Search found 60 matches
- Fri Mar 15, 2019 9:34 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Effects of Temperature on Rate Constant
- Replies: 1
- Views: 303
Effects of Temperature on Rate Constant
Why does raising the temperature increases the rate constant of reactions with higher activation barriers more than it does the rate constant of reactions with lower activation barriers?
- Fri Mar 15, 2019 9:34 pm
- Forum: Second Order Reactions
- Topic: Non-integer orders
- Replies: 7
- Views: 1111
Non-integer orders
Will we ever be expected to know/find non-integer (like 1.5) reactant orders?
- Fri Mar 15, 2019 9:33 pm
- Forum: Second Order Reactions
- Topic: Half-life of Second-Order
- Replies: 4
- Views: 484
Half-life of Second-Order
In the textbook, at the end of section 15.6, it gives a table detailing all the components of each order of a reaction. For the half-life of a second-order reaction, it writes that the equation is t1/2=. However, underneath that, it says "(not used)." Does anyone know what this means/why t...
- Sun Mar 10, 2019 4:59 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Steady State or Pre-Equilibrium approach
- Replies: 1
- Views: 213
Steady State or Pre-Equilibrium approach
Do we have to learn the steady state approach in the book or should we just study pre-equilibrium one he taught us in lecture?
- Sun Mar 10, 2019 4:59 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Rate Determining Step
- Replies: 1
- Views: 271
Rate Determining Step
Will the problems always state which step is fast and slow so that we could determine the rate determining step or do we have to some how figure it out based on the context given?
- Sun Mar 10, 2019 4:58 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Reaction Profiles
- Replies: 2
- Views: 360
Reaction Profiles
How can we tell from a reaction profile whether a reaction is spontaneous? I understand that it must be energetically favorable, but at what point is the activation energy low enough? Do we just assume that it is low enough when the hump is relatively low?
- Sun Mar 03, 2019 10:05 pm
- Forum: General Rate Laws
- Topic: 2nd order Integrated Rate Law Graph
- Replies: 1
- Views: 197
2nd order Integrated Rate Law Graph
What are the axises for the 2nd order Integrated Rate Law Graph? I know that the first order rate law graph is ln[A] vs. time.
- Sun Mar 03, 2019 10:04 pm
- Forum: General Rate Laws
- Topic: General Rate Law Orders
- Replies: 3
- Views: 416
General Rate Law Orders
How does one know whether a reaction is first order or second order using the graph?
- Sun Mar 03, 2019 10:04 pm
- Forum: General Rate Laws
- Topic: Unique Average Rate versus Average Rate
- Replies: 1
- Views: 207
Unique Average Rate versus Average Rate
When we're asked to find the rate of consumption or rate of formation of a molecule in a reaction, when is it necessary to divide (change in concentration)/(change in time) by the number of moles of that molecule?]
- Sat Feb 23, 2019 3:36 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Order of species in cell diagram
- Replies: 1
- Views: 202
Order of species in cell diagram
I understand that for a cell diagram, the anode is on the left, the cathode is on the right, and the electrodes are at the ends... but within the anode or cathode, does it matter what order you write the species in?
- Sat Feb 23, 2019 3:35 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt Bridge
- Replies: 2
- Views: 242
Salt Bridge
How does a salt bridge work? The textbook says that its to prevent contact between the two aqueous solutions because when different ions mingle they can affect the cell potential but its function is described as "allowing the flow of ions" wouldn't this mean its letting them meet?
- Sat Feb 23, 2019 3:34 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Potential Calculation
- Replies: 1
- Views: 187
Cell Potential Calculation
Why do we subtract anode from cathode from in order to calculate the cell potential?
- Sun Feb 17, 2019 9:13 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Two Gibbs Free Energy Formulas
- Replies: 2
- Views: 292
Two Gibbs Free Energy Formulas
While the two Gibbs Free Energy formulas are both applicable, how do we distinguish when to use which? For example, if given the concentrations of the products and the reactants, will we then use the deltaG=-RTlnK?
