Search found 102 matches
- Tue Mar 10, 2020 12:56 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Arrhenius Equation
- Replies: 4
- Views: 329
Re: Arrhenius Equation
Through graphing the Arrhenius equation, we can see that the slope of the Arrhenius plot is proportional to the activation energy. A higher activation energy indicates a stronger temperature dependence of the rate constant.
- Tue Mar 10, 2020 12:53 am
- Forum: *Enzyme Kinetics
- Topic: How do you tell if something is a catalyst vs an intermediate?
- Replies: 16
- Views: 5615
Re: How do you tell if something is a catalyst vs an intermediate?
A catalyst needs to be there in the beginning of reaction to start reaction off. The intermediate will not appear in the beginning of a reaction because it is not a reactant. It is both formed and consumed so that it does not appear in the overall chemical equation.
- Tue Mar 10, 2020 12:51 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Kinetics v Therodynamics
- Replies: 8
- Views: 535
Re: Kinetics v Therodynamics
Thermodynamics explains whether or not a reaction will occur while kinetics explains the speed of a reaction. They are very intertwined and related to each other.
- Tue Mar 10, 2020 12:50 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: intermediate
- Replies: 26
- Views: 1874
Re: intermediate
The intermediate is both formed and consumed in the reaction but does not appear in the overall chemical equation.
- Tue Mar 10, 2020 12:49 am
- Forum: Experimental Details
- Topic: Which Experiment to Use
- Replies: 5
- Views: 1040
Re: Which Experiment to Use
If used correctly, the experiments that you choose to use should yield the same result. In other cases, there are only certain experiments that can be used to determine what the question is asking.
- Tue Mar 10, 2020 12:48 am
- Forum: Experimental Details
- Topic: determining order of reaction
- Replies: 6
- Views: 627
Re: determining order of reaction
Also, if you are given the elementary steps of a reaction, you may be able to determine the order of a reaction.
- Tue Mar 10, 2020 12:47 am
- Forum: Biological Examples
- Topic: Catalysts
- Replies: 7
- Views: 793
Re: Catalysts
Dr. Lavelle also noted the difference between intermediates and catalysts in which catalysts are initially there and then reformed while intermediates are created and consumed in the reaction.
- Sun Mar 08, 2020 11:16 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Bimolecular Molecularity
- Replies: 2
- Views: 236
Re: Bimolecular Molecularity
A bimolecular can have two different molecules interacting (A and B) or 2 of the same molecule interacting (A). The rate laws would be k[A][B] and k[A]^2 respectively.
- Sun Mar 08, 2020 10:29 pm
- Forum: Second Order Reactions
- Topic: half life
- Replies: 6
- Views: 340
Re: half life
Half life is the time needed for concentration to fall to half its initial value. Half life is independent of initial concentration but is inversely related to the rate constant.
- Sun Mar 08, 2020 10:26 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: A
- Replies: 8
- Views: 430
Re: A
Also, A varies by reaction but is mostly independent of temperature.
- Sun Mar 08, 2020 10:25 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: A in the Arrhenius Equation
- Replies: 8
- Views: 506
Re: A in the Arrhenius Equation
Since molecules need to collide at the correct orientation in order to react, orientation must be accounted for in the Arrhenius equation. This dependence on orientation leads to less molecules reacting than if we only accounted for collisions based on kinetic energy.
- Sun Mar 08, 2020 10:22 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Exothermic vs. Endothermic
- Replies: 10
- Views: 1800
Re: Exothermic vs. Endothermic
Endothermic and exothermic reactions both have an activation energy. But for endothermic reactions, the products have higher energy than the reactants and for exothermic reactions, the products have lower energy than the reactants.
- Sun Mar 08, 2020 10:21 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: molecularity
- Replies: 5
- Views: 332
Re: molecularity
Since termolecular was all that was discussed in class, I think so. Especially since termolecular reactions are already fairly uncommon since it requires 3 molecules to simultaneously collide.
- Sun Mar 08, 2020 10:20 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts
- Replies: 28
- Views: 1518
Re: Catalysts
Catalysts lower the activation barrier, so a greater fraction of reactants can cross the new lower barrier and convert into products.
