Search found 60 matches

by 904914909
Wed Mar 06, 2019 5:29 pm
Forum: General Rate Laws
Topic: Rate Laws and Temperature
Replies: 4
Views: 54

Re: Rate Laws and Temperature

k once calculated is only for that temperature, which is why we have the Arrhenius equation to help calculate the new k when temperature changes
by 904914909
Wed Mar 06, 2019 5:26 pm
Forum: General Rate Laws
Topic: does k change if rxn is multiplied?
Replies: 6
Views: 61

Re: does k change if rxn is multiplied?

k is a constant for the equation so it should not change if the rxn is multiplied
by 904914909
Wed Mar 06, 2019 5:24 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: zero and first
Replies: 5
Views: 49

Re: zero and first

zero order reactions do not depend on the initial concentrations while 1st order reactions are directly proportional to the concentrations
by 904914909
Mon Mar 04, 2019 8:47 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: rate of change
Replies: 4
Views: 206

Re: rate of change

the coefficents of the balanced reaction relate the rates to each other
by 904914909
Mon Mar 04, 2019 8:46 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Activation energy
Replies: 8
Views: 114

Re: Activation energy

Activation energy is the energy needed for a reaction to occur, so the lower the activation energy, the more thermodynamically favorable the process is
by 904914909
Mon Mar 04, 2019 8:41 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: how is kinetics different?
Replies: 17
Views: 170

Re: how is kinetics different?

Thermo talks about the amount of energy transferred while kinetics talks about the rate that energy is transferred
by 904914909
Sat Feb 23, 2019 9:56 am
Forum: Balancing Redox Reactions
Topic: Redox Rxn
Replies: 3
Views: 41

Re: Redox Rxn

I think we just need to memorize the normal periodic trends that we used last quarter and then we will figure out the transition metal ones based on the rxn
by 904914909
Sat Feb 23, 2019 9:54 am
Forum: Balancing Redox Reactions
Topic: Test 2 Material
Replies: 11
Views: 130

Re: Test 2 Material

This is what the class website says : "Test 2 covers all topics on Gibbs free energy and electrochemistry up to but not including the Nernst equation (which is all the new material covered in class Weeks 6 and 7)", so I think everything from after the midterm up to Monday
by 904914909
Sat Feb 23, 2019 9:53 am
Forum: Balancing Redox Reactions
Topic: difference between oxidation and reduction
Replies: 8
Views: 74

Re: difference between oxidation and reduction

oxidation loses electrons so the charge becomes more positive, while reduction gains electrons so the charge becomes more negative
by 904914909
Fri Feb 15, 2019 1:42 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Quick Conceptual question
Replies: 7
Views: 104

Re: Quick Conceptual question

Enthalpy is a measure of heat transfer while entropy is a measure of disorder in a system
by 904914909
Fri Feb 15, 2019 1:41 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isobaric
Replies: 11
Views: 164

Re: Isobaric

isobaric means that the volume is still changing so you can still calculate work
by 904914909
Fri Feb 15, 2019 1:40 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7337
Views: 826128

Re: Post All Chemistry Jokes Here

What was the chemists favorite drink?
ChemisTEA
by 904914909
Fri Feb 08, 2019 12:52 am
Forum: Phase Changes & Related Calculations
Topic: Units of enthalpy
Replies: 5
Views: 79

Re: Units of enthalpy

kJ/mol
by 904914909
Fri Feb 08, 2019 12:48 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated System
Replies: 5
Views: 77

Re: Isolated System

An isolated system is useful to calculate changes that happen based solely on the reaction and not due to exchanges with the surrounding
by 904914909
Fri Feb 08, 2019 12:46 am
Forum: Calculating Work of Expansion
Topic: Degeneracy
Replies: 6
Views: 87

Re: Degeneracy

Degeneracy is the number of possible states that atoms can exist in and it is related to entropy because the higher the degeneracy the more potential for disorder and higher entropy.
by 904914909
Fri Feb 01, 2019 7:59 pm
Forum: Calculating Work of Expansion
Topic: negative vs. positive internal energy
Replies: 2
Views: 54

Re: negative vs. positive internal energy

When U is negative, that means the net energy is out of the system or the system is doing work on the surrounding. When U is positive, that means net energy is into the system or the surroundings are doing work on the system.
by 904914909
Fri Feb 01, 2019 7:56 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Qsystem+Qsurr=0?
Replies: 6
Views: 93

Re: Qsystem+Qsurr=0?

