Search found 60 matches
- Sat Mar 09, 2019 10:47 pm
- Forum: First Order Reactions
- Topic: Pseudo-first order?
- Replies: 1
- Views: 253
Re: Pseudo-first order?
The pseudo first order can be used when there are multiple reactants in a reaction
- Sat Mar 09, 2019 10:46 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: reactions with multiple reactants
- Replies: 1
- Views: 225
Re: reactions with multiple reactants
When mixing the reactants, just put one in large excess so that when it reacts the amount that reacts would not have an impact on the concentration and so the order of a certain reactant can be determined. For example, if one reactant had a concentration of 1.9 x 10 ^-5 M and another had a concentra...
- Sat Mar 09, 2019 10:40 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Initial Concentration and Equilibrium Concentration
- Replies: 3
- Views: 635
Re: Initial Concentration and Equilibrium Concentration
I think it just means that if you have more reactant initially then compared to how much product would be formed if you had less reactant there would be more. Like if you had 2 moles of reactant and it made 3 moles of product, if you had 4 moles of reactant then it would make 6 moles of product.
- Sun Mar 03, 2019 1:52 pm
- Forum: Second Order Reactions
- Topic: Reaction orders
- Replies: 3
- Views: 462
Re: Reaction orders
A first order reaction means that when the reactant increases the product increases by the same factor and a second order means that, depending on the way in which it is a second order reaction, an increase in the reactant means an increase in the rate by the factor squared or an increase in the two...
- Sun Mar 03, 2019 1:49 pm
- Forum: General Rate Laws
- Topic: Unique vs instantaneous rate
- Replies: 6
- Views: 633
Re: Unique vs instantaneous rate
When calculating the instantaneous rates you are finding it for a specific species and the unique rate takes into account the stoichiometric coefficient of the equation and so it makes all the unique rates for each species that same
- Sun Mar 03, 2019 1:38 pm
- Forum: General Rate Laws
- Topic: rate Determing Steps
- Replies: 1
- Views: 228
Re: rate Determing Steps
The rate determining step is just the slowest step of the reaction and is the only one (or ones if there are multiple) that will effect the rate of the reaction and so performing an experiment where you change the concentrations of different reactants and see the impact on the rate can help you dete...
- Mon Feb 25, 2019 3:35 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: E vs E knot [ENDORSED]
- Replies: 1
- Views: 270
Re: E vs E knot [ENDORSED]
The difference between E and E knot is that E knot is when the cell is under standard conditions and E is for the cell under any conditions
- Mon Feb 25, 2019 3:34 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing half reactions [ENDORSED]
- Replies: 1
- Views: 232
Re: Balancing half reactions [ENDORSED]
You take the parts of the chemical reaction that are involved in the oxidation reaction and the parts that are involved in the reduction reaction and make two half reactions and the point is to make sure that there is an equivalent number of electrons on each side that will cancel
- Mon Feb 25, 2019 3:32 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst equation [ENDORSED]
- Replies: 2
- Views: 472
Re: Nernst equation [ENDORSED]
It helps you find the cell potential when the cell is not under standard conditions, like when the cell is not at 1M
- Mon Feb 18, 2019 12:21 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Negative Temperature
- Replies: 5
- Views: 526
Re: Negative Temperature
since the temperature is in kelvin and there is no such thing as negative kelvin whether or not the second value is positive or negative is dependent upon the entropy of the system
- Mon Feb 18, 2019 12:18 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Midterm Grades
- Replies: 35
- Views: 2798
Re: Midterm Grades
If it is anything like the way grading was done last quarter then it should be after lecture on Wednesday, but it may be different because of the holiday weekend.
- Mon Feb 18, 2019 12:16 pm
- Forum: Van't Hoff Equation
- Topic: Temperature Dependence of K
- Replies: 5
- Views: 579
Re: Temperature Dependence of K
Yes, the equation is just demonstrating the concept that we previously learned that K changes depending on the temperature at which the reaction is taking place
- Tue Feb 12, 2019 9:18 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: free expansion
- Replies: 2
- Views: 313
Re: free expansion
free expansion means that it is expanding into a vacuum and so there is no work being done because it does not have to push against any pressure from the outside.
- Tue Feb 12, 2019 9:17 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: expansion of ideal gas
- Replies: 1
- Views: 163
Re: expansion of ideal gas
if an ideal gas is expanding isothermally that means that it is happening at a constant temperature and this can happen because as the system is expanding and the volume is increasing and the work is being done, the temperature is being kept constant by heat that is flowing into the system to mainta...
