## Search found 50 matches

Mon Mar 19, 2018 11:25 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius equation
Replies: 2
Views: 441

### Arrhenius equation

For the equation with 2 temperatures, does it matter which temperature is t1 and t2?
Mon Mar 19, 2018 11:20 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Delta U
Replies: 3
Views: 454

### Delta U

Why is delta U a state function if it depends on q and w, which are not state functions?
Mon Mar 19, 2018 11:18 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: k1 and k2
Replies: 2
Views: 1618

### k1 and k2

K can equal k1/k'1, but can it also equal k2/k'2? Is it just convention as to which step is the rate determining step?
Sun Mar 11, 2018 6:58 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius equation for 2 temperatures
Replies: 2
Views: 212

### Arrhenius equation for 2 temperatures

Will the Arrhenius equation containing 2 different temperatures be included in the final equation sheet? Or will there only be the equation with 1 temperature?
Sun Mar 11, 2018 4:13 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Calculating the standard potential using ∆G=-nFE
Replies: 1
Views: 221

### Re: Calculating the standard potential using ∆G=-nFE

Yes that is the correct answer
Sun Mar 11, 2018 4:12 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Electrochem Review session problem 14.47
Replies: 2
Views: 189

### Electrochem Review session problem 14.47

For today's review session, one example given was 14.47. In the solution manual the answer to this problem for part a is Q=10^6, but when calculating for Q, I got the answer to be 3.3x10^6. Is this an error in the manual or is the number so big that the 3.3 is insignificant?
Sun Mar 04, 2018 2:29 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 15.47
Replies: 1
Views: 142

### 15.47

In the solution manual, it states that one of the intermediates is a chloride ion. I was wondering how the chloride ion gets removed if the other reaction only shows a neutral chlorine atom.
Sun Mar 04, 2018 2:22 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: 15.23?
Replies: 3
Views: 255

### Re: 15.23?

0.034 is the concentration in terms of B. You have the initial concentration in terms of A so you must convert [B] to [A] using the stoichiometric coefficients.
Sun Mar 04, 2018 2:14 pm
Forum: Second Order Reactions
Topic: Slope of second order reaction
Replies: 3
Views: 311

### Slope of second order reaction

Why is the slope of a second order reaction positive compared to first and zero order reactions?
Sun Feb 25, 2018 11:58 pm
Forum: Balancing Redox Reactions
Topic: Water in balancing reactions
Replies: 4
Views: 290

### Water in balancing reactions

Is it always necessary to use water to balance the redox reactions?
Fri Feb 23, 2018 3:35 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Reaction Order [ENDORSED]
Replies: 2
Views: 250

### Reaction Order[ENDORSED]

It was stated that the overall reaction order is the sum of n and m, but what are the orders of "n" and "m" called?
Fri Feb 23, 2018 9:36 am
Forum: General Rate Laws
Replies: 6
Views: 2346

For the general rate law, will the reactants always have a negative sign in front of them? Is this simply because the reactants are being decomposed?
Sun Feb 18, 2018 6:39 pm
Forum: Balancing Redox Reactions
Topic: Basic conditions
Replies: 3
Views: 268

### Basic conditions

When balancing reactions under basic conditions, do we just need to add OH- rather than H+?
Sun Feb 18, 2018 6:08 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Electrolyis
Replies: 3
Views: 363

### Re: Electrolyis

In lecture it was stated that there will not be calculations regarding electrolysis, but we should at least know the conceptual information.
Sun Feb 18, 2018 6:06 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: E equations
Replies: 3
Views: 289

### Re: E equations

As mentioned above, both equations are the same except for the fact that one uses base e and the other uses base 10. The equation with base 10 is more typically used because pH is based on a log base 10 scale.
Sun Feb 11, 2018 10:59 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isothermic
Replies: 4
Views: 339

### Re: Isothermic

Bansi Amin 1D wrote:What is meant by constant measures?

If there are equal measures or dimensions, then the volume has to be the same. Isochoric and isometric can be used interchangeably.
Sun Feb 11, 2018 10:35 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Do we ever need to convert pressure?
Replies: 1
Views: 132

### Re: Do we ever need to convert pressure?

In the equation that you mentioned, the pressure can be used in any units because they will cancel out as they are being divided.
Sun Feb 11, 2018 10:07 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Delta S total [ENDORSED]
Replies: 2
Views: 268

### Delta S total[ENDORSED]

During the midterm review, it was stated that $\Delta S_s_y_s=-\Delta S_s_u_r_r$ when Delta S total is 0. Could someone explain how it can be zero and what the significance is?
Sun Feb 04, 2018 11:37 pm
Forum: Van't Hoff Equation
Topic: Equation
Replies: 4
Views: 363

