Search found 57 matches

by Katie Sy 1L
Sun Mar 10, 2019 1:35 pm
Forum: General Science Questions
Topic: Free Expansion
Replies: 3
Views: 199

Re: Free Expansion

expansion joints on bridges and overpasses. for example, a bridge deck gets longer in the heat of summer and contracts in the cold of winter
by Katie Sy 1L
Sun Mar 10, 2019 1:34 pm
Forum: Van't Hoff Equation
Topic: Overview
Replies: 8
Views: 283

Re: Overview

it relates the change in the equilibrium constant, Keq, of a chemical reaction to the change in temperature, T, given the standard enthalpy change, ΔH, for the process.
by Katie Sy 1L
Sun Mar 10, 2019 1:33 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Test 2: Melting Ice
Replies: 6
Views: 231

Re: Test 2: Melting Ice

it's a spontaneous reaction because ice will melt by itself, not needing any external heat to be added to the system, which is why deltaG is negative
by Katie Sy 1L
Tue Mar 05, 2019 1:10 pm
Forum: Administrative Questions and Class Announcements
Topic: Week 9 HW
Replies: 6
Views: 113

Re: Week 9 HW

i think just kinetics since that's what we covered this week in class
by Katie Sy 1L
Tue Mar 05, 2019 1:09 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Study Advice
Replies: 31
Views: 435

Re: Study Advice

attending study sessions are super helpful. and if you find a specific topic difficult, i recommend searching it on youtube and watching a video where they do practice problems
by Katie Sy 1L
Tue Mar 05, 2019 1:08 pm
Forum: General Rate Laws
Topic: Table with different Concentration
Replies: 4
Views: 57

Re: Table with different Concentration

i would assume so since these type of questions were asked on the homework
by Katie Sy 1L
Wed Feb 27, 2019 8:52 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Phases used in a Galvanic Cell
Replies: 3
Views: 43

Re: Phases used in a Galvanic Cell

liquids can be listed. make sure to separate them from the other phases in the diagram
by Katie Sy 1L
Wed Feb 27, 2019 8:46 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Predicting Gibbs Free Energy Sign
Replies: 3
Views: 276

Re: Predicting Gibbs Free Energy Sign

you can't predict it based on just temperature. you would need enthalpy or entropy or both
by Katie Sy 1L
Wed Feb 27, 2019 8:44 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.11
Replies: 2
Views: 56

Re: 14.11

you want to flip one of the half reactions so the electrons from each half reaction are able to cancel out. when you flip a half reaction, the sign of that cell potential will switch
by Katie Sy 1L
Mon Feb 18, 2019 3:38 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy Problems
Replies: 3
Views: 62

Re: Gibbs Free Energy Problems

we don't need to memorize any, they'll be given to us
by Katie Sy 1L
Mon Feb 18, 2019 3:37 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy change: V, P, T
Replies: 4
Views: 217

Re: Entropy change: V, P, T

Higher volume leads to greater entropy because the larger the volume the more ways there are to distribute the molecules in that volume; the more ways there are to distribute the molecules (energy), the higher the entropy The entropy of a system decreases with an increase in pressure. This is due to...
by Katie Sy 1L
Mon Feb 18, 2019 3:34 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Meaning of subscript r
Replies: 3
Views: 56

Re: Meaning of subscript r

I'm not sure but I think it just means reaction
by Katie Sy 1L
Thu Feb 14, 2019 10:45 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp equilibrium constant
Replies: 6
Views: 134

Re: Kp equilibrium constant

it doesn't matter what the units are as long as you keep them consistent for each molecule in the equilibrium equation
by Katie Sy 1L
Tue Feb 12, 2019 11:29 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy Change by Volume and Pressure
Replies: 2
Views: 56

Re: Entropy Change by Volume and Pressure

no you don't need to do it twice. just be consistent in either using the volumes or pressures
by Katie Sy 1L
Tue Feb 12, 2019 11:27 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Reasons for Heat Capacity
Replies: 2
Views: 78

