Search found 101 matches

by Matthew Tsai 2H
Sat Mar 14, 2020 7:33 pm
Forum: General Rate Laws
Topic: average rate
Replies: 4
Views: 78

Re: average rate

The negative just means that the reactant concentration is decreasing over time, which makes sense given that they are consumed as the reaction progresses.
by Matthew Tsai 2H
Sat Mar 14, 2020 7:32 pm
Forum: General Rate Laws
Topic: Factors Affecting k
Replies: 16
Views: 156

Re: Factors Affecting k

Generally, k increases with temperature.
by Matthew Tsai 2H
Sat Mar 14, 2020 7:32 pm
Forum: General Rate Laws
Topic: rate laws
Replies: 8
Views: 125

Re: rate laws

Yes, the overall rate would depend on the slowest step.
by Matthew Tsai 2H
Sat Mar 14, 2020 6:49 pm
Forum: General Rate Laws
Topic: integrals and derivatives
Replies: 7
Views: 110

Re: integrals and derivatives

I don't believe any derivations or integrals will be tested; the formulas are all provided on the equation sheet.
by Matthew Tsai 2H
Sat Mar 14, 2020 5:46 pm
Forum: General Rate Laws
Topic: half life
Replies: 5
Views: 56

Re: half life

You would use the same integrated rate law depending on the order of reaction and set concentration to 1/4, 1/8, etc. of the initial concentration and solve for t.
by Matthew Tsai 2H
Thu Mar 05, 2020 10:05 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Electromotive force (emf)
Replies: 9
Views: 100

Electromotive force (emf)

Can someone explain what emf is exactly and if we need to know anything about it other than that it represents max work?
by Matthew Tsai 2H
Thu Mar 05, 2020 10:04 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: max work and cell potential
Replies: 3
Views: 58

Re: max work and cell potential

Assuming temperature and pressure are constant, work can only be done electrochemically. In this case, max work can be calculated as the amount of charge (signified by nF, moles of electrons*charge in coulombs per one mole of electrons) multiplied by the potential difference they are traveling acros...
by Matthew Tsai 2H
Thu Mar 05, 2020 10:02 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: reduction and oxidation
Replies: 4
Views: 53

Re: reduction and oxidation

Whichever species has the higher positive standard reduction potential will act as the oxidizing agent and be reduced.
by Matthew Tsai 2H
Thu Mar 05, 2020 10:01 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Temperature
Replies: 2
Views: 53

Re: Temperature

If the reaction is exothermic, increasing the temperature will decrease K, and if the reaction is endothermic, increasing the temperature will increase K.
by Matthew Tsai 2H
Thu Mar 05, 2020 10:00 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: lnQ vs logQ
Replies: 5
Views: 81

Re: lnQ vs logQ

I think both of these equations can basically be used interchangeably.
by Matthew Tsai 2H
Wed Feb 26, 2020 12:01 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Standard Cell Potential
Replies: 4
Views: 59

Re: Standard Cell Potential

Eo is under standard conditions, while E changes as the reaction progresses.
by Matthew Tsai 2H
Mon Feb 24, 2020 9:26 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Eo as an intensive property
Replies: 9
Views: 111

Re: Eo as an intensive property

Because intensive properties do not change when amount of substance is changed, this is most relevant when it comes to balancing redox reactions. Multiplying an entire half reaction by any constant does not change Eo.
by Matthew Tsai 2H
Mon Feb 24, 2020 9:24 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic vs. electrolytic
Replies: 4
Views: 42

Re: Galvanic vs. electrolytic

In a galvanic cell, electrons flow spontaneously, but in an electrolytic cell, electrical energy drives electron flow in the opposite direction (nonspontaneous).
by Matthew Tsai 2H
Mon Feb 24, 2020 9:22 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Maximum Potential and Voltage
Replies: 6
Views: 70

Re: Maximum Potential and Voltage

The value for the maximum electrical potential difference between the cathode and anode is the voltage of the cell.
by Matthew Tsai 2H
Mon Feb 24, 2020 9:18 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Flow of Galvanic cell
Replies: 3
Views: 32