- Sun Mar 08, 2020 6:42 pm
- Forum: General Rate Laws
- Topic: slow step
- Replies: 4
- Views: 323
Re: slow step
The molecule involved in the slow step is what determines the rate generally.
- Sun Mar 08, 2020 6:40 pm
- Forum: Second Order Reactions
- Topic: units
- Replies: 5
- Views: 607
Re: units
fYou can always solve the units for k by dividing the units for rate (mol x L^-1 x s^-1) by the units of your concentrations (which depend on the order of the reaction).
- Sun Mar 08, 2020 6:38 pm
- Forum: Second Order Reactions
- Topic: Termolecular
- Replies: 43
- Views: 2141
Re: Termolecular
Also, for termolecular reactions, the 3 molecules must simultaneously collide, so termolecular reactions are less common.
- Sun Mar 08, 2020 6:37 pm
- Forum: Second Order Reactions
- Topic: Half Life
- Replies: 7
- Views: 1217
Re: Half Life
They will likely be on the formula sheet, but if you do need to derive the formula, plug in t=1/2 to get the half life formula.
- Sun Mar 08, 2020 6:35 pm
- Forum: First Order Reactions
- Topic: Time Conversions
- Replies: 9
- Views: 1050
Re: Time Conversions
The units should be the same so that they will cancel out when doing calculations. Also, sometimes, the question will ask for the answer in a particular unit.
- Sun Mar 08, 2020 6:35 pm
- Forum: First Order Reactions
- Topic: Finding Order of Reactions
- Replies: 4
- Views: 648
Re: Finding Order of Reactions
You should get the same rate constant for different experiments if your rate law is correct. You can also do it for multiple experiments if you want to check your answers.
- Sun Mar 08, 2020 6:34 pm
- Forum: First Order Reactions
- Topic: rate constants
- Replies: 30
- Views: 1285
Re: rate constants
Rate constants will be positive, but you can still get a graph with a negative slope, such as in 1st order reactions where the slope is -k.
- Sun Mar 08, 2020 6:32 pm
- Forum: First Order Reactions
- Topic: 7B.1
- Replies: 2
- Views: 391
Re: 7B.1
Masses and concentrations are proportional. Through using the equation ln[A]t/[A]0, = -kt, we find that the proportion of [A]t to [A]0 is 1/10. So, 10% of the initial drug concentration remains in the body, which is (0.10)(20 mg) = 2.0 mg.
- Mon Mar 02, 2020 12:56 am
- Forum: Balancing Redox Reactions
- Topic: When to add H+ or H20
- Replies: 19
- Views: 2309
Re: When to add H+ or H20
Also, remember to use H+ and H2O to balance acidic solutions and OH- and H2O to balance basic solutions.
- Mon Mar 02, 2020 12:55 am
- Forum: Balancing Redox Reactions
- Topic: Anode and Cathode
- Replies: 9
- Views: 516
Re: Anode and Cathode
Also, for cell diagrams, the cathode will be depicted on the right, even if the cell reaction is not spontaneous in that direction.
- Mon Mar 02, 2020 12:54 am
- Forum: Balancing Redox Reactions
- Topic: Oxidizing/reducing agent
- Replies: 18
- Views: 992
Re: Oxidizing/reducing agent
The oxidizing agent is what is causing something else to be oxidized. So, it itself will be reduced in order for this to happen. The same is true for the reducing agent.
- Mon Mar 02, 2020 12:53 am
- Forum: Balancing Redox Reactions
- Topic: Acidic vs. Basic Solutions
- Replies: 8
- Views: 602
Re: Acidic vs. Basic Solutions
In acidic solutions, the concentration of hydronium ions that the concentration of hydroxide ions so H+ should be used to properly balance the half-rxns. So, for basic solutions, OH- should be used because this is the ion that is at a higher concentration in the solution.
- Mon Mar 02, 2020 12:51 am
- Forum: Balancing Redox Reactions
- Topic: Left and Right
- Replies: 4
- Views: 336
Re: Left and Right
This way, we can also more clearly see which atoms are being reduced and oxidized and make sure the movement of electrons is accurate.
- Sun Feb 23, 2020 11:44 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Derivations
- Replies: 5
- Views: 275
Re: Derivations
I think we only need to know how to use them, but the derivations can be helpful in understanding the concepts behind the equations.