- Tue Feb 12, 2019 9:14 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Extensive vs Intensive
- Replies: 5
- Views: 571
Re: Extensive vs Intensive
an intensive property is something that is true no matter how much mass there is of a substance while an extensive property depends on how much product is present
- Sun Feb 03, 2019 10:31 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Reversible v irreversible
- Replies: 4
- Views: 367
Re: Reversible v irreversible
Free Expansion means that there is unrestrained expansion, like in an open system where the gas will continue to expand because there is nothing that is stopping it from doing so
- Sun Feb 03, 2019 10:28 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Negative or Positive Work
- Replies: 3
- Views: 367
Re: Negative or Positive Work
If the system does work then the work is positive, if work is done on the system then the work is negative
- Sun Feb 03, 2019 10:26 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: kJ vs J
- Replies: 9
- Views: 833
Re: kJ vs J
It should not matter because KJ is just 1000 J, as long as you are using the proper units so that everything will cancel properly you should be good.
- Sun Jan 27, 2019 5:12 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: death in biological systems
- Replies: 5
- Views: 489
Re: death in biological systems
It might be referring to that time in lecture when he talked about the ATP concentration in healthy muscle tissue and dead muscle tissue and we were supposed to find the expected equilibrium concentrations for ADP and Pi in the dead tissue
- Sun Jan 27, 2019 5:09 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: ICE
- Replies: 19
- Views: 1507
Re: ICE
equilibrium concentration
- Sun Jan 27, 2019 5:09 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Inert Gas
- Replies: 6
- Views: 601
Re: Inert Gas
An inert gas will not affect the equilibrium because it is not a part of the reaction and will not change the pressures of the gases in the reaction
- Mon Jan 21, 2019 7:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 7th edition 6D.15(b)
- Replies: 1
- Views: 182
Re: 7th edition 6D.15(b)
The compound will dissolve in the solution and the Al will combine with water to form Al(H2O)6 ^+3 and its conjugate base would be Al(H2O)5OH^+2
- Mon Jan 21, 2019 7:18 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Percent Protonation
- Replies: 6
- Views: 545
Re: Percent Protonation
it is the concentration of the conjugate acid over the concentration of the initial base multiplied by 100
- Mon Jan 21, 2019 7:16 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Salt Solution
- Replies: 5
- Views: 682
Re: Salt Solution
Yes, these ions are spectator ions and will not change the pH because they are stable as ions and do not donate or pull protons to or from the solution
- Mon Jan 14, 2019 9:58 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Autoprotolysis
- Replies: 3
- Views: 322
Re: Autoprotolysis
As long as a molecule has a proton to donate and lone pairs to accept a donated proton then it should be able to go through an autoprotolysis reaction
- Mon Jan 14, 2019 9:56 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: the value of equilibrium constant
- Replies: 3
- Views: 349
Re: the value of equilibrium constant
No, the values are different because there are two different units or properties of the gases being measured in each case and so they will give different values. There is a formula to convert between the two though
- Mon Jan 14, 2019 9:53 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Are Either Products or Reactants Favored?
- Replies: 3
- Views: 168
Re: Are Either Products or Reactants Favored?
The only time when neither direction is favored is when K is equal to one, any other time one direction is favored it is just not considered to be strongly favored unless K>10^3 or K<10^-3
- Wed Jan 09, 2019 11:47 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K and Kc
- Replies: 8
- Views: 588
Re: K and Kc
I think that when just K is listed it usually is referring to Kp because the pressures give a more accurate value than the concentrations
- Wed Jan 09, 2019 11:38 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Problem #1 5J 7th Edition
- Replies: 1
- Views: 154
Re: Problem #1 5J 7th Edition
Le Chatelier's Principle states that when a system is stressed it will try to correct that stress, basically when you change the concentrations or the partial pressures of the system you are changing the value of Q, but the value of K remains constant and so the system will either proceed towards th...
- Wed Jan 09, 2019 11:33 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Catalysts
- Replies: 3
- Views: 291
Re: Catalysts
Catalysts increase the speed of a reaction by lowering the activation energy of the reaction, they would have no effect on the equilibrium constant or stress the system they would just make the system approach equilibrium at a quicker speed
- Sun Dec 02, 2018 12:02 pm
- Forum: Sigma & Pi Bonds
- Topic: Rotating Bond?
- Replies: 4
- Views: 706
Re: Rotating Bond?
pi bonds can't rotate because they are overlapping side to side and not head to head like a sigma bond.
- Sun Dec 02, 2018 11:57 am
- Forum: Lewis Acids & Bases
- Topic: Bronsted vs. Lewis
- Replies: 3
- Views: 365
Re: Bronsted vs. Lewis
A Bronsted base is just a proton acceptor and a bronsted acid is a proton donor. A Lewis base is an electron pair acceptor and a Lewis base is an electron pair donor. In almost all cases the molecule that is the bronsted base will also contain the molecule that is a lewis base and same for acids. Ex...
