Search found 16472 matches

by Chem_Mod
Mon Jan 21, 2019 2:12 pm
Forum: Polyprotic Acids & Bases
Topic: Question 6E.3 7th edition
Replies: 2
Views: 27

Re: Question 6E.3 7th edition

The book states that the second deprotonation will always occur, but so long as the provided Ka2 is less than about Ka1/1000 then the second deprotonation will be so small that it will not affect the pH significantly and can thus be ignored.
by Chem_Mod
Mon Jan 21, 2019 2:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: homework
Replies: 2
Views: 20

Re: homework

You should be getting a negative number for pH, this is an extremely strong acid since the concentration of H 3 O + is on an order of magnitude that is greater than 10 -1 . This is when an acid will not follow the normal pH scale, where the pH is between 0 and 14, instead when you have whats called ...
by Chem_Mod
Mon Jan 21, 2019 1:59 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 7th Edition 6B #9
Replies: 1
Views: 24

Re: 7th Edition 6B #9

The answer in the book is actually incorrect. You're answer is correct and the book is almost correct but they made a small mistake. If instead of using [H 3 O + ]* [OH - ] =1 x 10 -14 to find [OH - ], you first convert [H 3 O + ] into pH you would get the pH = -log[1.5]= -0.176. The book says pH=0....
by Chem_Mod
Sun Jan 20, 2019 10:46 pm
Forum: Administrative Questions and Class Announcements
Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Replies: 111
Views: 2589

Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)

Julia Lee wrote:Can someone please explain to me how number 4 part d and number 5 are solved for the the Chemical Equilibrium worksheet?


Hi Julia, can you please detail at which step you are stuck on? Or what concepts you think should be used?
by Chem_Mod
Sun Jan 20, 2019 10:43 pm
Forum: Administrative Questions and Class Announcements
Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Replies: 111
Views: 2589

Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)

Key for Week 2. Good luck on quizzes!

Corrections:

4a is 4.40, not 4.30
by Chem_Mod
Sat Jan 19, 2019 11:00 pm
Forum: Ideal Gases
Topic: ice
Replies: 4
Views: 52

Re: ice

For weak acids and bases the ICE tables are exactly the same as "regular" equilibrium problems. However, for strong acids and bases there are no ICE tables as the species dissociates 100%.
by Chem_Mod
Sat Jan 19, 2019 1:42 pm
Forum: Administrative Questions and Class Announcements
Topic: Week 3 Sun/Mon/Tues UA Sessions
Replies: 1
Views: 325

Week 3 Sun/Mon/Tues UA Sessions

Regarding UA schedule for week 3 due to Monday holiday. On Monday Week 3 (holiday), you may attend Ashley Van Belle, Step-up, 7-9pm in Covel 210 (switched with Lyndon for week 3 only) On Tuesday Week 3, you may attend Lyndon Bui, Workshop, 6-8pm in Covel 210 Students living off-campus can attend ses...
by Chem_Mod
Sat Jan 19, 2019 12:01 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Week 2 Discussion Notes (2E,2I,2K)
Replies: 1
Views: 164

Week 2 Discussion Notes (2E,2I,2K)

Hi all,

Attached please find this week discussion notes.

Have a great long weekend!

Best,
Joyce
by Chem_Mod
Fri Jan 18, 2019 9:29 pm
Forum: Administrative Questions and Class Announcements
Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Replies: 111
Views: 2589

Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)

Here is the worksheet for this Sunday's session covering acid and base calculations:
by Chem_Mod
Fri Jan 18, 2019 9:59 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka vs. Kb
Replies: 11
Views: 56

Re: Ka vs. Kb

Ka and Kb are used for acid and base respectively, usually dealing with the dissociation process in water. Kc is the equalibrium concentration and is used widely used in different reactions.
by Chem_Mod
Thu Jan 17, 2019 11:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Thermodynamic Stability HW 5I.13
Replies: 2
Views: 18