- Sun Feb 23, 2020 11:43 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Sign of delta G
- Replies: 9
- Views: 545
Re: Sign of delta G
Yes, because one of the equations for delta G depends on Q.
- Sun Feb 23, 2020 11:42 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: applying gibbs free energy
- Replies: 5
- Views: 400
Re: applying gibbs free energy
Which equation you use can tell you different things about Gibbs free energy. Look at the different variables in each equation and use what is applicable based on the question.
- Sun Feb 23, 2020 11:41 pm
- Forum: Van't Hoff Equation
- Topic: Constants in Van’t Hoff Equation [ENDORSED]
- Replies: 4
- Views: 397
Re: Constants in Van’t Hoff Equation [ENDORSED]
The entropy and enthalpy are different at different temperatures but their delta's are the same.
- Sun Feb 23, 2020 11:40 pm
- Forum: Van't Hoff Equation
- Topic: Van’t Hoff Equation
- Replies: 11
- Views: 883
Re: Van’t Hoff Equation
The vant hoff equation can be used to calculate K at different temperatures if stand enthalpy of real lion is known.
- Sun Feb 09, 2020 10:11 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: work/energy units
- Replies: 3
- Views: 129
Re: work/energy units
Both are probably acceptable for the final answer but we may have to convert in order to do the calculations because only certain units are compatible with certain constants or values (like heat capacity)
- Sun Feb 09, 2020 10:06 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Units for heat of reaction
- Replies: 9
- Views: 235
Re: Units for heat of reaction
Also, if you keep track of units, it makes it easier to do any calculations you may need.
- Sun Feb 09, 2020 10:01 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Favorability of Endothermic Reactions
- Replies: 5
- Views: 185
Re: Favorability of Endothermic Reactions
yes, because the reaction would have more heat to absorb from the surroundings. Therefore, you can think of it as heat not being a limiting reactant.
- Sun Feb 09, 2020 9:57 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Higher the heat capacity
- Replies: 4
- Views: 107
Re: Higher the heat capacity
The heat capacity is the constant of proportionality between heat supplied to a system and temperature rise that results.
- Thu Feb 06, 2020 1:26 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: delta U
- Replies: 9
- Views: 372
Re: delta U
The equation delta U = q + w works because both heat and work are equivalent means of energy transfer.
- Thu Feb 06, 2020 1:21 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: when is w=0 and when is q=0?
- Replies: 6
- Views: 920
Re: when is w=0 and when is q=0?
Also, if w = 0, the internal energy of the system is determined only by q. If q = 0, the internal energy of the system is determined only by w.
- Thu Feb 06, 2020 1:20 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Reversible Reactions
- Replies: 5
- Views: 207
Re: Reversible Reactions
Reversible reactions in thermodynamics refer to thermal equilibrium when the temperature of the system and surroundings is the same. Thermal equilibrium is dynamic and responsive to change, even infinitesimal.
- Thu Feb 06, 2020 1:14 pm
- Forum: Phase Changes & Related Calculations
- Topic: -w vs w
- Replies: 15
- Views: 589
Re: -w vs w
the sign of w indicates whether work is being done on the system or the system is working. Remember that the sign of work is in relation to the system.
- Thu Feb 06, 2020 1:12 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Expansion work/ Compression
- Replies: 7
- Views: 336
Re: Expansion work/ Compression
Remember that the sign for work is always in regard to the system. In expansion, the system is doing the work and is therefore losing energy so work is negative. In compression, work is being done on the system, so work will be a positive value.
- Thu Feb 06, 2020 1:10 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Cp and Cv
- Replies: 10
- Views: 445
Re: Cp and Cv
I don't think we have to memorize actual values but we will have to know what they mean.
- Sun Feb 02, 2020 10:44 pm
- Forum: Phase Changes & Related Calculations
- Topic: ∆H
- Replies: 17
- Views: 581
Re: ∆H
You can also look at the temperature change of the surroundings and use that to conclude whether the reaction is exothermic or endothermic. If a reaction is exothermic, it releases heat into surroundings. If a reaction is endothermic, it absorbs heat from the surroundings.
- Sun Feb 02, 2020 10:40 pm
- Forum: Phase Changes & Related Calculations
- Topic: about system and surroundings
- Replies: 8
- Views: 327
Re: about system and surroundings
The system is the region of interest and the surroundings is everything else. So, in these cases, the thermometer and the engine would be the systems. Everything else would be the surroundings.