Re: Flow of Galvanic cell

Cations from the salt bridge travel to the solution surrounding the cathode, not the cathode itself, in order to balance out the negative charge buildup in solution as positive cations are precipitated out of the solution. Otherwise, buildup of charge would prevent electrons from flowing through the...
by Matthew Tsai 2H
Mon Feb 24, 2020 9:13 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic/voltaic cell
Replies: 6
Views: 59

Re: Galvanic/voltaic cell

All galvanic cells are electrochemical cells; a galvanic cell specifically refers to an electrochemical cell in which a voltage difference across a cathode/anode drives a spontaneous redox reaction.
by Matthew Tsai 2H
Tue Feb 18, 2020 12:12 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Equilibrium
Replies: 15
Views: 137

Re: Equilibrium

Delta G is zero at equilibrium because the concentrations of products and reactants are not changing and neither the forward nor reverse reaction is favored; given that the system isn't doing work, there is nothing that would cause a change in free energy of the system.
by Matthew Tsai 2H
Tue Feb 18, 2020 12:10 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: delta G vs. delta G naught
Replies: 6
Views: 75

Re: delta G vs. delta G naught

Delta G naught is a constant for a given chemical equation (measured under standard conditions) while delta G changes as the reaction progresses and conditions change.
by Matthew Tsai 2H
Tue Feb 18, 2020 12:09 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 5G.17
Replies: 2
Views: 52

Re: 5G.17

As the reaction progresses, I is being converted to I2, which is shown as [I] decreases as [I2] increases proportionally. Eventually, once the system reaches equilibrium, the concentrations of the reactants and products remain constant.
by Matthew Tsai 2H
Tue Feb 18, 2020 12:06 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: importance of -RTlnk
Replies: 7
Views: 67

Re: importance of -RTlnk

∆Gº=-RTlnK is derived from the equation ∆G = ∆Gº + RT lnQ; if the reaction is at equilibrium and no work is being done, ∆G is equal to zero and Q=K which is where the equation comes from.
by Matthew Tsai 2H
Tue Feb 18, 2020 12:02 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: ∆G = ∆Gº + RT lnQ
Replies: 12
Views: 162

Re: ∆G = ∆Gº + RT lnQ

∆Gº refers to change in Gibbs free energy under standard conditions (usually this value will be given)
∆G refers to change in Gibbs free energy for the system (this is usually what we will be calculating for)
by Matthew Tsai 2H
Sat Feb 15, 2020 11:56 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Delta U = 0
Replies: 8
Views: 165

Re: Delta U = 0

Any time there is no change in temperature, delta U is zero.
by Matthew Tsai 2H
Sat Feb 15, 2020 11:54 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Negative work
Replies: 14
Views: 238

Re: Negative work

When a system does work, it loses energy in the process, so the value for w is negative.
by Matthew Tsai 2H
Sat Feb 15, 2020 11:53 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Meaning of q=-w
Replies: 14
Views: 264

Re: Meaning of q=-w

When the change in internal energy is zero, it means that all the heat added to the system must be used by the system to do work.
by Matthew Tsai 2H
Sat Feb 15, 2020 11:52 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Intensive and Extensive Properties
Replies: 7
Views: 143

Re: Intensive and Extensive Properties

Extensive properties depend on the amount of substance (heat capacity) while intensive properties are applicable to the substance in general (specific heat)
by Matthew Tsai 2H
Sat Feb 15, 2020 11:48 am
Forum: Calculating Work of Expansion
Topic: Positive or negative work
Replies: 15
Views: 252

Re: Positive or negative work

Generally we refer to everything from the perspective of the system, which means that positive work means that work is being done on the system. You can also think of doing work ON some system as adding energy to it, so it makes sense that work is positive.
by Matthew Tsai 2H
Tue Feb 04, 2020 8:07 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: question on lecture notes about closed system
Replies: 5
Views: 49

Re: question on lecture notes about closed system

It is important to note that the beaker does not insulate because this ensures that transfer of heat can still occur (otherwise it would be an isolated system).
by Matthew Tsai 2H
Tue Feb 04, 2020 7:59 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: closed vs isolated
Replies: 14
Views: 119