- Sun Feb 17, 2019 9:12 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs Free energy and spontaneity
- Replies: 2
- Views: 224
Gibbs Free energy and spontaneity
Why is it that when Gibbs free energy of the system is negative then the process is spontaneous and the delta S universal is positive? How does delta G being negative make the process spontaneous?
- Sun Feb 17, 2019 9:12 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Determining Spontaneity
- Replies: 1
- Views: 218
Determining Spontaneity
A system is spontaneous when Delta G is negative and also when Delta S total is positive. Why can't we tell the spontaneity of a system by looking at Delta H?
- Sat Feb 09, 2019 10:34 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Units
- Replies: 1
- Views: 207
Units
When calculating standard reaction enthalpy, entropy, and Gibbs free energy from formation values, why do the answers have units with /mol? Shouldn't /mol cancel out since you multiply by the coefficient in the calculation?
- Sat Feb 09, 2019 10:32 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Changes in Entropy
- Replies: 2
- Views: 267
Changes in Entropy
Is there a preferred way to describe a change in entropy of a system? Rather than just saying the amount of disorder within the system has increased or decreased how can we be more specific in this description?
- Sat Feb 09, 2019 10:30 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Spontaneity
- Replies: 2
- Views: 226
Spontaneity
If deltaH is positive and deltaS is negative, what is the spontaneity?
- Sat Feb 02, 2019 9:09 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Reversible v irreversible
- Replies: 4
- Views: 339
Reversible v irreversible
For entropy, which equations do you use for isothermal reversible vs. irreversible free expansion? What does free expansion mean?
- Sat Feb 02, 2019 9:09 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Entropy in Reversible Process
- Replies: 2
- Views: 225
Entropy in Reversible Process
Why is the total entropy in the universe 0 (Entropy system = Entropy surroundings) for reversible processes?
- Sat Feb 02, 2019 9:08 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Entropy Equation Specific Heat Capacity
- Replies: 2
- Views: 275
Entropy Equation Specific Heat Capacity
How do you know when to use 3/2 R instead of the specific heat capacity provided on the cover sheet?
- Thu Jan 24, 2019 1:17 pm
- Forum: Phase Changes & Related Calculations
- Topic: Elements in different states
- Replies: 2
- Views: 259
Elements in different states
Can all elements be converted into solid, liquid, or gas states given that the right amount of energy and pressure is applied?
- Thu Jan 24, 2019 1:16 pm
- Forum: Phase Changes & Related Calculations
- Topic: Reversible and Irreversible Processes
- Replies: 1
- Views: 212
Reversible and Irreversible Processes
Reversible and irreversible processes have different equations but what exactly is the difference between the processes? How can the differences be logically explained?
- Thu Jan 24, 2019 1:14 pm
- Forum: Phase Changes & Related Calculations
- Topic: Temperature vs. heat vs. energy
- Replies: 4
- Views: 378
Temperature vs. heat vs. energy
I get that temperature and heat are different things but how they are related. For example, does an increase in temperature always lead to an increase in heat content (or the other way around). Also is energy just another term for heat content?
- Sat Jan 19, 2019 9:15 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Molar Concentration
- Replies: 3
- Views: 160
Molar Concentration
If you are given a molar concentration for a molecule with a stoichiometric coefficient does that concentration need to be multiplied by the stoichiometric coefficient to find the concentration of the single molecule?
- Sat Jan 19, 2019 9:14 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: X Value
- Replies: 3
- Views: 334
X Value
I know that 10^-5 or lower is when we can disregard the x but if something is 10^-4, can we still disregard and just check that the x value divided by the initial concentration is less than 5%
- Sat Jan 19, 2019 9:12 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Concentrations Effect on K
- Replies: 8
- Views: 518
Concentrations Effect on K
If the concentration of each reactant and product increased by the same amount, would K also increase or would it stay the same since it is a ratio?
- Sat Jan 12, 2019 6:15 pm
- Forum: Ideal Gases
- Topic: K and Q
- Replies: 7
- Views: 453
K and Q
If Q and K both have the same formula why are they not equal to each other?
- Sat Jan 12, 2019 6:13 pm
- Forum: Ideal Gases
- Topic: Concentration or Partial Pressure
- Replies: 13
- Views: 917
Concentration or Partial Pressure
When do we use concentration to find the equilibrium constant and when do we use partial pressure to find equilibrium constant? Will the question ask for one of the two specifically?
