Search found 51 matches

by Alexandria Weinberger
Thu Mar 15, 2018 11:56 pm
Forum: Balancing Redox Reactions
Topic: Half-Reactions Sheet
Replies: 5
Views: 217

Re: Half-Reactions Sheet

Yes we should be provided with all of that information unless finding a reaction potential is part of the question.
by Alexandria Weinberger
Thu Mar 15, 2018 11:54 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic vs Concentration Cells
Replies: 1
Views: 88

Galvanic vs Concentration Cells

What is the difference between a galvanic and concentration cell?
by Alexandria Weinberger
Sat Mar 10, 2018 5:50 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: example 15.4: Measuring a Rate Constant
Replies: 2
Views: 207

Re: example 15.4: Measuring a Rate Constant

Yes you will be expected to determine orders and rate constants based on experimental data.
by Alexandria Weinberger
Sat Mar 10, 2018 5:47 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Rate Law being affected by product [ENDORSED]
Replies: 2
Views: 214

Re: Rate Law being affected by product [ENDORSED]

You would usually only consider the forward reaction.
by Alexandria Weinberger
Sat Mar 10, 2018 5:44 pm
Forum: General Rate Laws
Topic: Pseudo-Reactions [ENDORSED]
Replies: 2
Views: 180

Re: Pseudo-Reactions [ENDORSED]

You’ll need to use the pseudo-orders when very limited experimental data is given, because you will have to manipulate the concentrations yourself. They will most likely make you find the pseudo-order and give you the data when one reactant’s concentration is small and the others are large and so on.
by Alexandria Weinberger
Mon Feb 26, 2018 2:20 pm
Forum: General Rate Laws
Topic: Negative Sign [ENDORSED]
Replies: 7
Views: 306

Re: Negative Sign [ENDORSED]

We want the rates to be positive, so if a product is being used up in a reaction, the overall term has to be negative, therefore the negative sign at the front.
by Alexandria Weinberger
Mon Feb 26, 2018 2:19 pm
Forum: General Rate Laws
Topic: Unique Rate [ENDORSED]
Replies: 4
Views: 175

Re: Unique Rate [ENDORSED]

The unique rate of reaction is the rate at which each component will decompose or form in a reaction and it is different for every reaction (therefore unique). The individual rates take into account the coefficients for each reactant or product because depending on how many moles are used in the rea...
by Alexandria Weinberger
Mon Feb 26, 2018 2:10 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: E rxn vs E standard at equilibrium [ENDORSED]
Replies: 2
Views: 170

Re: E rxn vs E standard at equilibrium [ENDORSED]

Erxn is not 0 at equilibrium. At equilibrium, Erxn=Estandard. So therefore at equilibrium, deltaG is=0 because deltaG=-nFE. If -nFErxn=-nFEstandard, then the overall is 0.
by Alexandria Weinberger
Mon Feb 26, 2018 2:08 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Q and K
Replies: 7
Views: 287

Re: Q and K

The concept of Q and K should be the same throughout chemistry, since they are purely related to equilibrium, although can be applied to other topics.
by Alexandria Weinberger
Mon Feb 26, 2018 2:06 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: ln vs log [ENDORSED]
Replies: 5
Views: 208

Re: ln vs log [ENDORSED]

Using ln versus log will yield the same answer. The only reasons one might want to use log over ln is to stay consistent within chemistry (usually use log for concentrations) and pH is found by using log.
by Alexandria Weinberger
Mon Feb 26, 2018 2:03 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 14.37 part a
Replies: 2
Views: 92

Re: 14.37 part a

HCl will dissolve into H+ and Cl- ions in solution. In the reaction, Cl- does not react with anything and therefore does not contribute to the balancing of the half reactions.
by Alexandria Weinberger
Mon Feb 26, 2018 2:01 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: #14.23 finding n [ENDORSED]
Replies: 3
Views: 152

Re: #14.23 finding n [ENDORSED]

By balancing the half reactions, you will find that the number of electrons transferred between the two equations will be 6. n is the number of electrons transferred in a redox reaction, so therefore n is going to be 6.
by Alexandria Weinberger
Mon Feb 26, 2018 1:58 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: 14.27
Replies: 6
Views: 266

