Search found 102 matches
- Fri Mar 13, 2020 9:57 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Extensive and Intensive Properties
- Replies: 12
- Views: 1062
Re: Extensive and Intensive Properties
Extensive properties change with the amount of substance available. Intensive properties do not change with the amount of substance available. For example, if I had 10g of Fe and 100g of Fe, then the amount of heat it takes to heat up 1 g or 1 mol of that substance doesn't change.
- Fri Mar 13, 2020 9:55 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: calorimetry
- Replies: 9
- Views: 659
Re: calorimetry
By regular, do you mean a constant-pressure calorimeter? This would be like an insulated styrofoam cup with an open top.
A bomb calorimeter has constant volume, so it isn't open. This is usually considered an isolated system, for no heat or matter can be exchanged with the environment.
A bomb calorimeter has constant volume, so it isn't open. This is usually considered an isolated system, for no heat or matter can be exchanged with the environment.
- Fri Mar 13, 2020 9:52 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Different electrodes
- Replies: 2
- Views: 248
Re: Different electrodes
If there is solid metal in the redox reaction (like Cu), then that can be used as the anode or cathode. If there is no solid metal (like Fe3+ to Fe2+), then a nonreactive metal like C (graphite) or Platinum should be used.
- Fri Mar 13, 2020 9:48 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Negative overall order
- Replies: 4
- Views: 630
Re: Negative overall order
I think it is rare, but if you increase the concentration of certain reactants, then the overall reaction rate will decrease.
I found an example of the conversion of ozone to oxygen here: https://www.quora.com/What-are-negative-order-reactions-And-what-are-the-examples
I found an example of the conversion of ozone to oxygen here: https://www.quora.com/What-are-negative-order-reactions-And-what-are-the-examples
- Fri Mar 13, 2020 9:43 am
- Forum: General Rate Laws
- Topic: Natural Log Rate Order
- Replies: 4
- Views: 367
Re: Natural Log Rate Order
First-order reactions have a linear relationship between time and ln([A]).
- Fri Mar 13, 2020 9:40 am
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: Test 2
- Replies: 4
- Views: 459
Re: Test 2
My TA dropped it off at her mailbox at Young Hall. Ask your TA about it
- Fri Mar 13, 2020 9:34 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: F in the equation for standard Gibbs energy
- Replies: 4
- Views: 390
Re: F in the equation for standard Gibbs energy
It is Faraday's constant and should be given in the equations sheet.
- Fri Mar 13, 2020 9:31 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Slow step of reaction?
- Replies: 5
- Views: 432
Re: Slow step of reaction?
Yes, I think the slow step is determined experimentally in real life. Then a mechanism is proposed to match it.
- Thu Mar 12, 2020 5:09 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: finding moles
- Replies: 6
- Views: 468
Re: finding moles
"n" is the number of electrons that are transferred as you balance the respective reduction and oxidation reactions.
- Thu Mar 12, 2020 5:09 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: How do you know a cell can do work?
- Replies: 7
- Views: 518
Re: How do you know a cell can do work?
There has to be some difference in the cell potential of both cells for it to do work.
- Thu Mar 12, 2020 5:07 pm
- Forum: Balancing Redox Reactions
- Topic: Test 2 Return
- Replies: 20
- Views: 1226
Re: Test 2 Return
The grades are up on MyUCLA, but I would email your TA if you want more specific information.
- Wed Mar 11, 2020 10:40 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: S = 0
- Replies: 21
- Views: 1199
Re: S = 0
Having zero entropy is theoretical. The substance must be in a perfect crystal structure at absolute zero. This would eliminate any positional entropy as well as any entropy from movement.
- Wed Mar 11, 2020 10:38 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: spontaneity
- Replies: 39
- Views: 1941
Re: spontaneity
Gibbs free energy is defined by a combination of enthalpy, temperature, and entropy. If Gibbs free energy is negative, that means the reaction is spontaneous, and if it is positive, the reaction will not be spontaneous. Note, spontaneity does NOT mean that the reaction will just proceed quickly, jus...
- Wed Mar 11, 2020 10:32 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Meaning of q=-w
- Replies: 14
- Views: 2375
Re: Meaning of q=-w
Basically, if the change in energy of the system is 0, then that means no energy is lost or gained in the system. That means that any heat is used to do work or vice versa.