- Sun Feb 02, 2020 10:38 pm
- Forum: Phase Changes & Related Calculations
- Topic: State Functions
- Replies: 9
- Views: 405
Re: State Functions
A state function is a property that depends only on the current state of a system, independent on how the state was prepared. For example, internal energy, pressure, volume, temp, and density are state functions. Work and heat are not.
- Sun Feb 02, 2020 10:36 pm
- Forum: Phase Changes & Related Calculations
- Topic: internal energy
- Replies: 11
- Views: 552
Re: internal energy
Also, heat and work are equivalent means of energy transfer and are the only to change the internal energy of a system.
- Sun Feb 02, 2020 10:34 pm
- Forum: Phase Changes & Related Calculations
- Topic: Open vs Isolated System
- Replies: 15
- Views: 1241
Re: Open vs Isolated System
Also, the first law of thermodynamics states that the internal energy of an isolated system is constant. This would not be true for an open system where the system can exchange both matter and energy with the surroundings.
- Thu Jan 23, 2020 11:43 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: H20 in the ICE table
- Replies: 26
- Views: 1344
Re: H20 in the ICE table
whether we leave out water in the ICE table is dependent on the question, so make sure to read the chemical equation carefully.
- Thu Jan 23, 2020 11:42 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5% rule
- Replies: 13
- Views: 555
Re: 5% rule
The % ionization is the concentration of the molecule in the ionized state divided by the concentration of the molecule in the unionized state. If this is less than 5%, not a significant amount of the molecule ionized compared to the initial concentration.
- Thu Jan 23, 2020 11:40 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Water in K constant
- Replies: 6
- Views: 220
Re: Water in K constant
water is not included in the K constant when it is a solvent because it is viewed as pure. Liquids and solids are not included in the K constant since their concentrations do not significantly change.
- Mon Jan 20, 2020 5:47 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Relationship between pressure and volume
- Replies: 10
- Views: 357
Re: Relationship between pressure and volume
Pressure and volume are inversely proportional because conceptually, the smaller the volume/space, the less room the gases have and therefore the higher the pressure.
- Mon Jan 20, 2020 5:42 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Conjugate Acids and Bases
- Replies: 4
- Views: 207
Re: Conjugate Acids and Bases
it is also helpful to know that if there is a strong acid, it will have a weak conjugate base and a strong base will have a weak conjugate acid. Therefore, by knowing the strength of the conjugate, we can determine the strength of the acid or base.
Re: Ligands
Bidentate is a form of polydentate. Polydentate can also refer to tridentate, tetradentate. Chelating are polydentate, but polydentate is not necessarily chelating.
Re: Metals
You only use the Latin name + ate when the overall charge of the compound is negative.
- Sat Dec 07, 2019 10:22 pm
- Forum: Naming
- Topic: Explanation of overall charge of ion
- Replies: 2
- Views: 250
Re: Explanation of overall charge of ion
Each Cl inside the bracket is one negative. But also there are 2 Cl, each one negative, for a combination of -4. So, Pt must have an oxidation number of 4 for the total complex to be neutral.
- Sat Dec 07, 2019 10:19 pm
- Forum: Naming
- Topic: (en), (dien), etc.
- Replies: 6
- Views: 311
Re: (en), (dien), etc.
Both the abbreviation and the full names are acceptable for naming.
- Sat Dec 07, 2019 10:16 pm
- Forum: Biological Examples
- Topic: Chemotherapy drugs
- Replies: 7
- Views: 466
Re: Chemotherapy drugs
We should know cisplatin and how its shape affects its function
- Mon Nov 25, 2019 10:37 pm
- Forum: Naming
- Topic: Coordination compounds
- Replies: 2
- Views: 221
Re: Coordination compounds
A coordination compound is an electrically neutral compound, in which at least 1 of the ions is a complex of a central metal with other molecules attached.
- Mon Nov 25, 2019 10:35 pm
- Forum: Naming
- Topic: Correct naming conventions
- Replies: 5
- Views: 294
Re: Correct naming conventions
Also, the -ate is added to the stem of the metal's name. For example, iron would be named ferrate.
