Search found 105 matches
- Sun Mar 14, 2021 1:33 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Catalyst
- Replies: 27
- Views: 1042
Re: Catalyst
It increases the speed of both forward and reverse pathways of the reaction by lowering the activation energy.
- Sun Mar 14, 2021 1:27 am
- Forum: Second Order Reactions
- Topic: Molecularity
- Replies: 17
- Views: 723
Re: Molecularity
The molecularity is the number of species in an elementary step (i.e. the number of collisions) which has to agree with the order of the rate law. (Lecture 24)
- Sun Mar 14, 2021 1:04 am
- Forum: First Order Reactions
- Topic: Half Life Unit
- Replies: 38
- Views: 1425
Re: Half Life Unit
Half-life is typically given in seconds or minutes but it depends on the chemical reaction in question. Some are slower and others are faster so units may vary.
- Sun Mar 14, 2021 1:03 am
- Forum: Zero Order Reactions
- Topic: Half life
- Replies: 19
- Views: 899
Re: Half life
Lecture 23
Dervied equation for half-time of a zero order reaction:
t1/2 = [A]0/2k
Dervied equation for half-time of a zero order reaction:
t1/2 = [A]0/2k
- Sun Mar 14, 2021 12:58 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Orders of reactants
- Replies: 14
- Views: 719
Re: Orders of reactants
The order of each reactant tells us the relationship between the concentration of the reactant and the rate of the reaction. Additionally, it provides insight into the reaction mechanisms (lecture 24).
- Sun Mar 14, 2021 12:54 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: About k
- Replies: 26
- Views: 2732
Re: About k
K is the equibrium constant and if K is large, then that means there are more products than reactants.
k on the other hand, is the rate constant and tells us how fast the reaction is and in which direction it is proceeding.
k on the other hand, is the rate constant and tells us how fast the reaction is and in which direction it is proceeding.
- Sun Mar 14, 2021 12:49 am
- Forum: General Rate Laws
- Topic: Intermediate
- Replies: 59
- Views: 3504
Re: Intermediate
An intermediate is produced and consumed as the reaction occurs so it is not present in the overall reaction.
- Sun Mar 14, 2021 12:48 am
- Forum: General Rate Laws
- Topic: Pseudo Rates
- Replies: 8
- Views: 668
Re: Pseudo Rates
Pseudo-rates can be used to determine reaction rates in an experiment with multiple reactants where all except one of the reactants are in large excess.
- Sun Mar 14, 2021 12:34 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: "Thermodynamically Stable" vs "Kinetically Stable"
- Replies: 10
- Views: 1662
Re: "Thermodynamically Stable" vs "Kinetically Stable"
The reactant(s) is said to be kinetically stable when the the delta G is negative but no product is formed. In this case, kinetics is controlling the reaction rather than thermodynamics because the reactions occurs very very very... very slowly.
- Sun Mar 14, 2021 12:22 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: What was your favorite chem topic?
- Replies: 137
- Views: 8478
Re: What was your favorite chem topic?
Andersen Chu 2H wrote:Not electrochemistry
Unfortunate but also same :(
- Sun Mar 14, 2021 12:17 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: EA
- Replies: 23
- Views: 1160
Re: EA
It depends on the textbook, but in Dr. Lavelle's lectures, Ea is used to denote activation energy.
- Sun Feb 28, 2021 9:35 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: E vs E naught
- Replies: 36
- Views: 1537
Re: E vs E naught
Eº is E under standard conditions which are 1M and 1atm, similar to standard gibbs free energy Gº which is also under standard conditions.
- Sun Feb 28, 2021 9:33 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt Bridges
- Replies: 41
- Views: 2921
Re: Salt Bridges
Salt bridges prevent ions from accumulating by allowing electron flow from the anode to the cathode (i.e. it maintains neutrality).
- Sun Feb 28, 2021 9:30 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Reactions
- Replies: 22
- Views: 965
Re: Balancing Reactions
The order does not matter as long as the coefficients of the products and reactants are correct.
- Sun Feb 28, 2021 9:21 pm
- Forum: Balancing Redox Reactions
- Topic: Determining Phases
- Replies: 28
- Views: 974
Re: Determining Phases
The phases will usually be given in the question and your final answer will usually have the same phases as the problem originally stated.
