## Search found 52 matches

Wed Mar 07, 2018 9:47 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Rate Constant K
Replies: 3
Views: 359

### Re: Rate Constant K

Concentration affects K.
Mon Mar 05, 2018 4:30 pm
Forum: Experimental Details
Topic: Rate Constant
Replies: 4
Views: 569

### Rate Constant

How do you know which experiment of the ones listed to analyze when finding the rate constant? 15.17C, for example, uses its Experiment 1, but 15.19C uses its Experiment 4.
Mon Mar 05, 2018 4:29 pm
Forum: Experimental Details
Topic: 15.17A
Replies: 1
Views: 472

### 15.17A

Why doesn't a second element's simultaneous decrease in concentration appear to affect the examined element's proportionate increase in concentration?
Sun Mar 04, 2018 10:41 pm
Forum: General Rate Laws
Topic: solving for a
Replies: 2
Views: 167

### Re: solving for a

Though we haven't learned this in class, it can be 0.5 if it can be split to then react with the second reactant.

Therefore it is not always a whole number.
Sun Mar 04, 2018 10:38 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: test 2 last Q
Replies: 3
Views: 270

### Re: test 2 last Q

Follow-up question regarding this question, what equation did you use to find Q?
Sun Mar 04, 2018 10:36 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Affects rate of chemical reactions
Replies: 2
Views: 207

### Re: Affects rate of chemical reactions

Adding catalysts to a reaction can increase the rate of the reaction. The ratio of reactant to product can also affect the rate of the forward reaction. (Larger ratio means the reaction goes forward faster.)
Mon Feb 26, 2018 11:39 pm
Forum: General Rate Laws
Topic: Order of reactions?
Replies: 3
Views: 204

### Re: Order of reactions?

Zero is when the rate does not depend on the reactant concentration.
First is when the rate is proportionate to the reactant concentration.
Second is when the rate is proportionate to the square of the reactant concentration.
Mon Feb 26, 2018 11:35 pm
Forum: General Rate Laws
Topic: 15.17
Replies: 4
Views: 270

### 15.17

Why, when solving for the rate, is [B] squared?
Mon Feb 26, 2018 11:34 pm
Forum: General Rate Laws
Topic: 15.9
Replies: 5
Views: 343

### 15.9

Why do we divide by [(mol A) * L^-1]^n when determining units?
Sun Feb 25, 2018 10:57 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Tangent line
Replies: 4
Views: 302

### Re: Tangent line

Yes, as taking the tangent at the beginning would mean the reaction is misrepresented as going faster than it is at the end, and the reverse would be true for taking the tangent at the end.
Sun Feb 25, 2018 10:56 pm
Forum: First Order Reactions
Topic: 15.37
Replies: 2
Views: 189

### Re: 15.37

I’m not sure how to do all of it, but use the rule of 70 for part (a).
Wed Feb 21, 2018 1:13 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Water [ENDORSED]
Replies: 1
Views: 129

### Water[ENDORSED]

Do you ever write H2O in the cell diagram? Why or why not?
Fri Feb 16, 2018 2:44 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Lecture Example
Replies: 2
Views: 158

### Lecture Example

During lecture today, Dr. Lavelle solved the potential energy of the cell given:
Ag+ (1.0 M) —> Ag+(0.1 M)
He then solved the potential out to be
E(cell) = Eº - (0.0592/n)log[P]/[R] = 0 - (0.0592/1)log10 = 0.0592 V

Maybe I miswrote this, but how is E(cell) positive in the end?
Thu Feb 15, 2018 8:08 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Replies: 2
Views: 216

What equation can you assume to be true in an adiabatic reaction, and what about the adiabatic reaction makes it true?
Thu Feb 15, 2018 8:06 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Magnitude
Replies: 2
Views: 177

### Magnitude

During discussion, I heard, “If both the cathode and anode energies are positive, you should lower the magnitude.” What is magnitude exactly, and how do you lower it?
Sat Feb 10, 2018 7:37 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Pt (s) [ENDORSED]
Replies: 4
Views: 304

### Pt (s)[ENDORSED]

When do you know to put Pt(s) on only one side or both sides of the || for the cell diagram?
Sat Feb 10, 2018 7:36 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Commas in Cell Diagram
Replies: 2
Views: 271

### Commas in Cell Diagram

Why would one use a comma instead of a | between two components of a cathode?
Sat Feb 10, 2018 7:36 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Multiplying Cathode Equation
Replies: 2
Views: 156

### Multiplying Cathode Equation

Why doesn't multiplying the equation of the cathode change the Eº of the cathode?
Sat Feb 03, 2018 6:49 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Using Appropriate Equation
Replies: 2
Views: 121

### Using Appropriate Equation

Can you only use the following equation when the temperature is 298K? If so, why? If not, when do you use it?
Sat Feb 03, 2018 3:28 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy Changes Due to Change in Pressure
Replies: 2
Views: 135

