Pt(s) or C(s,graphite)? Do they have the same function? Are there any cases where you could use one but not the other?
- Wed Feb 27, 2019 8:28 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic Cell Diagram [ENDORSED]
- Replies: 3
- Views: 506
Re: Galvanic Cell Diagram [ENDORSED]
Does it matter the order when they are only separated by a comma? E.g., if there are two aqueous solutions, does it matter which one we list first?
- Wed Feb 20, 2019 9:58 pm
- Forum: Balancing Redox Reactions
- Topic: H2O
- Replies: 3
- Views: 356
H2O
How do you know when/where to add H2O or H+ to the half reactions/balanced reaction when it is not in the original reaction given?
- Wed Feb 20, 2019 9:55 pm
- Forum: Balancing Redox Reactions
- Topic: determining cathode from anode
- Replies: 11
- Views: 1922
Re: determining cathode from anode
Megan_Ervin_1F wrote:Also it is just standard for the anode to appear on the left
You can remember this because it is alphabetical from left to right (anode-cathode).
- Wed Feb 20, 2019 9:52 pm
- Forum: Balancing Redox Reactions
- Topic: Week 7 Homework
- Replies: 15
- Views: 1253
Re: Week 7 Homework
I think anything that will be on Test 2 is fine. He posted what would be covered on the test in his last announcement.
- Wed Feb 13, 2019 4:46 pm
- Forum: Phase Changes & Related Calculations
- Topic: ΔH vs ΔU?
- Replies: 8
- Views: 1400
Re: ΔH vs ΔU?
Can deltaU ever equal deltaH?
- Wed Feb 13, 2019 4:44 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: ΔS=q/t
- Replies: 8
- Views: 931
Re: ΔS=q/t
What are the requirements to be able to use q/T? Just constant temp?
- Wed Feb 13, 2019 4:43 pm
- Forum: Calculating Work of Expansion
- Topic: moles and entropy
- Replies: 3
- Views: 431
Re: moles and entropy
Does this mean in a problem that gives you the amount of liters of an ideal gas (i.e. 5 L of Ne), you’d assume the molarity is 0.2?
- Thu Feb 07, 2019 12:27 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Irreversible vs. Reversible Expansion
- Replies: 4
- Views: 396
Re: Irreversible vs. Reversible Expansion
In real life, reversible reactions are unrealistic, but we use them to approximate. Almost all real reactions are irreversible.
- Thu Feb 07, 2019 12:26 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Open vs Closed System
- Replies: 13
- Views: 4590
Re: Open vs Closed System
In an open system both material and energy can be exchanged, but in a closed system only energy can. To put this in everyday terms, compare a glass of water with a sealed bottle of water. In the glass, water and heat can be added, but in the sealed bottle, only heat can be added.
- Thu Feb 07, 2019 12:22 am
- Forum: Phase Changes & Related Calculations
- Topic: Heating Curve
- Replies: 4
- Views: 420
Re: Heating Curve
Since temperature doesn’t change during phase change, for steam to become water again (when it hits your skin), it has to release a lot of energy, while still at 100 degrees Celsius, and all this energy goes into burning your skin.
- Wed Jan 30, 2019 9:14 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Regular heat capacity: why?
- Replies: 4
- Views: 399
Re: Regular heat capacity: why?
Sometimes if you are calculating the total energy transfer, you would need to calculate heat capacity from specific heat, by multiplying by the amount of substance, so it could be useful to have the heat capacity for the amount of substance you have in the first place.
- Wed Jan 30, 2019 9:04 pm
- Forum: Calculating Work of Expansion
- Topic: negative vs. positive internal energy
- Replies: 2
- Views: 323
negative vs. positive internal energy
What is happening physically in a system when the change of internal energy of a system is negative vs. positive?
- Wed Jan 30, 2019 8:57 pm
- Forum: Calculating Work of Expansion
- Topic: Units
- Replies: 1
- Views: 213
Units
Hi, can someone please explain the units and how they cancel in the work equation?
- Wed Jan 23, 2019 11:14 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Strong Acids and Bases
- Replies: 3
- Views: 400
Re: Strong Acids and Bases
Does this mean we don't need to calculate the pKa or pKb for strong acids or bases?
- Wed Jan 23, 2019 11:11 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Solubility
- Replies: 1
- Views: 225
Solubility
How can equilibrium constants be used to predict solubility?
- Wed Jan 23, 2019 11:08 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Strong vs Weak Acids
- Replies: 2
- Views: 325
Strong vs Weak Acids
Why do solutions of weak acids have higher pH values than solutions of strong acids at the
same concentration?
same concentration?
- Thu Jan 17, 2019 12:25 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Concentration less than 10^-7
- Replies: 4
- Views: 341
Re: Concentration less than 10^-7
Is this because you are basically taking the answer you got (e.g. 10^-9) and adding it to the already existing 10^-7, so it doesn't really change from neutral?
