## Search found 102 matches

Fri Mar 13, 2020 8:22 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Dr. Lavelle's week 10 review - last question
Replies: 3
Views: 89

### Re: Dr. Lavelle's week 10 review - last question

To solve this question, you need to determine the rate law for each student's reaction and see if it matches with the overall experimentally determined rate law. To do this, you should determine the rate law for each elementary reaction, as well as the equilibrium constant. As you can see in the sol...
Fri Mar 13, 2020 8:17 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Week 10 Reaction Mechanisms
Replies: 1
Views: 40

### Week 10 Reaction Mechanisms

I'm getting confused between the different k variables in this problem. How exactly does the observed rate k equate to k2K1? I understand how to derive the rate for both students, but I don't understand why Student B's k2K1 is equivalent to the overall k.
Thu Mar 12, 2020 10:22 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Week 10 Review Problem
Replies: 2
Views: 31

### Week 10 Review Problem

Why don't you multiply the cell potential by 2 in the reduction half reaction?
Wed Mar 11, 2020 9:37 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 7D.7
Replies: 1
Views: 40

### 7D.7

For the reversible, one-step reaction A + A <-> B + C, the forward rate constant for the formation of B is 265 L/mol*min and the rate constant for the reverse reaction is 392 L/mol*min. The activation energy for the forward reaction is 39.7 kJ/mol and that of the reverse reaction is 25.4 kJ/mol. (a)...
Wed Mar 11, 2020 9:32 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Fast Step/Slow Step
Replies: 7
Views: 96

### Re: Fast Step/Slow Step

The slowest step determines the rate because the reaction cannot proceed until the slowest step has gone to completion. Essentially, if you think about it like a group on a hike, the slowest person determines the pace of everyone because the group cannot go on without them.
Mon Mar 09, 2020 11:38 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Intermediates
Replies: 3
Views: 41

### Re: Intermediates

I don't think we'll have to sort the order of the intermediate steps, but we should know that the sum of the elementary steps is equivalent to the overall reaction, and that its mechanism agrees with the determined rate law.
Mon Mar 09, 2020 11:35 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: gibbs free energy
Replies: 15
Views: 167

### Re: gibbs free energy

In a reaction, Gibbs free energy is the energy available to do work.
Mon Mar 09, 2020 11:33 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating K
Replies: 6
Views: 59

### Re: Calculating K

K is a constant, and when calculating K, the units of molarity or partial pressure actually cancel out.
Mon Mar 09, 2020 11:32 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isothermal Irreversible Free Expansion
Replies: 3
Views: 96

### Re: Isothermal Irreversible Free Expansion

The term isothermal refers to a constant temperature. Irreversible free expansion is the expansion of a gas. If you think about it logically, it is irreversible because it is not a natural process for a gas to condense to a smaller volume. Because irreversible free expansion is a spontaneous process...
Mon Mar 09, 2020 11:28 am
Forum: General Rate Laws
Topic: Overall rate law
Replies: 8
Views: 138

### Re: Overall rate law

Like someone said before, it's essentially an all or nothing kind of behavior. Someone explained it to me in a helpful analogy: if you're hiking with a group of people, the slowest person in the group determines the pace of their hike. The other people, no matter how fast they are, must keep the pac...
Sun Mar 01, 2020 10:52 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Anode and Cathode
Replies: 8
Views: 139

### Re: Anode and Cathode

The anode is the part of the cell that performs oxidation, so the element/compound inside loses an electron. This electron transfers over to the cathode, which performs reduction and adds the electron to the corresponding element/compound inside.
Sun Mar 01, 2020 10:48 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cathode/Right & Anode/Left
Replies: 7
Views: 67

### Re: Cathode/Right & Anode/Left

The default setup typically ensures that the anode is on the left and cathode is on the right for standard cell notation.
Sun Mar 01, 2020 10:47 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Degree symbol
Replies: 10
Views: 105

### Re: Degree symbol

The degree symbol means that the variable is the standard variable in that state. The standard value can be considered the default value to use in calculations, like for the standard enthalpy of formation, or the standard entropy of reaction.
Sun Mar 01, 2020 10:44 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: electron flow
Replies: 4
Views: 36