- Mon Nov 25, 2019 10:34 pm
- Forum: Naming
- Topic: roman numerals
- Replies: 7
- Views: 673
Re: roman numerals
The roman numerals refer to the oxidation number of the central metal atom or ion. It can be determined by finding the difference between the charges of the ligands and the overall charge of the molecule.
- Mon Nov 25, 2019 10:31 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: brackets
- Replies: 13
- Views: 605
Re: brackets
Anything that is outside the brackets is not bound to the central metal atom or ion.
- Mon Nov 25, 2019 10:29 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: coordination number
- Replies: 3
- Views: 130
Re: coordination number
en is bidentate, meaning it has two binding sites, so each en will contribute a coordination number of 2. edta is hexadentate, so it has 6 binding sites.
Re: adding O
i think the anionic ligands end in -o. And if the anion ends in -ide, it becomes -ido, -ate becomes -ato, and -ite becomes -ito.
- Sun Nov 24, 2019 11:11 pm
- Forum: Naming
- Topic: Metallocene
- Replies: 1
- Views: 92
Re: Metallocene
A metallocene is a "sandwich compound" in which the ligands act as the outside pieces or "bread" and the metal atom is the "filling"
- Sun Nov 24, 2019 11:08 pm
- Forum: Naming
- Topic: Cobalt vs. Cobaltate
- Replies: 4
- Views: 365
Re: Cobalt vs. Cobaltate
Additionally, sometimes the -ate is added to the stem of the metal's name not the metal name as it appears on the periodic table. For example, iron is denoted ferrate.
- Sun Nov 24, 2019 11:07 pm
- Forum: Naming
- Topic: Roman Numerals
- Replies: 3
- Views: 299
Re: Roman Numerals
If you know the charges of the other ligands or anions, and the overall charge of the molecule, you can figure out the oxidation state of the transition metal because it must add up to the overall charge.
- Sun Nov 24, 2019 11:04 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Ligands
- Replies: 4
- Views: 219
Re: Ligands
A ligand is a a Lewis base attached to the central metal atom/ion. Each ligand typically has at least 1 lone pair, which forms a coordinate covalent bond with the metal.
- Sun Nov 17, 2019 8:48 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: Boiling Points
- Replies: 7
- Views: 523
Re: Boiling Points
Boiling points increase as the strength of the intermolecular forces increases. For example, a molecule with Hydrogen bonds will likely have a higher boiling point than a molecule with only induced dipole forces because the Hydrogen bonds require more energy to break. Higher temperatures have more e...
- Sun Nov 17, 2019 8:43 pm
- Forum: Bond Lengths & Energies
- Topic: Angle for bond
- Replies: 3
- Views: 294
Re: Angle for bond
The bond angle would be less than 109.5 because the lone pair repulsion is greater than bonding pair repulsion.
- Sun Nov 17, 2019 8:41 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: formal charge
- Replies: 6
- Views: 483
Re: formal charge
Also, with enough practice, you can remember how many lone pairs and bonding pairs like to have. For example, Oxygen likes to have 2 lone pairs and 2 bonding pairs because this gives it a formal charge of zero.
- Sun Nov 17, 2019 8:40 pm
- Forum: Lewis Structures
- Topic: Drawing Lewis Structures
- Replies: 18
- Views: 590
Re: Drawing Lewis Structures
The formal charges don't necessarily have to be zero, but you should try to minimize formal charge as much as possible for a more stable molecule.
- Sun Nov 17, 2019 8:39 pm
- Forum: Dipole Moments
- Topic: Cancelling dipole moments
- Replies: 11
- Views: 4521
Re: Cancelling dipole moments
The dipoles will cancel if they are in opposite direction and of same magnitude. They will be same magnitude if they involve the same atoms. If the dipoles cancel, the resulting molecule will be non polar with polar bonds.
- Fri Nov 15, 2019 5:39 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shape v Electron Geometry
- Replies: 4
- Views: 329
Re: Molecular Shape v Electron Geometry
Lone pairs do influence molecule shape but only atom positions are used to name the shape.
- Fri Nov 15, 2019 5:36 pm
- Forum: Dipole Moments
- Topic: Can nonpolar molecules with polar bonds have dipole dipole interactions?
- Replies: 4
- Views: 320
Re: Can nonpolar molecules with polar bonds have dipole dipole interactions?
