## Search found 107 matches

Sun Mar 15, 2020 10:54 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Activation Energy and Energy of a Reaction
Replies: 5
Views: 102

### Re: Activation Energy and Energy of a Reaction

Because k is directly proportional to temperature, it would increase with an increase in temperature.
Sun Mar 15, 2020 10:48 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Glass Electrode
Replies: 5
Views: 97

### Re: Glass Electrode

A glass electrode is an example of an ion-selective electrode, meaning that it detects the concentration of a specific ion. pH meters are usually glass electrodes.
Sun Mar 15, 2020 10:44 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Reverse reaction rate?
Replies: 4
Views: 106

### Re: Reverse reaction rate?

Because K, the equilibrium constant, is equal to the forward rate divided by the reverse rate, knowing K and the forward rate will give you the reverse rate.
Sun Mar 15, 2020 10:42 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic and Voltaic
Replies: 5
Views: 85

### Re: Galvanic and Voltaic

They are the same type of cell, at least in the context of this class.
Sun Mar 15, 2020 10:42 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electrode Mass
Replies: 10
Views: 225

### Re: Electrode Mass

Changing the size of the electrode doesn't change cell potential, but it will change the "battery" life.
Sun Mar 15, 2020 10:40 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Affecting E cell
Replies: 4
Views: 118

### Re: Affecting E cell

Standard E cell will not change but E cell itself will change. The equation E = E* - (RT/Fn)lnQ, where Q involves concentrations of reactants and products, shows that concentration affects E cell.
Sun Mar 15, 2020 10:38 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: isochoric
Replies: 4
Views: 206

### Re: isochoric

Isochoric indicates a constant volume and isometric indicates equal dimensions.
Sun Mar 15, 2020 10:37 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Doing work vs work done
Replies: 8
Views: 163

### Re: Doing work vs work done

w is positive when work is done on the system and w is negative when the system does work.
Sun Mar 15, 2020 10:01 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Concentrations
Replies: 2
Views: 72

### Re: Concentrations

The voltage of the cell is related to the concentrations as seen by the equation E = E* - (RT/Fn)lnQ. Q is concentration-dependent, so E is concentration-dependent.
Sun Mar 15, 2020 9:50 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Gibbs free energy
Replies: 8
Views: 182

### Re: Gibbs free energy

Standard Gibbs Free Energy is defined for given reactions at standard conditions. Gibbs Free Energy is the actual energy available to do work at whichever stage of the reaction its in, and therefore changes as the reaction progresses.
Sun Mar 15, 2020 9:48 pm
Forum: Balancing Redox Reactions
Topic: Oxidation/Reduction
Replies: 17
Views: 270

### Re: Oxidation/Reduction

You only consider the atom within the molecule because although molecules do have overall charges, the oxidation number of the atom will change with respect to which molecule its in as a reactant versus as a product.
Sun Mar 15, 2020 9:42 pm
Forum: Zero Order Reactions
Topic: Units
Replies: 9
Views: 135

### Re: Units

The units for a zeroth order reaction is M/s, or mol/(L*s).
Sun Mar 15, 2020 9:39 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Fast Reactions
Replies: 4
Views: 86

### Re: Fast Reactions

Because the slowest step is the rate determining step, in the sense that it is able to be measured within a time interval, fast reactions are not included in rate laws.
Sun Mar 15, 2020 9:38 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Deriving the equation
Replies: 4
Views: 103

### Re: Deriving the equation

When you use the two delta G equations and set them equal to each other (deltaG = - RTln(K)) and (deltaG = -nFE), you can derive the Nernst equation
Mon Mar 02, 2020 10:14 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: salt bridge
Replies: 4
Views: 69

### Re: salt bridge

If there was no salt bridge, the anode solution would be very positive and the cathode solution would be very negative and the reaction would stop. The salt bridge neutralizes some of the positive ions produced in the anode using the anion of the salt and the negative ions produced at the cathode us...
Mon Mar 02, 2020 10:12 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Kelvin or Celsius?
Replies: 47
Views: 1074

### Re: Kelvin or Celsius?

It's supposed to be in Kelvin. Generally, we use Kelvin, but it is okay to use Celsius in equations involving the "change of T" since the scaling is the same for Kelvin and Celsius.
Sun Mar 01, 2020 11:23 pm
Forum: Balancing Redox Reactions
Topic: Reducing Agent
Replies: 5
Views: 87

