Search found 60 matches
- Mon Mar 18, 2019 11:59 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Reaction Profiles
- Replies: 3
- Views: 671
Re: Reaction Profiles
Basically the slower the step the higher the peak
- Mon Mar 18, 2019 11:58 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Pre Equilibrium Approach
- Replies: 3
- Views: 723
Re: Pre Equilibrium Approach
We use the preequilibrium approach in order to get rid of intermediates in the final rate law
- Mon Mar 18, 2019 11:57 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Steady State Approximation
- Replies: 3
- Views: 680
Re: Steady State Approximation
The steady state is a much more complicated method compared to preequilibrium and therefore we won’t be required to know if for the class, preequilibrium gives us sufficient accuracy for the scope of the class
- Sat Mar 09, 2019 9:38 pm
- Forum: Second Order Reactions
- Topic: Determining the Order of a Reaction
- Replies: 3
- Views: 478
Re: Determining the Order of a Reaction
You find the order of the individual reactants, which can be found based on the information given, then adding up all the orders tells you the order of the overall reactant.
- Sat Mar 09, 2019 9:35 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Fast Step vs Slow Step
- Replies: 3
- Views: 388
Re: Fast Step vs Slow Step
The slow step has the same rate law as the reaction, this is because the rate of the reaction is determined by the slowest step, all other steps go at a higher rate, therefore, the reaction can only proceed as fast as its slowest step can produce the necessary products
- Sat Mar 09, 2019 9:30 pm
- Forum: Zero Order Reactions
- Topic: Zero order
- Replies: 10
- Views: 1694
Re: Zero order
A zero-order reaction is one in which the rate is independent of the concentration, we use artificial zero-order reactions to determine the order of reactants in a reaction. By supplying an excess amount of all reactants except one and then varying the concentration of the non-excess reactant to fin...
- Sun Mar 03, 2019 9:42 pm
- Forum: General Rate Laws
- Topic: Overall sum
- Replies: 7
- Views: 799
Re: Overall sum
The Overall reaction order is the sum of the exponents and provides insight as to the complexity of the reaction.
- Sun Mar 03, 2019 9:35 pm
- Forum: General Rate Laws
- Topic: Calculus Review
- Replies: 8
- Views: 965
Re: Calculus Review
I think we only need to know some of the basic topics covered in Calculus AB (or equivalent)
- Sun Mar 03, 2019 9:32 pm
- Forum: General Rate Laws
- Topic: Reaction Order
- Replies: 2
- Views: 278
Re: Reaction Order
The reaction order is all the exponents of the reactants added together
- Sun Feb 24, 2019 8:47 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: ions
- Replies: 2
- Views: 312
Re: ions
yes, an ion is alway aqueous. Ions can only exist in solution therefor if there is an ion it must be in solution or it can't exist.
- Sun Feb 24, 2019 8:45 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: SHE
- Replies: 3
- Views: 386
Re: SHE
The standard hydrogen electrode is essentially a null electrode. The electrode itself is an inert metal (such as platinum) and while we don't know the exact cell potential we set it to be zero so it serves as a reference point. So every electrode's cell potential is calculated with reference to the ...
- Sun Feb 24, 2019 8:42 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell diagram
- Replies: 3
- Views: 345
Re: Cell diagram
essentially one line between means there is simply a porous disk which allows the solutions to mix, a double line means that the solutions are in different containers & are separated by solid walls that don't allow mixing but are connected by a wire that allows the transfer of electrons.
- Sun Feb 24, 2019 8:39 pm
- Forum: Balancing Redox Reactions
- Topic: How do you balance a redox reaction
- Replies: 4
- Views: 386
Re: How do you balance a redox reaction
while you balance it like any other equation the way you go about it is different. You add water because sometimes there are oxygens that appear on one side of the equation and not the other. To show the actual reaction we add water because that is where those oxygens came from. We then add protons,...
- Sun Feb 24, 2019 8:33 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Redox
- Replies: 4
- Views: 490
Re: Balancing Redox
Despite what the previous posts say E is not an independent of concentration. The standard cell potential is independent of concentration but that is because it assumes that everything is at standard conditions. However just cell potential is dependant on concentration because as a battery proceeds ...