- Sun Feb 28, 2021 9:17 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Redox Reactions
- Replies: 6
- Views: 362
Re: Balancing Redox Reactions
You add H2O to the side that doesn't have enough oxygen atoms when balancing a redox reaction.
- Sun Feb 21, 2021 11:36 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gas Constant R
- Replies: 43
- Views: 3697
Re: Gas Constant R
The gas constant used depends on the desired units for your final answer. If it includes joules, then 8.314 is suitable.
- Sun Feb 21, 2021 11:26 pm
- Forum: Van't Hoff Equation
- Topic: Van't Hoff Equation
- Replies: 11
- Views: 675
Re: Van't Hoff Equation
Following up with this question, does anybody have some advice as to how to solve problems with some form of calculus involved? I never took any in highschool so it's still quite difficult to grasp. I don't think this class will require you to solve problems using calculus, but if you need help, Dr...
- Sun Feb 21, 2021 11:23 pm
- Forum: Balancing Redox Reactions
- Topic: Redox Mnemonic
- Replies: 11
- Views: 968
Re: Redox Mnemonic
Oxidation Is Loss
Reducation Is Gain
I remember using OIL RIG throughout high school chemistry. This is the first time I've actually heard of LEO GER, but both work, just a matter of preferences.
Reducation Is Gain
I remember using OIL RIG throughout high school chemistry. This is the first time I've actually heard of LEO GER, but both work, just a matter of preferences.
- Sun Feb 21, 2021 11:15 pm
- Forum: Balancing Redox Reactions
- Topic: Cell/battery
- Replies: 26
- Views: 832
Re: Cell/battery
Cell and battery are used interchanageably in the context of this class.
- Sun Feb 21, 2021 10:47 pm
- Forum: Balancing Redox Reactions
- Topic: coefficients for oxidation number
- Replies: 22
- Views: 4705
Re: coefficients for oxidation number
Coefficients are used to balance the reaction, but they do not affect the oxidation number so they aren't used in the calculation.
- Sun Feb 14, 2021 10:18 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: G° vs G
- Replies: 30
- Views: 2411
Re: G° vs G
G° is simply the free energy at standard temperature and pressure, defined as 1 bar (or 1 atm) and 298K.
- Sun Feb 14, 2021 10:16 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: qrev vs q
- Replies: 21
- Views: 1863
Re: qrev vs q
qrev is the heat of reversible expansion which can be useful for approximations whereas q is just the heat of expansion.
- Sun Feb 14, 2021 10:12 pm
- Forum: Calculating Work of Expansion
- Topic: U, q, w
- Replies: 11
- Views: 781
Re: U, q, w
∆U = q + w
where ∆U is internal energy
q is heat released/absorbed
w is work done by/on the system
If the change in internal energy (∆U) is 0 (i.e. no temperature change, isothermal),
then the equation can be rearranged to:
q = - w
where ∆U is internal energy
q is heat released/absorbed
w is work done by/on the system
If the change in internal energy (∆U) is 0 (i.e. no temperature change, isothermal),
then the equation can be rearranged to:
q = - w
- Sun Feb 14, 2021 10:09 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Reversible vs Irreversible Work
- Replies: 5
- Views: 230
Re: Reversible vs Irreversible Work
Reversible work is done in infinitely small steps (hence why it's considered reversible) and it is highly efficient whereas irreversible work are real processes where work is done much more quickly although less efficient.
- Sun Feb 14, 2021 10:04 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: n in q=nCdeltaT
- Replies: 16
- Views: 688
Re: n in q=nCdeltaT
n is given in moles. If C is given in grams, then you can convert moles to grams for n.
- Sun Feb 07, 2021 10:21 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Work Definition
- Replies: 33
- Views: 1030
Re: Work Definition
Work is the energy transferred as a function of force times distance.
- Sun Feb 07, 2021 10:08 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Isothermal (reversible) vs. Irreversible
- Replies: 5
- Views: 225
Re: Isothermal (reversible) vs. Irreversible
Is isothermal just another way of saying no change and that's why it can also be referred to as reversible? Isothermal means that the temperature remains constant. There is change in isothermal expansion but it is an infinitisimally slow increase in the volume of the substance. Hence, it is conside...
- Sun Feb 07, 2021 10:04 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Closed System
- Replies: 52
- Views: 2581
Re: Closed System
An (ideally) insulated system is an isolated system where neither matter nor energy can be transferred between the system and surroundings while a closed system is one where matter cannot be transferred but energy (heat) can be transferred to/from the surroundings.
