## Search found 29 matches

Sat Mar 16, 2019 11:30 pm
Forum: *Enzyme Kinetics
Topic: Elementary Steps
Replies: 2
Views: 326

### Elementary Steps

Why can we not add the cell potential of elementary steps?
Sat Mar 16, 2019 11:25 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: w=-PdeltaW
Replies: 5
Views: 385

### Re: w=-PdeltaW

It can also be used in the equation of delta U=q+w. You can substitute w with -PdeltaV if w is not given to you in the problem.
Sat Mar 16, 2019 12:36 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Cp vs Cv
Replies: 6
Views: 1081

### Cp vs Cv

When would we use the values Cp= (5/2)R and Cv=(3/2)R?
Sun Mar 10, 2019 10:46 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Test 2
Replies: 12
Views: 475

### Re: Test 2

Did anyone understand what delta G should be for the question from test 2 where it talks about photosynthesis of an old tree?
Sun Mar 10, 2019 10:35 pm
Forum: Zero Order Reactions
Topic: Meaning of Zero, First, and Second Order?
Replies: 4
Views: 173

### Re: Meaning of Zero, First, and Second Order?

To figure out the order, you would keep in mind that the graph you need to take into consideration is concentration over time.
Sun Mar 10, 2019 10:30 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Instantaneous vs Average
Replies: 11
Views: 446

### Re: Instantaneous vs Average

What's the formula for instantaneous rate and average rate?
Sat Mar 02, 2019 7:17 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: delta G = 0 ??
Replies: 5
Views: 814

### Re: delta G = 0 ??

delta G=0 when the reaction has reached equilibrium
Sat Mar 02, 2019 7:12 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: salt bridge
Replies: 4
Views: 235

### Re: salt bridge

Since electrons are constantly being gained or lost, the solutions of the cathode and anode may gain a charge. If the solutions have a charge, the transferring of electrons will come to a stop. To allow the electrons to continue to be transferred, the salt bridge needs to maintain the solutions neut...
Sat Mar 02, 2019 6:52 pm
Forum: General Rate Laws
Topic: Kinetics
Replies: 3
Views: 157

### Kinetics

What is the difference between instantaneous rate, average rate, and unique rate?
Tue Feb 19, 2019 11:50 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: gibbs free energy
Replies: 10
Views: 314

### Re: gibbs free energy

If a reaction is spontaneous, it can either be spontaneous with all temperatures, spontaneous with low temperatures, or spontaneous with high temperatures. You can tell by looking at the values of delta H and delta S.
Tue Feb 19, 2019 11:32 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 5/2R vs 3/2R
Replies: 6
Views: 3186

### Re: 5/2R vs 3/2R

Cp=5/2r is used when you need to find the heat capacity of an ideal gas with a constant pressure. Cv=3/2R is used when you need to find the heat capacity of an ideal gas with a constant volume
Tue Feb 19, 2019 11:24 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs concept
Replies: 7
Views: 366

### Re: Gibbs concept

Gibbs is the free energy of a system that is available to do work. Delta G is the change of free energy that is equal to the delta H (change of enthalpy) minus the product of temperature and delta S (the change of entropy).
Thu Feb 07, 2019 12:38 pm
Forum: Phase Changes & Related Calculations
Topic: ΔH
Replies: 2
Views: 160

### ΔH

Is ΔH always equal to qp? Also, under what circumstances does ΔH=ΔU?
Thu Feb 07, 2019 12:33 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Degeneracy
Replies: 4
Views: 212

### Re: Degeneracy

X represents the number of states and I believe that the number of states will always be given to us
Tue Feb 05, 2019 11:29 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: thermo equation explanation
Replies: 4
Views: 224

### Re: thermo equation explanation

What is the difference between the equation mentioned above and the equation S=k(b) ln w?
Tue Feb 05, 2019 11:01 pm
Forum: Calculating Work of Expansion
Topic: +/- work values
Replies: 5
Views: 235

