Search found 43 matches

by ng1D
Sun Mar 15, 2020 7:58 am
Forum: Van't Hoff Equation
Topic: Chemistry analysis
Replies: 1
Views: 71

Chemistry analysis

What is a "chemistry" van't Hoff analysis to calculate ∆H°, ∆S° and ∆G°?
by ng1D
Sun Mar 15, 2020 7:55 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: ∆U and ∆H
Replies: 1
Views: 64

∆U and ∆H

Why does when q = qP then ∆U = ∆H - P∆V?
by ng1D
Sun Mar 15, 2020 7:51 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: pH of acids
Replies: 11
Views: 252

pH of acids

Why do solutions of weak acids have higher pH values than solutions of strong acids at the same concentration?
by ng1D
Sun Mar 08, 2020 11:49 pm
Forum: General Rate Laws
Topic: Rate change and species relation
Replies: 1
Views: 21

Rate change and species relation

How do we show how the rate of change of one species in a reaction is related to that of another species? Are they in the same reaction?
by ng1D
Sun Mar 08, 2020 11:47 pm
Forum: General Rate Laws
Topic: Elementary reactions
Replies: 5
Views: 27

Elementary reactions

For one of the learning outcomes, it says to write rate laws for elementary reactions. What is meant by elementary reactions?
by ng1D
Sun Mar 08, 2020 11:44 pm
Forum: General Rate Laws
Topic: Integrated rate law
Replies: 1
Views: 32

Integrated rate law

How do we know when to use an integrated rate law or k[A]? What is the difference?
by ng1D
Sun Mar 08, 2020 11:41 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Tangent
Replies: 3
Views: 43

Tangent

How do we show how the instantaneous rate is obtained by drawing a tangent to the graph of concentration versus time? Is there an equation or graph we need to know?
by ng1D
Sun Mar 08, 2020 11:38 pm
Forum: Zero Order Reactions
Topic: Order reactions and rate
Replies: 2
Views: 25

Order reactions and rate

How can I tell the difference between order reactions? What is the difference between order reactions and rate reactions?
by ng1D
Sun Mar 01, 2020 5:58 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electromotive force
Replies: 2
Views: 24

Electromotive force

What is the electromotive force and why does it represent the maximum potential difference?
by ng1D
Sun Mar 01, 2020 5:51 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electrochemical Series
Replies: 3
Views: 36

Re: Electrochemical Series

So given a reaction, we should be able to know if it is in its reduction or oxidation form?
by ng1D
Sun Mar 01, 2020 5:29 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Free energy
Replies: 3
Views: 61

Free energy

What do we need to know about the relationship between free energy and cell potentials?
by ng1D
Sun Mar 01, 2020 5:07 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electrochemical Series
Replies: 3
Views: 36

Electrochemical Series

From the learning outcomes, what does it mean that we should understand what is meant by the electrochemical series?
by ng1D
Sun Mar 01, 2020 5:02 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Calculating E°cell
Replies: 2
Views: 36

Calculating E°cell

What is the difference between E°cell= E°cathode − E°anode and E°cell= E°+E° and when would I use one over the other?
by ng1D
Sun Feb 16, 2020 6:18 pm
Forum: Balancing Redox Reactions
Topic: Half reactions
Replies: 7
Views: 69

Re: Half reactions

When balancing redox reactions, are we balancing the number of atoms or electrons?
by ng1D
Sun Feb 16, 2020 5:25 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Equilibrium [ENDORSED]
Replies: 3
Views: 51

Equilibrium [ENDORSED]

When a reaction of a system is at equilibrium, why is there no work done by the reaction?
by ng1D
Sun Feb 16, 2020 5:21 pm
Forum: Van't Hoff Equation
Topic: Temperature and K
Replies: 2
Views: 32

Temperature and K

How is K temperature dependent using the Van't Hoff Equations?
by ng1D
Sun Feb 16, 2020 5:09 pm
Forum: Balancing Redox Reactions
Topic: Half reactions
Replies: 7
Views: 69

Half reactions

In lecture, a redox reaction was separated into half reactions. What are half reactions and how are they separated?
by ng1D
Sun Feb 16, 2020 3:39 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Pressure
Replies: 3
Views: 38

Pressure

Does pressure affect free energy? If it does how?
by ng1D
Sat Feb 08, 2020 9:59 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy and Pressure
Replies: 3
Views: 30

Re: Entropy and Pressure

I think that when pressure increases, volume decreases and when volume decreases entropy also decreases.
by ng1D
Sat Feb 08, 2020 8:42 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Predicting Entropy
Replies: 2
Views: 44

Predicting Entropy

What compositions and conditions of a system would help predict which of two systems has the greater entropy?
by ng1D
Sat Feb 08, 2020 8:12 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Measuring ∆G°
Replies: 2
Views: 32

Measuring ∆G°

In class on Friday, it was mentioned that ∆G°is not measured directly. What does it mean that ∆G°is not measured directly?
by ng1D
Fri Feb 07, 2020 10:44 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneous Reaction
Replies: 8
Views: 54