Re: Thermodynamic Stability HW 5I.13

It would be discussed later in thermodynamics, but basically, if the enthalpy is negative, then the product is more stable than the reactant, vice versa
by Chem_Mod
Thu Jan 17, 2019 11:12 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp and Kc Conversions
Replies: 1
Views: 20

Re: Kp and Kc Conversions

Kp=Kc*RT^(delta n)

Delta n is the difference of the sum of the stoichiometric coefficients between the products and the reactants (gaseous only)
by Chem_Mod
Thu Jan 17, 2019 11:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5H.1 7th edition
Replies: 1
Views: 19

Re: 5H.1 7th edition

A hint would be write out the expression for the K for both cases, you would see the K for b is basically the square root of a
by Chem_Mod
Thu Jan 17, 2019 10:58 pm
Forum: Administrative Questions and Class Announcements
Topic: How to find my posts
Replies: 28
Views: 15269

Re: How to find my posts

If you want to create a new post, you would click on a sub topic located on the board index under 14B. You can then click "New Topic" in the upper left hand corner (under the subtopic name). You have to be reading a specific sub-topic to be able to create a "New Topic". If new po...
by Chem_Mod
Thu Jan 17, 2019 5:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Review of Weak Bases
Replies: 2
Views: 29

Re: Review of Weak Bases

Weak bases tend to have Kb values that are less than 10-3. Strong bases tend to have Kb values that are more than 10-3.
by Chem_Mod
Thu Jan 17, 2019 5:01 pm
Forum: Ideal Gases
Topic: 5% rule
Replies: 8
Views: 85

Re: 5% rule

We normally apply the 5% rule to acid/base types of reactions. Essentially though, the idea is to divide the change in dissociation (usually "x") by the original concentration the dissociation came from (whatever quantity you subtract x from).
by Chem_Mod
Thu Jan 17, 2019 2:02 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test 1
Replies: 6
Views: 75

Re: Test 1

About six.
by Chem_Mod
Thu Jan 17, 2019 1:57 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 12.45 6th edition
Replies: 1
Views: 30

Re: 12.45 6th edition

There is more details in the organic section, you can take a look at the nomenclature principles.
by Chem_Mod
Thu Jan 17, 2019 1:56 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Question 5I.13 part b
Replies: 1
Views: 34

Re: Question 5I.13 part b

This might be from solving the quadratic equation. Apply the equation and solve for the answer.
by Chem_Mod
Thu Jan 17, 2019 1:52 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 7th Edition 6B.9
Replies: 1
Views: 18

Re: 7th Edition 6B.9

pH =-log[H3O+], if you plug in the 1.5, you should get about 0.176
by Chem_Mod
Thu Jan 17, 2019 1:47 pm
Forum: Student Social/Study Group
Topic: ICE Table
Replies: 5
Views: 24

Re: ICE Table

We assume that x is much smaller compared to the number that x is being subtracted from (with in 5%). It simplifies the calculation from solving a quadratic equation.
by Chem_Mod
Thu Jan 17, 2019 1:43 pm
Forum: Ideal Gases
Topic: office hours
Replies: 1
Views: 20

Re: office hours

Yes, you you can still ask question on chemistry community
by Chem_Mod
Thu Jan 17, 2019 1:12 pm
Forum: Administrative Questions and Class Announcements
Topic: Homework
Replies: 5
Views: 256

Re: Homework

Yes

Homework is due every week. The homework handed in the day of the test is the same material on the test.

As I have mentioned in class the homework is the best preparation.
by Chem_Mod
Thu Jan 17, 2019 12:49 pm
Forum: Student Social/Study Group
Topic: Equations
Replies: 1
Views: 224

Re: Equations

You will be given the formula.