The system gains the heat of the surroundings in some reactions but the system loses the heat to the surroundings in other reactions so the net change in heat is 0 which is why Qsyst + Qsurr = 0.
by 904914909
Fri Feb 01, 2019 7:52 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Thermo Test/Midterm
Replies: 9
Views: 154

Re: Thermo Test/Midterm

I think we will be expected to know the basic shape of the structures but they won't need to be detailed.
by 904914909
Sat Jan 26, 2019 5:06 pm
Forum: Phase Changes & Related Calculations
Topic: Why steam causes severe burns
Replies: 9
Views: 113

Re: Why steam causes severe burns

In order to get to the phase of steam, the water will have had to accumulate more heat than just boiling water thus having the capability to cause more severe burns.
by 904914909
Sat Jan 26, 2019 5:03 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy as a state property
Replies: 2
Views: 51

Re: Enthalpy as a state property

Enthalpy is heat under constant pressure, so while enthalpy can be described as a state function, heat cannot because in its general definition it can have changing pressures
by 904914909
Sat Jan 26, 2019 5:01 pm
Forum: Phase Changes & Related Calculations
Topic: The qp symbol
Replies: 3
Views: 55

Re: The qp symbol

The q refers to heat but qp is enthalpy because it describes heat under a constant pressure. Enthalpy can be endothermic or exothermic, meaning qp can be positive or negative as well
by 904914909
Sun Jan 20, 2019 5:09 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Kw
Replies: 6
Views: 97

Re: Kw

they are equal in water because they are at equilibrium
by 904914909
Sun Jan 20, 2019 5:08 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: K vs. Q
Replies: 5
Views: 102

Re: K vs. Q

K is the equilibrium constant, the proportion of products to reactants when the reaction is at equilibrium. Q is the reaction quotient and it show the proportion of products to reactants when the reaction is not at equilibrium.
by 904914909
Sun Jan 20, 2019 5:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Arrow
Replies: 7
Views: 100

Re: Equilibrium Arrow

If a rxn completely dissociates, ie a strong acid or base, then an equilibrium arrow is not used
by 904914909
Fri Jan 11, 2019 3:27 pm
Forum: Ideal Gases
Topic: Reaction Quotient
Replies: 5
Views: 72

Re: Reaction Quotient

You use Kp or Kc based on the other information they give you, but gases can be found using either method.
by 904914909
Fri Jan 11, 2019 3:26 pm
Forum: Student Social/Study Group
Topic: New to Lavelle
Replies: 32
Views: 578

Re: New to Lavelle

I find the UA sessions really helpful and when preparing for tests to do a lot of practice problems, especially the ones that are integrated into the readings
by 904914909
Fri Jan 11, 2019 3:24 pm
Forum: Ideal Gases
Topic: Pressure of gasses
Replies: 5
Views: 96

Re: Pressure of gasses

I think stick to the formulas he has given us in lecture so far, bc this one hasn't been mentioned yet.
by 904914909
Tue Jan 08, 2019 7:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Aqueous in K expression
Replies: 4
Views: 64

Re: Aqueous in K expression

Aqueous substances are included in finding the equilibrium constant
by 904914909
Tue Jan 08, 2019 7:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: aqueous solutions
Replies: 2
Views: 35

Re: aqueous solutions

For the equilibrium constant, you only include the substances that are in the aqueous and gas phases so the inclusion of water will depend on the equation that you are looking at.
by 904914909
Tue Jan 08, 2019 7:19 pm
Forum: Ideal Gases
Topic: Solid/Liquid in Reactions
Replies: 4
Views: 57