### Re: +/- work values

To add to the previous comment, when a question says work is being done by the surroundings "w" is positive. If a question says work is being done on the surroundings "w" is negative.
Tue Feb 05, 2019 10:47 pm
Forum: Administrative Questions and Class Announcements
Topic: negative and positive entropy
Replies: 3
Views: 209

### Re: negative and positive entropy

A negative entropy means that the disorder of a system has decreased. For example, when a liquid freezes into a solid there is a negative entropy. A positive entropy means that there is an increase in disorder. Entropy increases from solid to liquid to gas. For example, when a liquid vaporizes entro...
Tue Jan 29, 2019 4:15 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: 6th Edition Problem 8.21
Replies: 8
Views: 327

### 6th Edition Problem 8.21

A piece of copper of mass 20.0 g at 100.0 C is placed in a vessel of negligible heat capacity but containing 50.7 g of water at 22.0 C. Calculate the final temperature of the water. Assume that no energy is lost to the surroundings. What is the general equation that needs to be used to find the fina...
Tue Jan 29, 2019 3:34 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Cv versus Cp
Replies: 4
Views: 209

### Re: Cv versus Cp

Cp is always greater because of the work of expansion it has to do.
Tue Jan 29, 2019 2:52 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 6th edition hw problem 8.19
Replies: 1
Views: 116

### Re: 6th edition hw problem 8.19

We need to take into account the heat needed to raise the temperature of the copper kettle because heating the copper kettle will allow the temperature of the water to increase.
Tue Jan 22, 2019 4:47 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Setting up Equilibrium Equations
Replies: 2
Views: 88

### Re: Setting up Equilibrium Equations

How do you identify a weak acid and a weak base?
Tue Jan 22, 2019 4:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Finding Ka or Kb
Replies: 2
Views: 287

### Finding Ka or Kb

In the homework, there are problems that require you to find Ka or Kb. The textbook says that you must refer to the acid and base tables that give you either Ka or Kb. However, I noticed that not all acids and bases are on the table, so how would I find Ka or Kb for an acid or base that is not menti...
Tue Jan 22, 2019 3:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating the pH - 6D.17 7th edition
Replies: 2
Views: 97

### Re: Calculating the pH - 6D.17 7th edition

Keep in mind that you can solve for x using approximation if the Ka is less than 10^-3
Sun Jan 20, 2019 5:51 pm
Forum: Ideal Gases
Topic: 5% rule
Replies: 12
Views: 1783

### Re: 5% rule

Emily Kennedy 4L wrote:if the approximation is above 5% then is the complete answer void?

If it is greater than 5%, the quadratic equation should be used instead to find x.
Sun Jan 20, 2019 5:46 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Temperature
Replies: 2
Views: 112

### Re: Temperature

Endothermic reactions requires heat while forming products then heating will favor product formation. If the temperature increases in an endothermic reaction, it will shift to the right. If the temperature decreases in an endothermic reaction, it will shift to the left. Exothermic reactions give off...
Sun Jan 20, 2019 1:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka and Kb as Inverses?
Replies: 7
Views: 471

### Re: Ka and Kb as Inverses?

If we are not given Ka, can we just find Ka by using an ice table?
Sun Jan 13, 2019 9:39 pm
Forum: Ideal Gases
Topic: When to Use PV=nRT
Replies: 8
Views: 558

### Re: When to Use PV=nRT

204929947 wrote:what does PV=nRT stand for???

It represents the ideal gas law.
P= Pressure, V=volume, n= number of moles, R= constant, T= Temperature
Sun Jan 13, 2019 8:50 pm
Forum: Ideal Gases
Topic: R [ENDORSED]
Replies: 5
Views: 323

### Re: R[ENDORSED]

Pressure= atm
V=liters
T=Kelvin
R= .0821 (liters x atm)/(moles x kelvin)
Pressure is usually given in atm, so the units of R would be the unit mentioned above. However, if pressure is given in another unit, the unit of R also changes to correspond to the unit of pressure that is given.
Sun Jan 13, 2019 8:36 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Catalyst
Replies: 4
Views: 110

### Re: Catalyst

A catalyst speeds up the the forward and back reaction by the same amount, which does not change the position of equilibrium.