See the link "Constants and Equations" on my class website.
by Chem_Mod
Thu Jan 17, 2019 12:48 pm
Forum: Student Social/Study Group
Topic: Test #1
Replies: 1
Views: 20

Re: Test #1

This depends on the question, usually gas reactions with given pressures will be a good sign.
by Chem_Mod
Thu Jan 17, 2019 10:53 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Change in Pressure
Replies: 2
Views: 22

Re: Change in Pressure

This is a short cut for changing pressure by reducing V, reaction going toward the direction with less moles of gases will help reduce the effect of increasing the pressure. The more standard approach will be looking at the effect of concentration change
by Chem_Mod
Thu Jan 17, 2019 10:50 am
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: pKa and pKb
Replies: 4
Views: 38

Re: pKa and pKb

A lower pKa value indicates a stronger acid. That is, the lower value indicates the acid more fully dissociates in water.
by Chem_Mod
Thu Jan 17, 2019 10:03 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 12.23 6th Edition
Replies: 2
Views: 22

Re: 12.23 6th Edition

Remember if it is neutral, the concentration of H3O+ and OH- are the same and their product is equal to the Kw
by Chem_Mod
Thu Jan 17, 2019 10:01 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Sixth Edition Question 11.87
Replies: 2
Views: 21

Re: Sixth Edition Question 11.87

It take energy to break the chemical bond in the diatomic gas which will need energy input
by Chem_Mod
Wed Jan 16, 2019 6:39 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solving Cubics [ENDORSED]
Replies: 1
Views: 359

Re: Solving Cubics [ENDORSED]

For Chem 14B simplifying the cubic equation when K is small is part of the syllabus. Solving cubic equations is not part of the syllabus. Therefore examples with large K and solving cubic equations will not occur in Chem 14B. See my detailed Outlines. Below is an example simplifying a cubic equation...
by Chem_Mod
Tue Jan 15, 2019 10:35 pm
Forum: Ideal Gases
Topic: Homework for week 2 [ENDORSED]
Replies: 10
Views: 104

Re: Homework for week 2 [ENDORSED]

Week 1 homework should definitely be equilibrium.

Week 2 homework can be either equilibrium, or acids and bases, or some of both as it is all ‘recently covered material’.

Week 3 homework should definitely be acids and bases.
by Chem_Mod
Tue Jan 15, 2019 10:34 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: test 1 [ENDORSED]
Replies: 7
Views: 101

Re: test 1 [ENDORSED]

See Announcements on my class website.
by Chem_Mod
Mon Jan 14, 2019 10:43 pm
Forum: General Science Questions
Topic: Strong and Weak Acids and Bases
Replies: 2
Views: 40

Re: Strong and Weak Acids and Bases

Strong acids and bases are defined as those which dissociate 100% in solution. Identifying an acid as strong or weak is memorization. There is a list of strong acids and bases in the textbook.
by Chem_Mod
Mon Jan 14, 2019 4:25 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Module 4 Post Assessment #14
Replies: 3
Views: 50

Re: Module 4 Post Assessment #14

Water being added does not shift the reaction in any particular way because it is a liquid solvent that is in excess. Partial pressure and moles/concentration are all analogous, when thinking about Le Chatelier's Principle. Therefore, if the partial pressure of CO2 (a reactant) is decreased then the...
by Chem_Mod
Mon Jan 14, 2019 4:13 pm
Forum: Student Social/Study Group
Topic: New to Lavelle
Replies: 32
Views: 422

Re: New to Lavelle

As a UA who has taken the course and has been a UA for multiple quarters, I found the notes I took during lecture along with the assigned homework problems to be the most helpful. Both of these resources can adequately prepare you for the midterm and the final. If you have questions/need extra help,...
by Chem_Mod
Mon Jan 14, 2019 4:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K changing with temperature [ENDORSED]
Replies: 3
Views: 39

Re: K changing with temperature [ENDORSED]

Equilibrium constants change from temperature. Other changes, like changing concentration, will shift a reaction out of equilibrium, but the reaction will eventually return to equilibrium with the same K. Only temperature permanently alters a K. Changing pressure does not affect K, but changing conc...
by Chem_Mod
Mon Jan 14, 2019 1:36 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Exothermic Reaction
Replies: 3
Views: 32