- Sat Jan 12, 2019 6:11 pm
- Forum: Ideal Gases
- Topic: bar or atm
- Replies: 8
- Views: 592
bar or atm
In the textbook the units are in bars but in Lavelle's slides he uses atm. Would we need to know how convert between the two during tests or will the question give us the units?
- Wed Dec 05, 2018 3:53 pm
- Forum: Naming
- Topic: Writing chemical formulas
- Replies: 2
- Views: 241
Writing chemical formulas
When writing the chemical formula for water, would it matter if we use "H2O" or "OH2"?
- Wed Dec 05, 2018 3:50 pm
- Forum: Naming
- Topic: Poly v Mono
- Replies: 2
- Views: 108
Poly v Mono
What does it mean to have a poly- versus a mono-dentate compound and does it affect the naming of the compound?
- Wed Dec 05, 2018 3:41 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: pOH from pH
- Replies: 2
- Views: 325
Re: pOH from pH
Yes. The pH + pOH = 14. The two expressions are opposites expressions. As the pH increases the pOH decreases and vice versa. Both values equal 14.
- Sun Dec 02, 2018 2:51 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Final pH
- Replies: 3
- Views: 334
Final pH
why do we subtract the pOH from 14 to find the final pH?
- Sun Dec 02, 2018 2:48 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Negative pH?
- Replies: 5
- Views: 521
Negative pH?
is it ever possible to get a negative pH? if so could someone explain how this could happen?
- Sun Dec 02, 2018 2:45 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Sig Figs for pH and pOH calculations
- Replies: 1
- Views: 207
Sig Figs for pH and pOH calculations
when we calculate the pH and pOH do we still take into account sig figs in the final answer?
- Tue Nov 20, 2018 10:32 am
- Forum: Hybridization
- Topic: Bond Angles
- Replies: 4
- Views: 434
Bond Angles
Is drawing the molecular shape of a molecule the only way to determine bond angles?
- Tue Nov 20, 2018 10:30 am
- Forum: Hybridization
- Topic: d Orbital
- Replies: 6
- Views: 539
d Orbital
Will we need to know how to draw d orbitals and know their shapes? I know that we need to know this for the s and p orbitals but I was wondering what exactly we need to focus on for the d orbitals.
- Tue Nov 20, 2018 10:25 am
- Forum: Hybridization
- Topic: Pi and Sigma Bonds
- Replies: 4
- Views: 438
Pi and Sigma Bonds
Whats the difference between pi and sigma bonds? And why can there be two pi bonds but not two sigma bonds?
- Sat Nov 17, 2018 2:45 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Square Planar Angles
- Replies: 3
- Views: 338
Square Planar Angles
In a molecule with a square planar structure will the angles between the remaining 4 bonded atoms remain 90 degrees? Or will the repulsion push them closer together?
- Sat Nov 17, 2018 2:38 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Double and Triple Bonds
- Replies: 2
- Views: 260
Double and Triple Bonds
In a double or triple bond why is the region of electron density equal one instead of two or three?
- Sat Nov 17, 2018 2:35 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR Chart
- Replies: 3
- Views: 363
VSEPR Chart
I came across a VSEPR chart and thought I'd share it.
- Sat Nov 10, 2018 9:50 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lewis Structures and VSEPR
- Replies: 1
- Views: 77
Lewis Structures and VSEPR
Do we need to draw lewis structures in a way that reflects the molecular shape? Also for future tests would it matter where we draw the lone pair in lewis structures?
- Sat Nov 10, 2018 9:43 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angle
- Replies: 2
- Views: 104
Bond Angle
If a trigonal pyramidal forms a coordinate covalent bond with its lone pair and its shape becomes a tetrahedral, would the bond angle become 109.5 degrees?
- Sat Nov 10, 2018 9:39 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Two Central Atoms [ENDORSED]
- Replies: 1
- Views: 279
Two Central Atoms [ENDORSED]
When there are two central atoms how would you name the lewis structure and use VSEPR to classify its shape?
