Search found 56 matches
- Mon Mar 16, 2020 1:24 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Kinetics
- Replies: 9
- Views: 856
Kinetics
What is the difference between kinetically and thermodynamically controlled?
- Thu Mar 12, 2020 2:58 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Question 5 UA Worksheet
- Replies: 1
- Views: 246
Question 5 UA Worksheet
Part b of Q5 on the UA worksheet. I am unclear how to write an equation that takes into account the addition of NaOH to the buffer solution. As well as how to take into account 50 mL of NaOH vs. 100 mL of acetic acid/acetate buffer.
- Tue Mar 10, 2020 10:35 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Outline 6 Learning Objective
- Replies: 3
- Views: 398
Outline 6 Learning Objective
How do you show the rate of change of one species in a reaction is related to another species?
- Sun Mar 08, 2020 8:57 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Vertical lines vs commas
- Replies: 7
- Views: 471
Re: Vertical lines vs commas
Vertical lines are used to separate species in different states. Commas are used to separate species in the same states.
- Sun Mar 08, 2020 8:55 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Platinum
- Replies: 10
- Views: 676
Re: Platinum
When there is no solid given in the cell diagram or reaction, you can always use platinum as the metal.
- Sun Mar 08, 2020 8:54 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Intermediate Species
- Replies: 9
- Views: 724
Re: Intermediate Species
Additionally, I believe reactions have the same intermediate species whether they are going in the reverse or forward direction.
- Sun Mar 08, 2020 8:53 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: K
- Replies: 11
- Views: 670
K
What factors is K dependent on?
- Sun Mar 08, 2020 8:50 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Cell Diagram
- Replies: 21
- Views: 1197
Re: Cell Diagram
I believe we can always assume the cathode is on the right side.
- Wed Mar 04, 2020 11:17 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Finding Q
- Replies: 7
- Views: 562
Re: Finding Q
You can write the total reaction to see what the products and reactions are. But, I believe the anode is usually the product and the cathode usually the reactant.
- Mon Mar 02, 2020 8:10 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagram
- Replies: 1
- Views: 161
Cell Diagram
What order do you put compounds in the reaction in when drawing the cell diagram? Does the order of reactants and products have any affect when drawing the salt diagram?
- Mon Mar 02, 2020 8:07 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt bridge
- Replies: 1
- Views: 166
Salt bridge
How exactly does a salt bridge work?
- Mon Mar 02, 2020 8:04 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: determine n
- Replies: 16
- Views: 1439
Re: determine n
n is the number of electrons transferred. In order to calculate n, you must write the half reactions for reduction and oxidation, balance them, and then see the number of electrons transferred.
- Mon Mar 02, 2020 8:02 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: G=-nFE
- Replies: 5
- Views: 421
Re: G=-nFE
We use this equation when calculating delta G in standard and nonstandard conditions.
In order to calculate n, you must write the reduction and oxidation half reactions, balance them, and then observe the number of electrons transferred.
In order to calculate n, you must write the reduction and oxidation half reactions, balance them, and then observe the number of electrons transferred.
- Mon Mar 02, 2020 8:00 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic cells
- Replies: 6
- Views: 504
Galvanic cells
Do galvanic cells always have to be spontaneous?
- Mon Feb 24, 2020 12:32 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: S = 0
- Replies: 21
- Views: 1199
Re: S = 0
Entropy = 0 in an isothermal reversible system
- Mon Feb 24, 2020 12:31 am
- Forum: Balancing Redox Reactions
- Topic: Balancing Redox Reactions
- Replies: 7
- Views: 463
Balancing Redox Reactions
When do we need to cancel H+ with OH- when balancing redox reactions?
- Mon Feb 24, 2020 12:29 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic vs. electrolytic
- Replies: 4
- Views: 325
Galvanic vs. electrolytic
How can we tell the difference between galvanic and electrolytic cells?
- Mon Feb 24, 2020 12:27 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Platinum
- Replies: 5
- Views: 393
Platinum
How is platinum used in redox reactions?
- Mon Feb 24, 2020 12:25 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: STP
- Replies: 13
- Views: 783
Re: STP
It is 0 degrees Celsius and atm.
- Wed Feb 19, 2020 1:34 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: G vs G knot
- Replies: 15
- Views: 1749
Re: G vs G knot
Similar to entropy and enthalpy, G knot is G at standard conditions.
- Wed Feb 19, 2020 1:32 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Sign of delta G
- Replies: 9
- Views: 610
Re: Sign of delta G
Yes, I think you could do that.
- Wed Feb 19, 2020 1:31 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Question 1 on Midterm
- Replies: 7
- Views: 581
Question 1 on Midterm
Why would removing some NO (g) from the system not increase the partial pressure of NO2 (g) at equilibrium?