### Re: electron flow

Yes, the flow of electrons is what causes a current, therefore causing electricity. This can be used interchangeably.
Mon Feb 24, 2020 12:31 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 4.45
Replies: 1
Views: 132

### 4.45

Potassium nitrate dissolves readily in water, and its enthalpy of solution is +34.9 kJ/mol. (a) Does the enthalpy of solution favor the dissolving process? Can someone explain this conceptually? For a, I don't really understand the solution manual's reasoning. It says that because deltaH system is p...
Sun Feb 23, 2020 9:40 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 4I.7
Replies: 1
Views: 81

### 4I.7

Use the information in Table 4C.1 to calculate the changes in entropy of the surroundings and of the system for (a) the vaporization of 1.00 mol CH 4(l) at its boiling point. Would delta S and delta S surr be equivalent (but opposite signs) in this case? I know that you use deltaS surr = -de...
Sun Feb 23, 2020 9:01 pm
Forum: Balancing Redox Reactions
Topic: 6K.3 part d
Replies: 3
Views: 35

### Re: 6K.3 part d

I can confirm that it's a typo, it really should be 2Cl-(aq) instead of Cl2(g)
Sun Feb 23, 2020 8:59 pm
Forum: Balancing Redox Reactions
Topic: Balancing Redox Equations
Replies: 7
Views: 94

### Re: Balancing Redox Equations

A good acronym to remember is LEO: losing electrons - oxidation. A compound undergoes reduction if it gains electrons, and undergoes oxidation if it loses electrons. You can tell by looking at the oxidation number of the element in the compound; if the oxidation number increases, then its charge bec...
Sun Feb 23, 2020 8:57 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Work
Replies: 5
Views: 91

### Re: Work

Work is done on a system if its value is positive; this is because the system absorbs energy from its surroundings.
The opposite should in turn make sense: if the system is doing work, its value is negative because energy is leaving the system to go to the surroundings.
Mon Feb 17, 2020 8:18 pm
Forum: Balancing Redox Reactions
Topic: Half Reactions (6K5d) [ENDORSED]
Replies: 1
Views: 49

### Half Reactions (6K5d)[ENDORSED]

What would the half reactions of this redox be? In part b, bromine reacted with itself, so it was the reactant in both reactions, but the description doesn't specify that for part d:
P4 (s) --> H2PO2-(aq) + PH3 (aq)
Mon Feb 17, 2020 6:51 pm
Forum: Balancing Redox Reactions
Topic: 6K.1
Replies: 1
Views: 33

### 6K.1

The following redox reaction is used in acidic solution in the Breathalyzer test to determine the level of alcohol in blood: H + (aq) + Cr 2 O 7 2- (aq) + C 2 H 5 OH (aq) --> Cr 3+ (aq) + C 2 H 4 O (aq) + H 2 O (l) Balance the half-reactions to produce...
Sun Feb 16, 2020 9:09 pm
Forum: Balancing Redox Reactions
Topic: Seperating Redoz RXNS
Replies: 7
Views: 50

### Re: Seperating Redoz RXNS

Half reactions don't necessarily mean the reaction is split in half exactly. Oxidation and reduction reactions are two halves of a redox reaction. So, when you're breaking the reaction up, you're breaking the redox reaction into one oxidation and one reduction reaction.
Sun Feb 16, 2020 9:08 pm
Forum: Balancing Redox Reactions
Topic: Electrochemisty
Replies: 10
Views: 124

### Re: Electrochemisty

Electrochemistry, as it sounds, is the study of the relationship between electricity and chemistry. What we mostly discussed on Friday is the transfer of electrons in electrons. Oxidation involves the loss of electrons, and reduction involves the gaining of electrons in reaction. A redox reaction is...
Sun Feb 16, 2020 9:02 pm
Forum: Balancing Redox Reactions
Topic: In Class Example
Replies: 4
Views: 37

### Re: In Class Example

He just broke the reaction up into two half reactions; it is not necessarily an end result, but a breakdown of what is going on in one redox reaction.
Sun Feb 16, 2020 9:00 pm
Forum: Balancing Redox Reactions
Topic: Redox Reactions
Replies: 12
Views: 85