- Wed Mar 11, 2020 10:30 pm
- Forum: Calculating Work of Expansion
- Topic: isobaric compression
- Replies: 7
- Views: 1673
Re: isobaric compression
The pressure of a system is not completely defined by the number of molecules in a system, but also their average kinetic energy, or temperature. Pressure can be conceptualized by molecules hitting a surface, and "pushing on it," in a way. The more collisions that there are, and the higher...
- Wed Mar 11, 2020 10:24 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Kelvin or Celsius?
- Replies: 86
- Views: 5905
Re: Kelvin or Celsius?
Kelvin. If the reaction happened at below 0°C, then the subsequent equation would be negative, having some weird consequences (i.e., negative pressure, negative volume).
- Wed Mar 11, 2020 10:23 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: HCl and NaOH producing dT
- Replies: 4
- Views: 460
Re: HCl and NaOH producing dT
The answer would be b. The amount of mols HCL and NaOH reacting would is the highest in this problem, as well as the lowest volume of liquid. Because there is less liquid in the beaker, the temperature difference would be higher.
- Wed Mar 11, 2020 10:21 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: endo/exo and temp
- Replies: 12
- Views: 1159
Re: endo/exo and temp
Using Le Chatlier's principle to simplify things, we can imagine heat as either a reactant or a product. In an exothermic reaction, heat can be treated as a product because heat is given off during an exothermic reaction. By increasing temperature, we are essentially increasing the heat available in...
- Wed Mar 11, 2020 10:19 pm
- Forum: Phase Changes & Related Calculations
- Topic: delta G0 versus delta G
- Replies: 15
- Views: 2634
Re: delta G0 versus delta G
The "°" in the equation refers to standard conditions. This means 25°C, 1 atm, 1M. If it isn't present, then the property may not be at standard conditions.
- Wed Mar 11, 2020 10:17 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Going from pKa to pH
- Replies: 10
- Views: 731
Re: Going from pKa to pH
^above, the w stands for water. kw is the equilibrium constant for water at 25°C. For the actual question, from pka, we can determine ka. Using ka, we can use an ice table, using the initial concentrations of the reactants and products to determine the [H+] concentration, and using [H+], we can dete...
- Wed Mar 11, 2020 10:13 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Approximating X
- Replies: 13
- Views: 858
Re: Approximating X
The general rule is that, if k is smaller than 10^-4, then it should be safe to assume that the change in concentration is negligible and that x can be ignored. Of course, you can always check that the difference is less than 5% to make sure.
- Wed Mar 11, 2020 10:12 pm
- Forum: Ideal Gases
- Topic: Kc vs Kp
- Replies: 109
- Views: 5079
Re: Kc vs Kp
If the reactants and products are given in units of pressure (bars, atmospheres, etc.), then use kp. If reactants and products are given in units of concentration (mol/L), then use kc.
- Wed Mar 11, 2020 10:10 pm
- Forum: Ideal Gases
- Topic: Acids and Basis: Salts
- Replies: 9
- Views: 664
Re: Acids and Basis: Salts
You can use an ICE table to help you figure out the concentrations in terms of known concentrations and changes in concentrations (usually determined in terms of 'x'). Depending on the size of k (if k is larger), then you may have to use the quadratic formula to solve for x. If the change in concent...
- Wed Mar 11, 2020 10:07 pm
- Forum: General Rate Laws
- Topic: intermediates
- Replies: 12
- Views: 744
Re: intermediates
Yes. Intermediates are molecules that are formed in one step of an overall reaction and consumed in one of the following steps. It will not show up in the overall reaction as it will cancel out once you add up the steps of the equation.
- Wed Mar 11, 2020 10:06 pm
- Forum: Second Order Reactions
- Topic: Finding out order
- Replies: 22
- Views: 1058
Re: Finding out order
Technically, yes the rate order could be determined if you know the units of k. The units for k do change for different order equations. If you check to see that the units cancel out and are equal on both sides of the equation, you should be okay.