Re: closed vs isolated

The main difference is that heat exchange can still occur in a closed system but not in an isolated system.
by Matthew Tsai 2H
Tue Feb 04, 2020 7:58 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Work done BY vs work done ON
Replies: 9
Views: 84

Re: Work done BY vs work done ON

When work is done BY a system, it is using energy in order to do the work, so w is negative. When work is done ON a system, the system absorbs energy so w is positive.
by Matthew Tsai 2H
Tue Feb 04, 2020 7:57 pm
Forum: Calculating Work of Expansion
Topic: second equation
Replies: 8
Views: 52

Re: second equation

In this case, the only time you would need to integrate would be if asked to derive the equation, in which case you would need to understand each step of the integral on a conceptual level. For actual calculations you can just use the formula.
by Matthew Tsai 2H
Tue Feb 04, 2020 7:55 pm
Forum: Calculating Work of Expansion
Topic: temperature
Replies: 7
Views: 60

Re: temperature

As an example, change in temperature from 0C to 100C = 100C. If you convert to K, you get 273K to 373K = 100K.
by Matthew Tsai 2H
Sat Feb 01, 2020 6:13 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeter
Replies: 3
Views: 35

Re: Calorimeter

In the equation, q represents heat of the substance reacted inside the calorimeter and C(cal) is the heat capacity of the calorimeter. The idea is that when heat is lost by the chemical reaction, it is gained by the calorimeter and vice versa so the negative sign is necessary.
by Matthew Tsai 2H
Sat Feb 01, 2020 6:09 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Closed vs isolated systems
Replies: 24
Views: 198

Re: Closed vs isolated systems

A closed system allows for exchange of heat with its surroundings (has the ability to release and/or absorb heat) while an isolated system does not.
by Matthew Tsai 2H
Sat Feb 01, 2020 6:07 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Closed Systems
Replies: 8
Views: 88

Re: Closed Systems

The main difference is insulation. Even if a system is sealed and no exchange of matter is occurring, heat exchange can still occur (e.g. a heat pack gives off heat)
by Matthew Tsai 2H
Sat Feb 01, 2020 6:05 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: isolated system
Replies: 13
Views: 105

Re: isolated system

An example would be any sealed, insulated container. Technically insulation is never perfect, and a very minimal amount of heat exchange can still occur between system and surroundings, but not enough to have any significant impact on calculations.
by Matthew Tsai 2H
Sat Feb 01, 2020 5:00 pm
Forum: Calculating Work of Expansion
Topic: External Pressure in Reversible Expansion
Replies: 1
Views: 26

External Pressure in Reversible Expansion

What are some actual practical ways external pressure can constantly change during reversible expansion in order to remain equal to the pressure of the gas in the system?
by Matthew Tsai 2H
Thu Jan 23, 2020 12:20 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Values for pKb and pKa
Replies: 3
Views: 67

Re: Values for pKb and pKa

Low pKa and low pH are generally associated with each other, while high pKa and high pH are also associated with each other. The same is true for pKb and pOH.
by Matthew Tsai 2H
Thu Jan 23, 2020 12:18 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: H20 in the ICE table
Replies: 26
Views: 231

Re: H20 in the ICE table

H2O could be included if it is in the gas phase and you are calculating Kp. Otherwise it should be excluded if it is liquid (which most of the time it will be).
by Matthew Tsai 2H
Thu Jan 23, 2020 12:17 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Exothermic vs. Endothermic reactions
Replies: 12
Views: 418

Re: Exothermic vs. Endothermic reactions

A question that asks if a reaction is endothermic or exothermic should provide delta H, in which if delta H is positive, the reaction is endothermic and if it is negative, the reaction is exothermic.
by Matthew Tsai 2H
Thu Jan 23, 2020 12:15 am
Forum: Ideal Gases
Topic: Inert Gases and Equilibrium
Replies: 6
Views: 66

Re: Inert Gases and Equilibrium

Adding an inert gas does not affect the equilibrium constant because it does not affect the partial pressure of any reactants/products.
by Matthew Tsai 2H
Thu Jan 23, 2020 12:13 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5% rule
Replies: 13
Views: 129