- Thu Jan 17, 2019 12:23 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equilibrium Constants
- Replies: 5
- Views: 384
Equilibrium Constants
How does K differ from Kc? If there is a difference, how would you solve for K when given Kc and vice versa?
- Thu Jan 17, 2019 12:21 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE tables
- Replies: 3
- Views: 287
ICE tables
How does an ICE table change when the stoichiometric coefficient isn't 1?
- Wed Jan 09, 2019 10:23 pm
- Forum: Ideal Gases
- Topic: Ideal vs Real Gas
- Replies: 6
- Views: 548
Re: Ideal vs Real Gas
For purposes of calculation, do we always assume it is an ideal gas?
- Wed Jan 09, 2019 10:13 pm
- Forum: Ideal Gases
- Topic: Memorization
- Replies: 12
- Views: 1276
Re: Memorization
Will there be any equilibrium constants that we need to memorize for certain equations or will all the information we need be given in the problems?
- Wed Jan 09, 2019 10:10 pm
- Forum: Student Social/Study Group
- Topic: New to Lavelle
- Replies: 32
- Views: 5320
Re: New to Lavelle
For the midterm and final Lavelle plans a lot of review sessions, but I would say the most helpful is Lyndon's because he goes over a review sheet that he made, but the other review sessions are more helpful if you have specific questions or topics you struggle with. The UA Karen also posts weekly r...
- Thu Dec 06, 2018 6:54 pm
- Forum: Naming
- Topic: Cyanide (cyano vs isocyano)
- Replies: 2
- Views: 977
Re: Cyanide (cyano vs isocyano)
How will we know which one to use if we aren't given the lewis structure?
- Thu Dec 06, 2018 6:50 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Strength of an acid/base
- Replies: 2
- Views: 364
Strength of an acid/base
How do we tell which weak acid or base is strongest when given several different compounds? (Like homework problem 12.49)
- Thu Dec 06, 2018 6:47 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: equilibrium constant
- Replies: 2
- Views: 309
Re: equilibrium constant
On one of the homework questions it asked to explain which compound was a stronger base, an it used the equilibrium constant as the justification for the answer. Does this mean there won't be a question like this on the final?
- Thu Nov 29, 2018 10:33 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Isoelectronic
- Replies: 14
- Views: 2167
Re: Isoelectronic
How does being isoelectric affect polarizability?
- Thu Nov 29, 2018 10:31 pm
- Forum: Biological Examples
- Topic: Myoglobin vs Hemoglobin
- Replies: 2
- Views: 197
Myoglobin vs Hemoglobin
Since myoglobin only has one spot available, which iron binds to, how does it bind to other myoglobins to form hemoglobin?
Re: Ligand
Will we be expected to memorize the names of several ligands according to the naming convention?
- Thu Nov 29, 2018 10:27 pm
- Forum: Dipole Moments
- Topic: Cis vs trans
- Replies: 4
- Views: 735
Cis vs trans
When we are told to draw a Lewis structure that could either be cis or trans, and we are asked to determine if it is polar, doesn’t this depend on how we drew the molecule? Is there a convention that favors cis or trans when drawing Lewis structures that would help us determine if a molecule is pola...
- Thu Nov 29, 2018 10:24 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizability
- Replies: 5
- Views: 458
Re: Polarizability
When anions or cations are isoelectric, how do we determine which has higher polarizability/polarizing power?
- Thu Nov 29, 2018 10:20 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 6th edition 4.23
- Replies: 3
- Views: 713
Re: 6th edition 4.23
I also had a question on this problem. On the Lewis structures for part b and c, why is there not a double bond for the oxygens?
- Thu Nov 15, 2018 1:03 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Will we have to calculate bond angles?
- Replies: 8
- Views: 747
Re: Will we have to calculate bond angles?
I think as long as you remember the general angles (like 109.5) then you can say how other shapes are affected by the relative repulsion strength of lone pair-lone pair, lone pair-bonding pair, and bonding pair-bonding pair.
- Thu Nov 15, 2018 12:59 pm
- Forum: Hybridization
- Topic: How to Determine
- Replies: 12
- Views: 1156
Re: How to Determine
How does hybridization affect molecular shape? Does this have to do with resonance?
- Thu Nov 15, 2018 12:57 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: bond angle
- Replies: 4
- Views: 438
Re: bond angle
When we are asked to estimate bond angles, such as when a lone pair causes distortion and the angle to be “slightly less than 109.5” for example, how will we know how much less it is? Will we ever be asked this on a test?
- Thu Nov 08, 2018 7:51 pm
- Forum: Bond Lengths & Energies
- Topic: Tests
- Replies: 5
- Views: 637
Re: Tests
The week of the 19th is Thanksgiving. I think you mean the week of Nov 26th.