### Re: Reducing Agent

Yes. This makes sense because the "reducing agent" is the one that causes reduction, meaning that it "gives" the reduced species electrons to gain. To "give" these electrons, it must first lose electrons, or be oxidized.
Mon Feb 24, 2020 2:32 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt bridge
Replies: 6
Views: 102

### Re: Salt bridge

The salt bridge neutralizes both solutions in a sense, so they don't quickly reach equilibrium. By "neutralizing," I mean that if a cation was being produced in one solution, the anion portion of the salt in the salt bridge would neutralize this positive charge.
Mon Feb 24, 2020 2:29 pm
Forum: Balancing Redox Reactions
Topic: Half reactions
Replies: 17
Views: 253

### Re: Half reactions

Balancing the half-reactions simply means separating the reduction process and oxidation process from the original reaction into two half-reactions, and then balancing these resulting reactions.
Mon Feb 24, 2020 2:25 pm
Forum: Balancing Redox Reactions
Topic: Oxidizing/Reducing Agent
Replies: 8
Views: 94

### Re: Oxidizing/Reducing Agent

The oxidizing agent gets reduced, which means that it gains electrons. The reducing agent gets oxidized, which means that it loses electrons.
Mon Feb 24, 2020 2:23 pm
Forum: Balancing Redox Reactions
Topic: Balancing Redox EQs
Replies: 10
Views: 132

### Re: Balancing Redox EQs

If it's an acidic solution, you add H+ ions to balance the H's. If it's a basic solution, you add H2O and OH- ions to opposite sides to the equation in equal moles to balance the H's.
Tue Feb 18, 2020 9:37 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Constant R
Replies: 15
Views: 314

### Re: Constant R

You use 8.314 when the units are J/(mol*K). You use 0.08206 when the units are (atm*L)/(mol*K).
Tue Feb 18, 2020 9:20 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Kelvin or Celsius?
Replies: 47
Views: 1074

### Re: Kelvin or Celsius?

Kelvin, because the gas constant R is usually in terms of Kelvins.
Tue Feb 18, 2020 9:20 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: converting T to kelvin
Replies: 21
Views: 387

### Re: converting T to kelvin

If the question specifies a temperature unit then use the given one. Otherwise, remember to perform your calculations with like-temperature units, so they correctly cancel out based on ratios.
Tue Feb 18, 2020 9:12 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: reaction at equilibrium
Replies: 6
Views: 91

### Re: reaction at equilibrium

No work is being done at equilibrium and delta g represents the energy left to do work. Therefore, delta g is 0.
Tue Feb 18, 2020 9:10 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Replies: 20
Views: 333

Adding inert gases increases the pressure of the system but doesn't affect the concentrations at equilibrium.
Mon Feb 10, 2020 9:41 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: X is to small
Replies: 8
Views: 157

### Re: X is to small

You can disregard x when K is less than 10^(-3) because it will be an extremely small value that won't affect your calculations. However, to ensure that you were correct in disregarding the x value, you must check if x is less than 5% of the original solution's concentration.
Mon Feb 10, 2020 9:37 pm
Forum: Phase Changes & Related Calculations
Topic: Work (w)
Replies: 8
Views: 68

### Re: Work (w)

Work isn't a state property because the energy used when doing work is different based on the path to achieve the final state. When expansion work occurs reversibly, more work is done than if it were to be done irreversibly.
Mon Feb 10, 2020 10:08 am
Forum: Ideal Gases
Topic: density
Replies: 5
Views: 202

### Re: density

Density is given in g/mL. Sometimes, the problem gives the amount of a substance in mL, and you can convert this value to grams and then moles to find the 'n' in PV=nRT.
Mon Feb 10, 2020 10:06 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: spontaneity
Replies: 18
Views: 170

### Re: spontaneity

A reaction is spontaneous when Gibbs Free Energy is negative.
Mon Feb 10, 2020 10:06 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Extensive and State properties
Replies: 3
Views: 47

### Re: Extensive and State properties

There's no direct relationship between these two concepts. State functions are simply properties that don't consider the path taken to achieve a given state, only considering the final state itself. Extensive properties are properties that change based on the amount of matter present. For example, h...
Sun Feb 02, 2020 6:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka approximation
Replies: 6
Views: 52

### Re: Ka approximation

The method for checking whether your approximation is valid is by calculating whether the percent ionization/deprotonation is less than 5%.
Sun Feb 02, 2020 6:34 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: higher entropies
Replies: 6
Views: 394