### Re: Redox Reactions

A redox reaction is a reaction that includes both a reduction and oxidation reaction. They can be separated into two half reactions: one oxidation and one reduction reaction. An oxidation reaction involves the loss of electrons, and reduction involves gaining electrons. I think that splitting the tw...
Wed Feb 12, 2020 11:19 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Different forms of entropy
Replies: 2
Views: 95

### Different forms of entropy

Can someone please explain the difference between delta S and delta Stot? The problems I'm reviewing ask for these and I don't know the difference between the two.
Sun Feb 09, 2020 11:37 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: graphs
Replies: 3
Views: 29

### Re: graphs

In a reversible reaction, there is a decrease in pressure, making its slope negative. Since there is constant pressure in an irreversible reaction, the slope is 0. The graphs' slopes correlate with whether or not the pressure is changing in reaction.
Sun Feb 09, 2020 11:35 pm
Forum: Gibbs Free Energy Concepts and Calculations
Replies: 3
Views: 37

No work occurs under free expansion, because there is no external pressure applied under a vacuum state.
Sun Feb 09, 2020 11:35 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm
Replies: 12
Views: 186

### Re: Midterm

The midterm is from 6-8, I'm pretty sure there's no class that day either.
Sun Feb 09, 2020 11:34 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Reversible Reactions vs. Irreversible Reactions
Replies: 6
Views: 88

### Re: Reversible Reactions vs. Irreversible Reactions

I don't think it would hurt to memorize, the reversible curve expresses a large change in pressure with a negative slope, and the irreversible curve is simply a straight horizontal line.
Sun Feb 09, 2020 11:32 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE BOX
Replies: 27
Views: 266

### Re: ICE BOX

If x is less than 10-3, it can be considered negligible.
Sun Feb 02, 2020 11:43 pm
Forum: Ideal Gases
Topic: Ideal gas constant
Replies: 4
Views: 71

### Re: Ideal gas constant

As you can see, the R constants use different units. When you're solving a problem, it is important to consider the units you are using when utilizing the gas constant. You can't use the two interchangeably because the units are different in either situation. However, they carry the same value, just...
Sun Feb 02, 2020 11:40 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: R constants
Replies: 21
Views: 783

### Re: R constants

It is important to look at the units of what the problem includes. All of the R constants will be provided on the equation sheet, so when you need to use the R constant, consider what units you are using and use the constant that aligns with these units.
Sun Feb 02, 2020 11:39 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Changing energy of systems
Replies: 1
Views: 19

### Re: Changing energy of systems

Someone correct me if I'm wrong, but I don't think you can do work on an open system because nearly everything is included within the system. For example, an open beaker that has water added to it is an open system, consisting of the old and new water. Work is not done because the mass of the water ...
Sun Feb 02, 2020 11:36 pm
Forum: Calculating Work of Expansion
Topic: Reversible process
Replies: 2
Views: 53

### Re: Reversible process

W is found using integrals because integrals add up the tiny increments of change in volume during expansion.
Sun Feb 02, 2020 11:34 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Open/Closed/Isolated System
Replies: 3
Views: 37

### Re: Open/Closed/Isolated System

It can't really go the other way. If mass is interchangeable, this would make the system open.
Sun Jan 26, 2020 12:36 pm
Forum: Phase Changes & Related Calculations
Replies: 5
Views: 66

I usually read the sections that we just finish covering in lecture. I don't think there's a chronological order to the readings he lists on the syllabus, especially because we are covering thermochemistry before thermodynamics (but the textbook sections list in the opposite order).
Sun Jan 26, 2020 12:34 pm
Forum: General Science Questions
Topic: Midterms
Replies: 22
Views: 364

### Re: Midterms

The midterm includes everything we have learned up until that date, which includes material from Test 1 and up until the midterm date. The final is cumulative. Tests 1 and 2 only test on certain topics, so they aren't cumulative.
Sun Jan 26, 2020 12:32 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Value of X
Replies: 7
Views: 55

### Re: Value of X

What everyone else said above is correct. Something to keep in mind is that if you are calculating for a weak acid/base, the change in molarity at equilibrium can be considered negligible because they do not 100% dissociate in solution. So, even though you have a change in X, the change is still clo...
Sun Jan 26, 2020 12:31 pm
Forum: Ideal Gases
Topic: R Constant
Replies: 26
Views: 359