- Sun Feb 07, 2021 10:01 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Positive and Negative q Value
- Replies: 19
- Views: 12866
Re: Positive and Negative q Value
When q is negative, the system is releasing heat into the surroundings (exothermic).
When q is positive, the system is absorbing heat from the surroundings (endothermic).
When q is positive, the system is absorbing heat from the surroundings (endothermic).
- Sun Feb 07, 2021 9:36 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: deltaU
- Replies: 29
- Views: 782
Re: deltaU
Delta U is the change in internal energy which is equal to the amount of heat absorbed/released plus the work done on/by the system.
- Sun Jan 31, 2021 5:24 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Molar Heat Capacity
- Replies: 11
- Views: 297
Re: Molar Heat Capacity
Molar heat capacity is the same as specific heat capacity except they have different units. MHC uses J/mol*K whereas SHC uses J/kg*C.
- Sun Jan 31, 2021 5:19 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess's Law
- Replies: 58
- Views: 2789
Re: Hess's Law
Hess's Law uses the fact that state functions are additive which allows you manipulate the given reactions to obtain the reaction and thus the reaction enthalpy.
- Sun Jan 31, 2021 4:55 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Enthalpy
- Replies: 26
- Views: 1083
Re: Enthalpy
Work is not a state function because it depends on the path taken whereas a state function such as enthalpy only depends on the final and initial states.
- Sun Jan 31, 2021 4:44 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: isochoric
- Replies: 10
- Views: 888
Re: isochoric
Their defintions are different but they can be used interchangeably.
- Sun Jan 31, 2021 4:42 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: State Function
- Replies: 22
- Views: 707
Re: State Function
Work isn't a state function because depends on the path taken (distance varies with path taken).
- Sun Jan 24, 2021 7:46 pm
- Forum: Phase Changes & Related Calculations
- Topic: Define Phase Change
- Replies: 78
- Views: 4900
Re: Define Phase Change
A phase change is simply when matter changes from one state to another (i.e. solid to liquid aka melting).
- Sun Jan 24, 2021 7:41 pm
- Forum: Phase Changes & Related Calculations
- Topic: Salt
- Replies: 19
- Views: 624
Re: Salt
Salts can be either acidic, basic, or even neutral (e.g. NaCl) depending on their cations and anions.
- Sun Jan 24, 2021 7:38 pm
- Forum: Phase Changes & Related Calculations
- Topic: State Property
- Replies: 11
- Views: 467
Re: State Property
Heat is not a state function because it doesn't depend only on the final and the initial state of the system. For instance, recall the hiking example Dr. Lavelle provided in class. The change in altitude is the same no matter the route taken but the heat that leaves your body (in order to do work) d...
- Sun Jan 24, 2021 7:28 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: pH of weak acid
- Replies: 9
- Views: 381
Re: pH of weak acid
We can assume that X is insignificant when Ka < 10-4. Alternatively if the inital concentration of the acid/base is 1000 times greater than the equilibrium constant, you can assume that the X is insignificant.
- Sun Jan 24, 2021 7:22 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: approximating
- Replies: 10
- Views: 387
Re: approximating
X is not a valid apprxoimation for X 2 . If you take out one of the X's in the products (numerator), then you're ignoring the concentration of that product completely.X ≠ X 2 . For the demoninator, you can approximate because a large value minus a very small value is still approximately that large v...
- Sun Jan 17, 2021 10:33 pm
- Forum: Ideal Gases
- Topic: Inverse Kc [ENDORSED]
- Replies: 41
- Views: 1900
Re: Inverse Kc [ENDORSED]
Inverse Kc is for the reverse reaction where it's reactants over products.
- Sun Jan 17, 2021 10:28 pm
- Forum: Ideal Gases
- Topic: Bars to atm [ENDORSED]
- Replies: 41
- Views: 1696
Re: Bars to atm [ENDORSED]
1 bar is approximately 1 atm. Bar is the SI unit while atm is more traditionally used in chemistry.
- Sun Jan 17, 2021 10:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Total pressure calculation
- Replies: 8
- Views: 1045
Re: Total pressure calculation
When you find the equilbrium partial pressures from your ICE table, you can add them all up to obtain the total pressure.