- Wed Feb 19, 2020 1:29 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Midterm question 8 [ENDORSED]
- Replies: 5
- Views: 528
Re: Midterm question 8 [ENDORSED]
In a reversible expansion change in entropy total = 0. Therefore - ΔS surroundings = ΔS system
In an irreversible free expansion ΔS surroundings = 0 and ΔS total = ΔS system
In an irreversible free expansion ΔS surroundings = 0 and ΔS total = ΔS system
- Wed Feb 19, 2020 1:24 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Comparing standard molar entropies
- Replies: 6
- Views: 490
Re: Comparing standard molar entropies
More complex molecules have larger standard molar entropies because there are more possible configurations and therefore more disorder, and therefore more entropy than smaller, less complex molecules.
- Tue Feb 18, 2020 9:40 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Polyprotic Acids
- Replies: 6
- Views: 453
Re: Polyprotic Acids
Polyprotic acids dissociate more than once. K1 is the K value for the first dissociation and K2 is that for the second dissociation.
- Tue Feb 18, 2020 9:39 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: ∆G = ∆Gº + RT lnQ
- Replies: 12
- Views: 2637
Re: ∆G = ∆Gº + RT lnQ
∆Gº is the delta G at standard conditions
- Tue Feb 11, 2020 12:15 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: 4D.5
- Replies: 1
- Views: 144
4D.5
In this question it states 22 KJ of expansion work is done on the system by compressing it into a smaller volume.
They set +22 kJ = -P delta V
Then state -22 kJ = P delta V
Why is this step necessary? How can work be negative is the system is being compressed?
They set +22 kJ = -P delta V
Then state -22 kJ = P delta V
Why is this step necessary? How can work be negative is the system is being compressed?
- Mon Feb 10, 2020 11:20 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: delta U = w
- Replies: 1
- Views: 86
delta U = w
When does q = 0, so delta U = w?
- Sun Feb 09, 2020 10:14 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Isothermal Irreversible
- Replies: 3
- Views: 217
Isothermal Irreversible
Is it possible for isothermal reactions to be irreversible, if so, how?
- Sun Feb 09, 2020 10:12 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Strong Acids
- Replies: 6
- Views: 328
Re: Strong Acids
We know something is a strong acid or base if it fully dissociates in water.
Some common strong acids are:
HCl4, HCl, HBr, HI, HNO3, H2SO4
Some common strong bases are :
LiOH, NaOH, KOH, Ca(OH)2, Sr(OH)2, Br(OH)2
Some common strong acids are:
HCl4, HCl, HBr, HI, HNO3, H2SO4
Some common strong bases are :
LiOH, NaOH, KOH, Ca(OH)2, Sr(OH)2, Br(OH)2
- Sun Feb 09, 2020 10:08 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Cv and Cp
- Replies: 3
- Views: 104
Re: Cv and Cp
You would use Cv when the system is at constant volume and Cp when the pressure is constant. For example, for a bomb calorimeter question you would use Cv because the system is at constant volume.
- Sun Feb 09, 2020 10:07 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Intensive vs. extensive, state vs. non state
- Replies: 6
- Views: 265
Re: Intensive vs. extensive, state vs. non state
An extensive property is one that is dependent on volume/size. A state function is a function such as specific heat capacity, where the path taken does not matter only the beginning and end points.
- Sat Feb 08, 2020 10:58 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Spontaneous reactions
- Replies: 3
- Views: 145
Re: Spontaneous reactions
We can only tell if a reaction is spontaneous based on delta S alone is delta S total > 0. This is because spontaneous reactions follow the second law of thermodynamics, which is that entropy is always increasing. If delta S total is > 0, entropy is increasing and the reaction is spontaneous.
- Sat Feb 08, 2020 6:29 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Irreversible Expansion
- Replies: 1
- Views: 72
Irreversible Expansion
Why do irreversible free expansion do zero work? ( this is used in question 4I.9)
- Sun Feb 02, 2020 11:58 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: enthalpy
- Replies: 7
- Views: 248
enthalpy
What is enthalpy?
- Sun Feb 02, 2020 11:56 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: equation
- Replies: 2
- Views: 178
equation
When do we need to use the q = C delta T equation.
- Sun Feb 02, 2020 11:54 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: state functions
- Replies: 10
- Views: 381
Re: state functions
A state function is a value that doesn't depend on path taken to obtain that state and its value is determined by its current state.
- Sun Feb 02, 2020 11:49 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Specific heat capacity
- Replies: 7
- Views: 451
Specific heat capacity
What is the difference between specific heat capacity and molar heat capacity?
- Sun Feb 02, 2020 11:45 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: extensive property
- Replies: 12
- Views: 679
Re: extensive property
An extensive property is one that depends on the amount of material. An example of this is volume.
- Wed Jan 22, 2020 8:29 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Percent Ionization
- Replies: 4
- Views: 122
Re: Percent Ionization
From what I have in my notes I think its %=[A-]/[HA] x 100% , but I'm also confused about this.
