## Search found 110 matches

Sat Mar 14, 2020 1:01 pm
Forum: Conjugate Acids & Bases
Topic: buffer solutions
Replies: 5
Views: 301

### Re: buffer solutions

I dont think so. But where is the information for this topic in the textbook?
Sat Mar 14, 2020 12:53 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concentration Cells
Replies: 8
Views: 152

### Re: Concentration Cells

Does the cell flow from anode to cathode or cathode to anode? which has the higher concentration anode or cathode?
Tue Mar 10, 2020 8:55 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 7.11
Replies: 1
Views: 37

### 7.11

My confusion is with part A. How do we determine which part is the slowest? Which affects the rate law?
Tue Mar 10, 2020 2:59 pm
Forum: Zero Order Reactions
Topic: Elementary Reactions
Replies: 5
Views: 103

### Re: Elementary Reactions

How are we supposed to know if something is an elementary reaction? What exactly is different from an elementary reactions and a classic reaction?
Tue Mar 10, 2020 2:58 pm
Forum: Zero Order Reactions
Topic: Elementary Reactions
Replies: 5
Views: 103

### Elementary Reactions

Is it true that coefficients to dont influence rate laws for elementary reactions?
Tue Mar 10, 2020 10:57 am
Forum: Second Order Reactions
Topic: Termolecular
Replies: 15
Views: 468

### Re: Termolecular

Termolecular reactions are when three molecules are involved in a rate law such as A+A+A=C or A+B+B=C
Tue Mar 10, 2020 10:55 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Instantaneous Rate
Replies: 13
Views: 185

### Re: Instantaneous Rate

Instantaneously was rate decreases with time. If you think about it, it makes sense that the reaction would slow as more of the reactants have been used up;.
Tue Mar 10, 2020 10:52 am
Forum: Zero Order Reactions
Topic: Zero Order
Replies: 8
Views: 88

### Re: Zero Order

As far as I can tell zero order reactions are not that common, but they proceed when the rate of the reaction is independent of the concentration of the substances.
Thu Mar 05, 2020 10:57 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6N.23
Replies: 1
Views: 52

### Re: 6N.23

a) You must pick metals that are below titanium in the electrochemical series. Meaning they are stronger reducing agents. For example aluminum or magnesium. b) cost, availability, and environmental impact c) Iron (Fe) is a stronger reducing agent so it could act as the anode of an electrochemical ch...
Thu Mar 05, 2020 10:43 am
Forum: Balancing Redox Reactions
Topic: Oxidation number
Replies: 5
Views: 62

### Re: Oxidation number

I've attached an image of a rule chart that I use. But basically you set up an algebraic equation for each compound and solve for the elements whose oxidation number you do not know.
Thu Mar 05, 2020 10:37 am
Forum: Balancing Redox Reactions
Topic: Acidic and Basic Redox Reactions
Replies: 9
Views: 77

### Re: Acidic and Basic Redox Reactions

The question will usually specify acidic or basic solution. If no solution is specified assume acidic.
Tue Feb 25, 2020 3:40 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6N.1
Replies: 2
Views: 62

### 6N.1

Why does the answer key use two electrons in the cathode reaction? Wouldn't one electron be sufficient to balance the charge from 3+ to 2+.
Mon Feb 24, 2020 9:22 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Anode/ Cathode
Replies: 3
Views: 53

### Anode/ Cathode

When is a reducing agent an anode or cathode? I thought the general rule was that oxidation= anode and reduction=cathode but If you look at the screen shot this problem uses the reverse. I am confused.
Mon Feb 24, 2020 9:19 pm
Forum: Balancing Redox Reactions
Topic: 6K.3 Part D
Replies: 3
Views: 73

### Re: 6K.3 Part D

This one was very confusing for me as well, but I think since Cl2 has to serve as both the oxidizing and reducing agent, if Cl is getting oxidized in Cl2 --> HClO, then the Cl2 also needs to get reduced somehow. The easiest way for this to occur would be to make the other half reaction Cl2 --> 2 Cl...
Sat Feb 22, 2020 12:21 pm
Forum: Balancing Redox Reactions
Topic: 6K.3 Part D
Replies: 3
Views: 73

### 6K.3 Part D

The answer key converts Cl2 on the products side of the equation to 2Cl-. Why does it do this? How would I know to do this is a similar problem?
Sat Feb 22, 2020 8:00 am
Forum: Balancing Redox Reactions
Topic: 6K.1
Replies: 3
Views: 45

