Search found 50 matches
- Mon Mar 19, 2018 1:21 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: heat capacity
- Replies: 1
- Views: 539
heat capacity
Are there any monatomic ideal gases that don't use the heat capacity constants 5/2R and 3/2R for constant pressure and constant volume
- Mon Mar 19, 2018 1:12 am
- Forum: Balancing Redox Reactions
- Topic: periodic trends
- Replies: 3
- Views: 658
periodic trends
what are the trends for reducing and oxidizing power on the periodic table
- Mon Mar 19, 2018 1:12 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: kinetic data
- Replies: 2
- Views: 483
kinetic data
how do you use kinetic data to distinguish between different reaction mechanisms?
- Mon Mar 19, 2018 1:08 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: equation involving enthalpy and entropy
- Replies: 1
- Views: 669
equation involving enthalpy and entropy
are there any types of molecules in a chemical equation that you would exclude when calculating reaction enthalpy or entropy?
- Mon Mar 19, 2018 1:06 am
- Forum: Calculating Work of Expansion
- Topic: reversible and irreversible expansion
- Replies: 3
- Views: 867
reversible and irreversible expansion
if a problem doesn't make it clear if reversible or irreversible expansion is occurring, how do you know which equation to use for work?
- Sun Mar 11, 2018 1:49 am
- Forum: General Rate Laws
- Topic: graphs
- Replies: 8
- Views: 981
graphs
besides knowing what the parts of the derived equations stand for like the slope and such, do we need to know how to draw the graphs for zero order, first order, and second order reactions?
- Sun Mar 11, 2018 1:47 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: units
- Replies: 4
- Views: 762
units
on the final, will we only need to know units in mol, L, and s or will Kpa show up because it was in the textbook
- Sun Mar 11, 2018 12:42 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: terms
- Replies: 1
- Views: 331
terms
what do the terms labile, nonlabile, and inert mean and how are they significant to calculating gibbs free energy
- Sun Mar 11, 2018 12:40 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: concept question
- Replies: 2
- Views: 524
concept question
why does gibbs free energy decreases more sharply with temperature for the gas phase of a substance than for the liquid phase?
- Sun Mar 11, 2018 12:20 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: residual entropy
- Replies: 2
- Views: 694
residual entropy
what's residual entropy and do we need to know and understand the concept for the final?
- Sun Mar 11, 2018 12:18 am
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: entropy of vaporization
- Replies: 1
- Views: 514
entropy of vaporization
To find the entropy of vaporization, why do we have to separate it into 3 steps as in heat the liquid to its boiling point, allow it to vaporize, then cool the vapor?
- Sun Mar 11, 2018 12:16 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: change in entropy
- Replies: 1
- Views: 336
change in entropy
when calculating a change in entropy, does it matter if it is through a reversible or irreversible path?
- Sat Mar 10, 2018 11:52 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: enthalpy of sublimation
- Replies: 5
- Views: 967
enthalpy of sublimation
Do we need to know the enthalpy of sublimation for the final?
- Sat Mar 10, 2018 11:46 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: change in internal energy
- Replies: 3
- Views: 700
change in internal energy
for examples involving calculating energy changes when heating an ideal gas, why do you have to separate the problem into two steps, step 1 being heating at constant volume to the final temperature, and step 2 being allowing the gas to expand isothermally?
- Sat Mar 10, 2018 11:25 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: molar heat capacity
- Replies: 1
- Views: 315
molar heat capacity
why is the molar heat capacity of an ideal gas at constant pressure greater than that at constant volume?
- Sat Mar 10, 2018 11:16 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: equipartition theorem
- Replies: 1
- Views: 334
equipartition theorem
Do we need to know anything about the equipartition theorem?
- Sat Mar 10, 2018 11:14 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: state functions
- Replies: 4
- Views: 929
state functions
why are heat and work not state functions?
- Sat Mar 10, 2018 11:12 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: calorimeter examples
- Replies: 1
- Views: 278
calorimeter examples
can someone provide some examples where we would have to relate the heat lost or gained by a reaction to the heat gained or lost by the calorimeter? or example for when we would use the q=-qcal equation
- Sat Mar 10, 2018 10:56 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: heat capacity [ENDORSED]
- Replies: 1
- Views: 262
heat capacity [ENDORSED]
how is heat capacity an extensive property and what are some other examples of extensive properties in thermodynamics?
- Sat Mar 10, 2018 10:52 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: adiabatic and diathermic
- Replies: 1
- Views: 317
adiabatic and diathermic
how are adiabatic and diathermic walls significant to the measurement of heat and what is the difference between the two?
- Sat Mar 10, 2018 10:36 pm
- Forum: Calculating Work of Expansion
- Topic: internal energy [ENDORSED]
- Replies: 1
- Views: 266
internal energy [ENDORSED]
In what cases does the internal energy remain constant between the initial and final state and in what cases is the internal energy at 0?
- Sat Mar 10, 2018 10:30 pm
- Forum: Calculating Work of Expansion
- Topic: reversible expansion [ENDORSED]
- Replies: 1
- Views: 298
reversible expansion [ENDORSED]
why can a system do more work in a reversible expansion versus irreversible expansion?
