## Search found 54 matches

Sun Mar 18, 2018 12:29 am
Forum: Calculating Work of Expansion
Topic: Work Equations: Which One to Use?
Replies: 3
Views: 330

### Work Equations: Which One to Use?

When do we use w= -Pexdelta v? When do we use w=-nRT ln (V2/V1)?
Sat Mar 17, 2018 9:15 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 8.85.c
Replies: 1
Views: 234

### 8.85.c

For 8.85.c, I was looking through the solutions manual and I was wondering where 0.492 kJ come from.
Sat Mar 17, 2018 9:01 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Determining Which Experiments
Replies: 2
Views: 239

### Determining Which Experiments

How do you know which experiments to choose in determining the order when some experiments have the same concentration and initial rate???
Mon Mar 05, 2018 9:46 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Replies: 2
Views: 223

Since the test is only gonna be from 15.1-6, hw prob 45 onwards won't be on the test right????
Mon Mar 05, 2018 5:16 pm
Forum: First Order Reactions
Topic: 15.21 SOS!!!!!
Replies: 2
Views: 227

### 15.21 SOS!!!!!

Where did ln [A]t / [A]o = -kt come from? I was looking at the formula sheet thinking it was an original formula, but I think it is derived???
Mon Mar 05, 2018 5:13 pm
Forum: Second Order Reactions
Topic: 15.19
Replies: 2
Views: 203

### 15.19

Can someone explain to me how the reaction is 2nd order in B?
Mon Mar 05, 2018 5:11 pm
Forum: General Rate Laws
Topic: Temperature Signifcance
Replies: 4
Views: 268

### Temperature Signifcance

For Problem #11, what was the significance of the temperature in the problem? Do we simply ignore the temperature?
Mon Mar 05, 2018 5:10 pm
Forum: General Rate Laws
Topic: unique reaction rate sign
Replies: 2
Views: 177

### unique reaction rate sign

Are unique reaction rates always positive?
Mon Mar 05, 2018 10:22 am
Forum: Zero Order Reactions
Topic: Units of k
Replies: 12
Views: 987

### Units of k

What are the units of k in zero-, first-, and second- order reactions? How are these units derived?
Sun Mar 04, 2018 9:18 pm
Forum: Zero Order Reactions
Topic: K limiting rate
Replies: 3
Views: 244

### K limiting rate

How does K limit the rate of a reaction?
Sun Mar 04, 2018 9:15 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Little Product
Replies: 4
Views: 311

### Little Product

I was looking through my notes and in one of the lecture slides, it says that it is easier to study initial rate when very little product is present. Why is this the case?
Sun Mar 04, 2018 9:11 pm
Forum: Zero Order Reactions
Topic: Determining Reactions
Replies: 2
Views: 190

### Determining Reactions

How do we determine if something is zero-, first-, or second- order reaction?
Sun Feb 25, 2018 6:06 pm
Forum: Zero Order Reactions
Topic: Relation to Reaction Stoichiometry?
Replies: 2
Views: 202

### Relation to Reaction Stoichiometry?

Is order related to the reaction stoichiometry? Why or why not??
Sun Feb 25, 2018 6:04 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Positive Slope???
Replies: 4
Views: 302

### Positive Slope???

Is it true that the slope of a tangent line for products is always positive? If so, why?
Sun Feb 25, 2018 6:01 pm
Forum: General Rate Laws
Topic: Negative Sign [ENDORSED]
Replies: 7
Views: 408

### Negative Sign[ENDORSED]

What is the significance of the negative sign in the equation -1/a delta[A]/delta t?
Mon Feb 19, 2018 11:08 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Pt
Replies: 1
Views: 109

### Pt

When do we put a Pt on the cell diagram?
Sun Feb 18, 2018 7:33 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst Equation
Replies: 4
Views: 355

### Nernst Equation

What does the Nernst equation exactly tell us?
Sun Feb 18, 2018 7:31 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concentration
Replies: 3
Views: 288

### Concentration

How does concentration affect cell potential?
Wed Feb 14, 2018 1:00 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Celsius to Kelvin Clarification
Replies: 3
Views: 348

### Celsius to Kelvin Clarification

Hi! This is kind of random, but when we're converting from Celsius to Kelvin, does Lavelle want us to add 273.15 or just 273???
Sun Feb 11, 2018 5:38 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Review Session Concept Clarification
Replies: 1
Views: 124

### Review Session Concept Clarification

There's this T/F statement in the practice MT. It is question 1E. Why is the statement "removing heat from a system is exothermic, so temperature must decrease" false? I remember someone said to refer to the graph during the review session, but I don't quite understand the concept behind it.
Sun Feb 11, 2018 5:34 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Vibrational Energy State
Replies: 4
Views: 256

