Search found 77 matches
- Wed Mar 11, 2020 9:54 am
- Forum: Administrative Questions and Class Announcements
- Topic: take home FINAL DEADLINE
- Replies: 15
- Views: 1029
take home FINAL DEADLINE
I was wondering by what time and day do we need to submit our take-home final by?
- Tue Mar 10, 2020 5:30 pm
- Forum: Balancing Redox Reactions
- Topic: Half Reactions
- Replies: 15
- Views: 756
Re: Half Reactions
in acidic solutions, you balance oxygen by adding H2O to the side lacking oxygen and you balance H by adding H+ to the side needing hydrogen. in basic solutions, you add H2O to the side lacking oxygen to balance oxygen. Then to balance hydrogen, add H2O to the side needing hydrogen and add OH- to th...
- Tue Mar 10, 2020 5:27 pm
- Forum: Zero Order Reactions
- Topic: 0 order
- Replies: 14
- Views: 1406
Re: 0 order
zero order means concentration of reactants has no effect on rate so if trial 1 had the same concentration of reactant a but had twice the concentration of reactant b compared to trial 2, trial 1 will still have the same rate as trial 2. essentially rate is unaffected by the change in reactant conce...
- Tue Mar 10, 2020 5:24 pm
- Forum: Second Order Reactions
- Topic: determining order
- Replies: 9
- Views: 569
Re: determining order
When given experimental data, input the given values into time vs ln[a] (first order), time vs 1/[a] (second order), and time vs [a] (zero order) and look for the graph with the linear graph. this determines the order of that particular reactant.
- Tue Mar 10, 2020 5:19 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts and Rate Law
- Replies: 4
- Views: 296
Re: Catalysts and Rate Law
From what I remember from Lavelle's lecture, catalysts are purely mechanisms that lower activation energy and are not included in the equation, therefore, they will not be in the rate law
- Tue Mar 10, 2020 5:14 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Problem 6N.1 part b
- Replies: 4
- Views: 400
Re: Problem 6N.1 part b
yes, if both half reactions only show 1 mole of electrons being transferred then n=1 thus the solution manual is wrong
- Tue Mar 10, 2020 5:11 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Slow step
- Replies: 7
- Views: 419
Re: Slow step
It will be given which step is the slow step as we can not determine which is the slow step purely based off the equations
- Tue Mar 10, 2020 5:02 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Discussion Sections
- Replies: 4
- Views: 326
Re: Discussion Sections
yea I'm curious about this too cuz i didn't turn in week 10 homework yet
- Mon Mar 09, 2020 3:47 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Slow Step
- Replies: 4
- Views: 320
Re: Slow Step
the question will usually indicate which step is the fast step and which is the slow step as we have not learned a process for determining slow steps yet
- Sat Mar 07, 2020 7:53 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: finding n in G=-nFE
- Replies: 15
- Views: 953
Re: finding n in G=-nFE
use the highest number of moles of electrons transferred according to the half reactions
- Sat Mar 07, 2020 6:39 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: the intermediate in a reaction
- Replies: 10
- Views: 669
Re: the intermediate in a reaction
the intermediate is a species produced in one step then consumed in the next step so the intermediate species will not appear in the overall reaction equation as it is depleted by the end of the next step.