### Re: higher entropies

A high value of entropy means that there is a lot of disorder in the environment. For example, gases have a higher entropy than solids as there is increased disorder in the positions, or micro states, gases exist in. Another example is when a reaction occurs and the number of moles of substance incr...
Sun Feb 02, 2020 6:31 pm
Forum: Ideal Gases
Topic: Kc vs Kp
Replies: 43
Views: 578

### Re: Kc vs Kp

Kp is used when the quantity of gases are given in context of pressure. Kc is used when the molarity of solutions or gases are given.
Sun Feb 02, 2020 6:29 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Standard Form of molecule
Replies: 6
Views: 98

### Re: Standard Form of molecule

Standard form of the substance is the form that a substance naturally occurs as in 25 degrees Celsius and 1 atm conditions. The most important thing to remember about standard form is that some molecules exist in their diatomic form at these conditions.
Sun Feb 02, 2020 6:26 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: extensive property
Replies: 12
Views: 158

### Re: extensive property

Extensive properties are those that depend on the amount of matter. Examples include mass and volume; mass increases as the amount of matter increases, and volume does the same. Intensive properties, such as melting point and boiling point, do not depend on the amount of matter present.
Sun Feb 02, 2020 6:23 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Delta U vs Delta H
Replies: 4
Views: 38

### Re: Delta U vs Delta H

Delta U indicates internal energy, and is composed of both delta H (enthalpy) and work. When no work is done, Delta U is equal to delta H. When no energy is transferred through heat and delta H is therefore 0, then Delta U is equal to work.
Sun Feb 02, 2020 6:21 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calculating q
Replies: 5
Views: 74

### Re: Calculating q

If the heat capacity is given, the m and n aren't in the equation. This is because specific heat capacity is given per mass unit, molar heat capacity is given per mole, and heat capacity is simply J/K.
Mon Jan 20, 2020 9:47 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pH sig figs
Replies: 9
Views: 102

### Re: pH sig figs

Only the numbers after the decimal matter when determining the number of significant figures to add. For example, if two sig figs are used in the question, then the answer should have two significant figures AFTER the decimal (ex: 5.41).
Mon Jan 20, 2020 9:44 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium constants vs equilibrium of the P&R
Replies: 3
Views: 29

### Re: Equilibrium constants vs equilibrium of the P&R

It is asking whether the concentration of the products when the reaction is at equilibrium will be higher when more of the reactants are added to the reaction.
Mon Jan 20, 2020 9:43 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Inert Gas
Replies: 6
Views: 77

### Re: Inert Gas

Inert gases don't interact with anything, which indicates that the initial concentrations remain the same after the addition of the inert gas.
Mon Jan 20, 2020 9:41 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: parts of salts that don't affect pH
Replies: 4
Views: 37

### Re: parts of salts that don't affect pH

The cations and anions of strong acids and bases don't play a role in affecting pH and are not included in equilibrium concentration.
Mon Jan 20, 2020 9:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: new Kc value when combining equations
Replies: 2
Views: 36

### Re: new Kc value when combining equations

To get the new Kc, you multiple the two original Kc's together.
Mon Jan 20, 2020 9:34 pm
Forum: Polyprotic Acids & Bases
Topic: Deprotonation
Replies: 3
Views: 91

### Re: Deprotonation

Because the Ka for the second deprotonation is very small, it doesn't have a substantial effect on pH.
Sun Jan 19, 2020 11:20 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: temperature
Replies: 10
Views: 88

### Re: temperature

The equilibrium constant varies with changing temperatures.
Sun Jan 19, 2020 11:18 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: reaction quotient
Replies: 4
Views: 38

### Re: reaction quotient

Q, a variable, describes the same reactant-product relationship as K, except K is a constant where Q=K would represent the reaction at equilibrium.
Sun Jan 19, 2020 11:17 pm
Forum: Ideal Gases
Topic: Using PV=nRT
Replies: 7
Views: 71

### Re: Using PV=nRT

It is on the equation sheet but you should understand the reasoning behind the derivation of this equation.
Sun Jan 19, 2020 11:16 pm
Forum: Ideal Gases
Topic: Partial Pressures
Replies: 4
Views: 62