Re: Exothermic Reaction

We can consider heat to be a product of an exothermic reaction. Therefore raising the temperature (adding heat) adds more "product," so the reaction shifts towards reactants.
by Chem_Mod
Mon Jan 14, 2019 1:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentration Affecting K
Replies: 7
Views: 48

Re: Concentration Affecting K

K is the standard we use to determine if a reaction is at equilibrium or determine what the concentrations should be at equilibrium. If we change the concentrations, we change Q and may cause the reaction to temporarily not be at equilibrium, but we do not change K.
by Chem_Mod
Mon Jan 14, 2019 1:26 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Types of Chemical Reactions
Replies: 3
Views: 34

Re: Types of Chemical Reactions

There are some reactions with ∆H = 0 called thermoneutral reactions, and temperature will not alter the equilibrium concentrations. However, they are rarely encountered.
by Chem_Mod
Mon Jan 14, 2019 1:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pure Liquids and Pure Solids
Replies: 5
Views: 40

Re: Pure Liquids and Pure Solids

The activities of pure liquids and solids are technically included in the equilibrium constant, but their activities do not change during the reaction, so the value of 1 is accurately used for their activities (or concentrations).
by Chem_Mod
Mon Jan 14, 2019 1:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: solids on the reactant side
Replies: 3
Views: 23

Re: solids on the reactant side

If a reactant or product is written as X(aq), it is dissolved in water, and water is present, even if not directly involved in the reaction. If it is listed as X(s), do not assume there is water unless it is explicitly written as a reactant or product or another reactant or product is aqueous. The w...
by Chem_Mod
Mon Jan 14, 2019 1:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 7th edition 5I.29
Replies: 1
Views: 20

Re: 7th edition 5I.29

Will you write out the question for those who don't have the 7th edition?
by Chem_Mod
Mon Jan 14, 2019 1:02 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 7th Edition Problem 5.35
Replies: 2
Views: 66

Re: 7th Edition Problem 5.35

Will you write out the question for those who don't have the 7th edition?
by Chem_Mod
Mon Jan 14, 2019 9:52 am
Forum: Administrative Questions and Class Announcements
Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Replies: 111
Views: 2589

Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)

Key for worksheet 1. Please note corrections: 1) #3 and #8, some reactants/products are in the solid phase. 2) 8c: I2 favors neither direction because it is in the solid phase, so it does not affect equilibrium, not because it is an inert gas. Inert gases are the last column of the periodic table (n...
by Chem_Mod
Sun Jan 13, 2019 6:34 pm
Forum: Ideal Gases
Topic: Units
Replies: 3
Views: 27

Re: Units

There are several difference units that can be used to describe the pressure of a gas (bar, atm, mmHg, torr etc...). While any of them can be used to describe the pressure of a gas, when doing calculations using the ideal gas law (PV=nRT), you need to make sure to use the correct gas constant (R) wh...
by Chem_Mod
Sat Jan 12, 2019 12:58 pm
Forum: Administrative Questions and Class Announcements
Topic: Peer Learning Sessions [ENDORSED]
Replies: 10
Views: 6342

Re: Peer Learning Sessions [ENDORSED]

There was a note on the door letting students know where to go as that room was locked and key could not be found. First day hiccup which is now fixed.
by Chem_Mod
Sat Jan 12, 2019 12:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium being shifted
Replies: 1
Views: 32

Re: Equilibrium being shifted

An equilibrium is said to either favor the reactants or products. However, adding a reactant or product (or changing something such as the pressure/volume when gasses are involved) SHIFT the equilibrium. The professor didn't want the word "shift" to be used when talking about which side of...
by Chem_Mod
Sat Jan 12, 2019 12:27 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solids and Liquids in Rxn
Replies: 6
Views: 46

Re: Solids and Liquids in Rxn

There are very very few reactions (if any at all) in which a pure solid and liquid react to yield another pure solid or liquid. If a pure solid and liquid did react, the resulting product would be dissolved to some extent in the pure liquid and thus have a concentration which would appear in the equ...
by Chem_Mod
Sat Jan 12, 2019 11:41 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: compression vs pressure
Replies: 6
Views: 233