### Entropy Changes Due to Change in Pressure

Why is the initial pressure the numerator of the ln segment of the equation, though volume and temperature changes entail the respective final value as their numerators?
Sat Feb 03, 2018 3:26 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Universe [ENDORSED]
Replies: 3
Views: 245

### Universe[ENDORSED]

What type of system is the universe, and how do you know?
Sun Jan 28, 2018 5:04 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: 9.19
Replies: 2
Views: 220

### 9.19

What equation do you use for the equation and why? What given values or key phrases in a word problem do you look for when determining to use this equation?
Sun Jan 28, 2018 4:52 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Cp and Cv Values
Replies: 2
Views: 505

### Cp and Cv Values

Why does the Cp value use the 5/2 fraction, but Cv use the 3/2 fraction? I know one is the derivative of the other but I’m not sure how that process works?
Sat Jan 27, 2018 12:21 am
Forum: Calculating Work of Expansion
Topic: Irreversible Work Chart
Replies: 5
Views: 226

### Irreversible Work Chart

Why does the pressure instantly drop at the beginning of the chart? In other words, what was the definition of the vertical brown line to the left?
Wed Jan 17, 2018 9:48 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Two Work Functions
Replies: 1
Views: 105

### Two Work Functions

When do you know whether to use the w=Pext(Delta)V equation or the w=nRTln(Vf/Vi)?
Wed Jan 17, 2018 9:45 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: R value in equation
Replies: 4
Views: 199

### R value in equation

How do you know which value of the constant R to use for different equations?
Sun Jan 14, 2018 3:16 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 8.103
Replies: 2
Views: 109

### 8.103

I am not sure where to begin when approaching this problem. What equation do you use and why? The solution manual is very vague.
Thu Jan 11, 2018 9:55 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: First Law and Calculating Final Temp (question 8.21)
Replies: 3
Views: 251

### Re: First Law and Calculating Final Temp (question 8.21)

To elaborate on why this is true, the energy released by the metal cannot escape the system, therefore it must transfer to the water. The negative sign serves to show that the energy gained by water is lossed by the metal and needs a negative sign to show that inverse relationship.
Wed Jan 10, 2018 11:03 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Equation for a non-state property?
Replies: 4
Views: 213

### Re: Equation for a non-state property?

The sum of the two non-state properties, work and heat, creates an equation that is a state property. Each of the two is dependent on the process of achieving the final from the initial, making the result not constant.
Wed Jan 10, 2018 2:44 pm
Forum: Phase Changes & Related Calculations
Topic: Light vs. Heat [ENDORSED]
Replies: 2
Views: 184

### Re: Light vs. Heat[ENDORSED]

The definitions of exo-/endothermic reactions are in respect to heat, therefore I do not think the terms apply to other forms of energy gain/loss.
Sun Dec 10, 2017 12:12 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: compression vs pressure
Replies: 6
Views: 355

### Re: compression vs pressure

Compression is the decrease of volume within the system, and pressure is the force upon the moles of reactants and products within the system. Their relationship is inverse. Pressure and compression both only change the molarities and the side of the reaction that the system favors, but they will no...
Sun Dec 10, 2017 12:08 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Replies: 1
Views: 197

How do I know when to use the quadratic equation to find x?
Tue Dec 05, 2017 10:19 pm
Forum: Bronsted Acids & Bases
Topic: 12.25
Replies: 2
Views: 260

### Re: 12.25

There are two molecules of OH within the molecule, making the ratio 1:2 of concentration of Ba(OH)2 to OH, making there be double the amount (or concentration) of the OH molecules.
Tue Dec 05, 2017 10:08 pm
Forum: Bronsted Acids & Bases
Topic: Expanding Equations [ENDORSED]
Replies: 2
Views: 259

### Expanding Equations[ENDORSED]

How do you know when to or not to separate the H from the molecule when completely expanding an acid-base chemical equation?
(I was not sure under what topic to ask this question.)
Wed Nov 29, 2017 2:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular v Electron Arrangement
Replies: 2
Views: 251

### Molecular v Electron Arrangement

What is the difference between the molecular and electron arrangements? Would you be able to say, for example, that the electron arrangement is tetrahedral, even if the molecular shape is trigonal pyramidal?
Tue Nov 28, 2017 3:34 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 11.1
Replies: 4
Views: 345

### Re: 11.1

To elaborate, increasing the amount of reactant increases the number of moles. This increase in moles then increases the moles per liter of the reactant, also known as the concentration. Because K will only change if the temperature changes, the ratio must be adjusted proportionately, and the produc...
Sun Nov 26, 2017 1:51 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chemical Equilibrium
Replies: 2
Views: 201