- Sat Mar 07, 2020 6:11 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: galvanic cells
- Replies: 8
- Views: 596
Re: galvanic cells
the half reaction with the more negative reduction potential will be the anode
- Sat Mar 07, 2020 6:09 pm
- Forum: General Science Questions
- Topic: Test 2 Grades [ENDORSED]
- Replies: 23
- Views: 1533
Re: Test 2 Grades [ENDORSED]
tests are handed back during discussion
- Fri Mar 06, 2020 11:48 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Figuring out n
- Replies: 15
- Views: 910
Re: Figuring out n
n is the moles of electrons transferred so use the number of electrons found in the half reaction with the most electrons
- Fri Mar 06, 2020 11:45 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst
- Replies: 10
- Views: 695
Re: Nernst
lnQ can always be converted to logQ thru the equation: lnQ=2.303logQ
- Fri Mar 06, 2020 11:41 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: units of k
- Replies: 9
- Views: 647
Re: units of k
units of k can be determined by (M/s) / (M^n) where n is the total reaction order
- Fri Mar 06, 2020 11:36 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Determining the cathode/anode
- Replies: 9
- Views: 714
Re: Determining the cathode/anode
the anode is the one with the most negative potential
- Fri Mar 06, 2020 11:27 pm
- Forum: First Order Reactions
- Topic: rate constants
- Replies: 30
- Views: 1285
Re: rate constants
rate constants are always positive and don't have units
- Fri Mar 06, 2020 11:25 pm
- Forum: First Order Reactions
- Topic: Time Conversions
- Replies: 9
- Views: 1051
Re: Time Conversions
both should have the same units. it does not really matter what unit it is as long as units match
- Tue Mar 03, 2020 9:41 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6N.7.b & n in nernst equation
- Replies: 1
- Views: 124
6N.7.b & n in nernst equation
so i thought n was the moles of electrons transferred but thats not the case for 6N.7.b. can someone explain
- Tue Mar 03, 2020 6:12 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6N.1.b
- Replies: 1
- Views: 185
6N.1.b
for b, the solution says In+3 needs 2 electrons to become In +2 and this sets n=2 for the Nernst equation but this number of moles of electrons is clearly wrong
- Tue Mar 03, 2020 1:17 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6M.1
- Replies: 1
- Views: 139
6M.1
why do we assume Cu+2/Cu is the anode?
- Sat Feb 29, 2020 2:15 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Anode vs Cathode
- Replies: 15
- Views: 787
Re: Anode vs Cathode
usually anode will be to the left and the cathode will be to the right. Also oxidation occurs at the anode and reduction happens at the cathode
- Sat Feb 29, 2020 2:13 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Redox Reactions
- Replies: 3
- Views: 245
Re: Balancing Redox Reactions
you balance reactions in acidic solutions by adding H2O to balance the oxygen and adding H+ to balance hydrogen. In basic solutions, you add H2O to balance the oxygens then to balance the hydrogen, you add H2O to the side needing the hydrogen then add OH- to the other side
- Sat Feb 29, 2020 2:10 pm
- Forum: Balancing Redox Reactions
- Topic: Test 2
- Replies: 19
- Views: 879
Re: Test 2
I think Lavelle said test 2 is the 2nd half of outline 4 and all of outline 5 (electrochemistry)
- Sat Feb 29, 2020 2:07 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic vs Voltaic Cells
- Replies: 4
- Views: 810
Re: Galvanic vs Voltaic Cells
from what i remember, galvanic and voltaic cells are the exact same thing
- Sat Feb 29, 2020 2:03 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: E potentials
- Replies: 5
- Views: 417
Re: E potentials
it will always be given as reduction as it allows for easy comparison to determine what will be oxidized and what will be reduced based the voltage value for the reduction reaction
- Sat Feb 29, 2020 1:54 pm
- Forum: Balancing Redox Reactions
- Topic: Reducing/Oxidizing Agents
- Replies: 13
- Views: 599
Re: Reducing/Oxidizing Agents
the molecule that contains the element being oxidized is the reducing agent and the molecule that contains the element being reduced is the oxidizing agent
- Tue Feb 25, 2020 9:52 pm
- Forum: Balancing Redox Reactions
- Topic: adding e-
- Replies: 7
- Views: 515
Re: adding e-
you add electrons to the side with the more positive charge to balance the charge on both sides of the equation