- Sat Mar 10, 2018 10:18 pm
- Forum: Calculating Work of Expansion
- Topic: different types of work
- Replies: 4
- Views: 467
different types of work
Do we have to know the different types of work on the final like extension, raising a weight, and surface expansion?
- Sat Mar 10, 2018 9:50 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: types of systems
- Replies: 3
- Views: 733
types of systems
What are some of the most commonly referenced examples of open, closed, and isolated systems?
- Sun Feb 11, 2018 11:31 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: cis vs trans [ENDORSED]
- Replies: 4
- Views: 2657
cis vs trans [ENDORSED]
can someone provide an example of how cis and trans orientations are involved in entropy?
- Sun Feb 11, 2018 11:28 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: troutons rule
- Replies: 3
- Views: 573
troutons rule
Do we need to know troutons rule at all?
- Sun Feb 11, 2018 11:17 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Second Law
- Replies: 2
- Views: 339
Re: Second Law
the equation wasn't specifically used in many examples as only example 9.3 used the equation directly, but the equation is derived to attain the equations for entropy change when there's a change in temperature with constant volume or pressure, and for entropy change of an ideal gas when it expands ...
- Tue Jan 30, 2018 5:42 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: heat capacities
- Replies: 5
- Views: 733
heat capacities
in problems where you need to find the final temperature using the equation, heat lost by ice=- heat gained by water
how do you know whether to use the heat capacity of the ice or the water in the equation?
how do you know whether to use the heat capacity of the ice or the water in the equation?
- Tue Jan 30, 2018 5:39 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: bond enthalpies
- Replies: 3
- Views: 419
bond enthalpies
Can someone provide an example of how to estimate the enthalpy of a reaction using mean bond enthalpies and explain the difference between this calculation and when given the bond enthalpies of the products, but not the reactants?
- Tue Jan 30, 2018 5:34 pm
- Forum: Phase Changes & Related Calculations
- Topic: hw problem #109
- Replies: 1
- Views: 234
hw problem #109
I don't understand the concept of how density is involved in solving for heat and why are the dimensions multiplied by the density?
Also, how do you find the mass of water?
Also, how do you find the mass of water?
- Sun Dec 10, 2017 4:01 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: example problem for Ka and Kb [ENDORSED]
- Replies: 1
- Views: 425
example problem for Ka and Kb [ENDORSED]
If you're given the value for pKa, but the compound you're given is a base, then how do you find Kb?
- Sun Dec 10, 2017 3:57 pm
- Forum: Amphoteric Compounds
- Topic: amphiprotic vs. amphoteric [ENDORSED]
- Replies: 2
- Views: 829
amphiprotic vs. amphoteric [ENDORSED]
according to the textbook definition, amphiprotic specifically pertains to water molecules, but I noticed In the homework problems that amphiprotic referred to other compounds as well acting as both proton donors and acceptors; What's the main difference between amphiprotic and amphoteric and is amp...
- Sat Dec 02, 2017 3:06 pm
- Forum: Naming
- Topic: naming compounds [ENDORSED]
- Replies: 3
- Views: 537
naming compounds [ENDORSED]
Which part of the compound when naming it is the lewis acid? Is it the central metal atom? Also, when naming compounds with polydentates, do we have to know more than what is listed in table 17.4 like other than en, dien, and edta?
- Sat Dec 02, 2017 3:01 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: coordination number/polydentates [ENDORSED]
- Replies: 1
- Views: 324
coordination number/polydentates [ENDORSED]
How do polydentates factor into figuring out the coordination number of a compound? Can someone provide an example of that? Also for identifying polydentates, do we only need to memorize table 17.4 for the final or should we know more than the ones listed in the table?
- Tue Nov 28, 2017 6:07 pm
- Forum: Hybridization
- Topic: Ch 4 Question 75
- Replies: 3
- Views: 489
Re: Ch 4 Question 75
to determine the polarity of a molecule, you must first draw the lewis structure of the molecule and in this case, carbon and oxygen are the two central atoms. Carbon has 3 hydrogens and an oxygen attached to it while oxygen has 1 hydrogen and 1 carbon atom attached to it. The oxygen atom has 2 lone...
- Tue Nov 28, 2017 5:53 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: chapter 4
- Replies: 1
- Views: 269
Re: chapter 4
According to the valence-bond theory, bonds form when unpaired electrons in valence-shell atomic orbitals pair; the atomic orbitals overlap end to end to form sigma bonds or side by side to form pi bonds between atoms in a molecule. In addition, for the structure of a molecule, hybrid orbitals are c...
- Thu Nov 16, 2017 2:50 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pairs
- Replies: 5
- Views: 680
Re: Lone Pairs
The first step to determining and drawing molecular shape is drawing the lowest energy lewis structure of the molecule to determine where the lone pairs go. Then you would go on to determine the shape of the molecule, the bond angles, and hybridization.
