## Search found 100 matches

Tue Mar 10, 2020 7:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5% rule
Replies: 1
Views: 44

### Re: 5% rule

You take the value that you solved for when approximating and then divide it by the initial concentration given. If it is less than 5% after you multiply it, then the approximation is valid. If is is greater than 5%, then the approximation is not valid and you have to keep the -x and use the quadrat...
Tue Mar 10, 2020 7:09 pm
Forum: Administrative Questions and Class Announcements
Topic: Homework 10
Replies: 11
Views: 163

### Re: Homework 10

Wait for your TA to email you first.
Tue Mar 10, 2020 7:08 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2
Replies: 5
Views: 146

### Re: Test 2

I have not received any email yet.
Tue Mar 10, 2020 7:02 pm
Forum: Biological Examples
Topic: COVID-19
Replies: 6
Views: 156

### Re: COVID-19

I’m wondering if our TAs want us to email the homework this week for credit.
Tue Mar 10, 2020 6:58 pm
Forum: Student Social/Study Group
Topic: The Final
Replies: 5
Views: 225

### Re: The Final

Most likely it will be online, but it’s best that we wait for Lavelle.
Sun Mar 08, 2020 8:20 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: calculating Q
Replies: 12
Views: 137

### Re: calculating Q

I believe that it is [anode]/[cathode].
Sun Mar 08, 2020 8:13 pm
Forum: Balancing Redox Reactions
Topic: Balancing basic reactions
Replies: 8
Views: 94

### Re: Balancing basic reactions

I add H2O and OH- on the right side for reduction and then balance both sides by adding H2O to the other side. For oxidation, add H2O and OH- on the left and balance the number of H by adding H2O on the right. That's assuming you need to add any oxygens or hydrogens.
Sun Mar 08, 2020 8:07 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Vertical lines vs commas
Replies: 7
Views: 37

### Re: Vertical lines vs commas

Commas are for when it's the same state (ex. Fe2+ (aq), Fe3+ (aq)), and vertical lines separate different states like g or aq.
Sun Mar 08, 2020 8:01 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: galvanic vs electrolytic
Replies: 12
Views: 122

### Re: galvanic vs electrolytic

For galvanic cells, spontaneous redox reactions convert the chemical energy to an electric energy. For electrolytic cells, non-spontaneous redox reactions convert the electric energy to a chemical energy.
Sun Mar 08, 2020 7:52 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 13
Views: 162

### Re: Cell Diagrams

You add Pt typically to the cell diagram when there are no other metals present.
Sun Mar 01, 2020 9:00 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagram Comma vs Line
Replies: 5
Views: 45

### Re: Cell Diagram Comma vs Line

My TA said to use the notation below as a guide.
solid|gas|aq||aq|gas|solid
Sun Mar 01, 2020 8:53 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Rust and Cathodic Protection
Replies: 1
Views: 41

### Re: Rust and Cathodic Protection

I would just familiarize yourself with the two questions on it from the textbook. If he actually tests us on it, then it will most likely resemble those.
Sun Mar 01, 2020 8:49 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Ion-selective Electrodes and Corrosion
Replies: 2
Views: 49

### Re: Ion-selective Electrodes and Corrosion

If it is on the outline or talked about during lecture, then it probably will be on the final.
Sun Mar 01, 2020 8:26 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 6
Views: 65

### Re: Cell Diagrams

I am pretty sure you can write it either way as long as you follow the conventions for writing out a cell diagram.
Sun Mar 01, 2020 8:22 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electrochemical Series
Replies: 5
Views: 58

### Re: Electrochemical Series

Electrochemical series is just the table that lists all the standard electrode potentials for different chemical species.
Sat Feb 22, 2020 10:40 pm
Forum: Administrative Questions and Class Announcements
Topic: Curve?
Replies: 5
Views: 71

### Re: Curve?

He might slightly adjust the overall grades at the end of the quarter, but he won't curve the tests individually.
Sat Feb 22, 2020 10:33 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: determining if a metal will dissolve in a solution
Replies: 2
Views: 21

