## Search found 61 matches

Sun Mar 17, 2019 4:49 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Cp vs Cv
Replies: 6
Views: 1012

### Re: Cp vs Cv

Use Cp when there is constant pressure and Cv when there is constant volume. The problem will specify if it is at constant pressure or volume.
Sun Mar 17, 2019 4:45 pm
Forum: First Order Reactions
Topic: Slopes of a plot
Replies: 7
Views: 673

### Re: Slopes of a plot

Since first order is ln[A]=-kt+ln[A]o it has a negative slope due to the -k.
Sun Mar 17, 2019 4:41 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Bimolecular
Replies: 13
Views: 649

### Re: Bimolecular

Bimolecularity refers to having two molecules colliding in a reaction.
Sun Mar 17, 2019 4:38 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Wmax
Replies: 3
Views: 565

### Re: Wmax

To have the greatest Wmax you want the greatest delta G
Sun Mar 17, 2019 4:35 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Endergonic vs. Endothermic
Replies: 6
Views: 833

### Re: Endergonic vs. Endothermic

Endergonic is a positive delta G while endothermic is a positive delta H
Sun Mar 17, 2019 4:31 pm
Forum: Phase Changes & Related Calculations
Topic: heating curves
Replies: 4
Views: 941

### Re: heating curves

The heating curve we were introduced to in class was one specific to water. All molecules have their own heating curves
Sun Mar 17, 2019 4:23 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: intermediate
Replies: 22
Views: 661

### Re: intermediate

Intermediates are produced in one elementary step and consumed in the next. They are not part of the overall reaction so they will not appear in the rate law.
Sun Mar 17, 2019 4:19 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts
Replies: 16
Views: 588

### Re: Catalysts

Catalysts lower the activation so it will lower the curve of the reaction.
Sun Mar 17, 2019 4:16 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Replies: 4
Views: 306

### Re: Adding an Inert Gas

Inert gases do not cause any shift in the system
Sun Mar 17, 2019 4:14 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Types of Molecularity
Replies: 4
Views: 886

### Re: Types of Molecularity

Unimolecular--1 reactant molecule
Bimolecular--2 reactant molecules
Termolecular--3 reactant molecules
Sun Mar 17, 2019 4:11 pm
Forum: Experimental Details
Topic: picking a trial
Replies: 7
Views: 444

### Re: picking a trial

It does not matter which trial is used, they will all give you the correct value.
Sun Mar 17, 2019 4:10 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Effects of Compression
Replies: 5
Views: 346

### Re: Effects of Compression

Yes it would affect the molecules in the gas phase. More specifically, compression increases pressure which will cause the side with less moles to be favored.
Sun Mar 17, 2019 3:58 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K and Kc
Replies: 6
Views: 438

### Re: K and Kc

K and Kc are basically the same thing, except that Kc specifically means concentrations like Kp would refer to partial pressures.
Sun Mar 17, 2019 2:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Q
Replies: 6
Views: 450

### Re: Q

They do not need to be in standard conditions
Sun Mar 17, 2019 2:41 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Work done vs work on system
Replies: 18
Views: 1382

### Re: Work done vs work on system

Work done on the system is positive while work done by the system is negative
Sun Mar 17, 2019 2:39 pm
Forum: Ideal Gases
Topic: K and Q
Replies: 8
Views: 460

### Re: K and Q

You exclude solids and liquids because they remain the same throughout the reaction
Sun Mar 17, 2019 12:24 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Reversible vs irreversible
Replies: 1
Views: 253

### Reversible vs irreversible

Why does gas expansion in a reversible, isothermal process perform more work than irreversible?
Sat Mar 16, 2019 9:00 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: k(1)/k(-1)
Replies: 4
Views: 340

### Re: k(1)/k(-1)

k is referring to the rate of the forward reaction while k' is referring to the rate of the reverse reaction
Sat Mar 16, 2019 8:55 pm
Forum: Administrative Questions and Class Announcements
Topic: LYNDON'S PORK RAMEN REVIEW
Replies: 37
Views: 3503