Re: Reasons for Heat Capacity

materials with more atoms per unit volume will generally have higher heat capacities on a per-mass basis and larger molecules will have a larger heat capacity on a per-mole basis
by Katie Sy 1L
Tue Feb 05, 2019 5:05 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 6th edition 8.51
Replies: 2
Views: 80

Re: 6th edition 8.51

to find the energy density in kJ/L, divide the amount of energy with the mass of one mole of TNT(227.14 g/mol) and then multiply it by the density of TNT (1.65 g/cm^3)
by Katie Sy 1L
Tue Feb 05, 2019 5:02 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 6th ed 103 units
Replies: 1
Views: 43

Re: 6th ed 103 units

in the solution manual, it shows the answers in Joules/moles
by Katie Sy 1L
Tue Feb 05, 2019 5:00 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 6th edition Hw problem 8.23
Replies: 1
Views: 46

Re: 6th edition Hw problem 8.23

you want to find Ccal so take 22.5 kj and divide that by the difference in temperature. your answer will be in kJ/C
by Katie Sy 1L
Mon Jan 28, 2019 3:44 pm
Forum: Ideal Gases
Topic: Problem 8.9 6th edition
Replies: 1
Views: 66

Re: Problem 8.9 6th edition

find the value of work by using the equation w=-Pressure * change in the volume. then to get deltaU, take q (given in the problem) and add it with work
by Katie Sy 1L
Mon Jan 28, 2019 3:41 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Extensive vs Intensive properties
Replies: 4
Views: 47

Re: Extensive vs Intensive properties

An extensive property depends on the amount of matter while an intensive property depends on what the type of matter is. an example of an extensive property would be volume while an intensive property would be hardness
by Katie Sy 1L
Mon Jan 28, 2019 3:39 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Neutralization reactions
Replies: 6
Views: 81

Re: Neutralization reactions

yes because bonds are being made, causing energy to be released into the surrounding
by Katie Sy 1L
Wed Jan 23, 2019 4:43 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: autoprotolysis
Replies: 5
Views: 129

Re: autoprotolysis

i don't think we'll need to know how to derive it but just know the relationship. but it's pretty simple to derive it so i would know it to just help you out later on
by Katie Sy 1L
Wed Jan 23, 2019 4:41 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Ka and pH
Replies: 6
Views: 106

Re: Ka and pH

i don't think there is one but just make sure to know the relationship between pka with ka and pkb with kb and you can use an ICE box to find the concentration to find the ka or kb values
by Katie Sy 1L
Tue Jan 22, 2019 9:38 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Does [H3O+][OH-] always equal 10^-14?
Replies: 9
Views: 140

Re: Does [H3O+][OH-] always equal 10^-14?

it is 10^-14 only when water is at a constant 25 degrees C
by Katie Sy 1L
Tue Jan 15, 2019 1:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculate pOH
Replies: 3
Views: 42

Re: Calculate pOH

yes because of the 2 hydroxide ions
by Katie Sy 1L
Tue Jan 15, 2019 1:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE table
Replies: 3
Views: 53

Re: ICE table

you only include gases and not solids or liquids because solids/liquids concentrations are constant throughout the reaction
by Katie Sy 1L
Tue Jan 15, 2019 1:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE charts
Replies: 3
Views: 50

Re: ICE charts

for ICE charts, use concentration values
by Katie Sy 1L
Thu Jan 10, 2019 8:27 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction quotient [ENDORSED]
Replies: 4
Views: 68

Re: Reaction quotient [ENDORSED]

If they're not gas, you can use the value of 1 as a replacer
by Katie Sy 1L
Tue Jan 08, 2019 7:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 7th Edition - 5G.3 Mistake?
Replies: 3
Views: 56

Re: 7th Edition - 5G.3 Mistake?