### Re: determining if a metal will dissolve in a solution

You have to compare the metal's standard reduction potential to that of H2. Metals above H2 on the activity series dissolve in acids, while metals below H2 do not dissolve in acids. I believe nitric acid is an exception for metals below H2.
Sat Feb 22, 2020 10:26 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: electrochemical series
Replies: 4
Views: 70

### Re: electrochemical series

Electrochemical series is the table that lists all the standard electrode potentials (reduction potential or oxidation potential) of different chemical species.
Sat Feb 22, 2020 10:01 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Writing half-rxn
Replies: 3
Views: 45

### Re: Writing half-rxn

You definitely need E values for both the cathode and the anode. Those half-reactions are given in appendix 2B of the textbook.
Sat Feb 22, 2020 9:55 pm
Forum: Balancing Redox Reactions
Topic: Basic conditions
Replies: 6
Views: 94

### Re: Basic conditions

My TA also said that if the problem mentions alkali you use OH-.
Sun Feb 16, 2020 11:34 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: spontaneity
Replies: 34
Views: 669

### Re: spontaneity

Aside from delta G, a reaction is spontaneous if delta H is negative and delta S is positive.
Sun Feb 16, 2020 11:29 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Delta E
Replies: 11
Views: 226

### Re: Delta E

Yes, delta E and delta U are both used to represent internal energy.
Sun Feb 16, 2020 11:26 am
Forum: Balancing Redox Reactions
Topic: skeletal equations
Replies: 3
Views: 50

### Re: skeletal equations

Both chemical formulas represent the same compound regardless of the order they are written in.
Sun Feb 16, 2020 11:22 am
Forum: Balancing Redox Reactions
Topic: oxidation vs reduction
Replies: 19
Views: 268

### Re: oxidation vs reduction

Oxidation is when a reactant loses electrons during the reaction whereas reduction occurs when it gains electrons during the reaction.
Sun Feb 16, 2020 11:13 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Midterm Curve
Replies: 45
Views: 553

### Re: Midterm Curve

Yeah he usually doesn't curve the midterm even if the average is low.
Sun Feb 09, 2020 7:23 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D.21
Replies: 3
Views: 31

### Re: 4D.21

I got -138.18 kJ like the solution manual. You probably have a small calculation error. Are all the signs correct and did you multiply each one by the correct number of moles?
Sun Feb 09, 2020 7:03 pm
Forum: Administrative Questions and Class Announcements
Topic: slides
Replies: 8
Views: 95

### Re: slides

There is the pizza rolls midterm review handout.
Sun Feb 09, 2020 6:59 pm
Forum: Phase Changes & Related Calculations
Topic: Heat & Temperature of Phase Changes
Replies: 5
Views: 39

### Re: Heat & Temperature of Phase Changes

When there is a phase change, temperature remains constant for a period of time because all the heat added is being used to break bonds.
Sun Feb 09, 2020 6:56 pm
Forum: Administrative Questions and Class Announcements
Topic: memorizing things?
Replies: 13
Views: 128

### Re: memorizing things?

It doesn't greatly affect the final answer, but you might as well use 273.15.
Sun Feb 09, 2020 6:54 pm
Forum: Student Social/Study Group
Topic: Midterm and Final Question
Replies: 18
Views: 266

### Re: Midterm and Final Question

Pizza rolls are the key words for the midterm review session worksheet that was today.
Sun Feb 02, 2020 7:39 pm
Forum: Calculating Work of Expansion
Topic: Volume
Replies: 3
Views: 28

### Re: Volume

Work=-P$\Delta$V
Sun Feb 02, 2020 7:31 pm
Forum: Calculating Work of Expansion
Topic: Expansion
Replies: 4
Views: 48

### Re: Expansion

Compression will have positive work on the gas whereas expansion will have negative work on the gas.
Sun Feb 02, 2020 7:22 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Phase change
Replies: 20
Views: 173