### Vibrational Energy State

I get that heavy molecules have higher "vibrational energy state." What exactly is vibrational energy state and how does it contribute to the molecule's entropy?
Sun Feb 11, 2018 5:32 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: entropy of vaporization
Replies: 1
Views: 151

### entropy of vaporization

Why is it possible to calculate the entropy of vaporization for water at room temperature? It is in the review session practice test (question 3c). The statement was "One cannot calculate the entropy of vaporization for water at room temperature because water has a boiling point of 373 K" ...
Sun Feb 04, 2018 5:34 pm
Forum: Van't Hoff Equation
Topic: Van't Hoff Eq.
Replies: 2
Views: 164

### Van't Hoff Eq.

What does the Van't Hoff Equation exactly tell us? What do we use it for?
Sun Feb 04, 2018 5:29 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Delta U (Concept Clarification)
Replies: 6
Views: 293

### Delta U (Concept Clarification)

Why does gas expand if delta U is zero? I quite don't understand the concept behind this statement.
Sun Feb 04, 2018 5:26 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Replies: 3
Views: 182

Why do all real processes have to be irreversible?
Sun Jan 28, 2018 5:09 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Boltzmann Equation Clarification
Replies: 3
Views: 165

### Boltzmann Equation Clarification

What does the Boltzmann Equation exactly tell us? What do we use it for?
Sun Jan 28, 2018 5:04 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: Gas atoms
Replies: 4
Views: 262

### Gas atoms

Can someone explain why gas atoms will never spontaneously go back to smaller volume? I sort of do not understand the concept behind this statement.
Mon Jan 22, 2018 5:59 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 8.61 Question
Replies: 2
Views: 86

### 8.61 Question

So the question was:

And here is the solution from the manual:

Can someone explain why we have to reverse the second equation? Shouldn't H2(g) be on the reactant side?
Fri Jan 19, 2018 3:59 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Concept Clarification
Replies: 3
Views: 171

### Concept Clarification

How does adding or removing an amount of a substance in an open system affect the energy of that system?
Fri Jan 19, 2018 3:55 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Done By The System vs. Done On the System
Replies: 3
Views: 158

### Done By The System vs. Done On the System

What do we need to keep in mind in regards to determining whether work is done by or on the system?
Fri Jan 19, 2018 3:50 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Difference between Closed and Isolated
Replies: 10
Views: 1253

### Re: Difference between Closed and Isolated

A closed system can exchange energy with the surroundings, but it cannot exchange matter.
An isolated system can neither exchange energy nor matter with the surroundings.
Sun Jan 14, 2018 2:54 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Calorimeter
Replies: 10
Views: 663

### Re: Calorimeter

We use a calorimeter to measure the amount of heat energy, which I think we can then use to calculate the specific heat of a substance.
Sun Jan 14, 2018 2:41 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Systems
Replies: 7
Views: 496

### Re: Systems

Boiling a soup in an open saucepan is an example of an open system because both matter and energy are being exchange with the surroundings. If you put a lid on the saucepan, it becomes a closed system because while the energy is being exchanged, it has a fixed amount of matter.
Sun Jan 14, 2018 2:33 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Closed vs. Isolated
Replies: 4
Views: 301

### Closed vs. Isolated

It is sometimes confusing to determine whether a system is a closed or isolated. How do we differentiate the two? I get that in a closed sytem, a matter cannot enter or leave it, but how do we know that if a system is not necessarily isolated?
Sat Dec 09, 2017 4:03 pm
Forum: Amphoteric Compounds
Topic: D-Blocks
Replies: 1
Views: 304

### D-Blocks

The textbook says that,

Metals form basic oxides, nonmetals form acidic oxides; the elements on a diagonal line from beryllium toward polonium and several d-block metals form amphoteric oxides.

How do we know if a d-block metal truly forms amphoteric oxides?
Sat Dec 09, 2017 3:58 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: SigFigs
Replies: 1
Views: 148

### SigFigs

What are the rules for determining the significant figures in pH or pOH? It is mentioned last night during the review session that only decimals in pH/pOH count for significant figures. Is this correct?
Sun Dec 03, 2017 5:16 pm
Forum: Lewis Acids & Bases
Topic: Distinguishing Lewis Acid
Replies: 2
Views: 189

### Distinguishing Lewis Acid

How do you distinguish a Lewis acid from a Bronsted acid?
Sun Dec 03, 2017 5:15 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Concept Q// Change in Temp
Replies: 3
Views: 231

### Concept Q// Change in Temp

How does heating favor the formation of reactants when the reaction is exothermic while forming product?
Sun Nov 26, 2017 6:33 pm
Forum: Dipole Moments
Topic: Polarity based on number of lone pairs
Replies: 2
Views: 234