- Wed Jan 22, 2020 8:24 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Approximation
- Replies: 5
- Views: 160
Re: Approximation
When the K value is < 10^-3, you can approximate. If you approximate, you must calculate the percent ionization in order to check. This value must be less than 5%.
- Wed Jan 22, 2020 8:23 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Polyprotic Acids
- Replies: 6
- Views: 453
Re: Polyprotic Acids
Polyprotic acids are acids that dissociate more than once. K1 is the value of K for the first ionization. K2 is the K value for the second ionization.
- Wed Jan 22, 2020 8:22 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE Box vs just solving
- Replies: 2
- Views: 91
Re: ICE Box vs just solving
You would need to use an ice box if you are given initial concentrations and/or asked to find concentrations at equilibrium. You can just solve if the concentrations you are given are equilibrium concentrations.
- Tue Jan 21, 2020 11:14 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Hw 6D.9
- Replies: 1
- Views: 324
Re: Hw 6D.9
The Ka value should be
Ka = [C6H3Co2-] [H3O+] / [C6H5COOH]
Ka = (2.64x10^-3)^2/((.110- (2.64 x 10^-3))
Ka = 6.5 x 10^-3
Ka = [C6H3Co2-] [H3O+] / [C6H5COOH]
Ka = (2.64x10^-3)^2/((.110- (2.64 x 10^-3))
Ka = 6.5 x 10^-3
- Tue Jan 21, 2020 11:08 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Sig Figs for pH/pOH
- Replies: 7
- Views: 375
Re: Sig Figs for pH/pOH
in pH/pOH the you only count sig figs after the decimal point.
- Thu Jan 16, 2020 1:31 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Autoprotolysis
- Replies: 2
- Views: 113
Autoprotolysis
When do we need to take into account the autoprotolysis of water needs to be taken into account?
- Thu Jan 16, 2020 1:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5.35 part b
- Replies: 4
- Views: 250
Re: 5.35 part b
The divide by 100 in order to convert pKa to bar. 1 pKa = .01 bar.
- Thu Jan 16, 2020 12:01 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5.35 finding partial pressure
- Replies: 2
- Views: 159
Re: 5.35 finding partial pressure
We are given the partial pressure in pKa on the y axis. We can use the fact that 1 pKa = .01 bar when setting up the equilibrium constant.
Kp = (Pb)(Pc)^2/ (Pa)^2
Kp = (5/100)(10/100)^2/(18/100)^2
This gives up the equilibrium constant for the reaction.
Kp = (Pb)(Pc)^2/ (Pa)^2
Kp = (5/100)(10/100)^2/(18/100)^2
This gives up the equilibrium constant for the reaction.
- Wed Jan 15, 2020 11:56 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Units in ICE Table
- Replies: 8
- Views: 261
Re: Units in ICE Table
In an ice table, the units must be in concentrations. mols/Liter
- Wed Jan 15, 2020 10:21 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: delta H
- Replies: 5
- Views: 161
Re: delta H
For right now, we only need to use delta H to determine is a reaction is endothermic or exothermic. If delta H is positive, the reaction is endothermic. If delta H is negative, the reaction is exothermic.
- Sun Jan 12, 2020 7:22 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: stoichiometric coefficients
- Replies: 5
- Views: 360
Re: stoichiometric coefficients
When writing the equilibrium constant K, the stoichiometric coefficients are the exponents to the concentrations of each part of the reaction.
- Sun Jan 12, 2020 8:44 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE tables
- Replies: 3
- Views: 196
Re: ICE tables
C stands for change in concentration. In the C row, you put what is left after the reaction occurs of each component. ex (initial concentration -x) or (initial concentration + x)
- Fri Jan 10, 2020 2:05 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5I.13
- Replies: 2
- Views: 115
5I.13
This question asks to refer to table 5G.2 to find the K value. How do you know whether to use the value listed as "K" or the one listed as "Kc."
- Fri Jan 10, 2020 1:37 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Change in k
- Replies: 11
- Views: 568
Re: Change in k
Changing the concentration does not change K because although the concentrations of reactants and products will be different, the overall ration of them in the equilibrium constant will remain the same. Higher concentration of reactant will produce a higher concentration of product.
- Fri Jan 10, 2020 9:30 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5I.5
- Replies: 4
- Views: 170
Re: 5I.5
I think the reason you are getting the wrong answer is because you are using 1.8 bar instead of 1.18 bar, but your steps are correct.
- Fri Jan 10, 2020 9:27 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Comparing K and Q
- Replies: 6
- Views: 290
Re: Comparing K and Q
We can compare K and Q values to see if a reaction has reached equilibrium or not. If Q < K, the forward reaction is still favored, and we have to wait longer for the reaction to reach equilibrium; [R] > [P] . If Q > K, the reverse reaction is favored; [P] > [R].