### Re: R Constant

In the equation sheet we're provided with, there are a number of different values to use for the R constant. It's important to look at which units are being used, which will tell you which one is appropriate to use.
Sun Jan 26, 2020 12:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: approximation
Replies: 4
Views: 41

### Re: approximation

X is approximated because weak acids do not 100% dissociate in solution. Because of this, we can assume that the value of change is so small that it is negligible.
Sun Jan 26, 2020 12:28 pm
Forum: Phase Changes & Related Calculations
Topic: Work
Replies: 3
Views: 67

### Re: Work

I'm not sure if I'm answering your question entirely but work is energy leaving or entering a system. Because of this, work done can affect the amount of available energy in a system.
Sun Jan 26, 2020 12:25 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ideal Gas QUestions
Replies: 8
Views: 81

### Re: Ideal Gas QUestions

Yes, if you think about it, the higher the pressure is, the less room there is for particles to move around.
Sun Jan 26, 2020 12:23 pm
Forum: Phase Changes & Related Calculations
Topic: Celsius and Kelvin
Replies: 11
Views: 86

### Re: Celsius and Kelvin

The ideal gas law always uses Kelvin when calculating temperature. Like everyone said, K = 273 + C.
Sun Jan 26, 2020 12:22 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: L.atm to Joules
Replies: 2
Views: 39

### Re: L.atm to Joules

Either should be fine, just make sure the units are correct when you're converting and coming up with your final answer!
Mon Jan 13, 2020 11:45 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5H.3
Replies: 2
Views: 32

### 5H.3

Use the information in Table 5G.2 to determine the value of K at 300 K for the reaction 2 BrCl(g) + H2(g) = Br2(g) + 2 HCl(g).
I can't quite find this exact reaction in the table. Is there something additional that I should be doing to find K?
This is what Table 5G.2 looks like:
Sat Jan 11, 2020 5:16 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: When to use Le Chatelier's
Replies: 4
Views: 47

### Re: When to use Le Chatelier's

Le Chatelier's Principle applies whenever an external change is added to the system. This can occur in the form of altering concentration, pressure, or temperature. An exception to this is if an inert gas is added to the reaction, which has no impact on the reaction.
Sat Jan 11, 2020 5:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: finding change in concentration in ICE tables
Replies: 3
Views: 34

### Re: finding change in concentration in ICE tables

When you don't know the quantitative change in concentration, you can replace the value with variable X. For example, CO and H 2 O would decrease X amount in reaction, while CO 2 and H 2 would increase X amount. By doing this, you can mathematically figure out the actual numerical value of X by usin...
Sat Jan 11, 2020 5:10 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Significance of principle
Replies: 6
Views: 54

### Re: Significance of principle

Le Chatelier's Principle is helpful in understanding that changes in concentration or pressure within the system will not affect K, and that the reaction will act accordingly so in order to keep K intact.
Sat Jan 11, 2020 5:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE box
Replies: 9
Views: 89

### Re: ICE box

If the solutions to the problem are the direct concentrations of a substance, there is no way the answer can be negative, as you cannot have negative concentration. I'm not really sure if this would ever come up, but the solution could be negative if this results in the desired concentration is stil...
Tue Jan 07, 2020 3:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Converting Kc to Keq
Replies: 2
Views: 46

### Converting Kc to Keq

Will we ever have to convert between K and Kc? I'm reading Focus 5H in the textbook and I'm kind of confused.
Sat Dec 07, 2019 11:22 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: dentates
Replies: 2
Views: 125

### Re: dentates

When there is chelation in a coordinate compound, the ligand attaches multiple times to the central atom. It essentially forms a ring of atoms including the central metal atom. Ligands typically bind at one site of the central atom, making them monodentate. A ligand that binds at two sites is bident...
Sat Dec 07, 2019 1:30 am
Forum: Lewis Acids & Bases
Topic: memorizing ligands
Replies: 5
Views: 193

### Re: memorizing ligands

I also don't have a mnemonic but quizlet is actually very helpful! When memorizing CN, NC, SCN, and NCS, I realized that the complementing compound beginning with N will always begin with iso-. For example, CN is cyanate, and NC is isocyanate. SCN is thiocyanate, and NCS is isothiocyanate. Hope this...
Thu Dec 05, 2019 9:22 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: compound names
Replies: 1
Views: 47

