Search found 50 matches
- Sun Mar 15, 2020 7:09 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3592766
- Sun Mar 15, 2020 6:36 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Delta S
- Replies: 8
- Views: 669
Re: Delta S
When using the equation (delta)S= C ln(T2/T1), How do you know which heat capacity to use?
- Sun Mar 15, 2020 6:33 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Finding enthalpy
- Replies: 2
- Views: 282
Re: Finding enthalpy
Also when there is constant pressure and no expansion work, (delta)H=q
- Sun Mar 15, 2020 6:29 am
- Forum: Phase Changes & Related Calculations
- Topic: phase change
- Replies: 6
- Views: 536
Re: phase change
Like the diagram in class, you can tell that there is a phase change when the heat or enthalpy is increasing, but the temperature is not increasing, or delta T is zero. Can the enthalpy increase AND the temperature remains the same while there still not being a phase change? Like I'm imagining the ...
- Sat Mar 14, 2020 4:15 pm
- Forum: First Order Reactions
- Topic: Linear versus Non-Linear
- Replies: 3
- Views: 379
Re: Linear versus Non-Linear
Would there ever be a first order linear slope that is positive and not negative?
- Sat Mar 14, 2020 4:08 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts
- Replies: 8
- Views: 516
Re: Catalysts
How do you spot a catalyst in a reaction? Or will it always be given?
- Sat Mar 14, 2020 4:07 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst Equation
- Replies: 6
- Views: 515
Re: Nernst Equation
I convert RT/F to 0.025693 V and it has always given me the correct answer when I plug it in. I think you need to be careful of how you round if you are calculating RT/nF
- Sat Mar 14, 2020 4:05 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Test 2 #6 b
- Replies: 1
- Views: 176
Test 2 #6 b
For question 6 part b) How will each of the following changes affect the cell potential: i) adding 100 mL pure water to cathode solution ii) halving the mass of anode electrode I am a bit confused with i) and how the cell potential would decrease when adding 100mL of water into the solution because ...
- Sat Mar 14, 2020 3:59 pm
- Forum: Van't Hoff Equation
- Topic: Test 2 Calculate K after a temperature change
- Replies: 1
- Views: 288
Re: Test 2 Calculate K after a temperature change
make sure to set up the equation by first isolating ln(K2). So the equation would be: ln(K2)=(deltaH/R) (1/T1 - 1/T2) + ln(K1). Then plug in your numbers. I have found that when I don't isolate the ln(K2) first I get a strange answer.
- Sat Mar 14, 2020 3:55 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Equations
- Replies: 8
- Views: 565
Re: Equations
In the text book I am seeing lots of equations that have (delta)G sub r, what does the r mean? I think its just reaction but I am not positive.
- Sat Mar 14, 2020 3:53 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equilibrium Constants
- Replies: 15
- Views: 932
Re: Equilibrium Constants
When the equilibrium constant K is larger than 10^3 does the reaction favor the products or the reactants?
- Sat Mar 14, 2020 10:35 am
- Forum: First Order Reactions
- Topic: Half Life
- Replies: 13
- Views: 845
Re: Half Life
How do you determine the order of the reaction when needing to calculate half life? Will it always be given? To determine the order, you will likely use scientific data, are told, or can assume pseudo-first reaction if the information permits. I am a bit confused about psuedo-first reaction, could ...
- Sat Mar 14, 2020 10:20 am
- Forum: First Order Reactions
- Topic: Half Life
- Replies: 13
- Views: 845
Re: Half Life
How do you determine the order of the reaction when needing to calculate half life? Will it always be given?
- Thu Mar 12, 2020 1:51 pm
- Forum: First Order Reactions
- Topic: Half Life
- Replies: 8
- Views: 540
Re: Half Life
How do you determine time (t) when given half life and the percentage something has decreased? EX: from self-test 7B.4A: In 1972, grain treated with methyl mercury was released for human consumption in Iraq, resulting in 459 deaths. The half-life of methyl mercury in body tissues is 70 days. How man...
- Thu Mar 12, 2020 12:37 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Take Home Final
- Replies: 16
- Views: 1033
Re: Take Home Final
Does anyone know how much time we will be given to do the final?
- Thu Mar 12, 2020 12:17 pm
- Forum: General Rate Laws
- Topic: Rate limiting step
- Replies: 13
- Views: 789
Re: Rate limiting step
How do you find the limiting step?