Re: 14.27

Gibb's Free Energy is a state function, so the values of individual reactions can be added together to find the free energy of the overall reaction. Standard potential is not a state function, so you cannot add potentials together or take away to find the potentials of intermediate reactions.
by Alexandria Weinberger
Mon Feb 26, 2018 1:55 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Dissolving [ENDORSED]
Replies: 3
Views: 158

Re: Dissolving [ENDORSED]

A metal will dissolve if the overall redox reaction's cell potential is positive. You can determine if it is positive by finding the half reactions, manipulating them so the metal is being dissolved, find their respective potentials and subtracting anode from cathode. If the result is positive, then...
by Alexandria Weinberger
Sun Feb 11, 2018 9:59 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy and compression
Replies: 3
Views: 143

Re: Entropy and compression

Entropy is (for lack of a better word) disorder. So if a gas is compressed, it is being packed into a tighter space, decreasing the amount of room for the particles to move around in. Therefore, since there is less area for the particles, the system is more ordered, so entropy decreases.
by Alexandria Weinberger
Sun Feb 11, 2018 3:25 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: delta U
Replies: 2
Views: 113

Re: delta U

We assume that deltaU=0 when the reaction is isothermal, so the internal energy does not change throughout. Therefore q=-w. The system can still be compressed or expanded, as long as the temperature does not change.
by Alexandria Weinberger
Sun Feb 11, 2018 3:18 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Entropy Change factors
Replies: 6
Views: 245

Re: Entropy Change factors

More complex molecules have more "things" or smaller particles in them that give them more micro states to be filled. So therefore being more complex makes them have higher entropy values.
by Alexandria Weinberger
Sun Feb 11, 2018 3:15 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Favorability
Replies: 4
Views: 177

Re: Favorability

Favorability mostly depends on Gibbs free energy value. If it is negative, then the reaction is favorable and will proceed spontaneously. If it is positive, the reaction will most likely not take place. Whether Gibbs free energy is negative or positive depends on the deltaS and deltaH values, as wel...
by Alexandria Weinberger
Sun Feb 11, 2018 3:13 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: How to calculate W [ENDORSED]
Replies: 6
Views: 318

Re: How to calculate W [ENDORSED]

W is the number of ways atoms or molecules can arrange themselves in a system.
You would find it by taking the number of possible states and raising it by the number of particles or compounds that can fill those states.
by Alexandria Weinberger
Sun Feb 11, 2018 3:12 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: How to calculate W [ENDORSED]
Replies: 6
Views: 318

Re: How to calculate W [ENDORSED]

W is the number of ways atoms or molecules can arrange themselves in a system.
You would find it by taking the number of possible states and raising it by the number of particles or compounds that can fill those states.
by Alexandria Weinberger
Sun Feb 11, 2018 3:10 pm
Forum: Van't Hoff Equation
Topic: Exothermic and decrease in tempterature
Replies: 4
Views: 287

Re: Exothermic and decrease in tempterature

If a reaction is endothermic, the reaction takes in heat to form products, leaving the surroundings with less heat. Therefore, if additional heat it added to the surroundings, to maintain equilibrium the system will produce more products to reduce the temperature in the surroundings.
by Alexandria Weinberger
Sun Jan 28, 2018 5:34 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 8.41 [ENDORSED]
Replies: 2
Views: 417

Re: 8.41 [ENDORSED]

First you would find the change in enthalpy as the ice cube melts (using the standard enthalpy of fusion). Then you would use q=mCdeltaT to find the final temperature of the former ice as it heats up to match the ice of the water it is in. Then you would set up the equation for water cooling to a fi...
by Alexandria Weinberger
Sun Jan 28, 2018 5:26 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Thermal Disorder vs. Positional Disorder
Replies: 2
Views: 78

Re: Thermal Disorder vs. Positional Disorder

Thermal disorder has to do with heat, mainly. When there is more heat, particles have more energy and will become more disordered so entropy will increase.
Positional disorder has to do with volume. When there is more room for particles to move, the disorder will increase and so will the entropy.
by Alexandria Weinberger
Sun Jan 28, 2018 5:24 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: degeneracy
Replies: 3
Views: 120