### Re: compound names

I think that it wouldn't hurt to know the ligand names of each structure. While reviewing, I've done past final exams and I've been asked to identify ligands like ethylenediamine (en) and oxolate.
Thu Dec 05, 2019 10:15 am
Forum: Polyprotic Acids & Bases
Topic: Chelate/polydentate
Replies: 2
Views: 91

### Re: Chelate/polydentate

A chelate is a compound with a ligand bonded to a central atom at two or more points. This looks like a ring structure attached to the central atom. A polydentate molecule has multiple ligands of this nature attached to the central atom. So, a chelate can be monodentate, bidentate, tridentate, polyd...
Tue Dec 03, 2019 12:08 pm
Forum: Lewis Acids & Bases
Topic: Products of Lewis Acids and Bases
Replies: 1
Views: 40

### Products of Lewis Acids and Bases

I know that Lewis acids accept electron pairs from Lewis bases, but how exactly do you know what the final product looks like? For example, what does the product of Cl - + SO 2 look like, and why? I know that Cl - is the Lewis base, and SO 2 is the Lewis acid, but I'm not exactly sure how the two in...
Tue Dec 03, 2019 11:38 am
Forum: Naming
Topic: Naming Coordination Compounds
Replies: 5
Views: 50

### Re: Naming Coordination Compounds

I think it would be really helpful to know the simpler ligands, since I'm pretty confident that we're going to be asked to name some coordination compounds on the final. For the insanely long ligand names, I think it's okay if we don't memorize those haha.
Sun Dec 01, 2019 8:18 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Why sulfuric acid is stronger than phosphoric acid
Replies: 4
Views: 105

### Why sulfuric acid is stronger than phosphoric acid

I was just wondering why phosphoric acid is weaker than sulfuric acid. When I tried looking at this online, most sources just listed the pKa's, and I don't think that is a sufficient way to answer my question.
Sun Dec 01, 2019 7:51 pm
Forum: Calculating the pH of Salt Solutions
Topic: PH
Replies: 5
Views: 70

### Re: PH

To add onto this, a more visual representation is this:
p[H] = -log10[H3O+]

So, for example, if [H3O+] = 1.0 * 10-7 mol/L, the pH would equal 7.
Sun Dec 01, 2019 7:44 pm
Forum: Naming
Topic: chelating
Replies: 3
Views: 55

### Re: chelating

Visually, you can tell if chelation occurs in a molecule if one of the ligands forms a ring of atoms that includes the central atom. In a Lewis structure, it would look like a ring on one of the ligands.
Sun Dec 01, 2019 7:41 pm
Forum: Administrative Questions and Class Announcements
Topic: Past exams
Replies: 7
Views: 153

### Re: Past exams

The Community Programs Office in the Student Activities Center on campus has a test bank of previous finals and tests that students may have previously submitted in past quarters. I'm not sure if Lavelle's tests are there, but I feel like there's a good chance especially because this class has been ...
Tue Nov 26, 2019 2:47 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted Acids and Bases
Replies: 6
Views: 71

### Re: Bronsted Acids and Bases

Someone else can add onto this, but I think it's helpful to know their exact function and role when reacting with other substances. For example, Bronsted acids are proton donors and Bronsted bases are proton acceptors. Also, it'd probably be helpful to recognize what makes up a strong/weak acid or b...
Tue Nov 19, 2019 10:59 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: induced dipole-induced dipole
Replies: 4
Views: 55

### Re: induced dipole-induced dipole

Yes, induced dipole-induced dipole forces can also be considered London forces. They can also be referred to as dispersion forces, or van der Waals forces.
Tue Nov 19, 2019 10:37 pm
Forum: *Liquid Structure (Viscosity, Surface Tension, Liquid Crystals, Ionic Liquids)
Topic: repulsion
Replies: 2
Views: 120

### Re: repulsion

Let's take a molecule with tetrahedral electron geometry, for example. If 4 bonded atoms are connected to the central atom, the molecular geometry will also be tetrahedral with bond angles measuring approximately 109.5 degrees. However, if only 3 bonded atoms and one lone pair of electrons are conne...
Mon Nov 18, 2019 9:26 pm
Forum: Dipole Moments
Topic: Net Dipole Moment
Replies: 4
Views: 61