Re: compression vs pressure

The relationship between pressure and volume is described by Boyle's Law which is PV=a constant. This shows us that pressure and volume have an inverse relationship. This means increasing the volume leads to a decrease in pressure while decreasing the volume leads to an increase in pressure. This is...
by Chem_Mod
Sat Jan 12, 2019 11:37 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier's Principle: Change in temperature
Replies: 2
Views: 21

Re: Le Chatelier's Principle: Change in temperature

The equilibrium constant of a reaction is essentially a ratio of the rate constant of the forward reaction to the rate constant of the reverse reaction (we have not discussed this in class). These rate constants are temperature dependent. This is why the K is dependent on temperature.
by Chem_Mod
Sat Jan 12, 2019 12:16 am
Forum: Administrative Questions and Class Announcements
Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Replies: 111
Views: 2589

DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)

Welcome back Chem 14B students! For those of you who aren't familiar with me, my name is Karen Leung, one of your UAs this quarter. I will be hosting workshops every Sunday 7-9pm this quarter, and I use worksheets I have made to facilitate my workshops. They will be posted on this SAME post here eve...
by Chem_Mod
Sat Jan 12, 2019 12:06 am
Forum: Administrative Questions and Class Announcements
Topic: Peer Learning Sessions [ENDORSED]
Replies: 10
Views: 6342

Re: Peer Learning Sessions [ENDORSED]

As I announced in class: Covel sessions started Wednesday Week 1.

I will follow up on this.
by Chem_Mod
Sat Jan 12, 2019 12:03 am
Forum: Ideal Gases
Topic: Pressure of gasses
Replies: 5
Views: 43

Re: Pressure of gasses

This is more of a physics topic but if your interested this is the general idea: To calculate the weight of the liquid we use the equation: weight (force)=mg (mass x gravity constant). The mass of the liquid can be determined using both the volume of the liquid and its density (m=Vd : where V=volume...
by Chem_Mod
Fri Jan 11, 2019 11:55 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Changes in Systems
Replies: 3
Views: 30

Re: Changes in Systems

Changing the pressure/volume of a reaction does not change the equilibrium constant but changing the temperature ALWAYS changes the equilibrium constant. This is becasue an equilibrium is in essence, a ratio of the rate constant of the forward reaction over the rate constant of the reverse reaction....
by Chem_Mod
Fri Jan 11, 2019 11:49 pm
Forum: Ideal Gases
Topic: Ideal Gases
Replies: 3
Views: 33

Re: Ideal Gases

In reality, no gas is ideal. An ideal gas is a theoretical gas which we give certain properties which allows us to simplify calculations. We can use these calculations as well as correction factors to make calculations about real gases. The ideal gas law is used to make calculations about ideal gass...
by Chem_Mod
Fri Jan 11, 2019 11:44 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating Kc
Replies: 4
Views: 30

Re: Calculating Kc

The chemical equation needs to be balanced becasue in the equilibrium equation, each species is raised to the power of its stoichiometric coefficient (which is obtained from the balanced chemical equation).
by Chem_Mod
Fri Jan 11, 2019 10:11 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Changing Pressure
Replies: 6
Views: 43

Re: Changing Pressure

Boyle's Gas Law (which we did not yet cover) says that pressure and volume are inversely related. Therefore, increasing the volume results in a decrease of pressure while a decrease of volume results in an increase of pressure. when an inert gas is added to the system in equilibrium at constant volu...
by Chem_Mod
Fri Jan 11, 2019 10:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc and Kp
Replies: 12
Views: 62

Re: Kc and Kp

Pure liquids and solids are not included in the equilibrium equation. This is becasue they dont really have a concentration. On another note, please be aware that this doesn't mean water isnt included in the equilibrium equation. If a reaction involves water as a gas then it IS included in the equil...
by Chem_Mod
Fri Jan 11, 2019 10:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Constant Values
Replies: 3
Views: 27