Re: Solid/Liquid in Reactions

Solids and liquid concentration can't change and so they don't have any effect on the equilibrium constant
by 904914909
Sun Dec 02, 2018 6:56 pm
Forum: Naming
Topic: Metal Prefixes
Replies: 2
Views: 70

Re: Metal Prefixes

I think we're supposed to know the compounds in the table that Lavelle posted on the course website
by 904914909
Sun Dec 02, 2018 6:47 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Compounds
Replies: 2
Views: 59

Re: Coordination Compounds

You can't determine between tetrahedral and square planar by looking at it, so if a compound has four ligands, you can label it as a tetrahedral complex or a square planar complex.
by 904914909
Sun Dec 02, 2018 6:42 pm
Forum: Amphoteric Compounds
Topic: Examples
Replies: 6
Views: 81

Re: Examples

Some other examples from problems in the book are HCO3- and HPO4^(2-)
by 904914909
Mon Nov 26, 2018 3:52 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: test #3
Replies: 14
Views: 278

Re: test #3

So what exactly is paramagnetism and diamagnetism?
by 904914909
Mon Nov 26, 2018 3:46 pm
Forum: Hybridization
Topic: Hybridization
Replies: 2
Views: 39

Re: Hybridization

Hybrid orbitals have lower energy than their unhybridized counterparts, so I think hybridization occurs to make the compounds more stable due to lower energy pockets.
by 904914909
Mon Nov 26, 2018 3:42 pm
Forum: Hybridization
Topic: Just Kind of Confused
Replies: 13
Views: 146

Re: Just Kind of Confused

So order only matters for electron configuration but not hybridization?
by 904914909
Fri Nov 16, 2018 2:21 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Tetrahedral shape
Replies: 5
Views: 83

Re: Tetrahedral shape

A molecule could have a distorted tetrahedral shape due to lone pair repulsion that causes bond angles to be less than suggested by the VSEPR model
by 904914909
Fri Nov 16, 2018 2:17 pm
Forum: Dipole Moments
Topic: Test
Replies: 15
Views: 209

Re: Test

From the course website: "Test 3 covers: End of Bonding from 3.12 (6 Ed.) and from 2D (7 Ed.); and all of Molecular Shape and Structure (see Syllabus and Outlines for details"
by 904914909
Fri Nov 16, 2018 1:02 pm
Forum: Sigma & Pi Bonds
Topic: Strength
Replies: 1
Views: 63

Strength

Do sigma and pi bonds have a different strength or is the main significant difference the way in which they overlap?
by 904914909
Sat Nov 10, 2018 5:11 pm
Forum: Resonance Structures
Topic: Expanded Octet and Resonance
Replies: 2
Views: 83

Re: Expanded Octet and Resonance

No, because having more than 4 single bonds would consist of an expanded octet. To have more than 4 single bonds the atom would have to be in the 3p block or higher.
by 904914909
Sat Nov 10, 2018 5:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shapes
Replies: 4
Views: 69

Re: Molecular Shapes

It is determined by the locations of the bonding and lone pairs and the repulsion associated with those electrons
by 904914909
Sat Nov 10, 2018 4:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Test
Replies: 2
Views: 49

Re: Test

The updated test and exam schedule on the course website has the next test listed for the week of November 27th so it shouldn't conflict with Thanksgiving break at all :)
by 904914909
Sat Nov 03, 2018 10:06 pm
Forum: Lewis Structures
Topic: Formal Charges on Midterm
Replies: 2
Views: 70

Re: Formal Charges on Midterm

At a workshop I went to, a UA said it would be a good idea to write them out but it wasn't completely necessary unless stated explicitly in the problem
by 904914909
Sat Nov 03, 2018 9:52 pm
Forum: Lewis Structures
Topic: lewis acid/base
Replies: 3
Views: 31

Re: lewis acid/base

A lewis acid is an electron acceptor while a lewis base is an electron donor
by 904914909
Sat Nov 03, 2018 9:50 pm
Forum: Octet Exceptions
Topic: Radicals - On Which Element Does the Unpaired Electron Go?
Replies: 2
Views: 98

Re: Radicals - On Which Element Does the Unpaired Electron Go?