- Wed Mar 11, 2020 10:04 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: intergrated rate law
- Replies: 9
- Views: 669
Re: intergrated rate law
They should be given on the equation sheet, so the derivation isn't necessary. Knowing how to apply it will be most likely all you need to know, but it doesn't hurt to know how to derive it.
- Wed Mar 11, 2020 10:02 pm
- Forum: First Order Reactions
- Topic: Half Life
- Replies: 13
- Views: 852
Re: Half Life
Half-life reaction rates are just a convenient way of measuring the time it takes for half the substance to decay. We could as easily have "quarter-life reaction rates," but this is more conventional. Most likely, it will just ask us to calculate the half-life of a certain substance of a g...
- Wed Mar 11, 2020 9:59 pm
- Forum: Zero Order Reactions
- Topic: 0 order
- Replies: 14
- Views: 1558
Re: 0 order
A 0 order reaction occurs when the concentration of the reactant doesn't matter. This most often happens when there is a catalyst present, and when the catalyst is catalyzing the reaction at "max" rate already, changing the concentration won't affect the overall reaction rate.
- Wed Mar 11, 2020 9:32 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: intermediate
- Replies: 26
- Views: 2085
Re: intermediate
An intermediate will appear in one of the step and be used up in a subsequent step. It will not show up in the overall reaction.
- Mon Mar 02, 2020 10:15 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Study Advice
- Replies: 73
- Views: 7207
Re: Study Advice
I personally find that taking practice tests (like Lyndon's) helps a lot with the application of these concepts, so doing problems off of the topic outlines would definitely be helpful.
- Mon Mar 02, 2020 10:09 am
- Forum: Van't Hoff Equation
- Topic: Van't Hoff
- Replies: 2
- Views: 293
Re: Van't Hoff
I think we'll be given the other components, and solving for just one of those variables.
- Mon Mar 02, 2020 10:07 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Voltage Signs for Oxidation Reactions
- Replies: 2
- Views: 156
Re: Voltage Signs for Oxidation Reactions
Yes, you reverse it for the oxidation reactions.
- Mon Mar 02, 2020 10:06 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: salt bridge
- Replies: 4
- Views: 350
Re: salt bridge
I think the salt bridge has a semi-permeable membrane that allows ions to pass through it. If the ions don't flow into the cells, then the charge wouldn't be balanced and the flow of electrons would stop almost immediately.
- Mon Mar 02, 2020 10:01 am
- Forum: Balancing Redox Reactions
- Topic: Anode and Xathod
- Replies: 9
- Views: 556
Re: Anode and Xathod
The anode is where the oxidation reaction takes place. The cathode is where the reduction reaction takes place. Typically, in cell diagrams, the anode is written on the left and the cathode is written on the right. An(ode)Ox(idation)Red(duction)Cat(ode) is an helpful tool to remember.
- Thu Jan 30, 2020 3:06 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Exothermic reaction
- Replies: 18
- Views: 740
Re: Exothermic reaction
If a reaction is exothermic, you can treat heat as a "reactant," where increasing the overall temperature will shift the equilibrium to the left, and decreasing the overall temperature will shift the reaction to the right.
- Thu Jan 30, 2020 3:04 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Negative pH
- Replies: 9
- Views: 329
Re: Negative pH
pH is simply -log([H3O+]). When the molarity of H3O+ is higher than 1 M, then the pH will begin to become negative. Acids aren't typically this strong, and there's actually a special category for such strong acids called superacids, but they aren't common.
- Thu Jan 30, 2020 3:02 pm
- Forum: Ideal Gases
- Topic: Inert Gas
- Replies: 12
- Views: 711
Re: Inert Gas
Inert gases are gases that don't react with any of the reactants or products. Noble gases are often used because they are notoriously unreactive.
- Thu Jan 30, 2020 2:58 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calorimeter q
- Replies: 2
- Views: 122
Re: Calorimeter q
When using a bomb calorimeter, we are usually measuring a change in the surroundings, and since q(system) = -q(surroundings), it'll be the opposite sign you measure in the surroundings. For example, for an exothermic reaction, you measure an increase in q of the surroundings, so q be positive for th...