Yes, because the molecule still has dipoles. What makes the molecule non polar overall is likely that the dipoles cancel out.
- Fri Nov 15, 2019 5:35 pm
- Forum: Dipole Moments
- Topic: Polarity
- Replies: 12
- Views: 577
Re: Polarity
A polar molecule must have polar bonds and dimples that do not cancel. A non polar molecule must have zero electric dipole moment.
- Fri Nov 15, 2019 5:34 pm
- Forum: Bond Lengths & Energies
- Topic: Bond lengths
- Replies: 8
- Views: 347
Re: Bond lengths
It did say in the textbook that a single bond would not be three times longer than a triple bond or a single bond would not be two times longer than a single bond.
- Fri Nov 15, 2019 5:32 pm
- Forum: Bond Lengths & Energies
- Topic: Boiling and Melting points
- Replies: 8
- Views: 372
Re: Boiling and Melting points
I think we should just know between two molecules with different interactions, we should be able to dictate which molecule will have the higher boiling and melting point. Typically, it will be the molecule with the stronger interactions that will have higher boiling and melting points.
- Sun Nov 03, 2019 8:57 pm
- Forum: Ionic & Covalent Bonds
- Topic: Distortion
- Replies: 4
- Views: 227
Re: Distortion
When a cation exerts an electrostatic attraction on the electrons surrounding the anion, the anion's electrons are pulled into the Bonding region/internuclear area. When there is electron density in the region between the nuclei, the spherical electron cloud of the anion is no longer spherical due t...
- Sun Nov 03, 2019 8:49 pm
- Forum: Electronegativity
- Topic: Electron affinity vs electronegativity
- Replies: 4
- Views: 232
Re: Electron affinity vs electronegativity
Electronegativity has the same trend as electron affinity. However, the mathematical definition of electronegativity is Ionization Energy + Electron Affinity divided by two. In other words, electronegativity is the average between ionization energy and electron affinity.
- Sun Nov 03, 2019 8:48 pm
- Forum: Bond Lengths & Energies
- Topic: dissociation energy
- Replies: 7
- Views: 263
Re: dissociation energy
Breaking a bond requires energy since bound atoms have lower energy than free atoms. Therefore, forming a bond releases energy.
- Sun Nov 03, 2019 8:47 pm
- Forum: Resonance Structures
- Topic: Drawing Resonance Structures
- Replies: 4
- Views: 264
Re: Drawing Resonance Structures
I went to a review session, and the TA said that you can either draw all the structures and explain that the actual structure is a hybrid or for example, if it is a double bond resonance, you can draw a single line and a dotted line for the second bond to represent the resonance.
- Sun Nov 03, 2019 12:17 am
- Forum: Lewis Structures
- Topic: Lewis Structures
- Replies: 9
- Views: 451
Re: Lewis Structures
Also, you can check which Lewis structure has the lowest energy by checking the formal charges. You want the most neutral/nonzero charges as possible.
- Sat Oct 26, 2019 11:25 pm
- Forum: Properties of Light
- Topic: Threshold Frequency
- Replies: 5
- Views: 263
Re: Threshold Frequency
The threshold frequency is synonymous with work function, which is the Energy needed to remove an electron. However, each individual photon must reach this threshold frequency, dependent on wavelength, not intensity. Therefore, light is acting like a particle, not like in the wave model.
- Fri Oct 25, 2019 11:53 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Conserved in Chem Rxn
- Replies: 5
- Views: 482
Re: Conserved in Chem Rxn
Also, while this isn't directly related to what you asked, also remember that energy is conserved in a reaction as well.
- Fri Oct 25, 2019 11:52 pm
- Forum: SI Units, Unit Conversions
- Topic: Percent Yield
- Replies: 6
- Views: 399
Re: Percent Yield
Normally, the higher the percent yield (the closer to 100%), the better the experiment because that means not much reaction was stuck to the side or involved in side reactions.
- Fri Oct 25, 2019 11:50 pm
- Forum: Significant Figures
- Topic: How many significant figures are in 7.00 x 10^2?
- Replies: 25
- Views: 3413
Re: How many significant figures are in 7.00 x 10^2?
The fact that the decimal is purposefully placed in the number means that you must count the zeroes after the decimal as significant. The power of 10 is not counted when considering significant figures.