### Equation

During lecture, Dr. Lavelle mentioned that Van't Hoff used a different equation than the one we are more likely going to use. Why exactly did he use a different equation and what for?
Sun Feb 04, 2018 11:07 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Equations
Replies: 3
Views: 222

### Equations

Could someone explain what the significance of wmax=deltaG is? Why is is important that maximum work is equal to deltaG? Thanks
Sun Feb 04, 2018 10:46 pm
Forum: Van't Hoff Equation
Topic: Entropy and enthalpy
Replies: 2
Views: 292

### Entropy and enthalpy

For the Van't Hoff equation, are we always going to assume that entropy and enthalpy will remain constant?
Sat Jan 27, 2018 10:19 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: W as a maximum
Replies: 3
Views: 220

### W as a maximum

What is the significance of W being a maximum at equilibrium for an isolated system?
Sat Jan 27, 2018 10:10 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Positional Entropy
Replies: 2
Views: 955

### Positional Entropy

How does positional entropy differ from thermal entropy?
Sat Jan 27, 2018 9:15 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Enthalpy of Reaction at lower temperatures [ENDORSED]
Replies: 2
Views: 196

### Enthalpy of Reaction at lower temperatures[ENDORSED]

Could someone please explain a little more why enthalpy of reaction has a bigger role at lower T? Thanks.
Sun Jan 21, 2018 11:23 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Memorizing Enthalpies [ENDORSED]
Replies: 5
Views: 233

### Re: Memorizing Enthalpies[ENDORSED]

If a problem requires enthalpies, they will be provided. I do not believe you have to memorize any of them.
Sun Jan 21, 2018 11:15 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: the sign of q
Replies: 5
Views: 203

### Re: the sign of q

When q is positive, heat has been absorbed by the system. When q is negative, the system has lost heat. If the system requires 5.5 kJ of heat that means that for the system to work it will have to absorb 5.5 kJ of heat. This means that q in this case will be positive.
Sun Jan 21, 2018 11:10 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond enthalpies
Replies: 4
Views: 322

### Bond enthalpies

In a test if we are asked to solve for the enthalpy of a reaction will we be given a chart with the enthalpies for the different bonds?
Sun Jan 14, 2018 9:36 pm
Forum: Calculating Work of Expansion
Topic: q and w
Replies: 1
Views: 133

### q and w

Example 8.5 in the textbook shows that for the reversible and irreversible pathways q and w have the same values, but the signs are different. Does this apply for all problem where only the sign is different in q and w?
Sun Jan 14, 2018 9:22 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Specific Heat Capacities
Replies: 3
Views: 176

### Specific Heat Capacities

Will we need to memorize any specific heat capacities of materials or will we be given the information as needed?
Sun Jan 14, 2018 8:47 pm
Forum: Calculating Work of Expansion
Topic: Constant External Pressure
Replies: 2
Views: 179

### Constant External Pressure

One of the equations we are given for work is w=-PexΔV, where external pressure is constant. Will the pressure always be constant or are there instances where the pressure will be different?
Sat Dec 09, 2017 2:57 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration of I-
Replies: 1
Views: 138

### Re: Electron Configuration of I-

[Xe] would be accepted unless stated that the written out electron configuration is wanted.
Sat Dec 09, 2017 2:46 pm
Forum: Balancing Chemical Reactions
Topic: Net Number of moles produced [ENDORSED]
Replies: 3
Views: 430

### Re: Net Number of moles produced[ENDORSED]

After balancing and finding the total moles on the reactants and the products side, the net number of moles will be the moles on the products side - the moles on the reactants side.
Sun Dec 03, 2017 11:15 pm
Forum: Polyprotic Acids & Bases
Topic: Polyprotic Acid Ka [ENDORSED]
Replies: 3
Views: 717

### Polyprotic Acid Ka[ENDORSED]

How do we know if a certain acid has more than one Ka? Is it based solely on the available H available to donate?
Sun Dec 03, 2017 10:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Reverse Reactions [ENDORSED]
Replies: 3
Views: 324

### Re: Reverse Reactions[ENDORSED]

The K value of the reverse reaction will be the reciprocal of the forward reaction, so the reverse reaction will be 1/K.
Sun Dec 03, 2017 2:32 pm
Forum: Ideal Gases
Topic: Temperature in PV=nRT
Replies: 9
Views: 672

### Re: Temperature in PV=nRT

The unit we use for temperature in this equation is Kelvin (K). If the temperature is given in Celsius, add 273.15 to convert to Kelvin.
Sun Nov 26, 2017 11:36 pm
Forum: Ideal Gases
Topic: R in PV=nRT [ENDORSED]
Replies: 7
Views: 652