### 6K.1

Why does the answer key use 2 electrons for the oxidation reaction when the oxidation number only changes by 1? Why does the answer key use 6 electrons for the reduction reaction when the oxidation number only changes by 3?
Tue Feb 11, 2020 4:20 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Stability and Bond Enthalpy
Replies: 3
Views: 35

### Re: Stability and Bond Enthalpy

Bond enthalpy denotes the amount of energy necessary to break or form a given bond. Thus the higher the bond enthalpy the tighter the bond.
Tue Feb 11, 2020 4:17 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat capacity
Replies: 3
Views: 56

### Re: Heat capacity

An easy way to decide which heat capacity to use is to write the c value last. Then choose the C value in which the correct units cancel. This is also applicable to deciding which R constant to use.
Tue Feb 11, 2020 4:15 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4E.5
Replies: 4
Views: 49

### Re: 4E.5

You first must draw out all of the Lewis structures. Then count all the bonds on the left side of the equation and all of the bonds on the right side of the equation. Then do bonds broken- bonds formed.
Tue Feb 11, 2020 4:12 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Units for Enthalpy
Replies: 2
Views: 26

### Re: Units for Enthalpy

The units for Enthalpy or delta H are in KJ/mol. If they are written in just KJ, 1 mole is assumed or there is a predefined mass.
Tue Feb 11, 2020 4:10 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Units for delta H
Replies: 3
Views: 66

### Re: Units for delta H

The unit for Delta H are KJ/mol. If the problem just says KJ, 1 mol is assumed or a predefined mass has already been stated.
Tue Feb 11, 2020 4:08 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta G and spontaneity
Replies: 4
Views: 59

### Delta G and spontaneity

I know a negative delta g means the reaction is spontaneous. A positive delate g means the reaction is not spontaneous. But does a negative delta g means the reaction favors products and a positive delta g means the reaction favors reactants.
Thu Feb 06, 2020 5:00 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 4.43
Replies: 3
Views: 48

### Re: 4.43

Matt Sanruk 2H wrote:Since it's at STP, the value must at the a value of 273.15k

What is STP?
Wed Feb 05, 2020 11:41 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 4.43
Replies: 3
Views: 48

### 4.43

Why did the solution manual use 273K rather than the 298K discussed earlier?
Sun Feb 02, 2020 4:32 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 4G.5
Replies: 1
Views: 32

### 4G.5

How do you determine the number of orientations for these cis/ trans structures?
Fri Jan 31, 2020 7:28 pm
Forum: Phase Changes & Related Calculations
Topic: DELTA H Vs Q
Replies: 7
Views: 66

### DELTA H Vs Q

SO are the units of Delta H KJ per mole while the units of Q are just KJ.
Fri Jan 31, 2020 7:25 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D.15
Replies: 4
Views: 55

### Re: 4D.15

The equations the solution manual uses are combustion reactions. Because we are told the substances’ enthalpy of combustion we can first write out those combustion reactions as the solution manual did. A combustion reaction happens when a substance reacts with water and produces CO2 and H2O. You go...
Thu Jan 30, 2020 12:34 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D.15
Replies: 4
Views: 55

### Re: 4D.15

Photos
Thu Jan 30, 2020 12:30 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D.15
Replies: 4
Views: 55

### 4D.15

Hey guys I had a question on a home problem. I’ve included the textbook, my work, and the solution manuals work. As you can see, I get a positive answer while the solution manual gets a negative one. The solution manual uses equations and I am not sure where they found them. Please help/ explain wha...
Tue Jan 28, 2020 12:29 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy at a constant pressure vs at a constant volume
Replies: 1
Views: 36

### Enthalpy at a constant pressure vs at a constant volume

What are the different formulas for calculating enthalpy at a constant pressure vs calculating enthalpy at a constant volume.
Tue Jan 28, 2020 12:27 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4C.3
Replies: 4
Views: 83

### Re: 4C.3

For part B how do we calculate the change in enthalpy? It is not included in the answer key
Tue Jan 28, 2020 12:22 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka and Kb
Replies: 10
Views: 108

### Re: Ka and Kb

Remember that Kb corresponds to bases and Ka corresponds to acids so it can be difficult to compare. First consider that K is [Products]/[Reactants]. So anytime K is very very small it means that there are way more reactants than there are products thus the solution is very weak. This reasoning work...
Mon Jan 27, 2020 11:08 am
Forum: Administrative Questions and Class Announcements
Replies: 18
Views: 244

Usually you will get partial credit on tests. But it may depend on your TA.
Mon Jan 27, 2020 11:04 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Ka and Kb
Replies: 10
Views: 144

### Re: Ka and Kb

ABombino_2J wrote:All acids/bases have a Ka or a Kb but strong acids and bases have such large Ka and Kb's that they are considered to fully dissociate.