- Sun Feb 24, 2019 8:30 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation
- Replies: 4
- Views: 573
Re: Oxidation
It is helpful to to think of it in terms of charges, when something is reduced it's charge is "reduced" to a lower number and if it is oxidized it looses electrons
- Sun Feb 24, 2019 8:28 pm
- Forum: Balancing Redox Reactions
- Topic: salt bridge?
- Replies: 3
- Views: 370
Re: salt bridge?
The salt bridge allows the two electrolytes to be separated. Originally in a Daniel cell the electrolytes & electrodes canceled out charges so in order to separate the electrolytes & electrodes a salt bridge needed to be added in order to have two solutions at relatively neutral charge. It d...
- Sun Feb 24, 2019 8:24 pm
- Forum: Balancing Redox Reactions
- Topic: Which Equation to Flip?
- Replies: 9
- Views: 4904
Re: Which Equation to Flip?
You flip the oxidation reaction. The reason Ecell is supposed to be positive is that is has an inverse relationship with delta G so when it is positive delta G is negative and the reaction is spontaneous, when it is negative delta G is positive and the reverse reaction is spontaneous.
- Sun Feb 24, 2019 8:22 pm
- Forum: Balancing Redox Reactions
- Topic: platinum
- Replies: 7
- Views: 706
Re: platinum
Platinum is added to the cell diagram whenever it is present, it is added into cells when we need a inert metal (non reacting metal) and we want water to be included in the reaction such as in a Standard Hydrogen Electrode. It isnt included in the reaction due to the fact that it doesn't react.
- Sun Feb 24, 2019 8:18 pm
- Forum: Balancing Redox Reactions
- Topic: Oxygen Oxidation Number
- Replies: 3
- Views: 441
Re: Oxygen Oxidation Number
Oxygen will tend to have a -2 charge due to the face that it wants an octet and due to its high electronegativity it will usually have the octet at the cost of having a formal charge of -2
- Sun Feb 24, 2019 8:14 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Redox equations in Basic conditions
- Replies: 3
- Views: 339
Re: Balancing Redox equations in Basic conditions
You have to add water to balance out the oxygens once you balance all other elements, so in this case it would be on the left. Then you add OH^- to balance the hydrogens and oxygens. Then lastly you balance the charges. Since you can't raise the charge of one side, you can only lower it you add elec...
- Sun Feb 24, 2019 7:22 pm
- Forum: Balancing Redox Reactions
- Topic: Order to balance
- Replies: 6
- Views: 582
Re: Order to balance
You follow the order in the previous posts but you don't balance electrons. Electrons are used to balance the charge of the reaction. Electrons are then balanced (by multiplying either the reduction or oxidation reaction) so that they cancel out in the redox reaction to show the transfer of electron...
- Sun Feb 24, 2019 7:20 pm
- Forum: Balancing Redox Reactions
- Topic: 1/2 Rxns: Elements vs. Compounds
- Replies: 3
- Views: 338
Re: 1/2 Rxns: Elements vs. Compounds
You only include reacting elements/molecules, spectator ions aren't important in chemical reactions and because of such aren't included. Water is used to balance out the oxygens and hydrogen ions(protons) are used to cancel out the hydrogens from other molecules. If the molecule doesn't react then i...
- Sun Feb 24, 2019 7:16 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Half Reactions
- Replies: 3
- Views: 326
Re: Balancing Half Reactions
The reason the charge isn't multiplied is due to the equation Ecell=-nR/DeltaG, Delta G is doubled when concentrations are doubled but so is n (the coefficient for moles), therefor the Ecell stays the same regardless of coefficient change
- Mon Jan 21, 2019 3:29 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Pure substances
- Replies: 3
- Views: 325
Re: Pure substances
This is because solids don't change in concentration because they don't have a concentration and liquids don't change because it is usually in excess and would cancel out on both sides.
- Mon Jan 21, 2019 3:26 pm
- Forum: Ideal Gases
- Topic: PV=nRT
- Replies: 8
- Views: 1164
Re: PV=nRT
The ideal gas law is used in order to convert from molarity to partial pressure, with K and R being given
- Mon Jan 21, 2019 3:23 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatelier's Principle
- Replies: 4
- Views: 440
Re: Le Chatelier's Principle
Amy Dinh 1A wrote:Adding on to that, his principle applies to changing physical parameters Pressure and Temperature.