Lavelle has a link on his website that addresses any textbook mistakes, trying checking there
by Katie Sy 1L
Tue Jan 08, 2019 7:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc vs. Kp
Replies: 7
Views: 126

Re: Kc vs. Kp

Kp is for partial pressures, so only involves gases
by Katie Sy 1L
Sat Dec 01, 2018 3:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Dissociation energy
Replies: 7
Views: 143

Re: Dissociation energy

positive refers to an input of energy vs negative would be a release of energy
by Katie Sy 1L
Sat Dec 01, 2018 3:42 pm
Forum: Administrative Questions and Class Announcements
Topic: Practice Questions for Final
Replies: 3
Views: 155

Re: Practice Questions for Final

lyndon's review session on tuesday should also have some good final practice
by Katie Sy 1L
Sat Dec 01, 2018 3:39 pm
Forum: Octet Exceptions
Topic: Which Elements
Replies: 3
Views: 235

Re: Which Elements

Sulfur, phosphorus, silicon, and chlorine are some common ones and boron and aluminum can form compounds in which they have six valence electrons
by Katie Sy 1L
Sun Nov 25, 2018 4:23 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2.45
Replies: 2
Views: 37

Re: 2.45

carbon's three bonding regions means there is one s orbital and 2 p orbitals (sp2)
by Katie Sy 1L
Sun Nov 25, 2018 4:21 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Test 3
Replies: 38
Views: 658

Re: Test 3

i believe so and possibly some past topics may be included but i'm not sure about that
by Katie Sy 1L
Sun Nov 25, 2018 4:20 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Linear structure with lone pairs
Replies: 6
Views: 129

Re: Linear structure with lone pairs

yeah it will be 180 degrees if it's linear
by Katie Sy 1L
Sun Nov 25, 2018 4:19 pm
Forum: Hybridization
Topic: Hybridization
Replies: 5
Views: 122

Re: Hybridization

yeah i believe so
by Katie Sy 1L
Sun Nov 25, 2018 4:17 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 3
Replies: 6
Views: 177

Re: Test 3

Yes I believe we will need to recognize and name shapes
by Katie Sy 1L
Thu Nov 15, 2018 11:31 am
Forum: SI Units, Unit Conversions
Topic: lewis structure shape
Replies: 6
Views: 361

Re: lewis structure shape

in addition to knowing the shapes, also know the angles associated with them
by Katie Sy 1L
Thu Nov 08, 2018 11:03 pm
Forum: Electronegativity
Topic: Electronegativity and Polarizability
Replies: 4
Views: 209

Re: Electronegativity and Polarizability

they're inversely related so a molecule with a greater electronegativity will have a lower polarizability
by Katie Sy 1L
Thu Nov 08, 2018 10:58 pm
Forum: Student Social/Study Group
Topic: Homework 6
Replies: 5
Views: 152

Re: Homework 6

i tried to focus on doing problems based on the lectures we've had the past week
by Katie Sy 1L
Thu Nov 08, 2018 10:56 pm
Forum: Lewis Structures
Topic: Placement of Elements?
Replies: 5
Views: 103

Re: Placement of Elements?

we're going to learn shape soon and then the placement will matter, but based on what we've learned so far, we don't have to have a certain placement
by Katie Sy 1L
Thu Nov 08, 2018 10:52 pm
Forum: Lewis Structures
Topic: Formal charges
Replies: 15
Views: 221

Re: Formal charges

i don't think it's required unless specified. but i always do because i find it to be super helpful to figure out the most stable form of a molecule
by Katie Sy 1L
Thu Nov 08, 2018 10:50 pm
Forum: Octet Exceptions
Topic: Octet vs formal charge
Replies: 16
Views: 534

Re: Octet vs formal charge

formal charge being 0 is more important because don't forget about elements that have octet exceptions
by Katie Sy 1L
Wed Oct 31, 2018 5:23 pm
Forum: Lewis Structures
Topic: Lewis Structures and adding multiple bonds
Replies: 2
Views: 61