- Fri Jan 24, 2020 10:29 am
- Forum: Phase Changes & Related Calculations
- Topic: Autoprotolysis
- Replies: 15
- Views: 826
Re: Autoprotolysis
It is proton transfer between two of the same molecule. For example, if we have two water molecules, one can donate a proton to the other, and result in OH- and H30+ molecules.
- Sun Jan 19, 2020 12:25 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Titration
- Replies: 1
- Views: 77
Re: Titration
That's a vague question, but a titration is a procedure to determine the concentration of an unknown acid or base using titrant of a known concentration. The titrant is added until the equivalence point is reached. Using the information on how much titrant was used, we can solve for the concentratio...
- Sun Jan 19, 2020 12:20 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Solids and Liquids
- Replies: 6
- Views: 276
Re: Solids and Liquids
Solids and liquids are essentially non-compressible, so their concentrations don't really change. Gas concentrations or ion concentrations will change though, those are the values we calculate for.
- Sun Jan 19, 2020 12:18 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Endothermic vs. exothermic
- Replies: 5
- Views: 239
Re: Endothermic vs. exothermic
If a reaction is endothermic, it means it absorbs heat when the reaction proceeds forward. Adding more heat allows more forward reactions to occur, shifting the equilibrium to the right. It something helps to think of heat as a reactant in this case, where, according to Le Chatlier's principle, addi...
- Sun Jan 12, 2020 6:28 pm
- Forum: Ideal Gases
- Topic: Ideal Gas Law
- Replies: 3
- Views: 126
Ideal Gas Law
Under what conditions does the ideal gas law deviate and why? Do we need to memorize why?
- Sun Jan 12, 2020 6:27 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: the "quick way"
- Replies: 4
- Views: 300
Re: the "quick way"
The "quick" way refers to looking at the moles of gas on each side of the equation, and when pressure changes, let's say increased, then the reaction will shift toward the side with fewer moles of gas because it "relieves" some of the pressure.
- Sun Jan 12, 2020 6:25 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: memorization
- Replies: 12
- Views: 603
Re: memorization
I don't think we'll be expected to memorize k values, and will most likely be given by the problem.
- Sun Jan 12, 2020 6:22 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Situations in which Q=K
- Replies: 7
- Views: 373
Re: Situations in which Q=K
If Q = K, then the reaction is at equilibrium.
- Sun Jan 12, 2020 6:22 pm
- Forum: Ideal Gases
- Topic: Bars vs atmospheres
- Replies: 13
- Views: 391
Re: Bars vs atmospheres
They are both units of pressure and can be interchanged through unit conversions (like pounds and kilograms).
- Sun Jan 12, 2020 6:19 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: appliction of principle
- Replies: 5
- Views: 256
Re: appliction of principle
It applies to changes in temperature, pressure (only when it changes the concentration from a change in volume), or a direct change in concentration (from adding reactants/products).
- Sun Jan 12, 2020 5:55 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Q and K
- Replies: 6
- Views: 407
Re: Q and K
K is a constant which doesn't change. Q is the reaction quotient, which is calculated the same as K, but the key difference is that k is calculated when the reaction is at equilibrium, while q doesn't have to be. q can be used to determine whether or not the equation will proceed forward or backward.
- Sun Jan 12, 2020 5:51 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Units for K
- Replies: 21
- Views: 673
Re: Units for K
K doesn't have units technically because they all cancel out, and it comes out to be just a number ratio.
- Sun Jan 12, 2020 5:50 pm
- Forum: Ideal Gases
- Topic: ICE tables
- Replies: 4
- Views: 323
Re: ICE tables
Ice tables are just to help us keep track of the molar concentrations before and after reactions occur. I stands for Initial concentration C stands for Change in concentration E stands for Equilibrium concentration We denote the change in concentration in terms 'x' usually, and solve for it to deter...
- Fri Jan 10, 2020 11:04 am
- Forum: Ideal Gases
- Topic: Difference between K and Q
- Replies: 9
- Views: 334
Re: Difference between K and Q
K, the equilibrium constant, is a constant, which at some set conditions, is a constant at equilibrium. Q is calculated the same way but is calculated to see whether the reaction proceeds forward or backward to reach equilibrium.