When pressure increases, the reaction favors the side with the least moles of gas.
It isn't that when pressure changes it will favor one side, it is when molarity is affected.
- Mon Jan 21, 2019 3:21 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Q and K
- Replies: 10
- Views: 833
Re: Q and K
Q and K are very similar, at equilibrium Q = K but any other time than that Q won't equal K but it will tell us which side will be favored in order to get to K.
- Mon Jan 21, 2019 3:18 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Salt
- Replies: 4
- Views: 450
Re: Salt
Knowing strong/weak acids and bases help to determine if the reaction is with salt. It isn't too different than an acid/base reaction you just have to write out the reations that affect ph and do the necessary calculations.
- Mon Jan 21, 2019 3:16 pm
- Forum: Ideal Gases
- Topic: 5% rule
- Replies: 12
- Views: 3474
Re: 5% rule
You use the 5% rule to determine if X is negligible, if it is over 5% then you just need to include (#-x) in your calculations when trying to find the value of X.
- Thu Dec 06, 2018 4:33 pm
- Forum: Conjugate Acids & Bases
- Topic: Ion concentration
- Replies: 2
- Views: 324
Re: Ion concentration
to find the concentration of (H30) you put e to the -pH and you can use stoichiometry to find concentrations of other molecules in the reaction.
- Thu Dec 06, 2018 4:27 pm
- Forum: Lewis Acids & Bases
- Topic: HCl vs. HI
- Replies: 7
- Views: 795
Re: HCl vs. HI
electronegativity only matters for molecules, not single atom ions, because the higher electronegativity will help spread the negative charge over a higher area and thus will make it more stable but electronegativity doesn't matter for single atom ions because regardless of the electronegativity the...
- Thu Dec 06, 2018 4:23 pm
- Forum: Lewis Acids & Bases
- Topic: Determining which H^+ ions are given off
- Replies: 4
- Views: 339
Determining which H^+ ions are given off
When trying to see how many H^+ ions can be given off by an acid, which ones are usually given off? Like I know those attached to nitrogen usually are given off but what if it is bonded to an O or another element?
- Thu Nov 29, 2018 11:07 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: AX2E2
- Replies: 14
- Views: 4623
Re: AX2E2
a molecule with formula AX2E2 will have a bond angle >>109.5 as the lone pairs repulse the atoms more that atoms repulse atoms, however a molecule with formula AX4E2 will have bond angles at exactly 90 degrees as the lone pair-atom repulsion will cancel out.
- Thu Nov 29, 2018 11:03 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Electron density
- Replies: 3
- Views: 664
Re: Electron density
yes the hybridization is the same as electron densities around the central atom as double and triple bonds require unhybridized p orbitals, single, double, and triple bonds as well as lone pairs each count as one electron density
- Thu Nov 29, 2018 11:00 pm
- Forum: Hybridization
- Topic: Delocalized Pi Bonding
- Replies: 3
- Views: 307
Re: Delocalized Pi Bonding
this is the cloud of electrons over a molecule it an have three pi bonds on every other bond, and due to resonance there are characteristics of double bonding at every bond at the same time, resulting in a delocalized pi bond over the entire molecule.
- Thu Nov 29, 2018 10:57 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: sigma and pi bonds
- Replies: 4
- Views: 504
Re: sigma and pi bonds
a sigma bond can rotate because it is connected at one point so the atoms can rotate freely, in a double or triple bond (containing a sigma and pi bonds) there are connections at either 3 or 5 points and so if it was to rotate, it would need to break the bonds at those points and reform them at the ...
- Thu Nov 29, 2018 10:52 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: trans/cis
- Replies: 4
- Views: 664
Re: trans/cis
yes because the formula for a cis/trans molecule is the exact same, the difference comes in how the atoms are positions which is where the cis/trans part comes in it tells you is the same elements are on the same side or on the opposite side
- Thu Nov 29, 2018 10:46 pm
- Forum: Hybridization
- Topic: Bond Strengths
- Replies: 4
- Views: 442
Re: Bond Strengths
a pi bond is weaker than a sigma bond because it is higher energy than a sigma bond, remember everything wants to be in the lowest energy state possible, pi bonds have a nodal plane between the nuclei which is where the electrons would like to be therefor it is weaker than a sigma bond as the electr...
