## Search found 59 matches

Thu Mar 14, 2019 9:53 pm
Forum: General Rate Laws
Topic: Sealed vessel
Replies: 1
Views: 90

### Sealed vessel

How does mass left = mass initial * e^-kt when the reaction takes place in a sealed vessel? ( referencing 7th edition 7B.15 part c)
Thu Mar 14, 2019 9:45 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 7th Edition Problem 7D.5
Replies: 3
Views: 113

### Re: 7th Edition Problem 7D.5

I am not sure what this means either and I also don’t understand how they got 1.8 for k’/k even when you subtract 0.59.
Thu Mar 14, 2019 9:37 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: k’ and A
Replies: 4
Views: 127

### k’ and A

Are there two different meanings for k’ and capital A in kinetics?
Thu Mar 07, 2019 5:15 pm
Forum: Second Order Reactions
Topic: Rounding Reaction Orders
Replies: 4
Views: 144

### Rounding Reaction Orders

Why do we round reaction orders when they are not exactly whole numbers?
Thu Mar 07, 2019 5:01 pm
Forum: General Rate Laws
Topic: a = reaction order
Replies: 1
Views: 83

### a = reaction order

The book and solutions manual use the variable "a" when referring to reaction order but it also uses it when referring to the stoichiometric coefficient of in the unique average rate equation. Is there any relation between these "a"s?
Thu Mar 07, 2019 4:35 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: k constant
Replies: 2
Views: 150

### k constant

Why do negative k values not exist?
Thu Feb 28, 2019 9:04 pm
Forum: Balancing Redox Reactions
Topic: Half Reactions in a Basic Solution
Replies: 4
Views: 148

### Re: Half Reactions in a Basic Solution

If you get confused thinking about all these OH- molecules and H2O molecules just think of it the exact same way you work with acidic solutions, only this time you want to neutralize the H+ you added so turn them into water by adding the same amount of OH- on both sides.
Thu Feb 28, 2019 8:59 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: finding DeltaG
Replies: 6
Views: 220

### finding DeltaG

Which equation is the most accurate for finding DeltaG and why?
Tue Feb 26, 2019 6:30 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Gibbs free energy J/mol
Replies: 1
Views: 90

### Gibbs free energy J/mol

Why is the mol included in the units if the equation for DeltaG=-nFEcell?
Shouldn’t the moles cancel out?
Thu Feb 21, 2019 9:04 pm
Forum: Van't Hoff Equation
Topic: Van't Hoff Equation
Replies: 4
Views: 163

### Re: Van't Hoff Equation

Usually Boltzmann’s constant will be indicated with a lower case k whereas the gas constant will be indicated with a uppercase R.
Thu Feb 21, 2019 9:01 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Work max and delta G
Replies: 2
Views: 80

### Work max and delta G

How is the maximum work and delta G equal?
Thu Feb 21, 2019 7:44 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Positive E cell
Replies: 1
Views: 93

### Positive E cell

Why does a positive Cell potential indicate a spontaneous reduction?
Thu Feb 21, 2019 7:37 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic/Voltaic Cells
Replies: 4
Views: 221

### Re: Galvanic/Voltaic Cells

The book makes it seem like a galvanic cell is a type of electrochemical cell but not vice versa. Is this correct?
Thu Feb 14, 2019 10:38 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Determine if molecule is in most stable form
Replies: 5
Views: 363

### Determine if molecule is in most stable form

Is there some way to determine if a molecule is in its most stable form with out it being given?
Thu Feb 14, 2019 10:29 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Ideal gases
Replies: 4
Views: 180

### Ideal gases

If you were given the specific heat capacity of an ideal gas at constant pressure or volume would that be the same as calculate 5/2*R or 3/2*R, respectively? If so which is more accurate?
Thu Feb 07, 2019 9:40 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 4F.11
Replies: 1
Views: 121