- Fri Dec 06, 2019 11:03 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Determining polarity from VSPER
- Replies: 4
- Views: 475
Re: Determining polarity from VSPER
You can use VSEPR to determine the shape, some of which can more easily lead to polarization than others. In general, though, you need to know the electronegativity of the atoms.
- Sun Dec 01, 2019 11:01 am
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Strength of Acids - Example from Lecture
- Replies: 6
- Views: 490
Re: Strength of Acids - Example from Lecture
Trichloroacetic acid has 3 chlorine molecules, which pull harder on the electrons because chlorine has a higher electronegativity than hydrogen does. The stability of the anion determines the strength of the acid. When either trichloroacetic acid or acetic acid loses a hydrogen ion, the oxygen is le...
- Sun Dec 01, 2019 10:56 am
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Reactions, Equilibrium
- Replies: 4
- Views: 322
Re: Reactions, Equilibrium
Remember that many chemical equations are at equilibrium, where there are forward and backward reactions happening all the tine. If a reaction is "favored to the right," the reactants will react/decay to form more products. If the reaction is "favored to the left," then the produ...
- Sun Dec 01, 2019 10:52 am
- Forum: Air Pollution & Acid Rain
- Topic: Clean Coal vs Dirty Coal?
- Replies: 16
- Views: 1482
Re: Clean Coal vs Dirty Coal?
I think it's based on the sulfur content. The higher the sulfur content of the coal, the "dirtier" it is because, when burned, it'll react with the air to create acid rain.
- Sun Dec 01, 2019 10:51 am
- Forum: Polyprotic Acids & Bases
- Topic: How can you tell
- Replies: 18
- Views: 1039
Re: How can you tell
If there's more than one H in front of the anion, let's say,
H2SO4, or H3PO4
It'll be polyprotic because there is more than 1 hydrogen in front.
H2SO4, or H3PO4
It'll be polyprotic because there is more than 1 hydrogen in front.
- Sat Nov 30, 2019 5:55 pm
- Forum: Lewis Acids & Bases
- Topic: Identifying lewis acids and bases
- Replies: 4
- Views: 239
Identifying lewis acids and bases
How can we identify lewis acids and bases?
- Sat Nov 30, 2019 5:54 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Strong acid/weak base interaction
- Replies: 1
- Views: 102
Strong acid/weak base interaction
Will we have to figure out the pH of a weak acid/strong base interaction at equilibrium?
- Sat Nov 30, 2019 5:53 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: pH vs. pOH
- Replies: 17
- Views: 2505
Re: pH vs. pOH
In most circumstances, we measure pH of a solution. It makes things easier/more standard, but we can also measure pOH. Just as pH is defined by -log[H+], pOH is defined by -log[OH-]. Because of the equilibrium constant of water, pH and pOH have an inverse relationship. pH = 14 - pOH, and pOH = 14 - ...
- Sat Nov 30, 2019 5:48 pm
- Forum: Polyprotic Acids & Bases
- Topic: polyprotic v. bronsted
- Replies: 3
- Views: 367
Re: polyprotic v. bronsted
A Bronsted acid is simply defined as a proton donor.
A polyprotic acid is an acid can give multiple H+ ions to a solution, so yes, it is considered a Bronsted acid.
A polyprotic acid is an acid can give multiple H+ ions to a solution, so yes, it is considered a Bronsted acid.
- Sat Nov 30, 2019 5:47 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: pH out of the 0-14 scale
- Replies: 2
- Views: 226
Re: pH out of the 0-14 scale
pH is a measure of the concentration of H+ ions, or more accurately, H3O+.
It's measured using the -log[H+].
The normal pH range is 1 - 14, but if the H+ concentration is higher (super acid) or lower (super base), it'll be outside that range.
It's measured using the -log[H+].
The normal pH range is 1 - 14, but if the H+ concentration is higher (super acid) or lower (super base), it'll be outside that range.
- Sat Nov 30, 2019 3:33 pm
- Forum: Biological Examples
- Topic: Cisplatin
- Replies: 3
- Views: 282
Cisplatin
Should we memorize the structure of cisplatin and transplatin? And what about hemoglobin and myoglobin?