Re: 5% rule

Also keep in mind x cannot be approximated to zero if it is by itself. So values like x, x^2, etc. would be kept but values like 0.1-x, 0.1+x, etc. can be approximated to 0.1
by Matthew Tsai 2H
Sat Jan 18, 2020 6:42 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Temperature Change
Replies: 9
Views: 181

Re: Temperature Change

If a reaction is endothermic (requires heat), then addition of heat drives the reaction forward because the heat is used similarly to another reactant. The same concept applies if heat is removed, or also for exothermic reactions.
by Matthew Tsai 2H
Sat Jan 18, 2020 6:35 pm
Forum: Ideal Gases
Topic: "omitting" the units
Replies: 7
Views: 113

Re: "omitting" the units

As mentioned in this thread, because the units in the numerator and the denominator are the same, you can think of K as "unitless" because it just indicates the direction and degree of reaction.
by Matthew Tsai 2H
Sat Jan 18, 2020 6:25 pm
Forum: Ideal Gases
Topic: Ideal Gas Law
Replies: 5
Views: 61

Re: Ideal Gas Law

Based on lectures/homework problems, the main use of the ideal gas law has been to convert between pressure and concentration of a gas.
by Matthew Tsai 2H
Sat Jan 18, 2020 6:23 pm
Forum: Ideal Gases
Topic: Solids and Liquids [ENDORSED]
Replies: 10
Views: 108

Re: Solids and Liquids [ENDORSED]

Regardless of conditions, solids and liquids will be pure substances with a concentration of 1, so for calculating the equilibrium constant of a reaction, they would have no effect.
by Matthew Tsai 2H
Sat Jan 18, 2020 6:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Eq. constants & solubility
Replies: 3
Views: 48

Re: Eq. constants & solubility

When given a dissolution reaction, it would make sense that if the forward reaction is favored (which means the Ksp value is high), the reactant is highly soluble.
by Matthew Tsai 2H
Wed Jan 08, 2020 7:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Small K value and Large K value
Replies: 10
Views: 107

Re: Small K value and Large K value

In lecture, Lavelle said that if the value is between the two limits neither the reactant nor the product is favored and it is in a sort of intermediate state. Does that mean that we most likely won't be asked a question on whether the reactants or products are favored if the K value falls between ...
by Matthew Tsai 2H
Wed Jan 08, 2020 7:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Partial Pressure of gas
Replies: 5
Views: 55

Re: Partial Pressure of gas

There are several units for pressure, but as long as you stay consistent with the same unit, the Kp value should be the same.
by Matthew Tsai 2H
Wed Jan 08, 2020 7:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K for Gases
Replies: 12
Views: 96

Re: K for Gases

For gases you should use Kp, because gases would have a "concentration" in the same way as aqueous solutions, as there is not really a solvent. Instead, the equivalent of concentration for a gas would be its partial pressure.
by Matthew Tsai 2H
Wed Jan 08, 2020 7:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Partial Pressure
Replies: 3
Views: 52

Re: Partial Pressure

Yes, in this case the partial pressures would be different because the moles of gas are different but the volume of the containers that they are in is the same.
by Matthew Tsai 2H
Wed Jan 08, 2020 7:03 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Partial Pressures
Replies: 4
Views: 43

Re: Partial Pressures

Nope, partial pressure can vary based on several factors (e.g. temperature, moles of gas, volume of container).
by Matthew Tsai 2H
Thu Dec 05, 2019 8:56 pm
Forum: Lewis Acids & Bases
Topic: Memorizing Charges of Transition Metals
Replies: 9
Views: 142

Re: Memorizing Charges of Transition Metals

It may be more intuitive to memorize the charges of common ligands (from the chart) and use that combined with net charge of the compound/complex in order to calculate the charge of the transition metal cation.
by Matthew Tsai 2H
Thu Dec 05, 2019 8:54 pm
Forum: Bronsted Acids & Bases
Topic: HF is a weak acid?
Replies: 8
Views: 136

Re: HF is a weak acid?