I agree. The larger of the value of these constant would indicate strong acids/bases.
Mon Jan 27, 2020 11:03 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: calculating % ionization
Replies: 4
Views: 72

### Re: calculating % ionization

% ionization is calculated by dividing the [H30] or [OH] concentration by the concentration of the original acid/ base. Essentially, the higher the concentration of the OH or H30 ions the higher the percent ionization.
Mon Jan 27, 2020 10:57 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5% Rule
Replies: 9
Views: 81

### Re: 5% Rule

JesseAuLec1Dis1G wrote:If I make the assumption because K is less than 10^-3, but the x value is less than 5% do I have to go back and use the quadratic formula to calculate x?

If the value is less than 5% you are good to go. If the value is more than 5% you would need to go back and use the quadratic formula.
Mon Jan 27, 2020 10:56 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Exothermic reaction
Replies: 18
Views: 261

### Re: Exothermic reaction

A reaction is exothermic when it releases heat. Exothermic reactions have a negative (DELTA H) value. When exothermic reactions are heated they will favor the production of the reactants. Another way to phrase this is that when an exothermic reaction is heated the reaction will move in the reverse d...
Mon Jan 27, 2020 10:48 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: autoprotolysis
Replies: 7
Views: 88

### Re: autoprotolysis

I understand that autoprotolysis is the transfer of an H+ from an acid to a base in an equation (I think), I'm unclear on how pKW = pH + pOH is derived from it though. The PkW=Pka+Pkb equation is derived from autoprotolysis because autoprotolysis is the simplest example of acid and conjugate base p...
Mon Jan 27, 2020 10:41 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: autoprotolysis
Replies: 7
Views: 88

### Re: autoprotolysis

Autoprotolysis is the transfer of H+ ions within two identical molecules such as two H2O molecules. In this reaction two H2O molecules react to form one molecule of H30 and one molecule of OH
Mon Jan 20, 2020 9:59 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6E Polyprotic Acids and Bases
Replies: 2
Views: 39

### 6E Polyprotic Acids and Bases

In the solution Manuel it says "Ka2<< Ka1., the second ionization energy can be ignored"

What does this mean? When can the second ionization energy be ignored?
Thu Jan 16, 2020 8:55 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6D.13
Replies: 4
Views: 47

### Re: 6D.13

You should know that strong acids dissociate completely, which is why they don't have Ka constants, and thus result in solutions with higher H+ concentrations. Thus, if you are comparing two strong acid solutions, you can expect the one with a higher molarity to be more acidic. So is there a chart ...
Thu Jan 16, 2020 8:53 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6D.15 PART B
Replies: 5
Views: 62

### Re: 6D.15 PART B

Yes, I am sure that I am looking at the right solution manual question. The answer to part A is actually 5. I have included a screen shot of my work to show how to get 5 for part A.
Thu Jan 16, 2020 3:55 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Approximation
Replies: 8
Views: 68

### Re: Approximation

Approximation can be used for weak acids and bases problems when the K value is less than 10^-3. This means it is so small that it is not going to make a difference when calculating concentrations. After you use approximation, you should use the 5% rule to check if your calculation was valid/ if the...
Thu Jan 16, 2020 3:50 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6D.13
Replies: 4
Views: 47

### 6D.13

Please explain the reasoning behind this problem. The solution Manuel has no calculations just general reasoning including the strength of the acid or the conjugate base. What information from the problem is important to know/understand?
Thu Jan 16, 2020 3:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6D.15 PART B
Replies: 5
Views: 62

### Re: 6D.15 PART B

Here are the photos sorry.
Thu Jan 16, 2020 3:47 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6D.15 PART B
Replies: 5
Views: 62

### 6D.15 PART B

Can you explain to me why in the solution Manuel the Cl3 is replaced by (H20)6?
Tue Jan 14, 2020 10:32 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5.35
Replies: 4
Views: 62

### Re: 5.35

Thank you both.