### 4F.11

3.00 L of nitrogen gas at 18.5 C compress suddenly to 0.500 L. Process increased temperature of the gas to 28.1 C.

How do we know to just use one mole in the change in entropy equation?
Thu Feb 07, 2019 9:36 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy with change in pressure
Replies: 1
Views: 71

### Entropy with change in pressure

How do we use the change in entropy equation if there is a change in pressure only?
Thu Feb 07, 2019 9:34 pm
Forum: Calculating Work of Expansion
Topic: L*atm conversion to Joules
Replies: 2
Views: 111

### L*atm conversion to Joules

Why does the book use the the two gas constants (8.314 J/K/mol divided by 0.0826 L*atm/K/mol) instead of the direct unit conversion? And which should we use on the test?
Thu Jan 31, 2019 8:24 pm
Forum: Phase Changes & Related Calculations
Topic: 4C.13 7th Edition
Replies: 1
Views: 94

### 4C.13 7th Edition

This question is calculating the final heat of a glass of water after a cube of ice is added with no heat lost to the surroundings. Once we find the heat required to take the ice cube from solid to liquid plus the heat required to raise its temperature, then find the heat of the water the cube was d...
Thu Jan 31, 2019 6:36 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4C.3 Cp to (5/2 * R)
Replies: 1
Views: 96

### 4C.3 Cp to (5/2 * R)

How does Cp become 5/2 R in part a of 4C.3 7th edition?
Thu Jan 31, 2019 6:08 pm
Forum: Calculating Work of Expansion
Topic: Atmospheres to Joules
Replies: 2
Views: 102

### Atmospheres to Joules

How do we go from Atmospheres to Joules? Is this a direct unit conversion, and if so, do we need to memorize the value?
Thu Jan 24, 2019 9:41 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Solids and Liquids for pressure change
Replies: 3
Views: 140

### Solids and Liquids for pressure change

Why don't we consider solids and liquids when pressure is being changed?
Thu Jan 24, 2019 9:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6D.15 part b 7th
Replies: 1
Views: 95

### 6D.15 part b 7th

Where does Al(H2O)6 come from in the solutions manual? The initial molecule is AlCl3.
Thu Jan 24, 2019 9:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6D.3 7th
Replies: 1
Views: 87

### 6D.3 7th

Why must we subtract the calculated concentrations of H+ and OH- from the initial concentration when plugging it into the Kc equation?
Thu Jan 17, 2019 8:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Problem 5I.11 7th
Replies: 1
Views: 74

### Problem 5I.11 7th

Where do you get the concentration of O2 in this question?
Thu Jan 17, 2019 8:32 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: [H3O+] =[OH-]
Replies: 2
Views: 132

### [H3O+] =[OH-]

When does [H30+] = [OH-]?
Thu Jan 17, 2019 8:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pKa1 solutions manual
Replies: 1
Views: 81

### pKa1 solutions manual

What is the significance of the 1 after pKa in the solution manual like in question 6C.3 7th addition?
Thu Jan 10, 2019 6:51 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: degree symbol over some variables [ENDORSED]
Replies: 1
Views: 73

### degree symbol over some variables[ENDORSED]

What does the small circle that looks like a degree symbol over some variable in the equations indicate?
Thu Jan 10, 2019 6:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.5
Replies: 2
Views: 97

### 5G.5

How are flask 3 and 4 different? Both flasks have 6/11 decomposed X2 molecules.
Thu Jan 10, 2019 5:52 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE tables with initial values products
Replies: 1
Views: 31

### ICE tables with initial values products

Using the ATP +H2O <> ADP + Pi reaction example from class, if there were to have been initial values for ADP and Pi would you add them together and then add that value to the change in molarity?
Wed Dec 05, 2018 6:24 pm
Forum: Identifying Acidic & Basic Salts
Topic: zinc nitrite
Replies: 1
Views: 112

### zinc nitrite

how would you know that zinc has a plus two charge if just given the name "zinc nitrite"?
Wed Dec 05, 2018 5:38 pm
Forum: Identifying Acidic & Basic Salts
Topic: Ammonia and phosphoric acid
Replies: 1
Views: 243