- Sun Jan 17, 2021 10:18 pm
- Forum: Ideal Gases
- Topic: n/V = concentration
- Replies: 19
- Views: 2152
Re: n/V = concentration
so let's say there is a problem where they provide the mols and they are in a certain number of L in a container you would have to find the concentration with is basically mol/L in order to then proceed with the problem? That depends on the problem but mol/L is a common measurement of concentration...
- Sun Jan 17, 2021 10:11 pm
- Forum: Ideal Gases
- Topic: Kp?
- Replies: 30
- Views: 916
Re: Kp?
Partial pressure only applies to gases because you cannot change the pressure of liquids and solids significantly.
- Sun Jan 10, 2021 2:26 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: H2O
- Replies: 44
- Views: 1886
Re: H2O
You would only include H2O when it is in a gaseous phase.
- Sun Jan 10, 2021 2:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Units
- Replies: 27
- Views: 867
Re: Units
1 bar is very close to 1 atm so either will work. In lecture, Lavelle mentioned we will be using atm mostly.
- Sun Jan 10, 2021 2:19 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: I in ICE Chart
- Replies: 11
- Views: 418
Re: I in ICE Chart
In the case of a reverse reaction, you will be given the initial concentration of the products instead.
- Sun Jan 10, 2021 2:16 pm
- Forum: Ideal Gases
- Topic: value of R
- Replies: 24
- Views: 969
Re: value of R
The value of R will be provided on the constants and equations sheet. In lecture, Lavelle stated we will be using atm primarily so I would use the R value of 8.206 x 10^-2.
- Sun Jan 10, 2021 2:13 pm
- Forum: Ideal Gases
- Topic: Inert Gas
- Replies: 20
- Views: 560
Re: Inert Gas
An inert gas is a non-reactive gas. In other words, they are noble gases.
- Tue Dec 15, 2020 10:51 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Bond Angles
- Replies: 12
- Views: 561
Re: Bond Angles
The bond angle for AX3E depends on the molecule specifically but they are always less than 109.5 due to electron repulsion from the lone pair.
- Tue Dec 15, 2020 10:47 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: [OH-] and pOH difference
- Replies: 9
- Views: 1756
Re: [OH-] and pOH difference
The relationship between [OH-] and pOH is the same as the relationship between [H+] and pH. We use the logarithmic value (p- prefix) for convenience. pOH = -log[OH-] [OH-] = 10 -pOH You might find this image useful. https://www.sciencegeek.net/Chemistry/taters/graphics/pHSchematic.gif
- Tue Dec 15, 2020 10:41 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: Titration Graphs
- Replies: 6
- Views: 334
Re: Titration Graphs
Understanding the equilibrium point and the shape of the graph should be sufficient.
- Tue Dec 15, 2020 10:37 pm
- Forum: Air Pollution & Acid Rain
- Topic: Acid Rain Formula
- Replies: 6
- Views: 1693
Re: Acid Rain Formula
There are multiple formulas for acid rain because there are several reactions that make rain acidic. Here are some of the common ones: https://4.bp.blogspot.com/-Kf5m0cGVlqc/WwrcJQ71uYI/AAAAAAAAS1s/jlwP3BdDDVcWpJP32lUBq5rT6jrPekXswCLcBGAs/s1600/Screenshot_2018-05-27-21-28-02-069_com.google.android.a...
- Sun Dec 13, 2020 1:35 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: pH and pKA
- Replies: 6
- Views: 355
Re: pH and pKA
Ah okay I see, thanks! I kind of get the relationship between pH and pKa now.
- Sun Dec 13, 2020 1:26 pm
- Forum: Lewis Acids & Bases
- Topic: Water
- Replies: 63
- Views: 2677
Re: Water
Water is amphoteric so it can act as either an acid or base depending on the context of the reaction.
- Sun Dec 13, 2020 1:24 pm
- Forum: Polyprotic Acids & Bases
- Topic: Polyprotic Acids & Bases [ENDORSED]
- Replies: 1
- Views: 182
Polyprotic Acids & Bases [ENDORSED]
Are there any other common polyprotic acids/bases besides H2SO4, H2CO3, and H3PO4?
- Sun Dec 13, 2020 1:14 pm
- Forum: Air Pollution & Acid Rain
- Topic: Acid Rain
- Replies: 24
- Views: 3800
Re: Acid Rain
When rain reacts with pollutants in the air (sulfur dioxide or nitrogen oxides), it becomes acidic.