- Tue Feb 25, 2020 9:50 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Anode and Cathode
- Replies: 4
- Views: 342
Re: Anode and Cathode
anode is being oxidized so its losing electrons whereas cathode is being reduced so its gaining electrons
- Tue Feb 25, 2020 9:48 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: G(not) and G
- Replies: 15
- Views: 675
Re: G(not) and G
G9not) is under standard conditions whereas G is not and G(n0t) will contribute to the value of G
- Mon Feb 24, 2020 3:49 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagrams
- Replies: 9
- Views: 551
Re: Cell Diagrams
a single bar is a porous disk and a double bar is a salt bridge
- Mon Feb 24, 2020 3:49 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic/Voltaic Cells
- Replies: 4
- Views: 265
Re: Galvanic/Voltaic Cells
galvanic cells from what i understand are basically like batteries that produce a voltage difference and consist of a cation and anion that produces a transfer of electrons across the cell. the potential of this cell is greatest when little to no current is going thru
- Sat Feb 22, 2020 11:15 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: single line in cell diagram
- Replies: 3
- Views: 207
Re: single line in cell diagram
porous disk is repped by a single line and double line is salt bridge
- Sat Feb 22, 2020 6:37 pm
- Forum: Balancing Redox Reactions
- Topic: Charge of oxygen
- Replies: 15
- Views: 687
Re: Charge of oxygen
at least from previous classes I took, it is usually safe to assume that O2 will have a -2 charge
- Sat Feb 22, 2020 6:01 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: max potential in Galvanic Cell
- Replies: 4
- Views: 278
Re: max potential in Galvanic Cell
I think when current flows, the voltage decreases as electrons flow thus why max potential is when the switch is open
- Sat Feb 22, 2020 2:03 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: E cell
- Replies: 6
- Views: 425
Re: E cell
usually, a table with the standards will be given to us
- Thu Feb 20, 2020 9:51 pm
- Forum: Balancing Redox Reactions
- Topic: oxidation numbers
- Replies: 4
- Views: 271
Re: oxidation numbers
if oxidation number decreases, it means it was reduced by gaining electrons
- Wed Feb 19, 2020 2:03 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: G vs G knot
- Replies: 15
- Views: 1593
Re: G vs G knot
G knot is under standard conditions. G is the total so it will include G knot
- Wed Feb 19, 2020 2:02 pm
- Forum: Balancing Redox Reactions
- Topic: Test 2 [ENDORSED]
- Replies: 12
- Views: 640
Re: Test 2 [ENDORSED]
test 2 is the week after next week
- Tue Feb 18, 2020 9:36 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Kelvin or Celsius?
- Replies: 86
- Views: 5014
Re: Kelvin or Celsius?
temperature is always kelvin
- Tue Feb 18, 2020 9:40 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: ∆G = ∆Gº + RT lnQ
- Replies: 12
- Views: 2476
Re: ∆G = ∆Gº + RT lnQ
∆Gº is basically just ∆G but under standard conditions
- Tue Feb 18, 2020 9:37 am
- Forum: Van't Hoff Equation
- Topic: K rather than Kc
- Replies: 10
- Views: 694
Re: K rather than Kc
K=(RT)^(change in n) x Kc
- Fri Feb 14, 2020 4:09 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K
- Replies: 12
- Views: 636
Re: K
when calculating K look for (aq) or (g) and exclude (s) or (l)
- Sat Feb 08, 2020 4:31 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calorimeters
- Replies: 17
- Views: 913
Re: Calorimeters
calorimeters maintain the same volume so constant volume
- Sat Feb 08, 2020 4:30 pm
- Forum: Phase Changes & Related Calculations
- Topic: Steam burns more than water
- Replies: 5
- Views: 229
Re: Steam burns more than water
the energy from steam is higher than the energy for water
- Fri Feb 07, 2020 8:34 pm
- Forum: Phase Changes & Related Calculations
- Topic: Negative Work
- Replies: 18
- Views: 1346
Re: Negative Work
just remember a system doing work isn't gaining work therefore its doing negative work
- Fri Feb 07, 2020 8:33 pm
- Forum: Calculating Work of Expansion
- Topic: Units for Work
- Replies: 5
- Views: 240
Re: Units for Work
From what i remember, most professors usually provide conversions on the test in the form of a formula chart or at least include a needed conversion in the question
- Fri Feb 07, 2020 8:31 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Equations
- Replies: 3
- Views: 94
Re: Equations
i usually write all the formulas on one piece of paper to remember all the relevant equations for the topic at hand