### Ammonia and phosphoric acid

why don't these acids and base create water? I thought they always needed to generate a water molecule.
This is part b of Fundamentals J.9
Mon Dec 03, 2018 4:51 pm
Forum: Calculating the pH of Salt Solutions
Topic: pH 1-14
Replies: 2
Views: 103

### pH 1-14

why is having a pH outside of the 1-14 range rare?
Mon Dec 03, 2018 4:43 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Resonance
Replies: 1
Views: 92

### Resonance

Can someone explain how resonance effects acidity?
Mon Dec 03, 2018 4:34 pm
Forum: Identifying Acidic & Basic Salts
Topic: Salts cause acidity
Replies: 3
Views: 170

### Salts cause acidity

How do you know when adding a salt can cause it to become more acidic? why doesn't NaCl do this?
Thu Nov 22, 2018 11:30 am
Forum: Hybridization
Topic: Determining shape
Replies: 3
Views: 149

### Determining shape

Can someone explain again why we can’t use hybridization to find shape?
Wed Nov 21, 2018 1:05 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape of H2O
Replies: 1
Views: 206

### Shape of H2O

Is there any reason why the two lone pair electrons stay next to each other, making the molecule bent, besides the fact that it has 4 regions of electron density? Like why wouldn't they want to be opposite sides from each other and make the molecule linear?
Wed Nov 21, 2018 12:58 pm
Forum: Hybridization
Topic: Using hybrid orbitals
Replies: 2
Views: 91

### Using hybrid orbitals

Is it necessary to indicate the shell of the hybrid orbital? sp3, 2sp3...
Thu Nov 15, 2018 5:25 pm
Forum: Bond Lengths & Energies
Topic: bond energy clarification
Replies: 4
Views: 171

### bond energy clarification

In lecture, the slides had this list:
ion-ion -250kJ.mol^-1
ion-dipole -15 kJ.mol^-1
dipole-dipole -2kJ.mol^-1

I was just wondering if anyone could tell me what these values were of again?
Thu Nov 15, 2018 5:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T-shaped molecules
Replies: 2
Views: 106

### T-shaped molecules

Do T-shaped molecules with VSEPR formula AX3E2 and AX3E3 have the same angles? and if so why?
Thu Nov 15, 2018 5:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AX2E3 shape
Replies: 2
Views: 168

### AX2E3 shape

Why are molecules with this VSEPR formula linear when there are 3 lone pairs?
Thu Nov 08, 2018 11:13 am
Forum: Lewis Structures
Topic: Expanded octet
Replies: 4
Views: 208

### Expanded octet

Why can an expanded octet have 10,12... electrons when octets always need exactly 8?
Thu Nov 08, 2018 11:09 am
Forum: Dipole Moments
Topic: Van Der Waal vs Hydrogen Bons
Replies: 2
Views: 155

### Van Der Waal vs Hydrogen Bons

I was taught that in general Van Der Waals and usually weaker than hydrogen bonds but at some point can become stronger if the size of the molecules is big enough. I was wondering if this was correct, and if so, how would you find out when it becomes stronger?
Thu Nov 08, 2018 11:02 am
Forum: Dipole Moments
Topic: H2O and H2O intermolecular forces
Replies: 1
Views: 172

### H2O and H2O intermolecular forces

In my discussion, my TA said that there were dipole-dipole, Van Der Waal, and hydrogen bonds present between two water molecules and I was wondering where each of these would be between the two molecules.
Tue Oct 30, 2018 9:40 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Affinity
Replies: 2
Views: 130

### Electron Affinity

What does it mean to say that an electron is added to a gas-phase atom? I guess a better question might be what is a gas-phase atom?
Tue Oct 30, 2018 9:33 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Group 11 configurations
Replies: 1
Views: 108