### Re: Phase change

Breaking the bonds that are holding the solid together requires energy. Thus, delta H is positive since the reaction is endothermic (needs energy/energy absorbed).
Sun Feb 02, 2020 7:20 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Moles
Replies: 8
Views: 149

### Re: Moles

Many gases are just diatomic molecules or a combination of different elements. This doesn't affect the number of moles. Thus, you only need to consider the coefficient to get the number of moles.
Sun Feb 02, 2020 7:17 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Definition of First Law
Replies: 9
Views: 86

### Re: Definition of First Law

Energy is neither created nor destroyed. That is why it is known as conservation of energy.
Wed Jan 22, 2020 1:37 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5.33
Replies: 4
Views: 45

### Re: 5.33

Catalysts speed up the rate of a reaction, but they do not affect the amount of reactants or products at all.
Wed Jan 22, 2020 1:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: "shifting" eq?
Replies: 3
Views: 49

### Re: "shifting" eq?

If eq is shifted right, then products will be favored. If eq is shifted left, then reactants will be favored.
Wed Jan 22, 2020 1:31 pm
Forum: Phase Changes & Related Calculations
Topic: Exo/endo definition
Replies: 3
Views: 42

### Re: Exo/endo definition

Endothermic and exothermic mean heat is either being released or absorbed at a constant pressure. Endergonic and exergonic refer to changes in free energy. For endergonic reactions, energy is needed to drive the reaction in the forward direction. For exergonic reactions, energy is released in the fo...
Wed Jan 22, 2020 1:10 pm
Forum: Administrative Questions and Class Announcements
Topic: Grading of Tests
Replies: 18
Views: 242

### Re: Grading of Tests

My TA in 14A usually gave me points for following the right steps even though the final calculations were wrong.
Wed Jan 22, 2020 1:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Prepping for Test
Replies: 6
Views: 73

### Re: Prepping for Test

I would also recommend going to the workshops since those problems are more complex than the ones covered in step-up sessions.
Sun Jan 19, 2020 8:43 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm and final
Replies: 6
Views: 84

### Re: Midterm and final

Midterms and finals are cumulative, but the tests aren't.
Sun Jan 19, 2020 8:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: composite chemical equations
Replies: 2
Views: 33

### Re: composite chemical equations

Basically, the equilibrium constant for an overall reaction is the product of the equilibrium constants for its component reactions. Thus, you would combine the reactions H_{2}+Cl_{2}\rightleftharpoons 2HCl and 2BrCl\rightleftharpoons Br_{2}+Cl_{2} and then cancel the Cl on both sides since it appea...
Sun Jan 19, 2020 8:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Use of buffers
Replies: 2
Views: 23

### Re: Use of buffers

You need to know how to calculate the pH of a weak acid and its salt, which makes a buffer. The example Lavelle used in Friday lecture was nitrous acid and potassium nitrite.
Sun Jan 19, 2020 8:28 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Not including solids and liquids
Replies: 7
Views: 82

### Re: Not including solids and liquids

The activity of a pure solid or liquid is equal to 1 so it doesn't affect the value of the equilibrium constant.
Sun Jan 19, 2020 8:25 pm
Forum: Ideal Gases
Topic: homework #3
Replies: 16
Views: 241

### Re: homework #3

You can also answer questions from the new topics we'll cover during Wednesday lecture if your discussion follows it.
Sun Jan 19, 2020 8:22 pm
Forum: Ideal Gases
Topic: Using PV=nRT
Replies: 7
Views: 70

### Re: Using PV=nRT

This equation will most likely show up on the test. It is used for finding the equilibrium pressure of a gas.
Sun Jan 19, 2020 8:20 pm
Forum: Administrative Questions and Class Announcements
Topic: TeST 1
Replies: 5
Views: 62

### Re: TeST 1

It is chemical equilibrium up to acid and base equilibria. The outlines for all the topics are on Lavelle's website.
Sun Jan 19, 2020 8:18 pm
Forum: Phase Changes & Related Calculations
Topic: Autoprotolysis
Replies: 15
Views: 176