Due to the smaller size of fluorine, the H-F bond is very strong, preventing much dissociation in water and thus preventing HF from donating a proton.
by Matthew Tsai 2H
Thu Dec 05, 2019 8:53 pm
Forum: Bronsted Acids & Bases
Topic: Difference between bronsted and conjugate
Replies: 2
Views: 27

Re: Difference between bronsted and conjugate

Bronsted acids are proton donors and Bronsted bases are proton acceptors. When an acid donates its proton it becomes the conjugate base and when the base accepts the proton it becomes the conjugate acid.
by Matthew Tsai 2H
Thu Dec 05, 2019 8:48 pm
Forum: Conjugate Acids & Bases
Topic: Double Arrows
Replies: 3
Views: 65

Re: Double Arrows

Not sure if you will be penalized, but it would probably be best to get used to including double arrows for equilibrium reactions.
by Matthew Tsai 2H
Thu Dec 05, 2019 8:47 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted vs. Lewis Definitions
Replies: 2
Views: 35

Re: Bronsted vs. Lewis Definitions

The Lewis definition is just broader, so all Bronsted acids and bases will work as Lewis acids and bases as well. The only difference would be when dealing with compounds that don't have H+, in which case it would only work as a Lewis acid/base.
by Matthew Tsai 2H
Sat Nov 30, 2019 8:45 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: coordination number
Replies: 8
Views: 84

Re: coordination number

Coordination number just refers to the total number of bound ligands in the coordination sphere.
by Matthew Tsai 2H
Sat Nov 30, 2019 8:44 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligands
Replies: 3
Views: 31

Re: Ligands

A ligand must have a lone pair; otherwise it would be unable to bind to the central cation and form a coordination complex.
by Matthew Tsai 2H
Sat Nov 30, 2019 8:43 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate
Replies: 3
Views: 32

Re: Polydentate

A ligand is polydentate if it has multiple sites at which it can bind to a cation. The shape would look similar to an incomplete ring(s) with lone pairs at the ends.
by Matthew Tsai 2H
Sat Nov 30, 2019 8:41 pm
Forum: Amphoteric Compounds
Topic: compounds
Replies: 5
Views: 56

Re: compounds

Any compound is considered amphoteric if it acts as both an acid and a base, in other words it can either donate a proton or accept one (e.g. H2O)
by Matthew Tsai 2H
Sat Nov 30, 2019 8:33 pm
Forum: Lewis Acids & Bases
Topic: acid v. base?
Replies: 16
Views: 178

Re: acid v. base?

Lewis bases should have a lone pair to donate while lewis acids are usually positively charged and therefore able to accept an electron pair.
by Matthew Tsai 2H
Sun Nov 24, 2019 11:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent vs linear
Replies: 56
Views: 1125

Re: Bent vs linear

If there are either one or two electron pairs on the central atom along with the two bonded atoms, it would result in bent shape. Otherwise, the molecule would be linear in shape.
by Matthew Tsai 2H
Sun Nov 24, 2019 11:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 7
Views: 97

Re: Bond Angles

When the central atom has one or more lone pairs, the higher strength of electron pair-electron pair and electron pair-bonded pair repulsion compared to bonded pair-bonded pair repulsion results in the bonds being pushed to form smaller angles.
by Matthew Tsai 2H
Sun Nov 24, 2019 11:42 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AXE Format
Replies: 34
Views: 275

Re: AXE Format

I think it would be okay to just put AXE and the 1s would be redundant.
by Matthew Tsai 2H
Sun Nov 24, 2019 11:41 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Hydrogen Bonding
Replies: 13
Views: 153

Re: Hydrogen Bonding

Yes, generally with the conditions necessary for hydrogen bonding to occur, which is hydrogen bonded to a very electronegative atom (F, O, or N), the resulting molecule would be polar.
by Matthew Tsai 2H
Sun Nov 24, 2019 11:40 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T-shape
Replies: 21
Views: 378

Re: T-shape

You would get a T-shape with the formula AX3E2, so three bonded atoms (two along the y-axis) and one approximately perpendicular to them with two lone pairs.
by Matthew Tsai 2H
Tue Nov 12, 2019 9:37 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: Induced dipole vs dipole
Replies: 3
Views: 30