### Net Dipole Moment

Does BrF6 have a net dipole moment? I know that F is more electronegative, so the dipole moment travels from the central Br to each F atom. When I draw all of these vectors out, I think they sum up to be 0. Is this correct? Is there another way to look at this?
Mon Nov 18, 2019 7:49 pm
Forum: Determining Molecular Shape (VSEPR)
Replies: 2
Views: 40

Let's say we have an ionic compound like ICl 2 - . If you draw the Lewis structure for this, it has two bonded pairs and 3 lone electron pairs, which gives it a linear molecular geometry. Why will the bond angles be 180 o degrees? I thought that lone electron pairs typically repel the bonded atoms' ...
Mon Nov 18, 2019 4:52 pm
Forum: Sigma & Pi Bonds
Topic: E Density
Replies: 1
Views: 52

### Re: E Density

The number of regions of electron density help determine the shape of the molecule, concerning both electron and molecular geometry. For example, if the molecule's central atom has 4 regions of electron density surrounding it, you can infer that its electron geometry is tetrahedral. Its amount of lo...
Sat Nov 16, 2019 8:10 pm
Forum: Determining Molecular Shape (VSEPR)
Replies: 5
Views: 81

### Re: How to treat Radicals

Yes, you should treat a single electron as one full region of electron density. However, because there is only one electron compared to two in a lone pair, it most likely has a lower magnitude of electron repulsion.
Sat Nov 16, 2019 8:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Tool to Memorize VSEPR
Replies: 3
Views: 46

### Re: Tool to Memorize VSEPR

This was really helpful! Thanks for the resource, I'll definitely use this method when memorizing. :)
Sat Nov 16, 2019 8:00 pm
Forum: Bronsted Acids & Bases
Topic: Test2
Replies: 7
Views: 106

### Re: Test2

I am not sure if it is required to memorize all of the shapes, but I think it would certainly be extremely helpful. Honestly, bond angles and molecular structure/shape are a large part of the content we learned after the midterm, so I would recommend memorizing them just to be safe before the test.
Sat Nov 16, 2019 7:56 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Formula
Replies: 7
Views: 89

### Re: VSEPR Formula

Yes! One lone pair counts as one region of electron density. Molecular shape should always take into account how many regions of electron density surround the central atom, whether this be a bonded atom or a lone pair.
Sat Nov 16, 2019 7:55 pm
Forum: Dipole Moments
Topic: Dipole Moment
Replies: 3
Views: 58

### Re: Dipole Moment

I don't think we will have to calculate any values concerning dipole moments on a test, but I am pretty sure that we will have to recognize and identify which molecules participate in dipole moments with each other by determining relative electronegativity within their atoms.
Sat Nov 16, 2019 7:52 pm
Forum: Bronsted Acids & Bases
Topic: Test2
Replies: 7
Views: 106

### Re: Test2

Test 2 should cover everything from after the midterm (around Focus 2D) up to the VSEPR model and bonding angles. Hope this helped!
Sat Nov 16, 2019 7:51 pm
Forum: General Science Questions
Topic: Test 2
Replies: 5
Views: 73

### Re: Test 2

I believe Prof. Lavelle said that Test 2 covers everything after the midterm (beginning from Focus 2D) up until the content we learned this Friday, which is the subject of bond angles and the VSEPR model. If I am wrong, someone correct me!
Sat Nov 16, 2019 7:32 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone pairs and angles
Replies: 1
Views: 38

### Re: Lone pairs and angles

The VSEPR model is only able to qualitatively determine the measure of bond angles, but never quantitatively. Because molecules with lone pairs tend to push atoms farther away, the bond angles will always be smaller compared to normal geometric structure. However, it is impossible for us to actually...
Tue Nov 12, 2019 11:31 am
Forum: Administrative Questions and Class Announcements
Topic: Week 7 Homework
Replies: 7
Views: 107

### Week 7 Homework

Hi everyone,
From which section on the syllabus does the homework problems begin for the homework due week 7?
Tue Nov 05, 2019 11:33 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 2A5
Replies: 1
Views: 60