### Re: LYNDON'S PORK RAMEN REVIEW

Why for number ten is it that having a negative standard reaction potential mean that it will be non-spontaneous and therefore the coin will not dissolve?
Sat Mar 16, 2019 8:52 pm
Forum: Zero Order Reactions
Topic: third order
Replies: 11
Views: 476

### Re: third order

Possibly, it is in the curriculum.
Fri Mar 15, 2019 9:14 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 7th Edition 6N.9
Replies: 1
Views: 101

### 7th Edition 6N.9

A tin electrode in 0.015M Sn(NO 3 ) 2 (aq) is connected to a hydrogen electrode in which the pressure of H 2 is 1.0 bar. If the cell potential is 0.061 V at 25 degrees Celsius, what is the pH of the electrolyte at the hydrogen electrode? How do you set up the cell equation with the given information...
Fri Mar 15, 2019 6:45 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Adding Pt(s) to cell diagram
Replies: 5
Views: 143

### Re: Adding Pt(s) to cell diagram

Are there any exceptions to this?
Fri Mar 15, 2019 6:42 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 7th edition 6N.3a
Replies: 1
Views: 225

### 7th edition 6N.3a

In the solutions, they kept the partial pressures and concentrations in the calculations and proceeded to solve. Why are the concentrations not converted to partial pressures or vice versa so that all of the values are in the same form?
Fri Mar 15, 2019 10:07 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Adding Pt(s) to cell diagram
Replies: 5
Views: 143

### Adding Pt(s) to cell diagram

When do we add Pt(s) to a cell diagram?
Thu Mar 14, 2019 10:06 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Activation Energies
Replies: 2
Views: 110

### Activation Energies

How does the activation energies of reactions help determine if it is endothermic or exothermic? For example, in the 7th edition question 7D.7b asks if the reaction is endothermic or exothermic and the solution talks about the activation energies of the forward and reverse reaction.
Thu Mar 14, 2019 9:41 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 7D.5
Replies: 1
Views: 68

### 7D.5

The rate constant of the reaction between CO 2 and OH - in aqueous solution to give the HCO 3 - ion is 1.5 x 10 10 L.mol -1 s -1 at 25 degrees Celsius. Determine the rate constant at human body temperature (37 degrees Celsius), given that the activation energy for the reaction is 38 kJ.mol -1 . In t...
Sun Feb 10, 2019 1:58 pm
Forum: Administrative Questions and Class Announcements
Topic: UA Sessions Today
Replies: 2
Views: 178

### Re: UA Sessions Today

These are the scheduled Sunday sessions:
Ajith Raja 11am-1pm (Drop-In), Nathan Mallipeddi 1-3pm (Step-Up), Ryan Cerny 6-7pm (Drop-In), Karen Leung 7-9pm (Workshop), Ryan Cerny 9-10pm (Drop-In)

You can also find this information on Dr. Lavelle's website under "Important Midterm Information"
Sun Feb 10, 2019 1:55 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Midterm #1 14B
Replies: 17
Views: 963

### Re: Midterm #1 14B

If you search "hotdog" you'll be able to find his post.
Fri Feb 08, 2019 11:18 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calculating q
Replies: 1
Views: 115

### Calculating q

What is the difference between $q=mC\Delta T$ and $q=C\Delta T$ and in which situations would I use them?
Mon Jan 21, 2019 4:32 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5J13 7th Ed
Replies: 2
Views: 108

### Re: 5J13 7th Ed

Looking at the equilibrium constants of each of the reactions at their respective temperatures, the equilibrium constant for the reaction at 700. K is smaller than the constant at 600. K. This tells us that the reactants are favored more in the higher temperature.
Mon Jan 21, 2019 4:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Strong and Weak Acids
Replies: 3
Views: 126

### Strong and Weak Acids

Why do solutions of weak acids have higher pH values than solutions of strong acids at the
same concentration?
Sat Dec 08, 2018 10:28 am
Forum: Octet Exceptions
Topic: Exceptions
Replies: 10
Views: 713