Re: Induced dipole vs dipole

An induced dipole refers to when a polar molecule induces a dipole moment in a nonpolar molecule when they are near each other. For example, if the nonpolar molecule is near a positive dipole of a polar molecule, its electrons would be attracted towards it, forming a negative dipole. While the nonpo...
by Matthew Tsai 2H
Tue Nov 12, 2019 9:29 pm
Forum: Electronegativity
Topic: dipole moments
Replies: 7
Views: 69

Re: dipole moments

If you visualize the electron cloud surrounding a molecule, it would make sense that the more electronegative atom(s) would pull the shared electrons closer to itself, forming a negative dipole moment on that region of the molecule and a positive dipole moment on the opposite end.
by Matthew Tsai 2H
Tue Nov 12, 2019 9:27 pm
Forum: Bond Lengths & Energies
Topic: Van Der Waals BP
Replies: 6
Views: 69

Re: Van Der Waals BP

Forces that affect boiling point are based on the strength of the intermolecular forces, so the ones that would most affect BP are the ones that are the strongest. So ionic interactions would have the highest effect, followed by hydrogen bonding, then ion-dipole interactions, and the last few all b...
by Matthew Tsai 2H
Tue Nov 12, 2019 9:19 pm
Forum: Dipole Moments
Topic: Strength of Interactions
Replies: 4
Views: 53

Re: Strength of Interactions

I believe h-bonding is the strongest type of intermolecular force that can exist in covalent molecules as it is the strongest dipole-dipole interaction. But in general, ion-ion attraction is the strongest intermolecular force due to the large charge difference that exists between atoms.
by Matthew Tsai 2H
Tue Nov 12, 2019 9:13 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR model
Replies: 4
Views: 174

Re: VSEPR model

VSEPR stands for Valence Shell Electron Pair Repulsion, and VSEPR theory refers to the concept that molecular shape can be determined (at least for smaller molecules) based on the number of bonded atoms and lone pairs due to their tendency to maximize distance from each other. The AXE formula just i...
by Matthew Tsai 2H
Sun Nov 10, 2019 4:53 pm
Forum: Bond Lengths & Energies
Topic: Strongest Bond
Replies: 15
Views: 168

Re: Strongest Bond

For intermolecular forces:
LDF/Van der Waals < dipole-dipole < h-bonds (the strongest type of dipole-dipole attraction)
by Matthew Tsai 2H
Sun Nov 10, 2019 4:41 pm
Forum: Dipole Moments
Topic: Polarity
Replies: 8
Views: 70

Re: Polarity

Generally, if there is a particular part of the molecule that is more electronegative and the shape of the molecule does not allow for the charges to cancel (e.g. if the structure is not symmetrical), then the molecule is polar.
by Matthew Tsai 2H
Sun Nov 10, 2019 4:39 pm
Forum: Coordinate Covalent Bonds
Topic: Coordinate Covalent Bond
Replies: 8
Views: 194

Re: Coordinate Covalent Bond

Simply put, a coordinate covalent bond occurs when one atom provides both electrons used in the bond, as opposed to one electron from each atom in a normal covalent bond.
by Matthew Tsai 2H
Sun Nov 10, 2019 4:37 pm
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 3
Views: 44

Re: Resonance Structures

The common exceptions of atoms that do not require at least a full octet are the first four elements, along with boron and aluminum. Otherwise, there aren't really any naturally occurring examples of an element that doesn't fill its octet so any resonance structures that break the rule wouldn't be v...
by Matthew Tsai 2H
Sun Nov 10, 2019 4:34 pm
Forum: Ionic & Covalent Bonds
Topic: polarizing power
Replies: 7
Views: 72

Re: polarizing power

Yes; because these elements are located in the second period, they do not have access to the empty 3d orbital and cannot hold an expanded octet.
by Matthew Tsai 2H
Sat Nov 02, 2019 3:25 pm
Forum: DeBroglie Equation
Topic: Converting mass to kilograms for de broglie
Replies: 7
Views: 58