- Sun Dec 02, 2018 11:51 am
- Forum: Naming
- Topic: If a ligand has a name with...
- Replies: 5
- Views: 528
Re: If a ligand has a name with...
for example the ligand NH2CH2CH2NHCH2CH2NH2 is called diethylenetriamine and if there were two of them located in a cordination compound then it would be bisdiethylenetiramine in the naming
- Sun Nov 25, 2018 11:01 am
- Forum: Sigma & Pi Bonds
- Topic: Location of Sigma and Pi Bonds
- Replies: 5
- Views: 423
Re: Location of Sigma and Pi Bonds
A sigma bond is always the first bond that two atoms will make and they are overlapping head to head. All of the following bonds that will be made between the same two atoms are pi bonds that overlap side to side.
- Sun Nov 25, 2018 10:59 am
- Forum: Lewis Structures
- Topic: Exceptions to the Octet Rule
- Replies: 5
- Views: 541
Re: Exceptions to the Octet Rule
Period 3 elements can be an exception to the octet rule because they are able to use their d orbital for bonding. H, He, Li, Be, and B are also exceptions because they are more likely to lose their electrons than to accept more.
- Sun Nov 25, 2018 10:57 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Naming
- Replies: 4
- Views: 265
Re: Naming
If the question asks for the shape of electron arrangement, then you would consider all electron densities including the lone pairs. If he question asks for the molecular shape, then you would only consider the bonded atoms.
- Sat Nov 17, 2018 5:05 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 4.17d
- Replies: 2
- Views: 476
Re: 4.17d
The electron arrangement around the atom is a tetrahedral, but the molecule shape is a trigonal pyramidal. The lone pair takes up more space than a bonded pair of electrons because it is attached to only one atom instead of two. The lone pair forces the other atoms closer to each other which is why ...
- Sat Nov 17, 2018 5:03 pm
- Forum: Dipole Moments
- Topic: sigma, pi bonds rotation
- Replies: 2
- Views: 140
Re: sigma, pi bonds rotation
A pi bond influences rotation because it makes it so the molecule is unable to rotate since there is electron density on both sides of the internuclear axis. If the molecule would try to rotate around the bond it would break the bond.
- Sat Nov 17, 2018 4:56 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Triple Bonds
- Replies: 2
- Views: 214
Re: Triple Bonds
A sigma bond is an end to end overlap and so once a sigma bond is formed the molecule is unable to make a second sigma bond because there is no way to orient the molecule that would allow for another end to end overlap. Therefore the second and third bond that are made in a triple bond have to be si...
- Sat Nov 10, 2018 3:58 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Hydrogen Bonds
- Replies: 14
- Views: 1049
Re: Hydrogen Bonds
Hydrogen bonds only occur if the hydrogen atom is bound to N, O, or F and the partial positive charge created on the hydrogen atom is attracted to the partial negative charge on the N, O, or F atom.
- Sat Nov 10, 2018 3:54 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Strengths of Repulsion
- Replies: 2
- Views: 268
Re: Strengths of Repulsion
They are held tighter when they are in a bond because they are between two atoms, when they are lone pairs they are only attached to one atom and can spread out more
- Sat Nov 10, 2018 3:53 pm
- Forum: Dipole Moments
- Topic: Dipole-Induced Dipole
- Replies: 3
- Views: 318
Re: Dipole-Induced Dipole
A dipole is a molecule with a partially negative charge on one part of the molecule and a partially positive charge on another part of the molecule. This is always present in polar molecules, but in nonpolar molecules an induced dipole can be created. An induced dipole occurs when the electron densi...
- Sun Nov 04, 2018 6:09 pm
- Forum: Electronegativity
- Topic: Electronegativity
- Replies: 4
- Views: 446
Re: Electronegativity
yes, both decrease down a group and increase moving to the right in a period.
- Sun Nov 04, 2018 6:03 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Post Module #41
- Replies: 1
- Views: 519
Re: Post Module #41
I believe that the correct answer would be B A is wrong because the difference between energy levels as the energy levels increases is smaller, so for this problem going from n=5 to n=3 the electron would go from n=5 to n=4 and from n=4 to n=3 and for going from n=4 to n=2 the electron would go from...