Re: Equilibrium Constant Values

Equilibrium constants are never memorized as they are dependent on temperature (which means one would have to memorize them for every temperature). You will always be given the appropriate information needed to answer a question and should not be worried about memorizing any equilibrium constants.
by Chem_Mod
Fri Jan 11, 2019 10:05 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Effect of Pressure
Replies: 3
Views: 27

Re: Effect of Pressure

Just to clarify things, increasing the pressure (which can be done by decreasing the volume) or decreasing the pressure (which can be done by increasing the volume) does not result in a change in the equilibrium constant. It DOES however change the CONCENTRATION of the gasses as concentration is def...
by Chem_Mod
Fri Jan 11, 2019 10:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentration of P using the Quadratic Formula
Replies: 3
Views: 23

Re: Concentration of P using the Quadratic Formula

A quadratic equation by definition is one which can be expressed as Ax^2+Bx+C=0. The solution to these equations are values of x which when plugged into the equation make the equation shown true, and thus equal to zero.
by Chem_Mod
Fri Jan 11, 2019 9:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentration of P using the Quadratic Formula
Replies: 2
Views: 19

Re: Concentration of P using the Quadratic Formula

A quadratic equation by definition is one which can be expressed as Ax^2+Bx+C=0. The solution to these equations are values of x which when plugged into the equation make the equation shown true, and thus equal to zero.
by Chem_Mod
Fri Jan 11, 2019 3:34 pm
Forum: Ideal Gases
Topic: Week 1 Discussion Notes (2E, 2I, 2K)
Replies: 2
Views: 193

Week 1 Discussion Notes (2E, 2I, 2K)

Hi,

Attached please find notes and worksheet answer for week 1.

Best,
Joyce
by Chem_Mod
Thu Jan 10, 2019 9:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: HW Problem 5H.1 [ENDORSED]
Replies: 4
Views: 45

Re: HW Problem 5H.1 [ENDORSED]

If a reaction is multiplied by a number X, the equilibrium constant K' of the new reaction will be K^(X)
by Chem_Mod
Thu Jan 10, 2019 9:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Liquids and Solids in Equilibrium Constants
Replies: 5
Views: 36

Re: Liquids and Solids in Equilibrium Constants

The change of concentration for solid and liquid are so small so that they can be neglected.
by Chem_Mod
Thu Jan 10, 2019 9:25 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Definition of equilibrium
Replies: 4
Views: 33

Re: Definition of equilibrium

The concentration of both reactants and products do not change.
by Chem_Mod
Thu Jan 10, 2019 9:12 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 11.13
Replies: 1
Views: 38

Re: 11.13

If you look at all the components in the equilibrium constant K, you can find that for a and c, both of them only contain gases, for b there is no gas. However, you can also write a and c in terms of concentration.
by Chem_Mod
Thu Jan 10, 2019 9:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: calculation of equilibrium constant
Replies: 2
Views: 23

Re: calculation of equilibrium constant

For 1, you can use concentration in the calculation
For 2, if water is, for example, in the gas phase in the reaction
by Chem_Mod
Thu Jan 10, 2019 6:52 pm
Forum: Administrative Questions and Class Announcements
Topic: Audio-Visual Focus-Topics
Replies: 2
Views: 29

Re: Audio-Visual Focus-Topics

Much better to learn by discussing them.
by Chem_Mod
Thu Jan 10, 2019 2:44 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6th edition, 11.7?
Replies: 4
Views: 65

Re: 6th edition, 11.7?