### Re: Autoprotolysis

It is helpful to know since the autoprotolysis constant of water, Kw, is used to calculate hydronium and hydroxide concentration. That helps us determine if the solution is more acidic or basic.
Sun Jan 19, 2020 8:12 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test 1 Acids and Bases Topic
Replies: 9
Views: 118

### Re: Test 1 Acids and Bases Topic

I would memorize the strong acids and bases because it is really helpful.
Sun Jan 19, 2020 8:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Buffers
Replies: 2
Views: 45

### Re: Buffers

A buffer is defined as a chemical substance that helps maintain a relatively constant pH in a solution, even in the face of addition of acids or bases. The only thing I remember Lavelle mentioning in class was about how adding equal amounts of sodium acetate and acetic acid makes a buffer solution. ...
Sun Jan 19, 2020 8:00 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pa and Pb
Replies: 4
Views: 46

### Re: Pa and Pb

Pa is for acid and Pb is for bases. Ka is the dissociation constant for acids and Kb is the dissociation constant for bases.
Sun Dec 08, 2019 4:26 pm
Forum: Administrative Questions and Class Announcements
Replies: 5
Views: 155

### Re: Final Grade

Final grades have to be in for fall quarter.
Sun Dec 08, 2019 4:25 pm
Forum: Administrative Questions and Class Announcements
Topic: Online Textbook Access Code 14B
Replies: 2
Views: 72

### Re: Online Textbook Access Code 14B

I believe it is 24 month access, and the chem textbook is the same all throughout for the 14 series.
Sun Dec 08, 2019 4:21 pm
Forum: Lewis Acids & Bases
Topic: Mg(OH)2 Considered strong or weak base?
Replies: 5
Views: 165

### Re: Mg(OH)2 Considered strong or weak base?

Mg(OH)2 is a strong base since strong bases are oxides and hydroxides that bond to group 1 and 2 elements.
Sun Dec 01, 2019 11:22 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Final Information
Replies: 2
Views: 44

### Re: Final Information

Most likely he will discuss it during lecture tomorrow.
Sun Dec 01, 2019 11:20 pm
Forum: Naming
Topic: Naming
Replies: 3
Views: 59

### Re: Naming

It is known that when naming an ionic compound, the cation is always first before the anion. For instance, in NaCl sodium is the cation and chlorine is the anion.
Sun Dec 01, 2019 11:16 pm
Forum: General Science Questions
Topic: test taking nervousness
Replies: 19
Views: 358

### Re: test taking nervousness

I also find it helpful to skip questions that initially cause confusion. When I return to them later on, I always have a clearer mind and feel less stressed given that I know I have completed the easier problems I am more confident about.
Sun Dec 01, 2019 11:11 pm
Forum: Bronsted Acids & Bases
Topic: Water as an acid and base
Replies: 7
Views: 112

### Re: Water as an acid and base

Yes. It is in reference to hydrogen.
Sun Dec 01, 2019 11:08 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Electron Pair Donors
Replies: 3
Views: 32

### Re: Electron Pair Donors

Yes, that is why it is a Lewis base.
Sun Nov 24, 2019 7:09 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Bond order
Replies: 5
Views: 152

### Re: Bond order

Bond order is defined as the number of chemical bonds between a pair of atoms, and it indicates the stability of a bond.
Sun Nov 24, 2019 7:08 pm
Forum: Lewis Acids & Bases
Topic: HCl vs HF
Replies: 19
Views: 229

### Re: HCl vs HF

The hydrogen-chlorine bond in HCl is very weak and it completely dissociates in water. This qualifies HCl as a strong acid. On the other hand, the bonding in HF is relatively strong. Thus, it only partially dissociates in water and makes it a weak acid.
Sun Nov 24, 2019 7:04 pm
Forum: Trends in The Periodic Table
Topic: Pneumonic devices for trends
Replies: 4
Views: 176