- Sun Nov 04, 2018 5:46 pm
- Forum: Lewis Structures
- Topic: OCl2 Structure
- Replies: 1
- Views: 1024
Re: OCl2 Structure
Oxygen is more electronegative than chlorine (oxygen is 3.5 and chlorine is 3.0) so oxygen would be the central atom and is bonded once to each chlorine atom (Cl-O-Cl)
- Sun Oct 28, 2018 1:22 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Indeterminacy Question
- Replies: 2
- Views: 1402
Re: Indeterminacy Question
it will be in the range of +- delta x/2 because the uncertainty in x is the range of possible answers (if delta x is four then the range of answers is +-2)
- Sun Oct 28, 2018 1:19 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: D Block
- Replies: 1
- Views: 143
Re: D Block
yes, the electrons would be removed from the highest energy level first, which is the 4s when it has electrons
- Sun Oct 28, 2018 1:18 pm
- Forum: Ionic & Covalent Bonds
- Topic: ionization energy
- Replies: 7
- Views: 830
Re: ionization energy
The pull from the nucleus increases for each individual electron because it has less electrons to pull when it has a charge of plus one and so the electrons that remain are more difficult to remove and require more energy to remove than the first electron
- Sun Oct 21, 2018 7:20 pm
- Forum: Photoelectric Effect
- Topic: Kinetic Energy
- Replies: 3
- Views: 337
Re: Kinetic Energy
The kinetic energy is the energy that is transferred to the electron after it is ejected, which is the energy that is left over from the photon after it has overcome the work function which is the energy required to remove the electron from a specific metal
- Sun Oct 21, 2018 7:13 pm
- Forum: Photoelectric Effect
- Topic: Conditions that allow electron to be ejected from metal surface
- Replies: 12
- Views: 2235
Re: Come nditions that allow electron to be ejected from metal surface
Yes, the energy of the photon just has to be equal to or greater than the work function of that specific metal to eject an electron.
- Sun Oct 21, 2018 7:11 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: What is a nodal plane?
- Replies: 5
- Views: 3444
Re: What is a nodal plane?
A nodal plane is an area of the orbital where there is zero electron density. The p, d, and f orbitals have nodal planes while the s orbital does not. This is why the s orbital is a sphere while the p orbital has two lobes on either side of the nucleus with a nodal plane in between them.
- Mon Oct 15, 2018 8:38 pm
- Forum: Properties of Electrons
- Topic: Electrons in a stable state?
- Replies: 6
- Views: 611
Re: Electrons in a stable state?
So electrons in higher energy states contain higher potential energy, while electrons in lower energy states contain lower potential energy? Does this mean that electrons in higher energy states are more unstable than electrons in lower energy states? Yes, they are more unstable because the higher ...
- Mon Oct 15, 2018 8:26 pm
- Forum: Properties of Light
- Topic: Mass
- Replies: 4
- Views: 265
Re: Mass
light cannot exist in a stationary state and so there is no mass because it is not a possible situation
- Mon Oct 15, 2018 8:24 pm
- Forum: Photoelectric Effect
- Topic: Threshold Energy
- Replies: 2
- Views: 219
Re: Threshold Energy
If the threshold energy is not met then the incoming photon passes through the surface because it is unable to interact with the electrons of that metal since they are only able to absorb energy in discrete amounts
- Mon Oct 08, 2018 7:44 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Changing Units
- Replies: 10
- Views: 831
Re: Changing Units
as long as the answer is correct the units are not important
- Mon Oct 08, 2018 7:37 pm
- Forum: SI Units, Unit Conversions
- Topic: SI Units
- Replies: 10
- Views: 776
Re: SI Units
Do all our final answers need to be converted to the base SI unit (ex:meter, kilogram, mole) or do we just use the closest prefix to it? And if we leave our answer in the base SI unit and do not use a prefix simplifying the value would our answer be wrong even if both answers would be mathematicall...
- Mon Oct 08, 2018 7:33 pm
- Forum: Properties of Light
- Topic: Speed of light constant (c)
- Replies: 6
- Views: 514
Re: Speed of light constant (c)
I do not think that the sig figs in the constant are important because the sig figs in your answer rely on the numbers that are given to you in the problem, but the more sig figs you use for the constant the more accurate your answer will be.
- Wed Oct 03, 2018 9:03 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: molarity conversion
- Replies: 7
- Views: 458
Re: molarity conversion
Yes since molarity is mol/L if you did not convert the mL to L it would be the wrong units and your answer would not be giving molarity.
- Wed Oct 03, 2018 9:01 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: measuring mols vs grams in dilutions
- Replies: 2
- Views: 117
Re: measuring mols vs grams in dilutions
The unit for molarity is mol/L and so when diluting a solution the moles in the solution are relevant for finding the concentration of the new solution.
- Wed Oct 03, 2018 8:56 pm
- Forum: Limiting Reactant Calculations
- Topic: Limiting Reactant Question
- Replies: 7
- Views: 1448
Re: Limiting Reactant Question
Do you have to find moles before finding limiting reactant? Yes. To find the limiting reactant you need to find which one of the reactants there is less of and since they react together in a specific mole ratio, you need to find out how many moles of each product you have before you can know which ...