You need to set up a I.C.E table, only one pressure was given but you can find the percent of dissociation in the picture which points to the change during the reaction.
by Chem_Mod
Thu Jan 10, 2019 2:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: How to use ICE tables
Replies: 5
Views: 60

Re: How to use ICE tables

Yes. Because, partial pressure in a gas reaction is essentially a way to represent concentration and you can use the ideal gas law to convert.
by Chem_Mod
Thu Jan 10, 2019 2:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 7th Edition 5.H.3
Replies: 1
Views: 28

Re: 7th Edition 5.H.3

My advice will be to write out the expression for K in each step reaction and for the overall reaction. You will see why it is multiplication rather than addition.
by Chem_Mod
Thu Jan 10, 2019 2:15 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Integrated Exercises 11.91
Replies: 1
Views: 16

Re: Integrated Exercises 11.91

In addition to paste the question, please specify what is your concern on this?
by Chem_Mod
Thu Jan 10, 2019 1:14 pm
Forum: Ideal Gases
Topic: alternative forms of the equilibrium constant
Replies: 3
Views: 23

Re: alternative forms of the equilibrium constant

Samantha Hoegl Roy 2C wrote:
Chem_Mod wrote:Hi,
Could you show where you get this?

page 412 in the 7th edition, topic 5H.3


I see, you just need to know how to convert Kc and Kp if necessary, don't bother too much about remembering the long equation.
by Chem_Mod
Thu Jan 10, 2019 1:10 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Keq vs. Kc vs. Kp
Replies: 3
Views: 28

Re: Keq vs. Kc vs. Kp

Kp is more convenient if the reaction contains gases. Depend on each question, one might be better than others, but you can write any of them if there is no instruction in the question.
by Chem_Mod
Thu Jan 10, 2019 12:39 pm
Forum: Ideal Gases
Topic: alternative forms of the equilibrium constant
Replies: 3
Views: 23

Re: alternative forms of the equilibrium constant

Hi,
Could you show where you get this?
by Chem_Mod
Tue Jan 08, 2019 8:41 am
Forum: Administrative Questions and Class Announcements
Topic: Yekan Discussion slides (1B, 1H, 1J)
Replies: 6
Views: 258

Yekan Discussion slides (1B, 1H, 1J)

You can find the discussion slides for each week below
by Chem_Mod
Mon Jan 07, 2019 4:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.13 Reaction Quotient [ENDORSED]
Replies: 3
Views: 47

Re: 11.13 Reaction Quotient [ENDORSED]

No, equilibrium constant is signified by the letter K while reaction quotient is signified by the letter Q. K implies the reaction is at equilibrium meaning that it has reacted fully while Q is for reactions that are not at equilibrium.There is only one K, however you can solve for Q at any point wh...
by Chem_Mod
Mon Jan 07, 2019 4:25 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solids and Liquids
Replies: 4
Views: 39

Re: Solids and Liquids

We never include solids or liquids in equilibrium expressions.
by Chem_Mod
Mon Jan 07, 2019 4:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Activity and Concentration
Replies: 2
Views: 31

Re: Activity and Concentration

Activity is essentially how a certain concentration of a solution is acting relative to its actual concentration. It comes from the fact that very concentrated solutions will either express a property more highly or less highly due to non-ideal interactions. It is a little bit more conceptual than y...
by Chem_Mod
Mon Jan 07, 2019 4:22 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Activity and Concentration
Replies: 2
Views: 31

Re: Activity and Concentration

We do not go into detail on chemical activity, but it is a unitless quantity that we have replaced (by approximation) with concentration. This means for equilibrium constants, do not use units.
by Chem_Mod
Mon Dec 10, 2018 10:40 am
Forum: Lewis Acids & Bases
Topic: table 12.6
Replies: 1
Views: 79

Re: table 12.6

Take a look at the detailed answers in the homework problems on this topic to see the individual answers that differ from acid to acid.
by Chem_Mod
Mon Dec 10, 2018 10:36 am
Forum: Amphoteric Compounds
Topic: Amphoteric vs Amphiprotic [ENDORSED]
Replies: 1
Views: 53

Re: Amphoteric vs Amphiprotic [ENDORSED]

Correct
by Chem_Mod
Mon Dec 10, 2018 10:34 am
Forum: Amphoteric Compounds
Topic: acidic oxide [ENDORSED]
Replies: 1
Views: 37

Re: acidic oxide [ENDORSED]