- Tue Oct 30, 2018 10:53 pm
- Forum: Octet Exceptions
- Topic: FC and Octet Exceptions
- Replies: 1
- Views: 234
FC and Octet Exceptions
For different exceptions of the octet does the FC need to be fixed to zero or do the rules that the octet had overrule?
- Tue Oct 30, 2018 10:51 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: FC in relation to Bonds
- Replies: 2
- Views: 155
FC in relation to Bonds
How do single, double, and triple bonds affect formal charge?
- Tue Oct 30, 2018 10:48 pm
- Forum: Lewis Structures
- Topic: Stable Lewis Structures
- Replies: 4
- Views: 365
Stable Lewis Structures
When making Lewis Structures and deciding where to use double bonds how can we determine which version is more stable?
- Thu Oct 25, 2018 7:45 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Orbital Shape for Larger Quantum Numbers
- Replies: 3
- Views: 316
Orbital Shape for Larger Quantum Numbers
Does orbital f correspond to all values of n greater than or equal to four and all values of l greater than or equal to 3?
- Thu Oct 25, 2018 7:38 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Ground state vs. excited state
- Replies: 5
- Views: 709
Ground state vs. excited state
What does it mean for an electron configuration to represent a ground or excited state of an atom? Is it talking about the same/opposite spin?
- Thu Oct 25, 2018 7:22 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Quantum Numbers n, l, and m
- Replies: 5
- Views: 343
Quantum Numbers n, l, and m
Can the relationship between n, l, and m be described as shell, sub-shell, and orbital within a sub-shell, respectively? And does the value of l tell you the highest possible sub-shell of that particular energy level?
- Wed Oct 17, 2018 7:37 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Px Py Pz
- Replies: 1
- Views: 68
Px Py Pz
For exams how should we label electron configuration? For example, 2px^1 2py^2 2pz^3 is the same thing as 2p^3 so which format would be preferred on exams.
- Wed Oct 17, 2018 7:25 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Shells, subshells, and orbital
- Replies: 1
- Views: 63
Shells, subshells, and orbital
Whats the difference between shell, subshell, and an orbital? I've seen those terms being referred to in problems but I wasn't sure what the difference was between the three.
- Wed Oct 17, 2018 7:18 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Orbitals
- Replies: 1
- Views: 68
Orbitals
When writing the ground state of an element would it still be okay to order it as 4s2, 3d10 instead of 3d10, 4s2 even though 4s2 is filled in first. The answers to these problems are sometimes switched.
- Sat Oct 13, 2018 6:26 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3000851
Re: Post All Chemistry Jokes Here
I had to make these bad chemistry jokes
because all the good ones Argon.
because all the good ones Argon.
- Sat Oct 13, 2018 6:25 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3000851
Re: Post All Chemistry Jokes Here
Do you know any jokes about sodium hypobromite?
NaBrO.
NaBrO.
- Sat Oct 13, 2018 6:24 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3000851
Re: Post All Chemistry Jokes Here
What do you do with a sick chemist?
If you can't helium and you can't curium then you might as well barium!
If you can't helium and you can't curium then you might as well barium!
- Thu Oct 04, 2018 4:33 pm
- Forum: Significant Figures
- Topic: Sig Figs... when to round?
- Replies: 7
- Views: 850
Re: Sig Figs... when to round?
For some of the homework problems I got answers that are off by a few numbers because of sig figs and rounding. Would my answers still be correct and what is the accepted range for the answers?
- Thu Oct 04, 2018 3:06 pm
- Forum: Significant Figures
- Topic: All students read this sig fig post [ENDORSED]
- Replies: 170
- Views: 33550
Re: All students read this sig fig post [ENDORSED]
When finding the molar mass in the periodic table how many sig figs do we use?
- Thu Oct 04, 2018 2:59 pm
- Forum: SI Units, Unit Conversions
- Topic: How does grading for discussion posts work?
- Replies: 80
- Views: 8161
Re: How does grading for discussion posts work?
Riley Dean 1D wrote:Does anyone know when the cutoff for week one's discussion period is? Like how long we have to post for week one and when week two starts?
I think the cutoff is on Fridays. So basically three posts by Friday week one, three posts by Friday week two, etc.