### Re: Pneumonic devices for trends

I also like to draw two arrows pointing towards one another (down a group, across a period) and label whether or not it's increasing or decreasing.
Sun Nov 24, 2019 7:01 pm
Forum: Naming
Topic: Week 9 and Week 10 HW?
Replies: 21
Views: 270

### Re: Week 9 and Week 10 HW?

I believe section 9C since it has to do with coordination compounds.
Sun Nov 24, 2019 6:58 pm
Forum: Administrative Questions and Class Announcements
Topic: final exam
Replies: 9
Views: 167

### Re: final exam

Also are we going to finish with acid and base structures?
Sun Nov 17, 2019 1:21 pm
Forum: General Science Questions
Topic: Test 2
Replies: 7
Views: 83

### Re: Test 2

So the test will cover topics from section 2D in the textbook to what we've learned now?
Sun Nov 17, 2019 1:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity 2E.25
Replies: 2
Views: 50

### Re: Polarity 2E.25

Carbon dioxide is considered non-polar because of the symmetry of its bonding. The EN difference between C and O is 1.0, and it makes the bonds polar. Since the two polar bonds are at 180 degrees to each other, the dipoles cancel out.
Sun Nov 17, 2019 1:02 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: Intermolecular Force Strengths
Replies: 2
Views: 47

### Re: Intermolecular Force Strengths

I am pretty sure that it is sufficient to know the strengths relative to each other. Otherwise, I would ask Lavelle or your TA.
Sun Nov 17, 2019 12:57 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.21 d
Replies: 2
Views: 33

### Re: 2E.21 d

I believe Lavelle said in class that we are not expected to predict the exact angle. I am pretty sure that saying "less than 109.5 degrees" is fine.
Sun Nov 17, 2019 12:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar Molecules and Symmetry
Replies: 3
Views: 57

### Re: Polar Molecules and Symmetry

If atoms in a molecule are symmetrical, then the charges are balanced by each other and the molecule is considered nonpolar. If a molecule is asymmetrical, it is polar.
Sun Nov 10, 2019 10:03 am
Forum: Dipole Moments
Topic: Dipole Moments
Replies: 3
Views: 41

### Re: Dipole Moments

Dipole moments occur when there is a separation of charge between two ions in an ionic bond or between atoms in a covalent bond. It occurs due to differences in electronegativity. Thus, the dipole moment will be larger if the difference in electronegativity is greater.
Sun Nov 10, 2019 9:58 am
Forum: Bond Lengths & Energies
Topic: Bond Lengths
Replies: 3
Views: 55

### Re: Bond Lengths

Since double and triple bonds have more electrons, they have stronger attractive forces on the nuclei of the bonding atoms. These atoms are pulled closer together, and it creates shorter bond lengths.
Sun Nov 10, 2019 9:54 am
Forum: Administrative Questions and Class Announcements
Topic: Second Discussion Test
Replies: 9
Views: 188

### Re: Second Discussion Test

I believe the test is during your discussion section starting the 19th of November.
Sun Nov 10, 2019 9:44 am
Forum: Bond Lengths & Energies
Topic: Dissociation Energy
Replies: 9
Views: 101

### Re: Dissociation Energy

Forming bonds release energy and breaking bonds require energy.
Sun Nov 10, 2019 9:42 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: London vs. dipole-induced-dipole interaction
Replies: 3
Views: 34

### Re: London vs. dipole-induced-dipole interaction

Non-polar molecules are attracted through London dispersion attractions while polar molecules can be attracted through both London dispersion attractions and stronger dipole-dipole attractions.
Sun Nov 03, 2019 4:00 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Understanding Lyman and Balmer series
Replies: 3
Views: 65

### Re: Understanding Lyman and Balmer series

Provided that the transition is from a high energy level to the ground state level, n=1 is the final state while n=3 is the initial state.
Sun Nov 03, 2019 3:53 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 5
Views: 80