Re: degeneracy

I am having trouble understanding degeneracy and micro states as well
by Alexandria Weinberger
Sun Jan 28, 2018 5:22 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Boltzmann Equation Clarification
Replies: 3
Views: 111

Re: Boltzmann Equation Clarification

The Boltzmann Equation tells us that we can find the entropy just from the distributions of atoms/particles and the probability that they will occur. It, however, does depend on temperature.
by Alexandria Weinberger
Sun Jan 21, 2018 5:55 pm
Forum: Phase Changes & Related Calculations
Topic: Work Equation
Replies: 3
Views: 108

Re: Work Equation

The negative sign of -w is the system losing its energy by doing work on something else. When pressure is constant, and the system expands, deltaV is positive and therefore work is negative.
by Alexandria Weinberger
Sat Jan 20, 2018 7:42 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.99
Replies: 1
Views: 94

Re: 8.99

You have to split ZnCl2 into its ions (Zn2+ and 2Cl-) and use those formation enthalpies, then you will get the right answer
by Alexandria Weinberger
Fri Jan 12, 2018 3:25 pm
Forum: Phase Changes & Related Calculations
Topic: Hess Law [ENDORSED]
Replies: 5
Views: 265

Re: Hess Law [ENDORSED]

You would just flip the sign, since the energy would be going (inflow or outflow) the opposite way.
by Alexandria Weinberger
Thu Jan 11, 2018 10:28 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.49
Replies: 5
Views: 198

Re: 8.49

The textbook stated that all temperatures will be assumed to be 298 K unless stated otherwise because that is standard.
by Alexandria Weinberger
Thu Jan 11, 2018 10:25 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.51
Replies: 3
Views: 146

8.51

When finding the enthalpy of the reaction, why are the individual enthalpies for N2 and O2 not included in the calculation?
by Alexandria Weinberger
Thu Dec 07, 2017 11:44 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Percentage Deprotonation
Replies: 4
Views: 789

Re: Percentage Deprotonation

Percentage deprotonation would just be the molarity of the H+ ions over the initial concentration of what ever acid is being used. That will give the percent of protons dissociated into the solution.
by Alexandria Weinberger
Thu Dec 07, 2017 11:40 pm
Forum: Bronsted Acids & Bases
Topic: identifying based on structure
Replies: 4
Views: 230

Re: identifying based on structure

Ag+ is the acid because it will take an electron to become neutral, as F- will take a proton to become neutral so it is the base.
by Alexandria Weinberger
Fri Dec 01, 2017 5:18 pm
Forum: Naming
Topic: Finding Coordination Number
Replies: 6
Views: 318

Re: Finding Coordination Number

Coordination number is just the number of ligands attached to the central metal.
by Alexandria Weinberger
Fri Dec 01, 2017 5:16 pm
Forum: Naming
Topic: Order of Ligands
Replies: 8
Views: 372

Re: Order of Ligands

Ligands should be written in alphabetical order by the name of the ligand, not the prefix of the ligand.
by Alexandria Weinberger
Tue Nov 21, 2017 6:25 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction Quotient [ENDORSED]
Replies: 4
Views: 814

Re: Reaction Quotient [ENDORSED]

Pure solids and liquids are not included in the reaction quotient and K because their concentrations do not change throughout the reaction. Gases and aqueous solutions are the only ones that are included in calculations.
by Alexandria Weinberger
Tue Nov 21, 2017 6:18 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: When do you calculate Q prior to calculating concentrations?
Replies: 2
Views: 325

Re: When do you calculate Q prior to calculating concentrations?

You should always find Q just to check which way the reaction will proceed. Depending on what Q is, the reaction will produce more products or reverse and produce more reactants. This will determine whether the K constant will be the reciprocal or not to help you find the equilibrium concentrations.
by Alexandria Weinberger
Tue Nov 14, 2017 12:50 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: "more or less than 109.5 degrees"?
Replies: 4
Views: 338

Re: "more or less than 109.5 degrees"?