- Mon Dec 07, 2020 11:18 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: pH and pKA
- Replies: 6
- Views: 355
pH and pKA
Can someone explain/clarify the relationship between pH and pKA in terms of determining whether the acid being neutral or negatively charged? i.e. Why is it that when pH is lower than the pKa, the compound will be protonated? I think I'm missing some fundamentals here...
- Tue Dec 01, 2020 5:55 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: AX2E3 Bond Angle
- Replies: 7
- Views: 513
Re: AX2E3 Bond Angle
Yes, the distribution of electron densities would be trigonal bipyamidal. The 3 lone e- pairs would be equatorial, leaving the two atoms opposite of each other (axial). Since the atoms are opposite of each other, the molecular geometry would be linear -> bond angle: 180.
- Tue Dec 01, 2020 5:46 pm
- Forum: Biological Examples
- Topic: Biological Functions of Transition Metals
- Replies: 6
- Views: 294
Re: Biological Functions of Transition Metals
There is no trend, it is independent of order. Just know that the first row of the d-block transition metals have unique functions in biological systems and some examples covered in lectures.
- Tue Dec 01, 2020 5:41 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Ligand
- Replies: 4
- Views: 159
Re: Ligand
In the context of a coordination compound, the Cl- is an anion inside the coordination sphere with 8 e- so it uses 2e- to form a bond with the TM.
- Tue Dec 01, 2020 5:36 pm
- Forum: Naming
- Topic: Using ido or o
- Replies: 24
- Views: 776
Re: Using ido or o
In his lecture, Dr. Lavelle stated that either -ido (IUPAC) or -o (traditional) is acceptable.
- Tue Dec 01, 2020 5:34 pm
- Forum: Naming
- Topic: Ferrate vs iron
- Replies: 5
- Views: 233
Re: Ferrate vs iron
For complex anions, Latin names are used for the following: Silver -> Argenate, Copper -> Cuprate, Lead -> Plumbate, Tin -> Stannate, Gold -> Aurate, and Iron -> Ferrate.
- Sun Nov 29, 2020 9:12 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Oxidation State
- Replies: 3
- Views: 235
Re: Oxidation State
Oxidation number and oxidation state are the same thing. They are used interchangeably. Generally, for the first row of the d-block, the transition metals have a +2 oxidation state (the charge for transition metals is usually a case by case basis). You can determine the charge of a transition metal ...
- Sun Nov 29, 2020 9:05 pm
- Forum: Hybridization
- Topic: hybridization, but very simple
- Replies: 9
- Views: 569
Re: hybridization, but very simple
Yes its very simple.
2 regions of e- density -> sp
3 regions of e- density -> sp2
4 regions of e- density -> sp3
5 regions of e- density -> sp3d
... etc.
2 regions of e- density -> sp
3 regions of e- density -> sp2
4 regions of e- density -> sp3
5 regions of e- density -> sp3d
... etc.
- Sun Nov 29, 2020 9:03 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: sigma vs pi bonds
- Replies: 33
- Views: 1985
Re: sigma vs pi bonds
All single bonds are sigma bonds. Consequently, double bonds have one sigma and one pi bonds and triple bonds have one sigma and two pi bonds. (i.e. The bonds in addition to one sigma bond are all pi bonds). Pi bonds are stronger than sigma bonds. You can conceptually verify this because triple bond...
- Sun Nov 29, 2020 9:00 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar
- Replies: 10
- Views: 548
Re: Polar
If the dipole moments cancel out, then the molecule is not polar. In other words, if there is no net dipole moment, then the molecule is not polar. Visualizing the 3D structure and symmetry of a molecule might help you in determing whether a molecule is polar.
- Sun Nov 29, 2020 8:57 pm
- Forum: Hybridization
- Topic: delocalized pi bonds
- Replies: 15
- Views: 528
Re: delocalized pi bonds
Drawing the Lewis structure can help you identify whether a compound has delocalized pi bonds. For a compound that has a resonance structure(s) containing pi bonds (double and triple bonds), then it is said to have delocalized pi bonds because the pi orbitals extend over more than two atoms. An exam...
- Sun Nov 22, 2020 12:04 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pair E-
- Replies: 47
- Views: 1798
Re: Lone Pair E-
Yes, lone pair electrons are also regions of electron density. If they weren't then, molecular shape would be only determined by bonding electrons.