- Thu Feb 06, 2020 7:01 pm
- Forum: Calculating Work of Expansion
- Topic: Kelvin vs Celsius
- Replies: 5
- Views: 144
Re: Kelvin vs Celsius
You always use Kelvin no matter what equation it is so if you are given celsius convert to kelvin
- Mon Feb 03, 2020 9:15 pm
- Forum: Phase Changes & Related Calculations
- Topic: -w vs w
- Replies: 15
- Views: 590
Re: -w vs w
POV is from the system so if the system is doing work, its positive and if its having work done on it its negative
- Mon Feb 03, 2020 9:13 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Molar Heat Capacity
- Replies: 4
- Views: 167
Re: Molar Heat Capacity
its usually (n)(Cp or Cv)(delta T)
- Sun Feb 02, 2020 5:28 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Positive or negative work?
- Replies: 8
- Views: 242
Re: Positive or negative work?
Work is seen from the system's POV so if a piston is pushing down on a system, the system is the one receiving the work therefore the system isn't the one doing the work hence work by the system will be negative
- Sun Feb 02, 2020 1:21 pm
- Forum: Calculating Work of Expansion
- Topic: Gas constant
- Replies: 5
- Views: 241
Re: Gas constant
use the gas constant that matches the units given in the question
- Thu Jan 30, 2020 1:35 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Qv vs Qp
- Replies: 7
- Views: 120
Re: Qv vs Qp
q at constant volume and q at constant pressure
- Tue Jan 28, 2020 7:12 pm
- Forum: Ideal Gases
- Topic: Kc vs Kp
- Replies: 109
- Views: 4275
Re: Kc vs Kp
You use Kp because K=kp for all cases. Kc=K when certain conditions are met
- Tue Jan 28, 2020 7:10 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: reaction enthalpy
- Replies: 14
- Views: 436
Re: reaction enthalpy
To break bonds, energy has to be brought in aka endothermic reaction and to form bonds, energy must leave the system aka exothermic
- Mon Jan 27, 2020 10:46 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Homework sections
- Replies: 7
- Views: 267
Re: Homework sections
i would assume we are starting at 4A rn
- Sun Jan 26, 2020 2:15 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Temperature (K)
- Replies: 4
- Views: 90
Re: Temperature (K)
temperature can affect the rate of the reaction leading to different equilibrium concentrations
- Sun Jan 26, 2020 2:14 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Polyprotic Acids
- Replies: 2
- Views: 75
Re: Polyprotic Acids
yes it was included in the outline questions
- Sat Jan 25, 2020 8:04 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ka of strong acid
- Replies: 3
- Views: 85
Re: Ka of strong acid
Im guessing its more than one since Ka will usually be [conjeguate base][H30+]/[Strong acid] and [H30+]=[strong acid]
- Thu Jan 23, 2020 8:59 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: removing H2 from N2 + 3H2 -> 2NH3
- Replies: 7
- Views: 1894
Re: removing H2 from N2 + 3H2 -> 2NH3
removing H2 causes an absence of H2 thus causing the reaction to form more H2 since there is an absence of it
- Thu Jan 23, 2020 8:54 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Sapling Learning 14B
- Replies: 3
- Views: 247
Re: Sapling Learning 14B
you can still access the textbook thru the 14a course
- Wed Jan 22, 2020 8:52 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Percent Ionization
- Replies: 4
- Views: 87
Re: Percent Ionization
its [A-]/[HA] but if [H30+]=[A-] then [H30+]/[HA] will yield the same % value
- Tue Jan 21, 2020 10:11 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: exothermic reactions
- Replies: 19
- Views: 1852
Re: exothermic reactions
reverse reaction is endothermic thus forming reactants when heat is added
- Mon Jan 20, 2020 3:33 pm
- Forum: Ideal Gases
- Topic: R constant for PV=nRT
- Replies: 7
- Views: 389
Re: R constant for PV=nRT
R can have different values depending on what units are needed for the equation
- Sun Jan 19, 2020 11:21 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: reaction quotient
- Replies: 4
- Views: 170
Re: reaction quotient
usually if we're asked to calculate Q then a K value should be provided to help us determine if it has reached equilibrium
- Sat Jan 18, 2020 9:48 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Kb vs Ka
- Replies: 5
- Views: 111
Re: Kb vs Ka
Kb is for weak base reactions and Ka is for weak acid reactions
- Sat Jan 18, 2020 10:24 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Difference between K and Q?