### Polarity based on number of lone pairs

Why is a molecule polar when the central atom has one lone pair of electrons? Can we determine the polarity of a molecule just by looking at the number of lone pairs?
Sun Nov 26, 2017 6:29 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angle
Replies: 2
Views: 160

### Bond Angle

When we are asked to find the expected bond angle, do we have to be very specific or can we just give an estimate? For example, on problem 4.21 (d), N2H4 is trigonal pyrmidal and so the bond angle is 107° according to the answer key. If we say that the bond angle is slightly less than 109.5°, would ...
Sun Nov 19, 2017 7:19 pm
Forum: Biological Examples
Topic: TM Concept Clarification
Replies: 2
Views: 237

### TM Concept Clarification

How do transition metals bound to cage-like molecule?
Sun Nov 19, 2017 7:08 pm
Forum: Hybridization
Topic: Pi Bonds
Replies: 2
Views: 248

### Pi Bonds

Why can't pi bonds allow bond atoms to rotate?
Sun Nov 12, 2017 4:56 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Trigonal Bipyramidal
Replies: 2
Views: 168

### Trigonal Bipyramidal

Do the elements that are not the central atom in a trigonal bipyramidal molecule always have to be the same? If not, what are some examples of molecules that are trigonal bipyramidal where the non-central atoms are different from one another?
Sun Nov 12, 2017 4:49 pm
Forum: Dipole Moments
Topic: Dipole // Molecular Shape and Bond Polarity
Replies: 2
Views: 200

### Dipole // Molecular Shape and Bond Polarity

How do dipole moments depend on molecular shape and bond polarity?
Sat Nov 04, 2017 10:10 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Replies: 2
Views: 240

There's this one question on Test #3 where it asked about the uncertainty in velocity and the given info was the radius of the atom? When solving a Heisenberg problem, does the position have to be the diameter of the atom?
Tue Oct 31, 2017 9:34 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Sample Problem (Example 1.7// Textbook)
Replies: 2
Views: 219

### Sample Problem (Example 1.7// Textbook)

Hi! So I was looking at the sample problem from the book and the problem is: Estimate the minimum uncertainty in the position of a marble mass 1.0 g given that its speed is known to within plus/minus 1.0 mms^-1. On the "solve" part of the problem, it says to first convert mass and speed in...
Sat Oct 28, 2017 10:45 pm
Forum: Lewis Structures
Topic: Central Atom [ENDORSED]
Replies: 3
Views: 209

### Central Atom[ENDORSED]

How do we know which atom would be the central atom in a polyatomic molecule?
Sat Oct 28, 2017 10:29 pm
Forum: Resonance Structures
Topic: Resonance vs. Isomers [ENDORSED]
Replies: 3
Views: 558

### Resonance vs. Isomers[ENDORSED]

What is the difference between resonance structures and isomers?
Sun Oct 22, 2017 6:42 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg Concept Question
Replies: 2
Views: 235

### Heisenberg Concept Question

How and why does light affect an electron's momentum and position?
Sun Oct 22, 2017 6:38 pm
Forum: DeBroglie Equation
Topic: Concept Question [ENDORSED]
Replies: 2
Views: 234

### Concept Question[ENDORSED]

What does DeBroglie equation suggest? Does it just basically suggest that any particle with momentum has wavelike properties with wavelength?
Sat Oct 14, 2017 11:36 pm
Forum: Properties of Light
Topic: Concept // Wave-like Behavior [ENDORSED]
Replies: 4
Views: 293

### Concept // Wave-like Behavior[ENDORSED]

Aside from diffraction, what is another evidence that shows that electromagnetic radiation behaves like waves?
Sat Oct 14, 2017 11:27 pm
Forum: Properties of Light
Topic: Equation/Formula Clarification
Replies: 4
Views: 376

### Equation/Formula Clarification

For what type of problems should I use each formula?
c = λ ν
E = h ν
Ek= 1/2 mev^2
Ek=hv- phi
Wed Oct 04, 2017 10:56 pm
Forum: Balancing Chemical Reactions
Topic: H7 // Book Problem Clarification
Replies: 4
Views: 372

### H7 // Book Problem Clarification

When a problem says that Molecule A reacts with Element B in the presence of C, we don't have to write/include C in the equation right? For instance, in problem H7, the problem is: Write a balanced equation for [...] the reaction of ammonia gas with oxygen gas at high temperatures in the presence of...
Wed Oct 04, 2017 10:31 pm
Forum: Balancing Chemical Reactions
Topic: H1 // Book Problem [ENDORSED]
Replies: 7
Views: 532

### H1 // Book Problem[ENDORSED]

There's this one textbook question that goes: It appears that balancing the chemical equation Cu + SO2 ---> CuO + S would be simple if we could just add another O atom to the product side: Cu+ SO2 ---> CuO+S+O. (a) Why is that balancing procedure not allowed? Is this not allowed because by doing so,...