### Re: Formal Charge

Calculating the formal charge allows you to find the most stable structure. Thus, just follow the equation FC = # Valence electrons - (# Lone pair electrons + # Shared electrons/2).
Sun Nov 03, 2019 3:49 pm
Forum: Resonance Structures
Topic: Resonance structures
Replies: 5
Views: 53

### Re: Resonance structures

Resonance is helpful in determining which lewis structure to use. By calculating each formal charge, you can find the most stable one.
Sun Nov 03, 2019 3:39 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Amount of electrons in each shell
Replies: 3
Views: 47

### Re: Amount of electrons in each shell

Row 3 and below can have more than 8 electrons. Since the electron configuration of Co^3+is [Ar] 3d^4 4s^2, it has 6 valence electrons.
Sun Nov 03, 2019 3:32 pm
Forum: Student Social/Study Group
Topic: Midterm
Replies: 17
Views: 287

### Re: Midterm

Lavelle has stated on his website that the midterm covers the material up to the end of focus 2D.
Sun Oct 27, 2019 2:32 pm
Forum: Lewis Structures
Topic: Bond lengths
Replies: 3
Views: 38

### Re: Bond lengths

The value he gave us for C-C bond lengths in class were experimentally observed so I would just ask your TA.
Sun Oct 27, 2019 2:27 pm
Forum: Trends in The Periodic Table
Topic: Electron affinity.
Replies: 8
Views: 59

### Re: Electron affinity.

Basically when a neutral atom gains some electrons, an energy change occurs. This energy change is called the electron affinity.
Sun Oct 27, 2019 2:21 pm
Forum: Student Social/Study Group
Topic: Miderm Review
Replies: 10
Views: 284

### Re: Miderm Review

I am not sure if they have any, but you could try making a same-day appointment at the test bank and seeing if there are any old exams you could review.
Sun Oct 27, 2019 2:17 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic vs. Atomic Radii
Replies: 4
Views: 60

### Re: Ionic vs. Atomic Radii

Also, I believe whether or not the ion is positive or negative affects the distance for the ionic radius. Thus, a cation would have a smaller ionic radius while an anion would have a larger ionic radius.
Sun Oct 27, 2019 1:58 pm
Forum: Octet Exceptions
Topic: 8 valence electrons
Replies: 3
Views: 45

### Re: 8 valence electrons

Hydrogen and Beryllium are also exceptions to the octet rule because they often form incomplete octets (less than 8 valence electrons). Overall, I would just focus on P, S, Cl since they are the most common elements that make stable compounds with expanded octets.
Sun Oct 20, 2019 11:43 pm
Forum: *Shrodinger Equation
Topic: Hamiltonian
Replies: 6
Views: 86

### Re: Hamiltonian

Is the Hamiltonian likely to be used a lot in this course? Is there an example problem that demonstrates when you would use or solve for?
Sun Oct 20, 2019 11:25 pm
Forum: Student Social/Study Group
Topic: Midterm
Replies: 17
Views: 287

### Re: Midterm

So does the midterm cover the fundamentals up until the quantum world or will it include chemical bonds also?
Sun Oct 20, 2019 11:22 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Hund's Rule
Replies: 5
Views: 78

### Re: Hund's Rule

Hund's Rule states that electrons in the same subshell occupy different orbitals with a parallel spin because of the fact that there is less electron repulsion and the lowest amount of energy.
Sun Oct 20, 2019 11:18 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Clarification on electron configuration
Replies: 5
Views: 67

### Re: Clarification on electron configuration

Lavelle stated that the only ones that are important for Chem 14A are the s-block, the p-block, and the 1st row of the d-block.
Sun Oct 20, 2019 11:13 pm
Forum: *Shrodinger Equation
Topic: Schrodinger equation
Replies: 4
Views: 72

### Re: Schrodinger equation

The Schrodinger equation is basically used to describe an electron in an atom by calculating the electron's wave function. https://www.chemicool.com/definition/sc ... ation.html is pretty helpful in describing what it is and when it's applied.
Sun Oct 13, 2019 12:08 am
Forum: Significant Figures
Topic: rounding in sig figs
Replies: 5
Views: 235