I have one more question regarding this problem. I've included both my work and the answer key's work for finding the equilibrium constant. My question is "How would I have known to divide by 100 when finding the equilibrium constant?"
Sat Jan 11, 2020 4:46 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5.35
Replies: 4
Views: 62

### 5.35

Please explain how to do this problem? I do not even know where to begin. or how to read the graph?
Sat Jan 11, 2020 3:26 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5.33
Replies: 3
Views: 70

### Re: 5.33

In the case of this problem, why doesn't reducing the volume result in the production of more X molecules? The solution manual says that it would result in the production of more X2 molecules which doesn't make sense to me as in the equation there are more moles on the right side of the equation.
Sat Jan 11, 2020 2:22 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Temperature- Endothermic and Exothermic Reactions
Replies: 3
Views: 39

### Re: Temperature- Endothermic and Exothermic Reactions

I don't think we have gotten this far in class yet, but generally if ∆G < 0 then the reaction is exothermic, and if ∆G > 0 then the reaction is endothermic. The reaction is Δ G = Δ H − T Δ S. (I only know this from bio so I'm not sure if this will be the same or not for chem but I'm sure we'll lear...
Sat Jan 11, 2020 2:18 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier's Principle
Replies: 6
Views: 348

### Re: Le Chatelier's Principle

Le Chatelier's Principle can be used to determine how changes in a specific constraint of a reaction in equilibrium will affect the other constraints of the reaction. The principle can be best understood if you look at it like a fraction, as Kc is written in fraction form. (A/B=C) In situation, C ne...
Sat Jan 11, 2020 2:12 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: HW 5J.5
Replies: 8
Views: 60

### Re: HW 5J.5

Solids are not included when calculating the equilibrium constant. So in the case of this problem, C is ignored. Thus there are 2 moles on the right side of the equation, and only 1 mole on the left side of the equation.
Sat Jan 11, 2020 2:10 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier's Principle
Replies: 19
Views: 259

### Re: Le Chatelier's Principle

Le Chatelier's Principle can be used to determine how changes in specific constraints of a reaction in equilibrium will affect the other constraints of the reaction. The principle can be best understood if you look at it like a fraction. (A/B=C) In situation, C never changes. So if A is increased, t...
Sat Jan 11, 2020 2:06 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Temperature- Endothermic and Exothermic Reactions
Replies: 3
Views: 39

### Temperature- Endothermic and Exothermic Reactions

How do you determine if a reaction is endothermic or exothermic?
Tue Dec 03, 2019 5:02 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Resonance and Formal Charge
Replies: 4
Views: 155

### Re: Resonance and Formal Charge

The major contributor is the most stable resonance structure, where the central atom's charge is closest to 0. To determine charge of a molecule add all of the formal charges together.
Tue Dec 03, 2019 5:01 pm
Forum: Biological Examples
Topic: cisplatin
Replies: 5
Views: 123

### Re: cisplatin

I have heard on past chem finals, students have had to draw cisplatin. So maybe be familiar with the chemical formula and shape.
Tue Dec 03, 2019 4:58 pm
Forum: Amphoteric Compounds
Topic: Amphoteric, Amphiprotic, Polyprotic
Replies: 2
Views: 57

### Re: Amphoteric, Amphiprotic, Polyprotic

amphoteric: Can act as both an acid and a base
amphiprotic: Can donate or accept protons
ionic: has ionic character. Has to do with bonding.
polyprotic: can donate or accept multiple protons
Tue Dec 03, 2019 4:55 pm
Forum: Biological Examples
Topic: Biological Examples
Replies: 4
Views: 73

### Re: Biological Examples

What specific biological examples would we know for the final? And what should we know about them?
Tue Dec 03, 2019 4:54 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: 1 B27
Replies: 5
Views: 267

### Re: 1 B27

I am so confused by this problem. I have included two photos. One of my work and one of the solution guide's work. Where did the solution guide get the equation they used? What is wrong with the equations I used?
Sun Dec 01, 2019 11:37 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Midterm Problem
Replies: 4
Views: 188

### Re: Midterm Problem

Q6.A. Magnesium ions are a known cofactor in over 300 enzymatic reactions. What are the possible angular momentum quantum numbers of the highest energy electrons in these magnesium ions? Indicate the corresponding subshell of each angular momentum quantum number. The electron configuration of Mg is ...
Sun Dec 01, 2019 11:31 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Midterm Problem
Replies: 4
Views: 188