- Sat Nov 21, 2020 11:34 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Shape Names
- Replies: 50
- Views: 2283
Re: Shape Names
The shape is commonly referred to as either bent or angular. Some examples of this are H2O and NO2- (due to their lone pair(s)).
- Sat Nov 21, 2020 11:32 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Linear shape
- Replies: 7
- Views: 336
Re: Linear shape
When you draw the Lewis structure for NO2-, the N has a lone pair which is more repulsive than bonding pairs and pushes the O atoms away from it causing the bent shape.
- Sat Nov 21, 2020 11:26 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: H20 Bent Structure
- Replies: 14
- Views: 619
Re: H20 Bent Structure
The lone pairs are more repulsive than the bonding pairs and thus their electron distribution causes H2O to be bent as the lone pairs "push down" on the H atoms.
- Sat Nov 21, 2020 11:24 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar or Nonpolar
- Replies: 13
- Views: 1001
Re: Polar or Nonpolar
Are there other factors that affect polarity besides symmetry?
- Sun Nov 15, 2020 11:11 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic radius
- Replies: 18
- Views: 784
Re: Ionic radius
Adding more electrons to an anion would increase the ionic radius because there would be more electron repulsion for the same nuclear charge.
- Sun Nov 15, 2020 11:10 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Oxidations Numbers
- Replies: 4
- Views: 452
Re: Oxidations Numbers
You can find a guide to oxidation numbers on Sapling (https://sites.google.com/site/chempendix/oxidation). He hasn't gone over oxidation numbers in depth yet.
- Sun Nov 15, 2020 11:08 pm
- Forum: Octet Exceptions
- Topic: Radicals
- Replies: 6
- Views: 400
Re: Radicals
Radicals are highly reactive because they are unstable due to their unpaired valence electron. I think the question would typically tell you when a radical is involved.
- Sun Nov 15, 2020 11:04 pm
- Forum: Lewis Structures
- Topic: Recognizing lowest formal charge
- Replies: 11
- Views: 350
Re: Recognizing lowest formal charge
There's no way to recognize the formal charge without calculating so I draw Lewis structures by counting the number of electrons, then trying different bonds for the lowest formal charge.
- Sun Nov 15, 2020 11:02 pm
- Forum: Coordinate Covalent Bonds
- Topic: Hydrogen bonding
- Replies: 15
- Views: 806
Re: Hydrogen bonding
Hydrogen bonding is a intermolecular force unlike coordinate covalent bonds which are intramolecular.
- Sun Nov 08, 2020 11:59 pm
- Forum: Ionic & Covalent Bonds
- Topic: Octet rule exceptions
- Replies: 15
- Views: 531
Re: Octet rule exceptions
Be and Li tend to lose electrons so they don't form a full octet. H and He only have electron(s) in the 1s orbital (max of 2 e-) so they don't form a full octet.
- Sun Nov 08, 2020 11:57 pm
- Forum: Ionic & Covalent Bonds
- Topic: resources
- Replies: 7
- Views: 125
Re: resources
If you have time, I'd recommend Organic Chemistry tutor on Youtube. His explanations are pretty easy to understand and follow.
- Sun Nov 08, 2020 11:55 pm
- Forum: Lewis Structures
- Topic: octet rule
- Replies: 7
- Views: 209
Re: octet rule
The octet rules applies to the first three rows of the periodic table if I remember correctly. (Correct me if I'm wrong please)
- Sun Nov 08, 2020 11:53 pm
- Forum: Trends in The Periodic Table
- Topic: memorizing trends
- Replies: 14
- Views: 272
Re: memorizing trends
I would try to understand the conceptual reasoning behind the each of the trends. So even if you forget the trends, you can conceptually deduce the trends.
- Sun Nov 08, 2020 11:50 pm
- Forum: *Shrodinger Equation
- Topic: The Hamiltonian
- Replies: 8
- Views: 376
Re: The Hamiltonian
The Hamiltonian is just a specific word for double derivative in this context.
- Sun Nov 01, 2020 6:16 pm
- Forum: Ionic & Covalent Bonds
- Topic: Is ionic or covalent stronger?
- Replies: 31
- Views: 15516
Re: Is ionic or covalent stronger?
Ionic bonds are stronger than covalent bonds because their difference in electronegativity is greater than that of covalent bonds.