### Group 11 configurations

The solutions guide said that Ag+ had an electron configuration of 4d10. Do all group 11 ions follow this rule?
Tue Oct 30, 2018 9:28 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Ag+ Configuration
Replies: 5
Views: 1084

### Ag+ Configuration

Why is the electron configuration for Ag+ 4d10 instead of 4d9 5s1?
Thu Oct 25, 2018 5:21 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: orbital positions
Replies: 2
Views: 136

### orbital positions

During lecture Dr. Lavelle said that the x,y, and z labels for px,py, and pz were arbitrary but are they arbitrary for d orbital as well?
Thu Oct 25, 2018 5:15 pm
Forum: Quantum Numbers and The H-Atom
Topic: Degeneracy
Replies: 4
Views: 215

### Degeneracy

What is the difference in degeneracy for an H-atom and multielectron atoms? Do the same rules apply?
Mon Oct 22, 2018 5:37 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Indeterminacy Equation use
Replies: 2
Views: 156

### Indeterminacy Equation use

Is Heisenberg’s indeterminacy equation just to calculate the +/- value and is the value you calculate for deltaX, for example, the +/- value or do you need to divide it by two?
Wed Oct 17, 2018 8:52 pm
Forum: DeBroglie Equation
Topic: Wave properties
Replies: 3
Views: 176

### Wave properties

So in lecture and on homework, we talked about calculating the wavelength of a baseball and I wasn't sure what was meant by this. Can anyone help clarify how a ball has a wavelength?
Wed Oct 17, 2018 8:48 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Problem 1A.15
Replies: 1
Views: 68

### Problem 1A.15

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.

Which equation would you use to figure this out?
Wed Oct 17, 2018 5:26 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg's Uncertainty Equation
Replies: 1
Views: 102

### Heisenberg's Uncertainty Equation

Why does the solutions guide have the uncertainty equation as (delta)p(delta)x = (1/2)h but Lavelle taught it as (delta)p(delta)x >/= (1/4pi)h?
Fri Oct 12, 2018 2:14 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Changing negative to positive for change in energy
Replies: 1
Views: 41

### Changing negative to positive for change in energy

In lecture today, Dr. Lavelle said the reason you change the sign for the change in energy to a positive when you plug it into the E=hv and I forgot what he said. Can someone please help explain?
Fri Oct 12, 2018 2:11 pm
Forum: Photoelectric Effect
Topic: Work function
Replies: 3
Views: 94

### Work function

What is the difference between the work function and the workforce? Are they the same?
Fri Oct 12, 2018 2:10 pm
Forum: Einstein Equation
Topic: Homework Problem 1A.15
Replies: 1
Views: 113

### Homework Problem 1A.15

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. I'm not sure where to begin with this question and what it is referring to...
Thu Oct 04, 2018 4:00 pm
Forum: Balancing Chemical Reactions
Topic: H.11 part 2 balancing tricks?
Replies: 2
Views: 128

### H.11 part 2 balancing tricks?

Balance equation: Fe3O4 + CO --> Fe + CO2 I understand how to balance this equation by thinking about it but I wanted to see if anyone knew any tricks for balancing oxygen in this without jumping back and forth from reaction to the product to see if it balanced. I liked the trick Dr. Lavelle taught ...
Thu Oct 04, 2018 3:25 pm
Forum: Molarity, Solutions, Dilutions
Topic: Q G.13
Replies: 1
Views: 60

### Q G.13

To prepare a fertilizer solution, a florist dilutes 1.0 L of 0.20M NH4NO3 (aq) by adding 3.0 L of water. The nurse then adds 100. mL of the diluted solution to each plant. How many moles of nitrogen atoms will each plant receive?
Thu Oct 04, 2018 11:38 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Question E29 c.
Replies: 3
Views: 134

### Re: Question E29 c.

So we know from the molecular formula that we have 4 moles of H20. This means that we have to multiply 4 by the number of moles calculated in part A which was 0.42 moles. Doing this we get 0.168 moles of H2O but the question is asking how many molecules are present so we have to convert by multiplyi...