### Re: rounding in sig figs

The link that Lavelle posted on his website for sig figs states the rule. If the last digit is 5 and no number follows it , then you have to round to the nearest even number. Thus, if you need three sig figs and you have 0.4565, you have to round to the closest even number which is 6. Thus, it becom...
Sun Oct 13, 2019 12:00 am
Forum: Properties of Light
Topic: e=hv
Replies: 7
Views: 178

### Re: e=hv

Lavelle discussed in class how light rays are streams of EM energy that are made up of photons. Thus, since a photon is a unit for light and E=hv measures the energy of a photon, the equation is applied to light.
Sat Oct 12, 2019 11:47 pm
Forum: Significant Figures
Topic: Sig Figs at the Beginning or End
Replies: 14
Views: 427

### Re: Sig Figs at the Beginning or End

Like Karyn said, I would just wait to round to the correct sig figs after doing all the calculations. Usually the amount of sig figs depends on the least amount that is provided in the question. If you're using addition/subtraction and multiplication/division, then you base it off the rules for mult...
Sat Oct 12, 2019 11:26 pm
Forum: DeBroglie Equation
Topic: De Broglie Lecture Question
Replies: 2
Views: 41

### Re: De Broglie Lecture Question

Thank you Hannah!
Sat Oct 12, 2019 11:25 pm
Forum: Properties of Light
Topic: Rydberg constant
Replies: 7
Views: 100

### Re: Rydberg constant

Why is the Rydberg equation only applicable towards hydrogen atoms?
Sat Oct 12, 2019 11:17 pm
Forum: DeBroglie Equation
Topic: De Broglie Lecture Question
Replies: 2
Views: 41

### De Broglie Lecture Question

There was an example in class that said, "Calculate the De Broglie wavelength of an electron traveling at 5.3x10^{6}m.s^{-1} . Do you think your calculated wavelength, for electrons with similar velocities, could be experimentally verified/detected in this lab?" The solution was \lambda = ...
Wed Oct 02, 2019 11:08 pm
Forum: Balancing Chemical Reactions
Topic: Balancing Chemical Equations Formatting
Replies: 6
Views: 189

### Re: Balancing Chemical Equations Formatting

The subscript of two only applies to the element or elements in the parentheses that it is next to. Thus, Mg(N3)2(s) basically means that there is one Mg atom and 6 nitrogen atoms.
Wed Oct 02, 2019 11:03 pm
Forum: Balancing Chemical Reactions
Topic: Figuring Out State Symbols
Replies: 3
Views: 93

### Figuring Out State Symbols

It has been awhile since I have taken chemistry. I was just wondering if symbols for whether or not a reactant or product is aqueous, liquid, solid, or gas can be identified by looking at the molecular formula alone or if you need to know the chemical properties of the reactant or product to determi...
Wed Oct 02, 2019 10:57 pm
Forum: Limiting Reactant Calculations
Topic: Homework Problem M.9
Replies: 3
Views: 54

### Re: Homework Problem M.9

Remember when calculating the maximum mass of copper(II) hydroxide that you multiply that same mol ratio you used previously by the moles of sodium hydroxide and then convert the answer to g copper(II) hydroxide.
Wed Oct 02, 2019 10:46 pm
Forum: Balancing Chemical Reactions
Topic: Combustion Reaction Notation
Replies: 6
Views: 106

### Re: Combustion Reaction Notation

As Maggie puts it, it is important to note that both combustion and oxidation imply there is burning in the presence of oxygen.
Wed Oct 02, 2019 10:35 pm
Forum: Significant Figures
Topic: Question About Significant Figures and Rounding
Replies: 22
Views: 1130

### Re: Question About Significant Figures and Rounding

Follow-up question...If there is a multiplication/division problem and say 1 mol of _ is being used in the equation, are numbers that are just 1 ignored when considering sig figs? 1 mol only has 1 sig fig but many of the answers to the problems disregard this. Is there a special rule for 1s?

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