### Midterm Problem

Q5C. Calcium ions are important in the process of neurotransmitter release at the neuromuscular junction. Write the full electron-configuration for the ground-state of a calcium ion. Answer: Ca2+ 2pt 1s2 2s2 2p6 3s2 3p6 2pt How would we have know to write the electron configuration of calcium 2+? Wh...
Thu Nov 28, 2019 11:58 am
Forum: Hybridization
Topic: double bonds
Replies: 7
Views: 103

### Re: double bonds

Double bonds do not affect hybridization because a double bond still represents a single location of electron density. An easy way to determine what type of hybridization is to use steric numbers. Steric Number= number of bonded atoms + number of lone pairs. Notice that the number of bonds is not in...
Thu Nov 28, 2019 11:52 am
Forum: Lewis Acids & Bases
Topic: Identifying Acids and Bases
Replies: 8
Views: 151

### Re: Identifying Acids and Bases

Typically strong acids have a greater difference in electronegativity than weak acids. While weak bases have a smaller difference in electronegativity than strong bases.
Thu Nov 28, 2019 11:48 am
Forum: Amphoteric Compounds
Topic: Amphoteric
Replies: 8
Views: 108

### Re: Amphoteric

Yes, by referencing the periodic table you can tell which compounds are amphoteric. Semi metals are typically amphoteric. Meaning that if they lay on the jagged diagonal line they are amphoteric. In addition to this information. We can use the periodic table to determine which elements are solely a...
Thu Nov 28, 2019 11:47 am
Forum: Amphoteric Compounds
Topic: Amphoteric
Replies: 8
Views: 108

### Re: Amphoteric

Yes, by referencing the periodic table you can tell which compounds are amphoteric. Semi metals are typically amphoteric. Meaning that if they lay on the jagged diagonal line they are amphoteric.
Sat Nov 23, 2019 4:09 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: AXE formula
Replies: 32
Views: 5218

### Re: AXE formula

danielruiz1G wrote:is it possible to determine the shape of a molecule if you're only given the AXE formula, if so how do you do it?

The only real way to do it, is to memorize the chart. This chart is especially helpful because it includes hybridization and shape and polarity.
Sat Nov 23, 2019 4:06 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Denticity
Replies: 2
Views: 56

### Denticity

Can someone please explain Denticity to me? I do not understand how we are supposed to be able to determine if a molecule is polydentate, mono dentate, or didentate.
Mon Nov 18, 2019 3:24 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AXE notation
Replies: 10
Views: 123

### Re: AXE notation

AXE notation is the same as saying "What is the Vsepr formula?" Each of the letter stand for something: A= the central atom. Some chemistry courses will require you to write the central atom in the formula, but Dr Lavelle does not require this nor does he prefer that you do. On exams just ...
Mon Nov 18, 2019 3:20 pm
Forum: Hybridization
Topic: Hybridization and VSEPR
Replies: 1
Views: 29

### Re: Hybridization and VSEPR

I believe hybridization is based on molecular geometry. This chart can help you understand the relationship of hybridization and molecular geometry.
Mon Nov 18, 2019 3:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Pi Bond vs Sigma
Replies: 6
Views: 83

### Re: Pi Bond vs Sigma

Are one of these bonds stronger than the other? Pi bond vs Sigma? If so, why? Sigma bonds are stronger than pie bonds because the orbitals of a sigma bond overlap more during hybridization than the orbitals of a pie bond. It can be difficult to understand sigma and pie bonds without reading through...
Mon Nov 18, 2019 3:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Pi Bond vs Sigma
Replies: 6
Views: 83

### Re: Pi Bond vs Sigma

Sigma bonds are single bonds. Pie bonds are in double and triple bonded atoms. In a double/ triple bonded atom, one bond is always a sigma bond and the others are pie bonds.
Mon Nov 18, 2019 3:14 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSPER
Replies: 7
Views: 186

### Re: VSPER

This chart is extremely useful. I would recommend memorizing the sheet for your test 2.
Tue Nov 12, 2019 5:47 pm
Forum: Administrative Questions and Class Announcements
Topic: KAREN SUN 5-7PM WORKSHOP - DOWNLAOD WORKSHEETS HERE
Replies: 53
Views: 3505