### Re: R in PV=nRT[ENDORSED]

R represents the ideal gas constant, which depends on the units of measurements of the other variables.
Sun Nov 19, 2017 6:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Triple vs. double bonds
Replies: 2
Views: 307

### Re: Triple vs. double bonds

If the Carbon were to have a double bond with both chlorine and nitrogen then the formal charge of carbon would be 0, but the formal charges of chlorine and nitrogen would be +1 and -1, respectively. When making lewis structures we want to have the formal charges to be as close to 0 as possible. Whe...
Sun Nov 19, 2017 5:02 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Equatorial vs Axial [ENDORSED]
Replies: 3
Views: 302

### Re: Equatorial vs Axial[ENDORSED]

Think of the molecule as a spinning top. The center of the spinner is the central atom and the tip of the spinner along with the tip the touches the floor are the "axial atoms". The rest of the atoms can be thought of as the "body of the spinner" which are the equatorial atoms
Sun Nov 12, 2017 9:14 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 4
Views: 350

### Re: Bond Angles

Yes the bond angles will need to be known, there are certain patterns with the models so they should come easy if you practice with homework problems and review the notes.
Sun Nov 12, 2017 2:57 pm
Forum: DeBroglie Equation
Topic: When to use DeBroglie Equation
Replies: 4
Views: 317

### Re: When to use DeBroglie Equation

In the deBroglie equation, we have a constant (Planck's) and momentum. So we would use the equation when we know the mass and velocity of a particle.
Sun Nov 05, 2017 9:11 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Which one do I draw?
Replies: 5
Views: 464

### Re: Which one do I draw?

During lecture, we were told that we would not necessarily have to draw the 3D VSEPR models. We would most likely have to write down the molecular geometry of the compound.
Sun Nov 05, 2017 9:06 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Ionization Energy / Lewis Dot Structures
Replies: 2
Views: 319

### Re: Ionization Energy / Lewis Dot Structures

The trend in the periodic table is if you go from left to right, the ionization energy increases. Beryllium is on the left of the periodic table (alkali earth metals) and chlorine is on the right of the periodic table (halogens). Therefore, chlorine has higher ionization energy.
Sun Oct 29, 2017 11:28 pm
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 10
Views: 630

### Lewis Structures

If we are asked to make a lewis structure of a substance, should we include the resonance structures as well? Or would that only be necessary if initially asked?
Sun Oct 29, 2017 11:07 pm
Forum: Lewis Structures
Topic: Lewis Dot Diagrams [ENDORSED]
Replies: 2
Views: 167

### Lewis Dot Diagrams[ENDORSED]

When writing lewis dot diagrams does it matter on what direction of the symbol we start putting the dots for the valence electrons?
Sun Oct 22, 2017 10:26 pm
Forum: DeBroglie Equation
Topic: Momentum [ENDORSED]
Replies: 3
Views: 344

### Re: Momentum[ENDORSED]

I believe you would be given the mass also, typically the mass of a subatomic particle is given as kilograms in the DeBroglie equation
Sun Oct 22, 2017 10:17 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Electron configuration
Replies: 4
Views: 303

### Electron configuration

When we write electron configurations, do we have to write the atomic orbitals separately or can we write the configuration as just a certain subshell?
Sun Oct 15, 2017 7:30 pm
Forum: DeBroglie Equation
Topic: DeBroglie Equation & Units [ENDORSED]
Replies: 2
Views: 284

### Re: DeBroglie Equation & Units[ENDORSED]

Up to this point in the class I believe that yes only DeBroglie equation requires us to use a prefix like kilo-
Sun Oct 15, 2017 7:09 pm
Forum: Properties of Electrons
Topic: Hydrogen series
Replies: 5
Views: 472

### Hydrogen series

During lecture, the Balmer and Lyman series were mentioned. These are just two series, and I've heard of the Paschen series, but are there more hydrogen series and if so would they be necessary to learn? Thanks
Sun Oct 08, 2017 5:35 pm
Forum: Significant Figures
Topic: Significant figures Clarification [ENDORSED]
Replies: 3
Views: 405

### Re: Significant figures Clarification[ENDORSED]

Oh I see, so if I come up with a number that has, say 7 digits, I'd go to maybe 4 for the rest of the calculations and then at the end go to 3 significant figures?
Sun Oct 08, 2017 4:51 pm
Forum: Significant Figures
Topic: Significant figures Clarification [ENDORSED]
Replies: 3
Views: 405

### Significant figures Clarification[ENDORSED]

Let's say that in a question you are given a value with 3 significant figures. Would you have to go to 3 significant figures after every calculation? Or would you round at the very end of all the calculations?