Spontaneous Reaction

How do you how Gibbs Free Energy change accompanying a process is related to the direction of a spontaneous reaction? Does it mean that when ∆G is negative, a reaction is spontaneous?
by ng1D
Fri Feb 07, 2020 10:35 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: ∆H and q
Replies: 1
Views: 35

∆H and q

∆Ssurr=q(rev)/T can also be written as ∆Ssurr=∆H(sys)/T. Why can ∆H be used in place of q?
by ng1D
Sun Feb 02, 2020 8:38 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Microstates
Replies: 4
Views: 85

Microstates

What is the relationship between microstates and degeneracy? Are they the same thing or are the number of microstates related to degeneracy?
by ng1D
Sun Feb 02, 2020 8:01 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Identifying
Replies: 4
Views: 39

Identifying

In thermodynamic, why is it necessary to identify which type of system a reaction is occurring in?
by ng1D
Sun Feb 02, 2020 7:43 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: deltaU and deltaH
Replies: 4
Views: 43

deltaU and deltaH

What are the differences and similarities between deltaU and deltaH?
by ng1D
Sun Feb 02, 2020 7:38 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Constant Pressure
Replies: 2
Views: 21

Constant Pressure

When a reaction has a constant pressure, why is PdeltaV insignificant when the reaction involves solids and liquids?
by ng1D
Sun Feb 02, 2020 7:36 pm
Forum: Calculating Work of Expansion
Topic: Volume
Replies: 3
Views: 27

Volume

What is the relationship between volume and work? What would happen if volume increases/decreases?
by ng1D
Sat Jan 25, 2020 2:09 pm
Forum: Phase Changes & Related Calculations
Topic: Phase changes
Replies: 7
Views: 49

Phase changes

Are phase changes identified by a change from solid to liquid to gas and vice versa? And why does temperature remain constant during a phase change?
by ng1D
Sat Jan 25, 2020 1:49 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard state
Replies: 3
Views: 21

Standard state

What is the standard state of a substance and how do I know if a substance is in its standard state?
by ng1D
Sat Jan 25, 2020 9:31 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Melting and freezing
Replies: 7
Views: 68

Re: Melting and freezing

Yes, freezing would be an exothermic reaction because heat is released.
by ng1D
Sat Jan 25, 2020 9:24 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 5
Views: 52

Hess's Law

What is Hess's Law and how does it relate to state properties?
by ng1D
Sat Jan 25, 2020 9:21 am
Forum: Phase Changes & Related Calculations
Topic: Endothermic and Exothermic
Replies: 13
Views: 89

Endothermic and Exothermic

How do you tell whether a reaction is endothermic or exothermic by the direction of heat flow?
by ng1D
Fri Jan 17, 2020 8:49 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pH values of weak and strong acids
Replies: 6
Views: 48

pH values of weak and strong acids

Can someone explain why solutions of weak acids have higher pH values than solutions of strong acids at the
same concentration?
by ng1D
Fri Jan 17, 2020 8:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solubility
Replies: 2
Views: 42

Solubility

How do we use equilibrium constants to predict solubility?
by ng1D
Thu Jan 16, 2020 11:03 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Acids and Bases on test?
Replies: 3
Views: 32

Re: Acids and Bases on test?

There are learning outcomes for acids and bases on our class website. The link for the acid and bases learning outcomes: https://lavelle.chem.ucla.edu/wp-content/supporting-files/Chem14B/Chem14B_Outline2_Acids_and_Bases.pdf
by ng1D
Thu Jan 16, 2020 8:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Weak and strong acids/bases
Replies: 2
Views: 21

Weak and strong acids/bases

What is the difference between calculating weak acids or bases and strong acids or bases?
by ng1D
Thu Jan 16, 2020 3:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Approximation
Replies: 8
Views: 65

Re: Approximation

You would add for the reactants and subtract for products
by ng1D
Fri Jan 10, 2020 2:08 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: N2+3H2<->2NH3
Replies: 5
Views: 52

N2+3H2<->2NH3

What happens if N2 is increased, NH3 is increased, or H2 decreased? What does it mean when they go to the left or right?
by ng1D
Thu Jan 09, 2020 1:19 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q vs K
Replies: 8
Views: 75

Re: Q vs K

Q and K are similar in that they are calculated in the same way, Q = [P]/[R] and K = [P]/[R].
by ng1D
Thu Jan 09, 2020 12:55 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G3
Replies: 8
Views: 60

Re: 5G3

Gases are included in equilibrium constant equations.
by ng1D
Thu Jan 09, 2020 12:41 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.1C
Replies: 3
Views: 54

Re: 5G.1C

The equilibrium constant will remain the same because it is not affected by the amount of reactants or products. If there is a higher pressure of reactant, the pressure of the products will change so that it equals the equilibrium constant, which remains constant.
by ng1D
Thu Jan 09, 2020 12:11 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.7
Replies: 2
Views: 42

Re: 5G.7

Kp is the partial pressure equilibrium constant, which would be used for gases, but partial pressure can be converted into concentration of a gas by using the ideal gas law. I think because partial pressure can be converted into concentration, Kc can be used for gases.

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