- Thu Mar 12, 2020 12:17 pm
- Forum: General Rate Laws
- Topic: Rate limiting step
- Replies: 13
- Views: 789
Re: Rate limiting step
It is the slowest step in the reaction
- Thu Mar 12, 2020 12:12 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: determining k
- Replies: 13
- Views: 599
determining k
when trying to determine k, can you use any trial (when looking at multiple trials)?
- Thu Mar 12, 2020 9:59 am
- Forum: Student Social/Study Group
- Topic: Week 10 Review Question
- Replies: 5
- Views: 481
Week 10 Review Question
From Lavelle's Week 10 Review slides that he posted, On the first slide, how do you get the change in molar concentration? I am confused with how 0.075 and 0.225 were calculated.
- Wed Mar 11, 2020 5:05 pm
- Forum: Balancing Redox Reactions
- Topic: Half rxns
- Replies: 27
- Views: 1477
Re: Half rxns
When balancing basic half reactions, how do you know which side to put the OH- versus the H2O?
- Wed Mar 11, 2020 5:04 pm
- Forum: Balancing Redox Reactions
- Topic: Half rxns
- Replies: 27
- Views: 1477
Re: Half rxns
005384106 wrote:At what point do you add elections to the half reaction?
When all other elements are balanced and you just need to balance the charge of both sides
- Wed Mar 11, 2020 5:02 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Electromotive force (emf)
- Replies: 9
- Views: 649
Re: Electromotive force (emf)
005384106 wrote:Why do we measure the voltage difference of two cells?
The difference in potential voltage is what gives rise to electric current
- Wed Mar 11, 2020 4:59 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Relationship Between Ecell and K
- Replies: 9
- Views: 3280
Re: Relationship Between Ecell and K
Ecell and K are positively related so the larger the K means a more positive Ecell
- Wed Mar 11, 2020 4:56 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3592766
- Wed Mar 11, 2020 4:43 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Going from pKa to pH
- Replies: 10
- Views: 724
Re: Going from pKa to pH
What does the w in pKw stand for?
- Tue Mar 10, 2020 6:16 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagram and Ecell [ENDORSED]
- Replies: 29
- Views: 113597
Re: Cell Diagram and Ecell [ENDORSED]
bloodorangefield wrote:How do you tell the difference between when it is an anode vs when it is cathode?
anode is always on the left and cathode is on the right
- Tue Mar 10, 2020 6:07 pm
- Forum: Second Order Reactions
- Topic: 2nd Order Slope
- Replies: 2
- Views: 138
2nd Order Slope
Will the 2nd order slope ever be negative when plotting?
- Tue Mar 10, 2020 6:01 pm
- Forum: Van't Hoff Equation
- Topic: Van’t Hoff Equation
- Replies: 11
- Views: 941
Re: Van’t Hoff Equation
How do you know to use Van't Hoff Equation? Are there certain questions in problems that signal to use it?
- Tue Mar 10, 2020 5:59 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Using Equilibrium constants to predict solubility
- Replies: 4
- Views: 273
Re: Using Equilibrium constants to predict solubility
Also what is the relationship between the constants and solubility? are they positively correlated or negatively correlated?
- Tue Mar 10, 2020 5:58 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Using Equilibrium constants to predict solubility
- Replies: 4
- Views: 273
Using Equilibrium constants to predict solubility
How do you use Equilibrium constants to predict solubility? Would you use Le Chatelier's principle?
- Tue Mar 10, 2020 5:54 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Ka Kb
- Replies: 11
- Views: 690
Re: Ka Kb
What is the difference between pKa and Ka? same for pKb and Kb.
- Tue Mar 10, 2020 5:54 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Strong/weak acids & bases
- Replies: 14
- Views: 952
Re: Strong/weak acids & bases
How do you figure out the conjugate acid or base for a given base or acid?
- Tue Mar 10, 2020 5:52 pm
- Forum: Ideal Gases
- Topic: ideal gases
- Replies: 14
- Views: 982
Re: ideal gases
How do you distinguish if something is an ideal gas?
- Mon Mar 02, 2020 7:42 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Relationship between work and cell potential
- Replies: 1
- Views: 125
Relationship between work and cell potential
What is the relationship between work and cell potential?