- Sun Nov 24, 2019 1:06 am
- Forum: Biological Examples
- Topic: Biological Importance
- Replies: 6
- Views: 387
Re: Biological Importance
In class, we did discuss cisplatin and hemoglobin/myoglobin, but I think he was discussing these more to show the prevalence of coordination compounds in biological systems. It certainly wouldn't hurt to understand a little bit about how these molecules function, but I don't think we need to know th...
Re: Prefixes
What are some examples of when we would need to use this naming convention?
- Sun Nov 24, 2019 12:46 am
- Forum: Naming
- Topic: Coordination sphere
- Replies: 1
- Views: 115
Re: Coordination sphere
Ligands that are attached to the central ion (transition metal) would be considered inside the coordination sphere.
- Sun Nov 24, 2019 12:44 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Ligand
- Replies: 3
- Views: 260
Re: Ligand
They can be thought of as the electron pair donors. They attach to the transition metal to form the coordination compouds.
- Sun Nov 24, 2019 12:41 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Cation outside coordination sphere
- Replies: 2
- Views: 141
Re: Cation outside coordination sphere
The coordination sphere is made up of the ligands directly attached to the central ion.
If the coordination sphere has a net negative charge, it has the potential to attract cations to help neutralize the charge.
If the coordination sphere has a net negative charge, it has the potential to attract cations to help neutralize the charge.
- Mon Nov 18, 2019 4:27 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Stronger IMF's
- Replies: 2
- Views: 250
Re: Stronger IMF's
I can't say for certain but I believe that the number of electrons is more important than the shape. Whether it's linear or not will affect the IMF's, but I believe that, if anything, we will only have to compare molecules with the same molecular formula but different shapes, not something like this.
- Mon Nov 18, 2019 4:25 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 2
- Views: 181
Re: Bond Angles
Yes, know bond angles for shapes.
Some key numbers are: 180°, 120°, 109.5°, and 90°
Lone electron pairs will push bonds closer together, making them slightly less than what those angles would be.
Some key numbers are: 180°, 120°, 109.5°, and 90°
Lone electron pairs will push bonds closer together, making them slightly less than what those angles would be.
- Mon Nov 18, 2019 4:23 pm
- Forum: Hybridization
- Topic: Test 2
- Replies: 11
- Views: 605
Re: Test 2
Lavelle mentioned that hybridization wouldn't be on Test 2.
- Fri Nov 15, 2019 12:51 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Octahedral
- Replies: 5
- Views: 406
Re: Octahedral
All of the mentioned shapes have 6 pairs of electrons around the central atom. What differs is how many lone pairs and bonding pairs each has. Octahedral structures have 6 bonding pairs and 0 lone pairs. Square pyramidal structures have 5 bonding pairs and 1 lone pair. This one, as the name suggests...
- Fri Nov 15, 2019 12:46 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: bond angles
- Replies: 9
- Views: 616
Re: bond angles
When an atom has lone pairs of electrons, the bond angles are often written with a "less-than" symbol because lone electron pairs have a slightly higher repulsion than normal bonding pairs do, so they push them away more lone pairs, and thus a little closer to other bonding pairs.
- Mon Nov 11, 2019 12:58 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: Dipole-Dipole vs Dipole-Induced
- Replies: 2
- Views: 225
Re: Dipole-Dipole vs Dipole-Induced
There are differences. Dipole-dipole interactions are present in polar molecules that have a side with a partial negative and a side with a partial positive charge. These partial charges create attractions between the molecules. Induced-dipole induced-dipole interactions are present in all molecules...
- Mon Nov 11, 2019 12:54 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: forces and boiling points
- Replies: 6
- Views: 351
Re: forces and boiling points
The boiling point of a molecule is determined by that molecule's IMF's, or intermolecular forces. The stronger the IMF's the higher the boiling point, and the lower the IMF's the lower the boiling point. CH4 and CCl4 are similar atoms, but the key difference is that chlorine has many more electrons ...
- Mon Nov 11, 2019 12:50 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 Bonding with Elements
- Replies: 2
- Views: 131
Re: Hydrogen Bonding with Elements
Nitrogen, oxygen, and fluorine have a relatively high electronegativity. When bonded with a hydrogen atom, these atoms will typically have a stronger partial negative charge, leaving hydrogen with a stronger partial positive charge. This makes the IMF's of these molecules stronger.