### Re: KAREN SUN 5-7PM WORKSHOP - DOWNLAOD WORKSHEETS HERE

Will you have a review session this weekend to prepare for Test 2?
Tue Nov 12, 2019 5:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR formula for molecules of the same atom
Replies: 3
Views: 36

### Re: VSEPR formula for molecules of the same atom

I believe that I read in the textbook that the VSEPR formula for molecules of the same atom result in a linear shape.
Tue Nov 12, 2019 5:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR model
Replies: 4
Views: 182

### VSEPR model

What does VSEPR stand for? How do we determine a molecules VSEPR formula for a molecule.
Tue Nov 12, 2019 5:42 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR
Replies: 5
Views: 43

### Re: VSEPR

I went to a UA workshop last week. She said that we will be expected to memorize all of the shapes. She also suggests we memorize the VSEPR model.
Tue Nov 12, 2019 5:41 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Test 2
Replies: 3
Views: 45

### Test 2

What material will we be tested on for test 2 that occurs during Week 8?
Wed Nov 06, 2019 1:29 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty in Speed [ENDORSED]
Replies: 19
Views: 5707

### Re: Uncertainty in Speed[ENDORSED]

Use these equations:
(delta p)(delta x) = (1/2)(h/4 PIE)
(deltap) = m( delta v)

Sometimes this type of problem can be confusing because they dont give you the delta p equation.

Also remember to multiply the delta v uncertainty by 2 because it is plus or minus a certain amount.
Wed Nov 06, 2019 1:26 pm
Forum: Student Social/Study Group
Topic: Final Jitters
Replies: 178
Views: 34484

### Re: Final Jitters

I find it useful to take a nap before a midterm or final. especially when they are night midterms. To be honest after studying for weeks (like I do for chemistry exams), I can be really distracted and nervous before an exam. By taking a nap, I recharge my brain. But really you will need to find what...
Wed Nov 06, 2019 1:22 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Help Calculating
Replies: 3
Views: 154

### Re: Help Calculating

Thank you, the process makes more sense now. I was missing the equation for delta P. "ΔP is equal to mΔv because mass is constant and velocity is the only thing that changes. Set up the equation Δp=mΔv on the side to solve for Δp". Now that I know this, it makes more sense.
Wed Nov 06, 2019 1:19 pm
Forum: Administrative Questions and Class Announcements
Topic: Worksheet for 1D/1F 10/16
Replies: 24
Views: 1490

### Re: Worksheet for 1D/1F 10/16

For number 4 part b on the extra practice problems, why doesn't boron have to complete it's octet? In your answer key, boron only has 6 electrons accounted for in the lewis structure
Sat Nov 02, 2019 1:59 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Help Calculating
Replies: 3
Views: 154

### Help Calculating

I am kind confused when it comes to the Heisenberg uncertainty principle. Can you help me calculate this problem? It is from a worksheet made by the UA Karen Leung
Wed Oct 30, 2019 2:22 pm
Forum: Ionic & Covalent Bonds
Topic: Valence e-
Replies: 3
Views: 67

### Re: Valence e-

Usually in terms of Chemical bonds, we usually just include the s and p orbitals when defining the number of valence electrons in the valence shells. You should definitely check out the other posts on this topic.
Wed Oct 30, 2019 2:19 pm
Forum: Lewis Structures
Topic: Homework 2A 12
Replies: 3
Views: 75

### Re: Homework 2A 12

M2+ is not actually an element. The problem is asking you to name the 2+ ions with those electron configurations. Imagine M as x in an algebraic function.
Wed Oct 30, 2019 2:17 pm
Forum: Lewis Structures
Topic: Formal charge
Replies: 9
Views: 112

### Re: Formal charge

AN easy way to calculate formal charge of an atom is:

# of valence electrons for that element- number of dots-number of lines=formal charge
Wed Oct 30, 2019 2:16 pm
Forum: Lewis Structures
Topic: Bonds:
Replies: 3
Views: 50

### Bonds:

Do bonds count as one or two valence electrons in a Lewis Structure?
Wed Oct 30, 2019 2:11 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: S to D orbital?
Replies: 1
Views: 38

### S to D orbital?

When do the electrons from a future s orbital transfer to a d orbital to stabilize the electron configuration.
Sat Oct 26, 2019 5:31 pm
Forum: Ionic & Covalent Bonds
Topic: + and - ions
Replies: 3
Views: 88