### Re: Chemical Equilibrium

Yes. Their concentrations do not change, and adding them to the equation would be the equivalent of dividing and multiplying the equation by 1.
Fri Nov 17, 2017 3:07 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Quick Determination of FC [ENDORSED]
Replies: 6
Views: 617

### Re: Quick Determination of FC[ENDORSED]

I think to really understand formal charge people need to know that it assumes covalent bonds are shared equally when in that's not true when atoms are electronegative. This means that at time even though due to formal charge the atom may have a full shell, but in actuality the other bonded atom pu...
Fri Nov 17, 2017 3:05 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Substituting Ligands [ENDORSED]
Replies: 1
Views: 139

### Substituting Ligands[ENDORSED]

I vaguely remember discussing that H2O ligands can be substituted for NH3 molecules, for example, but am not quite sure why. Could anyone explain this to me?
Tue Nov 14, 2017 6:49 pm
Forum: Hybridization
Topic: Superscript
Replies: 3
Views: 357

### Superscript

What is the significance of the 3 superscript within the hybridization notation, 2sp^3 ?
Sat Nov 11, 2017 1:20 am
Forum: Formal Charge and Oxidation Numbers
Topic: Quick Determination of FC [ENDORSED]
Replies: 6
Views: 617

### Quick Determination of FC[ENDORSED]

When you have the Lewis structure of the molecule drawn out, this is one of the ways I learned to quickly find formal charge: 1. Find the number of valence electrons of the given atom based on the periodic table. (n) 2. Draw a circle around the atom in the Lewis structure; find the number of total a...
Sat Nov 11, 2017 1:16 am
Forum: Trends in The Periodic Table
Topic: Isoelectronic [ENDORSED]
Replies: 4
Views: 382

### Isoelectronic[ENDORSED]

One of the exam questions regarded finding elements that were not isoelectronic to F-. Would atoms that had the electron configuration equivalent to [He] be acceptable? Why/why not?
Sun Nov 05, 2017 1:21 pm
Forum: Properties of Light
Topic: Electric Field and Magnetic Field of Light
Replies: 4
Views: 244

### Re: Electric Field and Magnetic Field of Light

the shift of an electron's flight with respect to a photon's energy being shot at it. What is this experiment? Can u explain more of it? When the magnetic force is applied to a group of electron particles with a same initial trajectory, the electrons did not continue on the same trajectory once the...
Mon Oct 30, 2017 1:40 pm
Forum: Ionic & Covalent Bonds
Topic: Lewis Base Shorthand [ENDORSED]
Replies: 1
Views: 146

### Lewis Base Shorthand[ENDORSED]

When writing out the molecular formula BF3 + :NH3 --> NH3BF3, why does one draw the two dots next to NH3 reactant?
Sun Oct 29, 2017 2:28 pm
Forum: Resonance Structures
Topic: Efficiency [ENDORSED]
Replies: 2
Views: 278

### Efficiency[ENDORSED]

Is there a more efficient way to determine the most stable bond of a molecule than purely attempting all of the possible bonds?
Sun Oct 29, 2017 2:17 pm
Forum: Electronegativity
Topic: Exceptions [ENDORSED]
Replies: 2
Views: 207

### Exceptions[ENDORSED]

I remember Dr. Lavelle mentioning certain elements as exceptions to the general table trend regarding electronegativity. Does anyone know which elements they are and why they are an exception?
Sat Oct 21, 2017 11:59 am
Forum: *Shrodinger Equation
Topic: Expansion of Shrodinger Equation [ENDORSED]
Replies: 3
Views: 586

### Re: Expansion of Shrodinger Equation[ENDORSED]

The Hamiltonian is the energy that is enacted upon a wavefunction that changes gradually.
Sat Oct 21, 2017 11:52 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: p-orbital [ENDORSED]
Replies: 2
Views: 218

### Re: p-orbital[ENDORSED]

On exams, there will be given information on which axis the electron orbitals are on. If this information is not given, just write p.
Thu Oct 12, 2017 9:26 pm
Forum: Properties of Light
Topic: Balmer Vs. Lyman
Replies: 12
Views: 1572

### Re: Balmer Vs. Lyman

Balmer series, the visible region of light, and Lyman series, the UV region of light, each interact with electrons that have ground states in different orbitals. Balmer interacts with electrons that come from the second energy level (n=2), and Lyman interacts with electrons from the first energy lev...
Thu Oct 12, 2017 9:17 pm
Forum: Properties of Light
Topic: Electric Field and Magnetic Field of Light
Replies: 4
Views: 244

### Re: Electric Field and Magnetic Field of Light

The magnetic field goes vertically, and the way I remember is the North and South Poles hold the most magnetic force. The electric field goes horizontally, and this is because it must be perpendicular to the magnetic field in order to explain the shift of an electron's flight with respect to a photo...
Wed Oct 04, 2017 11:10 pm
Forum: SI Units, Unit Conversions
Replies: 2
Views: 579