- Mon Nov 11, 2019 12:46 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: difference between intermolecular forces
- Replies: 3
- Views: 202
Re: difference between intermolecular forces
Dipole-dipole interactions are attractions between polar molecules with partial charges. Hydrogen bonding is similar to dipole-dipole interactions but is considered stronger because of the presence of hydrogen, and another strongly electronegative atom (N, O, or F) For practical purposes, Lavelle sa...
- Mon Nov 11, 2019 12:40 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: London Forces??
- Replies: 3
- Views: 194
Re: London Forces??
All molecules have London forces. These forces happen as a result of the random, uneven electron distribution around molecules. The more electrons an atom has, the stronger these forces will be.
- Mon Nov 04, 2019 10:04 am
- Forum: Resonance Structures
- Topic: Octet
- Replies: 13
- Views: 854
Re: Octet
Filling the octet refers to the idea that most elements want to complete their valence shell.
The valence shell (for 2nd period, usually for elements after carbon) will be the s and p subshells, which will have 8 electrons total.
The valence shell (for 2nd period, usually for elements after carbon) will be the s and p subshells, which will have 8 electrons total.
- Mon Nov 04, 2019 10:01 am
- Forum: Lewis Structures
- Topic: Lewis Dot Structures
- Replies: 4
- Views: 173
Re: Lewis Dot Structures
I think that it's better to put one dot on each side
- Mon Nov 04, 2019 9:59 am
- Forum: Ionic & Covalent Bonds
- Topic: Strength and Length
- Replies: 18
- Views: 937
Re: Strength and Length
Longer bonds generally mean they're weaker, and shorter bonds generally mean they're stronger.
- Fri Nov 01, 2019 1:14 pm
- Forum: Bond Lengths & Energies
- Topic: Lone electron pairs weakening bonds
- Replies: 4
- Views: 171
Lone electron pairs weakening bonds
Dr. Lavelle talked about how fluorine, F2, has a weaker than expected bond strength because of lone electron pairs on neighboring atoms.
Why do lone electron pairs on neighboring atoms weaken the bonds?
Why do lone electron pairs on neighboring atoms weaken the bonds?
- Sat Oct 26, 2019 3:34 pm
- Forum: Ionic & Covalent Bonds
- Topic: Cation
- Replies: 23
- Views: 1837
Re: Cation
Cations are atoms that have lost an electron and therefore have a positive charge. Anions are atoms that have gained an electron and therefore have a negative charge. Cations and anions are important to understand because they tell us why certain things like ionic salts can form, and also has applic...
- Sat Oct 26, 2019 3:27 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron Configuration Notation
- Replies: 5
- Views: 258
Electron Configuration Notation
In high school, we would fill out the electron configuration with the order they would fill in... for example bromine: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5 ... but in Lavelle's lecture, he said that we should fill them in with respect to their energy levels... bromine: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p5 A...
- Fri Oct 25, 2019 10:35 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Sulfur bonding
- Replies: 5
- Views: 246
Sulfur bonding
In lecture today, Lavelle showed that sulfur can have 6 bonds (2 double bonds, 2 single bonds). Wouldn’t that be more than a full shell (of 8 e-)? Why is this allowed?
- Thu Oct 24, 2019 8:17 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron Configuration Exceptions
- Replies: 3
- Views: 121
Electron Configuration Exceptions
What kind of electron configuration exceptions are we expected to know? I know that Chromium and Copper will take an electron from the s subshell to stabilize the d subshell, but is there anything else we need to know?
- Sun Oct 20, 2019 11:13 pm
- Forum: Properties of Light
- Topic: speed of light and velocity
- Replies: 6
- Views: 252
Re: speed of light and velocity
Velocity and speed are often used interchangeably. None of the calculations we make in this class will necessarily require us to know the direction of light, so we just focus on the speed instead.
- Sun Oct 20, 2019 11:11 pm
- Forum: Properties of Light
- Topic: Balmer and Lyman Series
- Replies: 5
- Views: 242
Re: Balmer and Lyman Series
I believe you mean when the hydrogen electron gets excited. The lowest energy level is n=1, and it goes up from there, n = 2, 3, etc. Let's say we have an electron at n =2. When a photon with the right amount of energy hits an electron, it will excite it to a higher energy level, let's say n = 3. It...