To determine which atom the unpaired electron goes on, you have to look at the formal charges and determine which atom it will make the formal charge be closest to 0
by 904914909
Sun Oct 28, 2018 11:36 pm
Forum: Lewis Structures
Topic: Lines that Represent Bonds
Replies: 7
Views: 89

Re: Lines that Represent Bonds

Both mean the same thing, so using the 2 dots instead of the line would not be incorrect, but I think Dr. Lavelle uses the line because it is more convenient and clearer.
by 904914909
Sun Oct 28, 2018 11:31 pm
Forum: Trends in The Periodic Table
Topic: Periodic Trend - Ionization energy
Replies: 2
Views: 43

Re: Periodic Trend - Ionization energy

Elements in the top right corner have the highest electron affinity but it is less periodic than atomic radius
by 904914909
Sun Oct 28, 2018 11:23 pm
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 13
Views: 99

Re: Lewis Structures

The central atom is generally the atom with the lowest ionization energy, which is usually furthest away from row 17 (bc atoms in row 17 typically have the highest ionization energy)
by 904914909
Mon Oct 22, 2018 8:23 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Pauli Exclusion Principle
Replies: 3
Views: 52

Re: Pauli Exclusion Principle

This answer above is a great explanation!
by 904914909
Mon Oct 22, 2018 3:38 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 2. 39 [ENDORSED]
Replies: 5
Views: 277

Re: 2. 39 [ENDORSED]

So lowest energy configuration means that an atom is in ground state and anything else is excited?
by 904914909
Sun Oct 21, 2018 7:49 pm
Forum: *Shrodinger Equation
Topic: Test 2
Replies: 5
Views: 263

Re: Test 2

Test 2 covers quantum and bond/orbital materials up until the Friday lecture of week 3.
by 904914909
Mon Oct 15, 2018 8:47 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Negative v. Positive when calculating energy
Replies: 8
Views: 90

Re: Negative v. Positive when calculating energy

When energy is released, it is negative/exothermic and when energy is absorbed, the reaction is positive/endothermic
by 904914909
Mon Oct 15, 2018 5:19 pm
Forum: Quantum Numbers and The H-Atom
Topic: Number of Orbitals
Replies: 3
Views: 121

Re: Number of Orbitals

This is very helpful, thank you for the insight!
by 904914909
Mon Oct 15, 2018 5:16 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg's Indeterminacy Equation
Replies: 2
Views: 59

Re: Heisenberg's Indeterminacy Equation

Dr. Lavelle said in lecture that the 4pi comes from the derivation of the equation and that it is not specifically important that we know how to find it/why it is there for this class.
by 904914909
Mon Oct 08, 2018 11:19 pm
Forum: Properties of Light
Topic: Difference between "intensity of light" and "frequency of light"
Replies: 3
Views: 73

Re: Difference between "intensity of light" and "frequency of light"

That's a really great way to explain it, thanks for that clarification.
by 904914909
Mon Oct 08, 2018 11:18 pm
Forum: Properties of Electrons
Topic: Is this movement noticeable?
Replies: 4
Views: 186

Re: Is this movement noticeable?

With bigger objects, there position is almost always measurable so their uncertainty is negligible.
by 904914909
Wed Oct 03, 2018 4:48 pm
Forum: Empirical & Molecular Formulas
Topic: Online Resources
Replies: 2
Views: 74

Re: Online Resources

Bozeman Science has videos that are very similar to Crash Course that cover AP Chemistry topics.
by 904914909
Wed Oct 03, 2018 4:46 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student [ENDORSED]
Replies: 96
Views: 30818

Re: Advice from a Medical Student [ENDORSED]

Such useful advice to keep in mind! Thanks!
by 904914909
Wed Oct 03, 2018 4:42 pm
Forum: Balancing Chemical Reactions
Topic: Combustion
Replies: 6
Views: 135

Re: Combustion

Combustion is just the combination of an organic molecule with O2 and it includes the products CO2 and H2O

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