### Re: Exceptions

Exceptions being in the 3rd period since they can expand into their d orbital
Sat Dec 08, 2018 10:25 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: boiling point
Replies: 5
Views: 519

### Re: boiling point

When looking at boiling point, you want to examine intermolecular forces. Since NH3 is going to have stronger intermolecular forces (N--H is hydrogen bonding which is the strongest IMF) the boiling point will be greater.
Sat Dec 08, 2018 10:23 am
Forum: Properties of Light
Replies: 3
Views: 376

We need to know how to name coordination compounds
Sun Dec 02, 2018 5:05 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Compound
Replies: 1
Views: 89

### Coordination Compound

In the drawing of a coordination compound, some of the compounds were written in reverse to show which atom in that compound interacted with the central atom. How do we know when a different atom interacts with the central atom and to write the compound in reverse?
Sun Dec 02, 2018 4:44 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number
Replies: 10
Views: 292

### Re: Coordination Number

Coordination number corresponds to the number of bonded atoms around the central atom
Sun Dec 02, 2018 4:37 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Dissociation energy
Replies: 7
Views: 244

### Re: Dissociation energy

Because dissociation energy is an addition of energy to break a bond it is going to be positive.
Sun Nov 25, 2018 2:06 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability
Replies: 5
Views: 209

### Polarizability

What does it mean to say that highly distorted electrons are described as being highly polarizable?
Sun Nov 25, 2018 12:41 pm
Forum: Dipole Moments
Topic: canceling dipoles
Replies: 2
Views: 153

### Re: canceling dipoles

I like to think about a molecules shape to determine if there is symmetry or not in the polar bonds. If so, the dipoles cancel out meaning there is no net dipole.
Sat Nov 24, 2018 8:38 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: What is VSPER
Replies: 14
Views: 348

### Re: What is VSPER

VSEPR stands for "valence shell electron pair repulsion" and we probably do not need to have it memorized
Fri Nov 16, 2018 8:40 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AX3E2 Shape
Replies: 6
Views: 366

### Re: AX3E2 Shape

A molecule with AX3E2 VSEPR formula is going to have an electron geometry of trigonal bipyramidal (this takes into account the lone pairs) and a molecular geometry of a T-shape (this takes into account only the atoms, excluding the lone pairs).
Fri Nov 16, 2018 1:14 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 4
Views: 220

### Re: Bond Angles

I don't think it is possible to find an exact figure for the bond angles that are, for instance, less than 120 or 109.5. There are only estimates or a range that it could be in.
Fri Nov 16, 2018 1:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone pairs
Replies: 2
Views: 106

### Re: Lone pairs

I believe the reason is that lone pairs occupy more space, in other words they are more diffused. This causes them to push the other atoms closer together.
Fri Nov 09, 2018 1:23 pm
Forum: SI Units, Unit Conversions
Topic: Angstrom
Replies: 5
Views: 562

### Re: Angstrom

I talked to my TA about this and even though it isn't an SI unit Dr. Lavelle wants us to know the conversion.
Fri Nov 09, 2018 1:19 pm
Forum: Bond Lengths & Energies
Topic: Strength of Bonds
Replies: 9
Views: 418

### Re: Strength of Bonds

^ Yes, the stronger the bond the more energy it will take to break it resulting in a higher boiling point.
Fri Nov 09, 2018 1:17 pm
Forum: Bond Lengths & Energies
Topic: boiling points
Replies: 4
Views: 172

### Re: boiling points

Compounds with stronger intermolecular forces have higher boiling points because it takes more energy to break their bonds (the energy is given in the form of heat).
Fri Nov 02, 2018 10:03 pm
Forum: Lewis Structures
Topic: Midterm Chemical Formula Names
Replies: 3
Views: 149

### Re: Midterm Chemical Formula Names

Dr. Lavelle mentioned in lecture today that we do not need to know nomenclature yet.
Wed Oct 31, 2018 9:59 pm
Forum: Ionic & Covalent Bonds
Topic: octet rule
Replies: 11
Views: 366