The non-metals (C, N, S, etc.,) form oxides that produce acidic oxides such as:
H2CO3
HNO3
H2SO4
by Chem_Mod
Mon Dec 10, 2018 10:32 am
Forum: Biological Examples
Topic: Iron in myoglobin [ENDORSED]
Replies: 1
Views: 72

Re: Iron in myoglobin [ENDORSED]

Because the other 5 positions already have bonds.
by Chem_Mod
Sun Dec 09, 2018 10:16 pm
Forum: General Science Questions
Topic: Final Grades
Replies: 2
Views: 90

Re: Final Grades

Sometime after finals week.
by Chem_Mod
Sun Dec 09, 2018 4:48 pm
Forum: Administrative Questions and Class Announcements
Topic: Saying Thank You to Dr. Lavelle
Replies: 186
Views: 39394

Re: Saying Thank You to Dr. Lavelle

Thank-You!

Many great comments!

Encourages me to keep going and assisting young minds!
by Chem_Mod
Sun Dec 09, 2018 4:42 pm
Forum: Administrative Questions and Class Announcements
Topic: Thank you!
Replies: 1
Views: 50

Re: Thank you!

It was a super active quarter!
Great you found Chemistry Community helpful!
:-)
by Chem_Mod
Sun Dec 09, 2018 4:23 pm
Forum: Administrative Questions and Class Announcements
Topic: Worksheet 4 Key
Replies: 1
Views: 58

Re: Worksheet 4 Key

I am not aware of a worksheet 4.
Email whoever gave you one.
by Chem_Mod
Sun Dec 09, 2018 4:22 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: ionic and covalent character
Replies: 1
Views: 61

Re: ionic and covalent character

Only bonds can have ionic or covalent character.
by Chem_Mod
Sun Dec 09, 2018 2:56 pm
Forum: Administrative Questions and Class Announcements
Topic: Lost Items in Exam Rooms [ENDORSED]
Replies: 1
Views: 567

Lost Items in Exam Rooms [ENDORSED]

Several students left water bottles, etc., in exam rooms.
Go to your exam room to collect them.
by Chem_Mod
Sun Dec 09, 2018 1:14 pm
Forum: Calculating the pH of Salt Solutions
Topic: 6D.11
Replies: 1
Views: 39

Re: 6D.11

You change the salt because water now becomes a very saturating ligand (considering the metal is now surrounded by water) so it replaces chlorine. Metal cations usually act as acids because their positive charge will lead them to form ionic compounds with hydroxide ions in solution, therefore increa...
by Chem_Mod
Sun Dec 09, 2018 1:11 pm
Forum: Calculating the pH of Salt Solutions
Topic: Error in 6B.5 e)?
Replies: 1
Views: 23

Re: Error in 6B.5 e)?

Can you please post the full question so that everyone can have it for reference?
by Chem_Mod
Sun Dec 09, 2018 1:11 pm
Forum: Identifying Acidic & Basic Salts
Topic: Question J.15 (Sixth Edition)
Replies: 1
Views: 33

Re: Question J.15 (Sixth Edition)

Let's do an example. For part a, the counterion that is a weak base is the phenolate ion (C6H5O-). This would pick up proton to become phenol in solution, so the equation would be the phenolate ion plus hydronium, yields phenol.
by Chem_Mod
Sun Dec 09, 2018 1:09 pm
Forum: Amphoteric Compounds
Topic: 6A.17 (admin?)
Replies: 1
Views: 32

Re: 6A.17 (admin?)

Can you please post the question so that everyone can easily reference it?
by Chem_Mod
Sun Dec 09, 2018 1:08 pm
Forum: Lewis Acids & Bases
Topic: Question 12.53 (Sixth Edition)
Replies: 1
Views: 31

Re: Question 12.53 (Sixth Edition)

Trifluoroacetic acid is stronger because the negative charge that arises from deprotonation is better stabilized by the inductive effect from the three fluorines. Formic acid is the stronger acid in the second pair because hydrogen is less electron donating than a methyl group, so the negative charg...

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