Extra lone pairs will always push the bonds closer together, making bond angles that are more or less than the standard 109.5 degrees.
by Alexandria Weinberger
Tue Nov 14, 2017 12:48 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Memorization
Replies: 5
Views: 288

Re: Memorization

Try to learn the shapes rather than memorize, because if you can associate a certain shape with a certain molecule, then you will be okay. Knowing how many atoms connect to a central atom and what shape that makes is good for visualization when there are lone pairs that can distort it.
by Alexandria Weinberger
Tue Nov 14, 2017 12:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sigma vs. Pi Bonds
Replies: 5
Views: 255

Re: Sigma vs. Pi Bonds

Sigma bonds can rotate because they are only connected at one point, making the connecting atoms able to move around. Pi bonds cannot rotate because they are connected at two points and the bonds would break if they tried to rotate. If you tried to twist it any way, at least one of the bonds would b...
by Alexandria Weinberger
Tue Nov 14, 2017 12:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: CO2 vs. H2O
Replies: 6
Views: 564

Re: CO2 vs. H2O

In CO2 the dipole moments cancel out, while in H2O, they don't, making it polar.
by Alexandria Weinberger
Fri Nov 03, 2017 12:36 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Increasing polarization
Replies: 3
Views: 448

Re: Increasing polarization

O^2- has more protons than N^3-, making the effective nuclear charge of the oxygen anion greater than the nitrogen anion. This will have more of a pull on electrons. This greater effective nuclear charge will also be able to resist distortion or its electron cloud more, meaning that it won't be able...
by Alexandria Weinberger
Fri Nov 03, 2017 12:33 pm
Forum: Electronegativity
Topic: Electronegativity [ENDORSED]
Replies: 3
Views: 285

Re: Electronegativity [ENDORSED]

The periodic trend for electronegativity is it increases across the period and decreases down a group. this can be associated with the size of the atoms and the effective nuclear charge. Small atoms will have higher electronegativity (pull more electrons) than larger ones. This is why the elements w...
by Alexandria Weinberger
Wed Oct 25, 2017 10:18 pm
Forum: Ionic & Covalent Bonds
Topic: Homework 3.33
Replies: 2
Views: 222

Re: Homework 3.33

While having single bonds on everything may look and seem nice, you have to check the formal charges for each atom. The configuration with the lowest overall formal charge will be correct.
by Alexandria Weinberger
Wed Oct 25, 2017 10:16 pm
Forum: Ionic & Covalent Bonds
Topic: Test 3 preparation and date [ENDORSED]
Replies: 5
Views: 329

Re: Test 3 preparation and date [ENDORSED]

Dr Lavelle would most likely want you to focus on Heisenberg's Uncertainty Principle through Periodic trends concepts.
The homework should be on chapter 3.
The test will be on Tuesday, October 31st.
by Alexandria Weinberger
Sat Oct 21, 2017 7:30 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: N Quantum Number [ENDORSED]
Replies: 3
Views: 198

Re: N Quantum Number [ENDORSED]

n represents the size and energy and is the shell.
s,p,d,f are all determining the shape
by Alexandria Weinberger
Sat Oct 21, 2017 7:28 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty in position [ENDORSED]
Replies: 2
Views: 385

Re: Uncertainty in position [ENDORSED]

the formula is h/4pi *delta p
by Alexandria Weinberger
Wed Oct 11, 2017 8:32 pm
Forum: Properties of Electrons
Topic: Remembering the Mass of Electron
Replies: 2
Views: 367

Re: Remembering the Mass of Electron

This was really helpful! THANKS
by Alexandria Weinberger
Wed Oct 11, 2017 8:30 pm
Forum: Photoelectric Effect
Topic: Units Cancelling Out
Replies: 3
Views: 234

Re: Units Cancelling Out

The units in E=hv will cancel out because the units for Planck's constant is Joules*seconds and frequency is s^-1. Therefore you will be left with Joules, which is a unit for energy.
by Alexandria Weinberger
Thu Oct 05, 2017 8:22 pm
Forum: Molarity, Solutions, Dilutions
Topic: G5- moles of Na [ENDORSED]
Replies: 5
Views: 437

Re: G5- moles of Na [ENDORSED]

I was stuck on this problem too. Very helpful
by Alexandria Weinberger
Tue Oct 03, 2017 6:18 pm
Forum: Significant Figures
Topic: Calculating Significant Figures
Replies: 3
Views: 579

Re: Calculating Significant Figures

This was very helpful as I was getting confused after not doing these calculations in so long!

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