- Sun Mar 01, 2020 8:33 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Oxidation Numbers
- Replies: 5
- Views: 441
Oxidation Numbers
What are the rules for oxidation numbers? I am having trouble getting the n in while trying to calculate the Gibbs Free Energy when given cell potential.
- Tue Feb 11, 2020 10:04 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Pizza Rolls REVIEW Session DOWNLOAD HERE
- Replies: 67
- Views: 5738
Re: Pizza Rolls REVIEW Session DOWNLOAD HERE
Asha Agarwal 1E wrote:Can someone also explain #12B? Is there a specific equation to use?
You take the q=mC(delta)T of each part of the equation while using the Cpm values given for C and then you do the sum of the products minus the sum of the reactants.
- Tue Feb 11, 2020 8:02 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Pizza Rolls REVIEW Session DOWNLOAD HERE
- Replies: 67
- Views: 5738
Re: Pizza Rolls REVIEW Session DOWNLOAD HERE
I am confused with #12B. What equation do you use when trying to find delta H?
- Sun Feb 09, 2020 8:11 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: difference between molar entropies?
- Replies: 6
- Views: 364
Re: difference between molar entropies?
Standard entropies tend to increase with increasing molar mass.
- Sun Feb 09, 2020 8:09 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Ideal Gas Chart
- Replies: 3
- Views: 128
Re: Ideal Gas Chart
Could someone please summarize this chart please? What is R and why would it be the way it is on the chart? the gas chart is for monoatomic and diatomic ideal gases. Monoatomic Internal energy: 3/2nRT . Monoatomic molar Cv: 3/2 R . Monoatomic molar Cp: 5/2 R Diatomic Internal energy: 5/2nRT . Diato...
- Sun Feb 09, 2020 7:54 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Ideal Gas Chart
- Replies: 3
- Views: 128
Ideal Gas Chart
When are you supposed to use the chart for the monoatomic and diatomic that give Molar heat capacities? (ex. 3/2 R)
- Sun Feb 09, 2020 7:51 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Cv Cp
- Replies: 3
- Views: 142
Re: Cv Cp
For constant pressure the equation is W= -P(delta)V , what is the equation for constant volume?
- Mon Feb 03, 2020 10:29 pm
- Forum: Van't Hoff Equation
- Topic: Van't Hoff
- Replies: 6
- Views: 368
Van't Hoff
When do you use the Van Hoff equation?
- Mon Feb 03, 2020 10:28 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: q and w
- Replies: 10
- Views: 579
Re: q and w
Work will be negative if the system is expanding and will be positive if the system is compressing.
- Mon Feb 03, 2020 10:25 pm
- Forum: Calculating Work of Expansion
- Topic: Integrals
- Replies: 2
- Views: 99
Integrals
How do you know to use the integral when calculating the Work of Expansion?
- Mon Feb 03, 2020 8:53 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Molar Heat Capacity
- Replies: 4
- Views: 196
Molar Heat Capacity
How do you calculate the molar heat capacity?
- Sun Jan 26, 2020 10:57 pm
- Forum: Phase Changes & Related Calculations
- Topic: Hess's Law
- Replies: 8
- Views: 205
Re: Hess's Law
How can you prove that the total enthalpy change is the sum of the changes in it?
- Sun Jan 26, 2020 10:48 pm
- Forum: *Free Energy of Activation vs Activation Energy
- Topic: Spontaneous reactions
- Replies: 11
- Views: 4628
Re: Spontaneous reactions
Does gibbs free energy determine spontaneity and enthalpy? Or only enthalpy?
- Mon Jan 20, 2020 10:46 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: H20 in the ICE table
- Replies: 26
- Views: 1502
Re: H20 in the ICE table
I believe ICE table only pertains to gases
- Mon Jan 20, 2020 10:33 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Module
- Replies: 4
- Views: 208
Re: Module
I am still getting 2.2 even when I calculate the concentration of H2 and AsH3 by divided moles by 3.00L
- Mon Jan 20, 2020 10:25 pm
- Forum: Ideal Gases
- Topic: Topics on Test 1
- Replies: 37
- Views: 1385
Re: Topics on Test 1
Jaci Glassick 2G wrote:I know this is a bit away, but does anyone what topics will be covered on Test 1? Thank you!
Chemical Equilibrium and Acid and Base Equilibria