Search found 30 matches
- Thu Mar 14, 2019 11:04 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Molecularity
- Replies: 5
- Views: 474
Re: Molecularity
Molecularity is only concerned with the reactants. It does not matter how much product is formed.
- Thu Mar 14, 2019 11:03 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Catalysts in Rate Law
- Replies: 5
- Views: 564
Catalysts in Rate Law
For a given reaction mechanism, can catalysts be included in the rate law?
- Thu Mar 14, 2019 11:02 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: A in the Arrhenius Equation
- Replies: 4
- Views: 395
A in the Arrhenius Equation
In the Arrhenius Equation, I'm kinda confused what A means and when to apply it. Can someone help me out plz?
- Sun Mar 10, 2019 10:58 pm
- Forum: Second Order Reactions
- Topic: Final
- Replies: 32
- Views: 2402
Re: Final
It is cumulative. Hopefully it wont be too bad :)
- Sun Mar 10, 2019 10:56 pm
- Forum: Zero Order Reactions
- Topic: Zero order reactions
- Replies: 4
- Views: 463
Zero order reactions
I remember in class Dr. Lavelle mentioned that as the order of a reaction increases, the reaction becomes more rare. Does that mean then that zero order reactions are the most common?
- Sun Mar 10, 2019 10:54 pm
- Forum: First Order Reactions
- Topic: Rate dependency
- Replies: 5
- Views: 561
Re: Rate dependency
I think we only consider reactants because we are talking about the initial rate. At that point, there will be minimal products formed so the concentrations of products are not considered.
- Sun Mar 03, 2019 11:25 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Kinetics
- Replies: 7
- Views: 773
Re: Kinetics
I think we need to know derivatives for kinetics because we need to be able to calculate the instantaneous rate of change of concentration in a reaction.
- Sun Mar 03, 2019 11:24 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: how is kinetics different?
- Replies: 17
- Views: 1677
Re: how is kinetics different?
Thermodynamics deals with the amount of energy absorbed or released during a reaction, while kinetics deals with the speed of a reaction.
- Sun Mar 03, 2019 11:23 pm
- Forum: General Rate Laws
- Topic: Unique vs instantaneous rate
- Replies: 6
- Views: 632
Re: Unique vs instantaneous rate
The instantaneous rate is equal to the limit of the average rate as delta(t) approaches 0.
- Sun Feb 24, 2019 10:34 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Wmax and -W
- Replies: 2
- Views: 284
Re: Wmax and -W
I am also confused on this question.
- Sun Feb 24, 2019 10:33 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Spontaneous?
- Replies: 13
- Views: 1588
Re: Spontaneous?
Enthalpy cannot be used to determine spontaneity. By definition, a negative deltaG means a reaction is spontaneous. A positive deltaS I assume would also be considered spontaneous in most cases according to the Second Law of Thermodynamics.
- Sun Feb 24, 2019 10:31 pm
- Forum: Balancing Redox Reactions
- Topic: platinum
- Replies: 7
- Views: 697
Re: platinum
No. Platinum simply catalyzes the transfer of electrons. It is not chemically involved in the reaction.
- Tue Feb 19, 2019 1:05 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Delta G
- Replies: 4
- Views: 481
Re: Delta G
Gibbs free energy itself is a state function. Because it is a state function, we only ever need to consider the change in G from its initial state to its final state because state functions are independent of the path taken by the system.
- Tue Feb 19, 2019 1:03 am
- Forum: Van't Hoff Equation
- Topic: Derivation
- Replies: 9
- Views: 1236
Re: Derivation
I think the equations that we need to know are given to us on the formula sheet.
- Tue Feb 19, 2019 1:02 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs Free Energy
- Replies: 5
- Views: 558
Re: Gibbs Free Energy
Gibbs free energy is the energy available to do work. I think it means that this energy is able to be used up in a reaction and is not wasted as heat.
- Sun Feb 10, 2019 8:20 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Spontaneity
- Replies: 2
- Views: 258
Re: Spontaneity
Using the equation given to calculate Gibbs Free Energy, you can predict the spontaneity of a system. If deltaG>0, the change is non-spontaneous. If deltaG<0, the change is spontaneous.