Re: Converting mass to kilograms for de broglie

Yes, you would need to convert to kilograms because Planck's constant, h, uses kilograms.
by Matthew Tsai 2H
Sat Nov 02, 2019 3:23 pm
Forum: Quantum Numbers and The H-Atom
Topic: determining the number of orbitals
Replies: 7
Views: 107

Re: determining the number of orbitals

The quantum number that you would want to use to determine the number of orbitals in a given subshell would be l, which identifies the actual subshell: s (l=0), p (l=1), d (l=2), or f (l=3). They have 1, 3, 5, and 7 orbitals respectively.
by Matthew Tsai 2H
Sat Nov 02, 2019 3:20 pm
Forum: Photoelectric Effect
Topic: Ionization Energy vs Threshold Energy
Replies: 4
Views: 64

Re: Ionization Energy vs Threshold Energy

Threshold energy (represented by the work function) is relevant to the photoelectric effect because it refers to the energy required to remove a single electron from a certain metal surface. On the other hand, ionization energy is defined as the energy required to remove an electron from an atom in ...
by Matthew Tsai 2H
Sat Nov 02, 2019 3:17 pm
Forum: Coordinate Covalent Bonds
Topic: Difference between coordinate covalent and covalent bond
Replies: 6
Views: 3450

Re: Difference between coordinate covalent and covalent bond

In a coordinate covalent bond, one atom provides both of the bonding valence electrons.
by Matthew Tsai 2H
Sat Nov 02, 2019 3:10 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: What are the octet exceptions?
Replies: 11
Views: 127

Re: What are the octet exceptions?

Elements beyond the third row of the periodic table are able to hold extra valence electrons beyond the octet because they have an unfilled d-orbital.
by Matthew Tsai 2H
Sun Oct 27, 2019 6:20 pm
Forum: Resonance Structures
Topic: Resonance
Replies: 8
Views: 71

Re: Resonance

Resonance just refers to the concept that a single molecule is not restricted to a rigid structure. Rather, it can change into unique resonance structures.
by Matthew Tsai 2H
Sun Oct 27, 2019 6:19 pm
Forum: Lewis Structures
Topic: Lone pair
Replies: 8
Views: 77

Re: Lone pair

Yep, as previous answers stated, lone pairs just refer to a pair of electrons in an orbital that are not shared with another atom.
by Matthew Tsai 2H
Sun Oct 27, 2019 6:17 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Bonds
Replies: 11
Views: 143

Re: Covalent Bonds

Yes, covalent bonds can only be formed between two nonmetals.
by Matthew Tsai 2H
Sun Oct 27, 2019 6:15 pm
Forum: Ionic & Covalent Bonds
Topic: Valence Electrons
Replies: 16
Views: 225

Re: Valence Electrons

For the s and p block elements, the number of valence electrons is just the group number, but it can vary for the d block based on electron configuration. Charged ions may also carry extra or fewer valence electrons.
by Matthew Tsai 2H
Sun Oct 27, 2019 6:13 pm
Forum: Sigma & Pi Bonds
Topic: Single vs. Double bonds
Replies: 15
Views: 209

Re: Single vs. Double bonds

Because there are more electrons being shared between the atoms, there is a greater attractive force that pulls the atoms closer together, shortening bond length.
by Matthew Tsai 2H
Fri Oct 18, 2019 4:52 pm
Forum: Quantum Numbers and The H-Atom
Topic: Nodal Plane
Replies: 4
Views: 56

Re: Nodal Plane

A nodal plane is just a planar area in which electrons cannot be located. Due to the spherical shape of the s-orbital, it does not have any.
by Matthew Tsai 2H
Fri Oct 18, 2019 4:51 pm
Forum: Properties of Electrons
Topic: effective nuclear charge
Replies: 5
Views: 67

Re: effective nuclear charge

I don't think we will be expected to calculate a specific value for effective nuclear charge, but to conceptually understand it, effective nuclear charge can be used to determine which energy state an electron is in due to the shielding effect.
by Matthew Tsai 2H
Fri Oct 18, 2019 4:46 pm
Forum: Properties of Light
Topic: Equations and Constants
Replies: 6
Views: 100