- Sun Oct 20, 2019 10:40 pm
- Forum: Properties of Electrons
- Topic: Mass of Proton, Electron and Neutron
- Replies: 2
- Views: 153
Re: Mass of Proton, Electron and Neutron
It will be on the reference sheet. You won't need to memorize them.
- Sat Oct 19, 2019 8:28 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Magnetic Spin
- Replies: 4
- Views: 187
Magnetic Spin
Do we need to know magnetic spin for the test? Also, why is it + or - 1/2, and not a whole number?
- Sat Oct 19, 2019 8:23 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Electrostatic potential energy
- Replies: 2
- Views: 96
Re: Electrostatic potential energy
Electrostatic potential energy is essentially the force that charged particles, like protons and electrons, will "feel." Like charges will repel each other and opposite charges will attract. In multielectron systems, the net force on electrons in the outer shells is reduced due to shieldin...
- Thu Oct 17, 2019 9:11 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg constant
- Replies: 3
- Views: 156
Rydberg constant
Does the rydberg constant only work for hydrogen atoms? Or can you use it for every element to solve spectral line problems?
- Tue Oct 15, 2019 9:59 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: HW Question 1.D.13
- Replies: 3
- Views: 244
Re: HW Question 1.D.13
The question is asking for the angular quantum number, or l. In the question, they give us that n=7. n is the principal quantum number. The textbook goes more in depth about n, but for this question, they're asking for l. Given n, we can determine all the possible angular quantum numbers using the e...
- Tue Oct 15, 2019 12:48 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: 1B.25
- Replies: 2
- Views: 122
Re: 1B.25
h bar, or ℏ, is h/2π.
- Tue Oct 15, 2019 12:32 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: HW Question 1.B.27
- Replies: 2
- Views: 126
Re: HW Question 1.B.27
It's not h, it's h bar, or ℏ, which is equal to h/2π, or about 1.054457 x 10^34
- Tue Oct 15, 2019 12:30 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: HW Question 1.B.25
- Replies: 3
- Views: 148
Re: HW Question 1.B.25
The equation is ΔpΔx ≥ 1/2 ℏ.
Not that ℏ is equal to h/2π, so in essence, ΔpΔx is equal to h /π, or 1/2 ( h/2π ). I think this is where the other 1/2 came from.
Not that ℏ is equal to h/2π, so in essence, ΔpΔx is equal to h /π, or 1/2 ( h/2π ). I think this is where the other 1/2 came from.
- Tue Oct 15, 2019 12:24 am
- Forum: Properties of Light
- Topic: Angstrom
- Replies: 10
- Views: 514
Re: Angstrom
Usually leaving the answer in scientific notation (in powers of 10) is sufficient.
- Mon Sep 30, 2019 9:37 pm
- Forum: Limiting Reactant Calculations
- Topic: Methods of identifying Limiting Reactants
- Replies: 5
- Views: 832
Re: Methods of identifying Limiting Reactants
As far as I know, there isn't really any shortcut to determining the limiting reactant other than first converting the masses to moles, then comparing those numbers to the balanced chemical equation. I'm not really that efficient, I just trial and error, but this process shouldn't take too long.
- Mon Sep 30, 2019 9:31 pm
- Forum: Limiting Reactant Calculations
- Topic: Limiting Reactant Calculations in Two-Step Reactions
- Replies: 4
- Views: 774
Re: Limiting Reactant Calculations in Two-Step Reactions
It appears that both chemical equations are balanced, which makes things a bit easier. The first step is to convert both masses to moles. Given 0.036g of methane, and that the molar mass of methane is about 16g/mol, we can determine that we have about 2.25 x 10^-3 mols of methane. Given 0.108 grams ...
- Mon Sep 30, 2019 4:55 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Fundamental E Problem 1
- Replies: 3
- Views: 236
Re: Fundamental E Problem 1
Yes, in addition to knowing Avogadro's number, which is ~6.02 x 10^23, you would also need to take into account that the atom's radius is 144 pm, but its diameter would be 288 pm.