- Thu Nov 29, 2018 10:39 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: polar or not polar
- Replies: 4
- Views: 683
Re: polar or not polar
it helps to visualize the molecule in your head, on paper the Lewis model of CH2Cl2 may look symmetrical but in reality, no matter how it is positioned the 2 Cls will be opposite the 2 Hs which explains the polarity, the molecule needs to be symmetrical in 3D in order for it to be non-polar.
- Thu Nov 29, 2018 10:35 pm
- Forum: Hybridization
- Topic: hybridization notation
- Replies: 3
- Views: 410
Re: hybridization notation
The 2 in 2sp^2 is the energy level of the hybridized orbital it is simply the period of the element.
- Thu Nov 29, 2018 10:29 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: polarity
- Replies: 11
- Views: 873
Re: polarity
yes going off of the previous post, molecules that are symmetric are non-polar, for example, a square planar molecule is non-polar despite having two lone pairs due to it being symmetric, usually larger molecules with different elements that isn't symmetrical are non-polar. To help determine if it i...
- Thu Nov 29, 2018 10:26 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Dipole moment
- Replies: 7
- Views: 729
Re: Dipole moment
The Dipole Moment has a direct correlation with polarity so the more polar the larger the dipole moment.
- Sun Nov 11, 2018 8:12 pm
- Forum: Hybridization
- Topic: Composition of a bond (Sigma and Pi Bonds)
- Replies: 3
- Views: 541
Re: Composition of a bond (Sigma and Pi Bonds)
the 1 and 2 simply refer to the energy level of the orbital that is participating in the bond, so it is also the period number of the atom as that is the energy level of valence orbitals.
- Sun Nov 11, 2018 8:10 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: molecular shapes
- Replies: 13
- Views: 997
Re: molecular shapes
I think we have to be able to name the different shapes but its important to note that shape is different than the electron arrangement, the shape is named after the how the molecule looks (excluding lone pairs) so its possible for some vsepr models to have the same angles as there can be a lone pai...
- Sun Nov 11, 2018 8:05 pm
- Forum: Hybridization
- Topic: Energy levels
- Replies: 6
- Views: 785
Re: Energy levels
degeneracy relates to all energy levels, orbitals and subshells, it simply states subshells are the same exact energy, however, degeneracy is broken in the D orbital due to some subshells being lower energy then others
- Sun Nov 11, 2018 8:03 pm
- Forum: Sigma & Pi Bonds
- Topic: Difference between Bonds [ENDORSED]
- Replies: 7
- Views: 1204
Re: Difference between Bonds [ENDORSED]
A sigma bond is always first due to the fact that it is lower energy, so if the molecule always picks a lower energy state, it makes sense that a sigma bond is first, it is only after then that any other bond formed are pi because they require more energy then a sigma bond but less energy than the i...
- Sun Nov 11, 2018 7:57 pm
- Forum: Sigma & Pi Bonds
- Topic: Pi bonds
- Replies: 3
- Views: 630
Re: Pi bonds
yes, such as in benzene carbon has 3sp^2 orbitals, with two being bonded to other c-atoms and one being bonded to a hydrogen, the leftover unhybridized pz bond is what forms the molecular orbital above and below the ring structure of the benzene
- Sun Nov 11, 2018 7:54 pm
- Forum: Sigma & Pi Bonds
- Topic: Sigma v. Pi
- Replies: 6
- Views: 903
Re: Sigma v. Pi
A sigma bond has increased electron probability between nuclei whereas a pi bond has a nodal plane between nuclei making it higher energy than a sigma bond.
- Mon Oct 29, 2018 1:34 am
- Forum: Quantum Numbers and The H-Atom
- Topic: Nodal Planes and test 2
- Replies: 3
- Views: 310
Re: Nodal Planes and test 2
It's pretty easy to remember how many nodal planes are in an orbital by looking at the L value in quantum numbers, it is the same as how many nodal planes there are.