### + and - ions

I had a questions on a chemistry concept relating to determining the electron configuration of an ion- do you move left or right on the periodic table for charge?  For example:  1. Is the electron configuration of Fe^+ the same as the electron configuration of Mn (move left) or the same as Co (move ...
Wed Oct 23, 2019 5:36 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Subshell vs. Orbital
Replies: 9
Views: 162

### Re: Subshell vs. Orbital

Electron shells are divided into subshells and subshells are divided into orbitals. In terms of quantum numbers, n denotes the shell, l denotes the subshell, and ml denotes the orbital. Each orbital typically houses 2 electrons of opposite spin./
Wed Oct 23, 2019 5:31 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration Exceptions:
Replies: 3
Views: 45

### Electron Configuration Exceptions:

Why fo the elements of Cr and Cu have different electron configurations than the rest of the elements in the 3d block? For instance why is Cr's electron configuration: [Ar]3d^5 4s^1 instead of [Ar]3d^4 4s^2? What other elements are an exception to the expected electron configuration? Will we need to...
Wed Oct 23, 2019 5:29 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Oribital Notation
Replies: 3
Views: 50

### Re: Oribital Notation

Sometimes its difficult to know what order to write the orbitals. The best one to remember which orbitals have higher or lower energy is with this chart. Follow the arrows from bottom to top and when your done return to the bottom of the next arrow.
Wed Oct 23, 2019 5:27 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configurations
Replies: 13
Views: 550

### Re: Electron Configurations

Hey the order of electron shell energy is difficult to understand. The only way that I can remember the order of the energy is with this chart. Follow the arrows from bottom to top and then return to the bottom of the next arrow.
Wed Oct 23, 2019 5:21 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration
Replies: 2
Views: 35

### Re: Electron Configuration

Hund's rule states that: Every orbital in a sublevel is singly occupied before any orbital is doubly occupied. All of the electrons in singly occupied orbitals have the same spin (to maximize total spin). It is easier to understand if you picture electrons as magnets, two negatively polled magnets w...
Wed Oct 16, 2019 2:18 pm
Forum: Molarity, Solutions, Dilutions
Topic: What is Molarity?
Replies: 11
Views: 413

### Re: What is Molarity?

Molarity is a measure of concentration. The higher a substances molarity the more solutes. For example, if one sample of salt water has a molarity of 0.1M and another sample has a molarity of 0.9M, then the 0.1M water would be less. salty than the 0.9M sample.
Wed Oct 16, 2019 2:15 pm
Forum: Administrative Questions and Class Announcements
Topic: KAREN SUN 5-7PM WORKSHOP - DOWNLAOD WORKSHEETS HERE
Replies: 53
Views: 3505

### Re: KAREN SUN 5-7PM WORKSHOP - DOWNLAOD WORKSHEETS HERE

I went to your workshop last Sunday, and I found it extremely useful. Thank you for all the help. I will see you next week!
Wed Oct 16, 2019 2:13 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Bohr's Equation
Replies: 5
Views: 96

### Bohr's Equation

Will we be expected to derive Bohr's equation on the midterm like Dr. Lavelle did in class?
Wed Oct 16, 2019 2:01 pm
Forum: General Science Questions
Topic: Chemistry Community Registration
Replies: 2
Views: 83

### Chemistry Community Registration

Every week my chemistry community account locks me out. I am forced to reset my password each week. Has anyone else experienced this? Each week a reset my password to the same thing and it still locks me out the next week.
Wed Oct 16, 2019 1:59 pm
Forum: Properties of Light
Topic: Midterm- Electromagnetic spectrum
Replies: 3
Views: 54

### Midterm- Electromagnetic spectrum

For the first midterm will we need to memorize the electromagnetic spectrum?
Wed Oct 09, 2019 3:18 pm
Topic: Wavelength and Temperature
Replies: 2
Views: 75

### Re: Wavelength and Temperature

There is a short section in the textbook about Wein's law that helped me better understand this. You should check out section 1B of the textbook.
Wed Oct 09, 2019 3:16 pm
Forum: Properties of Light
Topic: Partical VS Wave
Replies: 2
Views: 117

### Partical VS Wave

I am having trouble understanding the difference between when light acts like wave and like a particle. Any advice for reading material/ videos?