- Sun Nov 01, 2020 2:37 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg Equation Confusion
- Replies: 9
- Views: 8834
Re: Rydberg Equation Confusion
n1 is always smaller than n2 because electrons are moving from higher energy state to a lower energy state. Therefore, n1 can be thought of as n final.
- Sun Nov 01, 2020 2:30 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Nodal planes
- Replies: 5
- Views: 217
Re: Nodal planes
A nodal plane is where the probability of finding an electron is 0 (i.e. no electrons can exist in the nodal plane). The s orbital has no nodal planes due to its spherical nature.
- Tue Oct 27, 2020 1:41 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg Equation Confusion
- Replies: 9
- Views: 8834
Re: Rydberg Equation Confusion
Nevermind, I figured it out (correct me if I'm wrong pls). The Rydberg equation for frequency uses the Rydberg constant Lavelle gave us on the equation sheet which is in Hz. On Sapling, the Rydberg constant (1.0974 x 10^7 m^-1) is for the wavelength equation. Tl;dr: Two different equations with two ...
- Tue Oct 27, 2020 1:28 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg Equation Confusion
- Replies: 9
- Views: 8834
Rydberg Equation Confusion
To my understanding, the Rydberg Equation for wavelength is: https://cdn.shopify.com/s/files/1/0093/2298/7617/files/Screen_Shot_2019-08-09_at_2.30.14_PM.png?v=1565325071 so how was the equation for frequency (below) obtained on the Constants and Equations sheet by Lavelle? https://i.imgur.com/RKxSit...
- Sun Oct 25, 2020 11:57 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Amplitude
- Replies: 16
- Views: 669
Re: Amplitude
Increasing the amplitude only increases the intensity. It does not affect wavelength or frequency.
- Sun Oct 25, 2020 11:56 pm
- Forum: DeBroglie Equation
- Topic: Derivation of Equations on Midterm?
- Replies: 17
- Views: 531
Re: Derivation of Equations on Midterm?
We won't have to derive the equations on the midterm since it's multiple choice; I think the test would focus more on how to apply the equations and which equations to apply rather than how to derive them.
- Sun Oct 25, 2020 11:52 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Orbitals
- Replies: 9
- Views: 265
Re: Orbitals
In the lecture, 5s state was an example of a silver atom's electron (5th row on ptable, n = 5) in s-orbital, hence 5s.
- Sun Oct 25, 2020 11:50 pm
- Forum: *Shrodinger Equation
- Topic: Schrodinger on MT
- Replies: 7
- Views: 396
Re: Schrodinger on MT
The questions will most likely be conceptual so you might want to rewatch the Shrodinger portion of lecture to review.
- Sun Oct 25, 2020 11:46 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Midterm 1
- Replies: 18
- Views: 567
Re: Midterm 1
The Heisenberg Indeterminacy concept will most likely be on the exam since he said anything up till 10/21 lecture would be on exam.
- Sun Oct 18, 2020 9:23 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric experiment vs atomic spectra
- Replies: 5
- Views: 209
Photoelectric experiment vs atomic spectra
I know Lavelle covered this in the lecture, but what is the difference between the photoelectric experiment and atomic spectra?
- Sun Oct 18, 2020 9:16 pm
- Forum: Photoelectric Effect
- Topic: photoelectric effect
- Replies: 17
- Views: 672
Re: photoelectric effect
Yes, threshold energy and work function are interchangeable.
- Sun Oct 18, 2020 9:10 pm
- Forum: Student Social/Study Group
- Topic: How are you studying?
- Replies: 204
- Views: 17408
Re: How are you studying?
I try to study with my friend for one hour each week. It's almost like having a gym buddy in terms of accountability. We both benefit from this by explaining to each other our understanding of the concepts covered and asking questions we previously didn't think of.
- Sun Oct 18, 2020 9:00 pm
- Forum: Einstein Equation
- Topic: m vs nm
- Replies: 66
- Views: 3309
Re: m vs nm
Lavelle mentioned in the lecture that it's acceptable to leave the answer in meters. I'm assuming that this also applies to exams.
- Sun Oct 18, 2020 8:59 pm
- Forum: Einstein Equation
- Topic: What are the units for E
- Replies: 16
- Views: 2816
Re: What are the units for E
Since the units for Planck's constant (h) are Joules second (J.s), the unit for E should Joules (J).