### Re: octet rule

Atoms want to have 8 electrons in their valence shell, so they seek to either gain or loose electrons. Having 8 valence electrons gives that atom a noble gas configuration which makes them the most stable.
Wed Oct 31, 2018 9:52 pm
Forum: Lewis Structures
Topic: lewis acid/base
Replies: 2
Views: 135

### Re: lewis acid/base

It is a lewis base if it donates its electron pair, and it is a lewis acid if it accepts an electron pair.
Thu Oct 25, 2018 9:25 pm
Forum: Properties of Light
Topic: Electromagnetic Spectrum
Replies: 5
Views: 263

### Re: Electromagnetic Spectrum

It will most likely be given, but it can be helpful to familiarize yourself with the spectrum to check if your answers are reasonable.
Thu Oct 25, 2018 9:16 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Module Question #17
Replies: 4
Views: 271

### Re: Module Question #17

I thought of it as 1/100 having one sig fig
Mon Oct 22, 2018 9:40 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2
Replies: 2
Views: 173

### Re: Test 2

I believe it's going to be more concept heavy than last test, so having a really good understanding all of the topics is going to be important.
Wed Oct 17, 2018 9:20 pm
Forum: DeBroglie Equation
Topic: Wave properties
Replies: 3
Views: 176

### Re: Wave properties

In class, we used the baseball as an example based off of the De Broglie equation (wavelength = h/p where p=mv). This equation can be used for anything that has a distinct resting mass, as does a baseball. The baseball example in particular shows that as momentum increases wavelength decreases, and ...
Wed Oct 17, 2018 9:33 am
Forum: Properties of Light
Topic: 7th Edition 1A.3
Replies: 4
Views: 109

### Re: 7th Edition 1A.3

Energy and frequency and directly proportional, because when the frequency increases so does the energy.
Wed Oct 17, 2018 9:22 am
Forum: Quantum Numbers and The H-Atom
Topic: Equation sheet
Replies: 4
Views: 207

### Re: Equation sheet

On Dr. Lavelle's website there is a link that has the equation sheet he puts on the front of his tests. It's under the course materials section with the title "Constants and Equations." Hope this helps!
Tue Oct 09, 2018 8:06 pm
Forum: SI Units, Unit Conversions
Topic: Conversions
Replies: 2
Views: 154

### Re: Conversions

I believe it is a metric ton, so the conversion would be 1 t = 1000 kg.
Tue Oct 09, 2018 8:02 pm
Forum: Molarity, Solutions, Dilutions
Topic: Promblem G5, Part C, Seventh Edition
Replies: 2
Views: 158

### Re: Promblem G5, Part C, Seventh Edition

In part c you are starting with mg instead of mmol. In parts a and b you were able to just use 0.07967 M as a conversion factor because you already started with moles. Part c makes you convert to the mg to g to mol and then mol to L using M. To help me keep the conversions straight, I split this up ...
Tue Oct 09, 2018 3:27 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: E29 Part D
Replies: 2
Views: 188

### Re: E29 Part D

I believe it is like doing percent composition without multiplying by 100 to get a percent. (percent composition is part mass/whole mass x 100) In this case, part mass/whole mass = fraction The amount of oxygen is (16.00 x 4), the 16.00 being the molar mass and the four comes from the number of mole...
Thu Oct 04, 2018 2:45 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Replies: 9
Views: 564

Yes, you use Avogadro's number :)
Tue Oct 02, 2018 9:14 am
Forum: Empirical & Molecular Formulas
Topic: Question F11 from 6th edition
Replies: 3
Views: 732

### Re: Question F11 from 6th edition

After I divided the three values by the smallest, I found the subscript of Na to be 2.9548, Al to be 1, and F to be 5.910. Since they're very close to a whole number, I just rounded up and got the empirical formula of Na3AlF6. It would be more obvious if the values needed to be multiplied to somethi...
Mon Oct 01, 2018 8:59 pm
Forum: General Science Questions
Topic: Periodic Table
Replies: 16
Views: 864

### Periodic Table

How should you round the atomic weights of the elements on the periodic table when using it for calculations and how many decimal places should you go out to?