## Search found 56 matches

Mon Mar 16, 2020 1:24 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Kinetics
Replies: 2
Views: 165

### 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: 110

### 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: 109

### 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: 65

### 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: 136

### 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: 158

### 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: 126

### 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: 16
Views: 285

### 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: 174

### 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: 42

### 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: 33

### 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: 648

### 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: 122

### 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.
Mon Mar 02, 2020 8:00 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic cells
Replies: 6
Views: 123

### 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: 18
Views: 361

### 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: 91

### 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: 67

### 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: 124

### 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: 201

### 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: 154

### 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: 178

### 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: 232

### 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: 209

### 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
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: 179

### 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: 112

### 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: 232

### 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: 32

### 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?
Mon Feb 10, 2020 11:20 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: delta U = w
Replies: 1
Views: 24

### 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: 47

### 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: 59

### 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
Sun Feb 09, 2020 10:08 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Cv and Cp
Replies: 3
Views: 22

### 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: 81

### 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: 57

### 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: 23

### 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: 79

### enthalpy

What is enthalpy?
Sun Feb 02, 2020 11:56 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: equation
Replies: 2
Views: 62

### 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: 94

### 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: 81

### 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: 162

### 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: 34

### 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: 47

### 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: 112

### 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: 26

### 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: 117

### 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
Tue Jan 21, 2020 11:08 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Sig Figs for pH/pOH
Replies: 7
Views: 65

### 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: 40

### 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: 44

### 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: 41

### 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.
Wed Jan 15, 2020 11:56 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Units in ICE Table
Replies: 8
Views: 99

### 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: 41

### 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: 55

### 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: 60

### 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: 35

### 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: 192

### 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: 71

### 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: 66

### 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].