- Thu Nov 16, 2017 2:45 pm
- Forum: Hybridization
- Topic: 2 regions of electron density
- Replies: 4
- Views: 611
2 regions of electron density
Why can't molecules with two regions of electron density have a bent shape?
- Thu Nov 16, 2017 2:39 pm
- Forum: Hybridization
- Topic: Difference between sigma and pi bonds?
- Replies: 6
- Views: 2325
Re: Difference between sigma and pi bonds?
sigma and pi bonds are associated with the electron density and how the electrons interact with each other. A sigma bond is formed by the pairing of electron spins in two atomic orbitals on neighboring atoms. sigma bonds are cylindrically symmetrical and they contribute towards an overlap or merging...
- Thu Nov 16, 2017 2:17 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar or Non-polar
- Replies: 3
- Views: 5453
Re: Polar or Non-polar
CCl2 would be predicted to be a linear (bond angle 180º) molecule, and because the two chlorine atoms attached are both of the same electronegativity, the resulting net dipole would be zero because the Cl electronegativity vectors cancel each other out.
- Sun Nov 12, 2017 3:27 pm
- Forum: Lewis Structures
- Topic: atomic structure of HOCO
- Replies: 8
- Views: 1216
atomic structure of HOCO
Why is the hydrogen not attached to the carbon in HOCO? Usually when bonded to hydrogens and oxygens, carbon is the main central atom, so I was confused why the correct structure has the hydrogen attached to the oxygen atom and not the carbon atom?
- Sun Nov 12, 2017 3:21 pm
- Forum: Lewis Structures
- Topic: Midterm Question CH3SH
- Replies: 5
- Views: 1065
Re: Midterm Question CH3SH
the reasoning behind it is because carbon is slightly less electronegative than sulfur; thus, carbon would be the main central atom with 3 hydrogens surrounding it as carbon atoms are larger than hydrogens which will most likely never be the central atom as they are small, highly electronegative ato...
- Sun Nov 12, 2017 3:01 pm
- Forum: Lewis Structures
- Topic: 3.67 a.
- Replies: 2
- Views: 340
Re: 3.67 a.
The radical goes on the chlorine atom because it is less electronegative than oxygen so the unpaired electron will be attached to the chlorine atom and because most of the time, you have to satisfy the octet rule for Oxygen first due to its high electronegativity.
- Sun Nov 12, 2017 2:48 pm
- Forum: Lewis Structures
- Topic: Expanded Valence Shell
- Replies: 2
- Views: 298
Re: Expanded Valence Shell
the larger the central atom, the larger the number of electrons that can surround it and expanded valence shells occur most commonly when the central atom is bonded to small electronegative atoms like F, Cl, and O. The greatest I can think of is iodine heptafluoride which has 7 bonds, but expanded v...
- Sat Oct 28, 2017 3:03 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Determining valence electrons for d-block elements [ENDORSED]
- Replies: 3
- Views: 13236
Re: Determining valence electrons for d-block elements [ENDORSED]
the number of valence electrons in d-block elements is most often equal to their group number which is equal to the number of electrons in the "valence shell." for example, scandium metal's electrons per shell are 2,8,9,2 and its outer shell has only 2 electrons, so the valence electron co...
- Sat Oct 28, 2017 2:40 pm
- Forum: *Particle in a Box
- Topic: particle in a box example
- Replies: 1
- Views: 698
particle in a box example
Can someone help me how to solve an example like this where you're given the info to treat a hydrogen atom as a one-dimensional box of length 120. pm containing an electron and predict the wavelength of the radiation emitted when the electron falls to the lowest energy level from the next higher ene...
- Sun Oct 22, 2017 5:38 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: heisenberg post-module question 21
- Replies: 1
- Views: 280
heisenberg post-module question 21
The electron is not confined to the nucleus and we now know that the size of an atom is determined by its electrons outside of the nucleus. For hydrogen its measured atomic diameter is 145,000 times its nuclear diameter of 1.7 x 10-15 m. In other words make the (correct) assumption that the electron...
- Sun Oct 22, 2017 5:07 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: post-module question #22
- Replies: 2
- Views: 278
post-module question #22
Use the above uncertainty in velocity (correct model) to calculate the electron's uncertainty in kinetic energy. Then calculate the uncertainty in kinetic energy per mole of electrons (that is, per mole of hydrogen atoms). Comment on your value. I don't understand how to calculate the uncertainty in...
- Thu Oct 12, 2017 4:41 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric effect example problem [ENDORSED]
- Replies: 2
- Views: 595
Photoelectric effect example problem [ENDORSED]
How do you solve a problem where the given information includes that an electron is ejected from a metal due to the photoelectric effect with a velocity in km per second and the work function is given, but you're supposed to calculate the wavelength of the photon absorbed.
- Thu Oct 12, 2017 4:31 pm
- Forum: Properties of Electrons
- Topic: Wave Properties of Electrons
- Replies: 3
- Views: 609
Re: Wave Properties of Electrons
The wave properties of electrons were discovered through the results of the photoelectric effect and diffraction experiments. Not only did they discover the wave-like properties of electrons, but they also discovered that electromagnetic radiation is particlelike and wavelike. This led towards the a...