Equations and Constants

Are there any specific equations or constants that aren't provided on the formula sheet but will be included on tests?
by Matthew Tsai 2H
Fri Oct 18, 2019 4:43 pm
Forum: Photoelectric Effect
Topic: Intensity v Frequency
Replies: 5
Views: 79

Re: Intensity v Frequency

Intensity is determined by amplitude of a wave while frequency is determined by the length (specifically how short) a wave is. In the famous photoelectric effect experiment, it was determined that the energy of light is proportional to frequency, rather than the expected which was amplitude/intensit...
by Matthew Tsai 2H
Fri Oct 18, 2019 4:39 pm
Forum: Properties of Electrons
Topic: Momentum
Replies: 11
Views: 91

Re: Momentum

Like previous answers mentioned, momentum is mass * velocity. So, if an object is moving at a slow velocity but has a large mass, it can still have a substantial momentum.
by Matthew Tsai 2H
Wed Oct 09, 2019 6:29 pm
Forum: Molarity, Solutions, Dilutions
Topic: Symbols for Molarity
Replies: 8
Views: 208

Re: Symbols for Molarity

Yes, as previous answers mentioned, they refer to the same thing. I believe "c" is used in general reference to some concentration while "M" is a more specific reference to molarity, which is a specific measure defined as mol/L.
by Matthew Tsai 2H
Wed Oct 09, 2019 6:27 pm
Forum: Significant Figures
Topic: %Mass Composition
Replies: 12
Views: 323

Re: %Mass Composition

The same rules for significant figures should still apply, and generally that would be anywhere from 4-5 sig figs based on what's given in the problem.
by Matthew Tsai 2H
Wed Oct 09, 2019 6:24 pm
Forum: Balancing Chemical Reactions
Topic: Fractions
Replies: 34
Views: 517

Re: Fractions

It's generally good practice to convert all the coefficients to integers, as that gives the most accurate representation of the chemical reaction.
by Matthew Tsai 2H
Wed Oct 09, 2019 6:06 pm
Forum: Molarity, Solutions, Dilutions
Topic: Polyatomic ions on Test 1
Replies: 4
Views: 101

Re: Polyatomic ions on Test 1

For the first test, it won't be required to have the names and formulas of polyatomic ions memorized, but I believe they will not always be provided in future tests.
by Matthew Tsai 2H
Wed Oct 09, 2019 6:04 pm
Forum: SI Units, Unit Conversions
Topic: SI Units
Replies: 2
Views: 96

Re: SI Units

One angstrom is 10^-10 meters (m), or 100 picometers (pm).
by Matthew Tsai 2H
Thu Oct 03, 2019 4:53 pm
Forum: Molarity, Solutions, Dilutions
Topic: Molarity
Replies: 9
Views: 148

Re: Molarity

Molarity is relevant when dealing with solutions. By doing molarity calculations, you can determine the moles of solute and how you may need to dilute the solution.
by Matthew Tsai 2H
Thu Oct 03, 2019 4:21 pm
Forum: Molarity, Solutions, Dilutions
Topic: Molality vs Molarity
Replies: 2
Views: 44

Re: Molality vs Molarity

Both are generally used to refer to solution concentration. Molarity, as we know, is calculated as moles of solute/L of solvent. Meanwhile, molality is moles solute/kg solvent. I think most of the time though, molarity is the preferred measurement to use.
by Matthew Tsai 2H
Thu Oct 03, 2019 4:19 pm
Forum: Molarity, Solutions, Dilutions
Topic: Molar Mass Clarification
Replies: 3
Views: 41

Re: Molar Mass Clarification

Molar mass refers to the mass in grams of one mole of a certain particle. For atoms, the molar mass is indicated on the periodic table (same as atomic mass). For molecules, just add up the molar masses of all its constituents.
by Matthew Tsai 2H
Thu Oct 03, 2019 4:14 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Avogadro's Number?
Replies: 16
Views: 367

Re: Avogadro's Number?

As the previous answers mentioned, it's just a specific name for the number 6.022 x 10^23. Generally you would just think of it as a mole.

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