### 2A5

Hi, this should be relatively simple but I'm struggling to understand the reasoning behind the correct answers for this problem: Give the ground-state electron configuration expected for each of the following ions: a) Cu + b) Bi 3+ c) Ga 3+ d) Tl 3+ I got [Ar] 4s 2 3d 8 for both a and c, and [Xe]4f ...
Sun Nov 03, 2019 8:46 pm
Forum: Trends in The Periodic Table
Replies: 11
Views: 300

I don't think we'll ever need to calculate the value of an atomic radius, but we should know the trends of increasing/decreasing atomic radii across periods or groups of the periodic table. For example, the atomic radius gets smaller as you go from left to right in a period because the higher positi...
Sun Nov 03, 2019 8:20 pm
Forum: Sigma & Pi Bonds
Topic: Quantum Numbers
Replies: 9
Views: 149

### Re: Quantum Numbers

Like Jennifer said, quantum numbers detail the state of an electron. They tell you the overall environment of the orbital, like size/energy (n), shape (l), orientation (ml), and spin state (ms).
Sun Nov 03, 2019 8:18 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Finding electron configurations
Replies: 4
Views: 73

### Re: Finding electron configurations

I believe that gallium's electron configuration is [Ar]4s 2 3d 10 4p 1 . To do this, you count the row that the element is in. Gallium is in period 4, so the s-orbital is in the 4th shell with all of its electrons filled (2). Then you enter the 3 d-block, where the maximum number of electrons in the...
Sun Nov 03, 2019 8:10 pm
Forum: SI Units, Unit Conversions
Topic: Do you always convert to SI units for calculations?
Replies: 3
Views: 170

### Re: Do you always convert to SI units for calculations?

I think it's important to keep in mind what you are solving for. For example, if you are solving for E, the units for E are Joules, which translates to kg*m 2 *s 2 . Therefore, it's helpful convert your constants and variables to match units of kg and m so that you don't get confused or end up with ...
Sun Nov 03, 2019 11:24 am
Forum: Properties of Light
Topic: n in Rydberg Equation
Replies: 1
Views: 45

### n in Rydberg Equation

Hi, can someone please define for me what n actually means in the Rydberg equation? Is it correct that it is the principal quantum number? What does that actually mean?
Sun Oct 27, 2019 6:33 pm
Forum: Properties of Electrons
Topic: Chemical bonds
Replies: 2
Views: 62

### Re: Chemical bonds

The formation of ionic compounds involve transferring electrons from a metal to a nonmetal atom, resulting in cations and anions. Covalent bonds bind nonmetal atoms to form molecules. The ionization energies of these atoms are too high to transfer electrons from one atom to another, so they simply s...
Sun Oct 27, 2019 6:29 pm
Forum: General Science Questions
Topic: Study Guides
Replies: 6
Views: 112

### Re: Study Guides

I don't believe there is a concrete study guide for the exams in this class. However, the Community Programs Office has a test bank of exams completed by students who took the course in previous quarters. If you're a first-year, you can print out a test without having to turn anything in. But after ...
Sun Oct 27, 2019 6:23 pm
Forum: Lewis Structures
Topic: 2B.7
Replies: 4
Views: 40

### Re: 2B.7

Correct; because every element has a unique atomic number that corresponds to their generic number of electrons (no exceptions are stated in this problem), finding the number of valence electrons and identifying the element in the table would get you to your answer.
Sun Oct 27, 2019 6:15 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Using periodic table to find configurations?
Replies: 3
Views: 62

### Re: Using periodic table to find configurations?

Yes! The periodic table is actually structured based on these similarities. As you can see in the middle section of the periodic table, all of those elements contain d-orbitals.
Sun Oct 27, 2019 6:12 pm
Forum: Octet Exceptions
Topic: octet rule exception
Replies: 3
Views: 57

### Re: octet rule exception

Yes, because the d-orbitals in elements in period 3 or higher are capable of holding up to 10 atoms.
Sun Oct 20, 2019 10:59 pm
Forum: Einstein Equation
Topic: energy emitted by H electrons
Replies: 5
Views: 113

### Re: energy emitted by H electrons

Yes, I believe this can only be applied to hydrogen atoms just because multi-electron atoms are more complex in nature and require deeper-level analysis.
Sun Oct 20, 2019 10:58 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Sequence of Orbitals in a Singl
Replies: 3
Views: 55