- Thu Nov 08, 2018 7:49 pm
- Forum: Sigma & Pi Bonds
- Topic: Easy way of remembering the difference
- Replies: 6
- Views: 725
Re: Easy way of remembering the difference
Do sigma and pi bonds occur in both ionic and covalent bonds or just covalent?
- Thu Nov 08, 2018 7:47 pm
- Forum: Electronegativity
- Topic: Trend Exceptions
- Replies: 5
- Views: 545
Re: Trend Exceptions
When looking at trends, what makes more of a difference, whether an element is further to the left or right or does up and down matter more?
- Thu Nov 01, 2018 2:13 pm
- Forum: Resonance Structures
- Topic: Definition of resonance
- Replies: 7
- Views: 907
Re: Definition of resonance
When we draw all the resonant structures, is that just a model for how the bond is actually somewhere between a single and double, or are there actually that many different structures?
- Thu Nov 01, 2018 2:06 pm
- Forum: Lewis Structures
- Topic: Drawing Lewis Structures
- Replies: 14
- Views: 2096
Re: Drawing Lewis Structures
When drawing Lewis structures that aren’t symmetrical, like ONF, does it matter which side the O or F go on?
- Thu Nov 01, 2018 2:03 pm
- Forum: Lewis Structures
- Topic: central atoms
- Replies: 8
- Views: 791
Re: central atoms
There is an exception with hydrogen because it will never be the central atom
- Thu Oct 25, 2018 6:10 pm
- Forum: Trends in The Periodic Table
- Topic: Atomic, Covalent, and Ionic Radius
- Replies: 5
- Views: 1110
Re: Atomic, Covalent, and Ionic Radius
How will we know if something is ionically or covalently bonded?
- Thu Oct 25, 2018 6:06 pm
- Forum: Einstein Equation
- Topic: E=hv [ENDORSED]
- Replies: 52
- Views: 18446
Re: E=hv [ENDORSED]
When it says we should be able to calculate the number of photons from this equation, we must have the total energy before we can do that, right?
- Thu Oct 25, 2018 6:00 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Uncertainty of an Electron's Velocity & Speed of Light
- Replies: 4
- Views: 501
Re: Uncertainty of an Electron's Velocity & Speed of Light
How close to the speed of light is "too close" for it to be considered realistic?
- Thu Oct 18, 2018 1:50 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: ground state electron configuration
- Replies: 5
- Views: 2311
Re: ground state electron configuration
I also have a question on this, how do you know how many electrons are on each orbital? Is this something that is constant between elements (i.e. the 1s orbital always has two) or does it vary from element to element?
- Thu Oct 18, 2018 1:46 pm
- Forum: Trends in The Periodic Table
- Topic: Period Table 'blocks'
- Replies: 5
- Views: 503
Period Table 'blocks'
What exactly does it mean when an element is in the "p-block" or "s-block", etc?
- Thu Oct 18, 2018 1:45 pm
- Forum: Einstein Equation
- Topic: Photons and E=hv
- Replies: 5
- Views: 879
Photons and E=hv
What is the relationship between number of photons and energy in the equation E=hv? Do you multiply E by number of photons?
- Thu Oct 11, 2018 5:45 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: shells versus orbitals
- Replies: 3
- Views: 853
Re: shells versus orbitals
How do we know how many shells and orbitals there are for each atom?
- Thu Oct 11, 2018 11:54 am
- Forum: Quantum Numbers and The H-Atom
- Topic: Balmer/Lyman... Series
- Replies: 4
- Views: 357
Balmer/Lyman... Series
Will we have to memorize any other series besides Balmer and Lyman?
- Thu Oct 11, 2018 11:36 am
- Forum: Properties of Light
- Topic: Electromagnetic Spectrum
- Replies: 2
- Views: 204
Electromagnetic Spectrum
Is it a good idea/necessary to memorize the electromagnetic spectrum with each type's wavelength range?
- Wed Oct 03, 2018 10:54 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Isotopes [ENDORSED]
- Replies: 12
- Views: 1513
Re: Isotopes [ENDORSED]
What causes atoms to have a different number of neutrons?
- Wed Oct 03, 2018 10:51 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Problem G5
- Replies: 8
- Views: 757
Problem G5
On problem G5, how do you solve part a and b where it is just asking about part of the compound?
- Wed Oct 03, 2018 10:46 pm
- Forum: SI Units, Unit Conversions
- Topic: Naming Compounds
- Replies: 9
- Views: 848
Re: Naming Compounds
Hi, I had a similar question, except I was also wondering how you know the state of each compound when it is not given.
- Wed Oct 03, 2018 10:41 pm
- Forum: SI Units, Unit Conversions
- Topic: Naming Compounds
- Replies: 9
- Views: 848
Re: Naming Compounds
Hi, I had a similar question, except I was also wondering how you know the state of each compound when it is not given.