- Fri Oct 25, 2019 11:48 pm
- Forum: Balancing Chemical Reactions
- Topic: Importance of the State of Molecules
- Replies: 6
- Views: 599
Re: Importance of the State of Molecules
Also, clarifying the state of molecules can be important for molecules like water, that can exist in multiple forms.
- Fri Oct 25, 2019 11:47 pm
- Forum: SI Units, Unit Conversions
- Topic: Angstrom
- Replies: 16
- Views: 747
Re: Angstrom
Dr. Lavelle regularly uses the Angstrom to describe bond length in lecture so I think this is a good indicator that is an important unit to know, even if it is not an SI unit.
- Fri Oct 25, 2019 11:45 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: EM radiation
- Replies: 3
- Views: 329
Re: EM radiation
It may also be good to know the general trends of EM radiation. For example, gamma rays have short wavelength and high frequency while radio waves have long wavelength and low frequency with visible light in the middle.
- Fri Oct 25, 2019 11:40 pm
- Forum: DeBroglie Equation
- Topic: When to combine equations
- Replies: 10
- Views: 508
Re: When to combine equations
Combining equations will often be necessary as you normally will not have all the requirements for a certain equation given to you easily. Practicing combining equations will help you recognize when to combine.
- Fri Oct 25, 2019 11:36 pm
- Forum: Einstein Equation
- Topic: When do we use the Einstein Equation?
- Replies: 14
- Views: 707
Re: When do we use the Einstein Equation?
The equation E=hv can also easily be rearranged to be used to solve for v as well if you know Energy. Planck's constant will always be the same.
- Fri Oct 25, 2019 11:34 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Energy of Electrons
- Replies: 6
- Views: 188
Re: Energy of Electrons
Electrons have higher energy when they are at a higher energy level because it requires more energy for them to be farther from the positive pull of the nucleus.
- Fri Oct 25, 2019 11:33 pm
- Forum: Trends in The Periodic Table
- Topic: Electron Affinity
- Replies: 4
- Views: 272
Re: Electron Affinity
Is electron affinity the same as electronegativity?
- Fri Oct 25, 2019 11:32 pm
- Forum: Trends in The Periodic Table
- Topic: Ionization Energy
- Replies: 7
- Views: 509
Re: Ionization Energy
Also, electron repulsion before the first electron was removed helps keep the ionization energy lower. Once the first electron is removed, there will be less electron repulsion, so the electron will be even harder to remove.
- Fri Oct 25, 2019 11:27 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Quantum Numbers
- Replies: 7
- Views: 208
Re: Quantum Numbers
Also, no two electrons can have the same four quantum numbers. If two electrons share the first three quantum numbers (n, l, ml), their spins must be different. One will be +1/2 while the other will be -1/2.
- Fri Oct 25, 2019 11:26 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Purpose of the Equation
- Replies: 9
- Views: 286
Re: Purpose of the Equation
If one property is known, the other cannot be known simultaneously. For example, if one knows the position of an electron, it is impossible to simultaneously know the momentum.
- Fri Oct 25, 2019 11:24 pm
- Forum: Properties of Electrons
- Topic: Mass of an Electron
- Replies: 14
- Views: 463
Re: Mass of an Electron
Electrons should have the same mass in all the elements. The same goes for protons and neutrons. It is the number of each that affects the overall mass of the atom.
- Thu Oct 24, 2019 6:05 pm
- Forum: Balancing Chemical Reactions
- Topic: Balancing equations.
- Replies: 35
- Views: 2395
Re: Balancing equations.
Also, when balancing equations, you can check your work when you're done to make sure you did it right. This has helped me catch errors multiple times.
- Wed Oct 23, 2019 6:14 pm
- Forum: Electronegativity
- Topic: Electronegativity values
- Replies: 3
- Views: 170
Re: Electronegativity values
I think we just need to know the general trends of electronegativity across the periodic table. For example, electronegativity increases across a period due to the increased number of protons in nucleus.
- Wed Oct 23, 2019 6:12 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron Configuration Exceptions:
- Replies: 3
- Views: 129
Re: Electron Configuration Exceptions:
Half filled subshells and full filled subshells are more stable. For the d subshell, having 5 or 10 electrons in the subshell is favorable because it is a lower energy state.