### Re: Sequence of Orbitals in a Singl

Yes, all three orbitals can be generalized together, but like Ethan said, all three must spin up in the same direction before being paired.
Sun Oct 20, 2019 10:55 pm
Forum: Properties of Electrons
Topic: 1A 15
Replies: 4
Views: 148

### Re: 1A 15

Thank you everyone! This was really helpful.
Mon Oct 14, 2019 12:20 pm
Forum: Administrative Questions and Class Announcements
Topic: Where are the problems for Quantum World?
Replies: 2
Views: 29

### Re: Where are the problems for Quantum World?

Hi! I had a similar problem because I also only have the 6th edition. If you go to Powell Library, you can check out the 7th edition and the solutions manual for 2 hours; the homework problems begin on page 9. I cross referenced the two books and I don't think that the 6th edition has the problems t...
Mon Oct 14, 2019 12:09 pm
Forum: Properties of Electrons
Topic: 1A 15
Replies: 4
Views: 148

### 1A 15

I'm having trouble with this problem: In the ultraviolet spectrum of atomic hydrogen, a line is observed at 102.6 nm. Determine the values of n for the initial and final energy levels of the electron during the emission of energy that leads to this spectral line. To be quite honest I'm not even sure...
Sun Oct 13, 2019 2:46 pm
Forum: Photoelectric Effect
Topic: Work Function
Replies: 2
Views: 50

### Re: Work Function

Yep, and each metal requires a different amount of energy to remove an electron from the surface. I am assuming that if you are solving for another variable like wavelength or the photon energy, the work function will be given but can be calculated manually using the equation @dtolentino4H provided.
Sun Oct 13, 2019 2:34 pm
Forum: Administrative Questions and Class Announcements
Topic: Finding Textbook Questions on the Quantum World
Replies: 4
Views: 71

### Re: Finding Textbook Questions on the Quantum World

Thank you everyone! I should have been more clear but I am using the 6th edition and am still struggling to find the questions. I think I'm going to visit the library soon to see how the questions line up.
Sat Oct 12, 2019 10:51 pm
Forum: Balancing Chemical Reactions
Topic: F.3
Replies: 5
Views: 209

### Re: F.3

I was also wondering the same thing. I have an easier time deriving formulas for telltale compounds (ex. dihydrogen monoxide, haha) but am not sure if I should remember the methods of deriving for acids or oxides.
Sat Oct 12, 2019 10:49 pm
Forum: DeBroglie Equation
Topic: De Broglie's Equation
Replies: 2
Views: 45

### Re: De Broglie's Equation

I believe that De Broglie's Equation can only be used for particles with a mass. I don't think light has a mass, so it wouldn't make sense to use the equation when mass is needed as a variable.
Tue Oct 08, 2019 6:30 pm
Forum: Administrative Questions and Class Announcements
Topic: Finding Textbook Questions on the Quantum World
Replies: 4
Views: 71

### Finding Textbook Questions on the Quantum World

I'm having trouble finding the exercises assigned in the syllabus under the Quantum World. One of the first sections of problems is Problems 1A: 3, 5, 7, 9, 11, and 15, but I can't seem to find them in the textbook. Can someone direct me to a page number, please? It would mean a lot! Also, just to c...
Thu Oct 03, 2019 11:42 pm
Forum: SI Units, Unit Conversions
Topic: Formula Units
Replies: 3
Views: 90

### Re: Formula Units

Essentially, formula units unnamed variables. There are always 6.022 * 1023 units in one mole of something. This could be atoms or molecules. I would say that you should just know that one mole converts to a quantity of Avogadro's number units.
Thu Oct 03, 2019 11:33 pm
Forum: Molarity, Solutions, Dilutions
Topic: E 27
Replies: 6
Views: 109

### Re: E 27

Ok so to answer part a, you want to start with the information they give you (1 molecule water) and you're trying to get to grams of H2O. To get there, you have to convert the 1 molecule of water to moles of water by dividing by Avogadro's number (6.022 x 10^23), since 1 mol = 6.022 x 10^23 molecul...
Thu Oct 03, 2019 10:57 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactant problems
Replies: 4
Views: 71

### Re: Limiting Reactant problems

Are you talking about side reactions that are given, or side reactions that occur by chance? I would probably only utilize information that is given in the problem.