- Mon Oct 29, 2018 1:30 am
- Forum: Dipole Moments
- Topic: London Forces
- Replies: 7
- Views: 957
Re: London Forces
They are the weakest of any type of attractive force as they are the weakest intermolecular and intramolecular are stronger than intermolecular, but basically, since electrons can randomly gravitate towards one side it creates a temporary dipole where a weak negative side is created with the electro...
- Mon Oct 29, 2018 1:21 am
- Forum: Quantum Numbers and The H-Atom
- Topic: s,p,d,f
- Replies: 8
- Views: 964
Re: s,p,d,f
It is because, in terms of energy level, 3D is closer in energy to 4S orbital, than 4D thus when being filled with electrons it is written where it is
- Mon Oct 29, 2018 1:16 am
- Forum: Sigma & Pi Bonds
- Topic: Detail of Bonds
- Replies: 3
- Views: 615
Re: Detail of Bonds
What exactly are sigma and pi bonds? Are they a type of covalent bond or are they the same as a covalent bond? I went over them briefly in AP Chem but not too much for me to understand them.
- Sun Oct 28, 2018 8:35 pm
- Forum: Octet Exceptions
- Topic: He, Li and Be
- Replies: 3
- Views: 570
Re: He, Li and Be
The rule is that below the third period the octet rule is followed (except for the first 4 elements), but after is when extended orbitals come into play
- Sun Oct 28, 2018 8:22 pm
- Forum: Ionic & Covalent Bonds
- Topic: Polyatomic Ions [ENDORSED]
- Replies: 4
- Views: 529
Re: Polyatomic Ions [ENDORSED]
Is there a list of common polyatomic ions we should memorize?
- Thu Oct 25, 2018 5:51 pm
- Forum: Trends in The Periodic Table
- Topic: Atomic, Covalent, and Ionic Radius
- Replies: 5
- Views: 1115
Re: Atomic, Covalent, and Ionic Radius
I think Covalent and Ionic Radii is the distance between the center of two atoms halved so if you look at the distance between the center of two atoms bonded together and halve it, it should be the covalent or ionic radii (depending on the bond between the atoms.
- Thu Oct 25, 2018 5:48 pm
- Forum: Trends in The Periodic Table
- Topic: Isoeletronic
- Replies: 3
- Views: 561
Re: Isoeletronic
While Atoms and ions may have the same amount of electrons it is important to remember they still have different properties, due the the difference in protons in the nucleus, so while ions may be isoelectronic, they can have different sizes and so forth.
- Thu Oct 25, 2018 5:46 pm
- Forum: Trends in The Periodic Table
- Topic: Removing 2nd Electron
- Replies: 9
- Views: 802
Re: Removing 2nd Electron
Removing the second electron is harder because as stated in class the atom becomes a cation (which normally attract electrons from other atoms) so it pulls on the electron more than before through a high Zeffective.
- Sun Oct 21, 2018 11:37 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Electron Spin States?
- Replies: 4
- Views: 244
Re: Electron Spin States?
My assumption is that the spin affected the photon by centrifugal force if the electron is spinning up then the spectral line will be sent upwards and if it spinning downward then the spectral line will be sent lower, which can be seen in the figure drawn by Lavelle in class as the two spectral line...
- Sun Oct 21, 2018 11:31 pm
- Forum: Trends in The Periodic Table
- Topic: electron affinity [ENDORSED]
- Replies: 15
- Views: 2053
Re: electron affinity [ENDORSED]
Florine is the most electronegative atom, using that fact you can establish a variety of periodic trends from the table, as you move from left to right on a period all subshells become smaller ever so slightly due to the increase in protons, and as you move from top to bottom the radius increases by...
- Sun Oct 21, 2018 11:20 pm
- Forum: Properties of Electrons
- Topic: Atomic Spectra
- Replies: 4
- Views: 477
Re: Atomic Spectra
The difference between the Ballmer Series and the Lyman series is only the region because that is by definition what makes it in the series. The wavelength of any photon that is emitted from an electron dropping energy levels in the UV spectrum belongs to the Lyman Series and if it falls in the visi...