- Sun Feb 10, 2019 8:17 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Delta U
- Replies: 8
- Views: 883
Re: Delta U
Based on the equation, deltaU=(3/2)nR(deltaT), deltaU is 0 when deltaT is 0. I am still a little confused about this myself. However, whenever you have an isolated system, deltaU always equals 0 because heat and work cannot be transferred into or out of the system.
- Sun Feb 10, 2019 8:14 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Counting Moles to Find Entropy
- Replies: 2
- Views: 573
Re: Counting Moles to Find Entropy
I think you just count the moles of gas, but I am not 100% certain
- Sun Feb 03, 2019 2:00 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: 3 methods for enthalpy calculation
- Replies: 10
- Views: 1976
Re: 3 methods for enthalpy calculation
I think on the test he will tell us which method to use. However, he did mention in class that using bond enthalpy is the least accurate means of calculation the enthalpy of the reaction. This is because, aside from diatomic molecules like Cl2, the bond enthalpies given are averages rather than exac...
- Sun Feb 03, 2019 1:52 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calorimeter
- Replies: 6
- Views: 568
Calorimeter
During lecture, Professor Lavelle spent a significant amount of time discussing calorimetry (i.e. bomb calorimeter). Should we be able to describe calorimetry for exams?
- Sun Feb 03, 2019 1:49 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: kJ v. kJ/mol
- Replies: 3
- Views: 564
kJ v. kJ/mol
I am a little confused when we should be calculating enthalpy in terms of kJ and kJ/mol. Can someone please explain?
- Sun Jan 27, 2019 8:29 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard Enthalpy
- Replies: 1
- Views: 185
Standard Enthalpy
Will we need to memorize the standard state of certain molecules when calculating the standard enthalpy or the standard enthalpy of formation? If so, which ones?
- Sun Jan 27, 2019 8:25 pm
- Forum: Phase Changes & Related Calculations
- Topic: Steam v. Boiling Water
- Replies: 4
- Views: 429
Steam v. Boiling Water
What is the explanation for why steam at 100*C causes a worse burn than boiling water at 100*C? I know he explained this in class but I am still a little confused.
- Sun Jan 27, 2019 8:20 pm
- Forum: Phase Changes & Related Calculations
- Topic: State Properties
- Replies: 5
- Views: 484
Re: State Properties
State functions only depend on their current state. For example, if you wanted to calculate the change in enthalpy, you would have to subtract the initial enthalpy from the final enthalpy. You can have different inputs of work but still attain the same change in enthalpy. It is similar to the work p...
- Sun Jan 20, 2019 11:01 am
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Conjugate?
- Replies: 5
- Views: 842
Re: Conjugate?
CH3COOH + H20 = H3O^+ + CH3COO^-
In this reaction, CH3COOH is the acid because it is donating a proton. Its conjugate base is CH3COO-. Water in this reaction acts as a base since it is receiving a proton, making its conjugate base to be H3O+.
In this reaction, CH3COOH is the acid because it is donating a proton. Its conjugate base is CH3COO-. Water in this reaction acts as a base since it is receiving a proton, making its conjugate base to be H3O+.
- Sun Jan 20, 2019 10:57 am
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Ka Kb significance
- Replies: 3
- Views: 2361
Re: Ka Kb significance
Ka and Kb are the equilibrium constants for the hydrolysis of acids and basis in water. The higher the Ka, the stronger the acid and the weaker its conjugate base. The higher the Kb, the stronger the base and the weaker its conjugate acid. pKa and pKb are just a simplified way to represent this.
- Sun Jan 20, 2019 10:39 am
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Conjugate Base versus an Acid
- Replies: 2
- Views: 464
Re: Conjugate Base versus an Acid
A conjugate base will have a lower Ka and a higher Kb versus an acid.
- Sun Jan 13, 2019 9:33 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Changing Temperature
- Replies: 4
- Views: 430
Changing Temperature
Does changing the temperature in a reaction affect both the K value and concentration?
- Sun Jan 13, 2019 9:31 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Example in Class
- Replies: 7
- Views: 456
Re: Example in Class
Decreasing the amount of NH3 would make Q<K, which would cause the reaction to shift right and more NH3 to form so that Q=K.
- Sun Jan 13, 2019 9:29 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Volume increasing
- Replies: 4
- Views: 283
Re: Volume increasing
Yes. If the volume of the container increases then the reaction will favor the side of the reaction with more moles. I think the reason for this is that when you increase the volume, you decrease the concentrations of gases since concentration = moles/volume.