Re: Lewis Structures and adding multiple bonds

you will know whether you'll need to add a double or triple bond depending if it changes the formal charge closer to 0. this means the atom will be more stable
by Katie Sy 1L
Wed Oct 31, 2018 5:22 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge of a compound
Replies: 3
Views: 112

Re: Formal Charge of a compound

yes the overall formal charge of the atom will equal the total of the formal charge of each element in the atom
by Katie Sy 1L
Fri Oct 26, 2018 3:37 pm
Forum: Ionic & Covalent Bonds
Topic: Ground State Electron Configurations
Replies: 7
Views: 99

Re: Ground State Electron Configurations

This is the closest noble gas, using this allows for the electron configuration to be shorter in length to write
by Katie Sy 1L
Fri Oct 26, 2018 3:36 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: 7th Edition Example 1B.5 (Page19)
Replies: 2
Views: 105

Re: 7th Edition Example 1B.5 (Page19)

The book is using the Heisenberg equation that is h with a dash over 2pi so that's why it's being multiplied by 2. I believe so?
by Katie Sy 1L
Sun Oct 21, 2018 10:35 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Quantum numbers
Replies: 5
Views: 93

Re: Quantum numbers

Yup! It's 4f because n=4 and l=3 which refers to the f block
by Katie Sy 1L
Thu Oct 18, 2018 1:31 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Homework 1E.13 Silver
Replies: 2
Views: 26

Re: Homework 1E.13 Silver

It's because you want to complete the 4d orbital before moving onto the 5s orbital. A full 4d orbital contains 10 electrons.
by Katie Sy 1L
Thu Oct 11, 2018 12:51 pm
Forum: Limiting Reactant Calculations
Topic: Percent Yield [ENDORSED]
Replies: 13
Views: 731

Re: Percent Yield [ENDORSED]

Actual Yield is the value the problem should give you. It's the amount actually produced in the experiment. Theoretical yield is the amount you should expect to produce while using information from the balanced equation and the starting amount of the reactant.
by Katie Sy 1L
Thu Oct 11, 2018 11:16 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Naming Simple Coumpounds
Replies: 2
Views: 167

Re: Naming Simple Coumpounds

I believe we don't need to know how to name compounds on the first test. However, we will eventually need to know them. I think the best way to learn them is just memorize them, make flashcards on quizlet. My TA said eventually, after doing a lot of practice problems,we'll start memorizing the names...
by Katie Sy 1L
Wed Oct 10, 2018 6:18 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Spectral Line Diagram
Replies: 1
Views: 44

Re: Spectral Line Diagram

Spectral Line Diagrams are mainly used to identify molecules or atoms from their exact, unique placement of their particular spectral line. It's another way to analyze frequencies in addition to the electromagnetic spectrum.
by Katie Sy 1L
Mon Oct 01, 2018 9:08 pm
Forum: General Science Questions
Topic: Periodic Table
Replies: 16
Views: 498

Re: Periodic Table

I tend to just use the whole number listed on the periodic table to make sure my answers are exact as possible, but if it's a super long number, I usually stop after 3 decimal places
by Katie Sy 1L
Mon Oct 01, 2018 11:50 am
Forum: SI Units, Unit Conversions
Topic: Unit "t"
Replies: 2
Views: 92

Re: Unit "t"

The "t" refers to the unit. In this case, it means metric ton (aka 1000 kg)
by Katie Sy 1L
Mon Oct 01, 2018 11:49 am
Forum: Significant Figures
Topic: Significant Figures
Replies: 10
Views: 258

Re: Significant Figures

I tend to use exact calculations throughout the problems ensuring there are no rounding errors by the end. Once I get my answer, then I take significant figures into consideration. I find this provides the most accurate answer.
by Katie Sy 1L
Mon Oct 01, 2018 11:37 am
Forum: SI Units, Unit Conversions
Topic: Grams/mole
Replies: 12
Views: 324

Re: Grams/mole

Yes these two notations mean the same thing. I believe it is a personal preference for which version to use. In some cases, it might be easier to type one out than the other. The negative 1 in the numerator means it will move to the denominator.

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