- Replies: 11
- Views: 505
Re: Difference between K and Q?
K represents the concentrations at equilibrium whereas Q represents concentrations not at equilibrium
- Thu Jan 16, 2020 1:34 pm
- Forum: Ideal Gases
- Topic: ICE tables
- Replies: 9
- Views: 1409
Re: ICE tables
usually questions will include words like "moles" which is used for concentrations. if it doesnt have "moles" i would guess pressures is the way to go
- Thu Jan 16, 2020 1:32 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K units
- Replies: 10
- Views: 460
Re: K units
K is just a number that is used to show the ratio of products to reactants. I dont think K is ever used in equations so it doesnt need units anyways
- Fri Jan 10, 2020 4:27 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Exercise 5G.1
- Replies: 4
- Views: 206
Re: Exercise 5G.1
according to one of the TA's, a Higher pressure of the reactant just implies that more reactant was added and the presence of reactants/products does not affect the equilibrium constant. Also, for d, a higher amount of reactants will yield a higher amount of products thus initial concentrations will...
- Thu Jan 09, 2020 10:17 pm
- Forum: Ideal Gases
- Topic: eq constant
- Replies: 4
- Views: 118
Re: eq constant
Essentially solids and liquids are in such great excess and it is impossible to come up with a value for their concentration hence why they are omitted
- Thu Jan 09, 2020 10:15 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: liquids and aqueous solutions
- Replies: 4
- Views: 103
Re: liquids and aqueous solutions
Aqueous solutions can have their concentrations measured and these concentrations are what allow us to calculate K. However, solids and liquids are in such great excess in solutions where it is too hard to calculate their concentrations hence why they are omitted from the equilibrium constant
- Thu Jan 09, 2020 10:11 pm
- Forum: Ideal Gases
- Topic: 5G1 true/false
- Replies: 8
- Views: 242
Re: 5G1 true/false
Instead of looking at K as Kc look at it as Kp. Kp= (partial pressure of products) / (partial pressure of reactants) according to this equation, an increase in the partial pressure of reactants would lead to a decrease in the equilibrium constant instead of an increase in the equilibrium constant, w...
- Thu Jan 09, 2020 10:07 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Temperatures and Equilibrium
- Replies: 4
- Views: 140
Re: Temperatures and Equilibrium
all reactions will eventually reach a point where molar concentrations will become constant so in other words all reactions attain equilibrium after a certain period of time. Temperature, however, will affect the forward and reverse reaction rates thus affecting the equilibrium constant.
- Thu Jan 09, 2020 10:04 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5G.1.C explanation (SSM)
- Replies: 2
- Views: 99
5G.1.C explanation (SSM)
in the student solutions manual, it says that question C is false because the amount of reactants/products doesn't affect the equilibrium constant if the temperature is constant but the question is asking if the equilibrium constant will increase if the reactant starts at a higher pressure so should...