### Re: Partial Pressures

If the partial pressure of one of the reactants increases, then the reaction will shift right and produce more products, increasing the products' partial pressures. The partial pressure of the other reactants therefore decreases.
Mon Jan 13, 2020 9:02 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Stability
Replies: 5
Views: 188

### Re: Stability

If the forward reaction (more product produced) is naturally favored, then the product is more stable.
If the reverse reaction (more reactant produced) is naturally favored, then the product is more stable.
Mon Jan 13, 2020 9:01 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q=K
Replies: 14
Views: 160

### Re: Q=K

K is the equilibrium constant, and a reaction naturally shifts with the goal of reaching equilibrium. So, although Q is representative of the actual system, the ideal state is Q=K.
Sun Jan 12, 2020 5:33 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction shifts right or left?
Replies: 14
Views: 227

### Re: Reaction shifts right or left?

Shift left means that more reactants will be produced so the reaction progresses to Q = K.
Shift right means that more products will be produced so the reaction progresses to Q = K.
Sun Jan 12, 2020 5:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Units and Conversions of Kp
Replies: 3
Views: 39

### Re: Units and Conversions of Kp

Pascals are generally used as the unit for pressure, but the conversion is 1 bar=10^5 Pa
Sun Jan 12, 2020 5:30 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: the "quick way"
Replies: 4
Views: 66

### Re: the "quick way"

The quick way you're referring to has to do with changes in pressure. The basic rule is that when pressure increases (volume decreased), the reaction will want to shift to the side (reactant vs. product) with less total moles. When pressure decreases (volume increased), the reaction will shift to th...
Sun Dec 08, 2019 7:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Linear VSEPR model
Replies: 21
Views: 508

### Re: Linear VSEPR model

Lone pairs impact the bond angle due to lone pair-bonding pair repulsion, decreasing the angle.
Sun Dec 08, 2019 7:01 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Ph and poH of weak acids
Replies: 8
Views: 96

### Re: Ph and poH of weak acids

As long as you understand the concept behind the properties of acids and their impact on pH and pOH, you will be able to answer the question as there won't be specific calculations or anything in 14A.
Sun Dec 08, 2019 7:00 pm
Forum: Bronsted Acids & Bases
Topic: Hydrogen Bonding
Replies: 16
Views: 257

### Re: Hydrogen Bonding

No, it is simply an intermolecular force.
Sun Dec 08, 2019 6:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: cis vs trans
Replies: 5
Views: 187

### Re: cis vs trans

In a cis molecule, the "function" atoms/molecules (e.g. Cl in cisplatin) lie on the same side, whereas in trans molecules, they are opposite of each other.
Sun Dec 08, 2019 6:57 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: vsepr formula
Replies: 7
Views: 206

### Re: vsepr formula

It is asking for the formula AXbEc, where A is the central atom, X is a ligand (unspecific) with subscript b as the number of ligands attached to A, and E indicates a lone pair with subscript c describing the number of lone pairs on central atom A.
Sun Dec 08, 2019 6:54 pm
Forum: Naming
Topic: Abbreviations
Replies: 6
Views: 167

### Re: Abbreviations

Yes, you can use the abbreviations.
Sun Dec 08, 2019 6:53 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T-shape
Replies: 21
Views: 418

### Re: T-shape

T-shape molecule is AX3E2, indicating that there is a central atom with two axial atoms and one equatorial atom, that together resemble the letter T.
Sun Dec 08, 2019 6:51 pm
Forum: Hybridization
Topic: Pi bond
Replies: 10
Views: 249

### Re: Pi bond

Yes, because pi bonds are formed by the overlapping of two unhybridized p-orbitals.
Sun Dec 08, 2019 6:49 pm
Forum: Naming
Topic: Cisplatin
Replies: 3
Views: 121

### Re: Cisplatin

It binds to the two consecutive N atoms' lone pairs. Each G has a nitrogen atom with a lone pair and the Cl on cisplatin is attracted to it.
Sun Dec 08, 2019 6:48 pm
Forum: Sigma & Pi Bonds
Topic: How to Find Sigma Bonds and Pi Bonds
Replies: 15
Views: 444

### Re: How to Find Sigma Bonds and Pi Bonds

A single bond has one sigma bond.
A double bond has one sigma bond and one pi bond.
A triple bond has one sigma bond and two pi bonds.
Sun Dec 08, 2019 6:47 pm
Forum: Naming
Topic: -ate
Replies: 11
Views: 284

### Re: -ate

You do not have to add anything for a positively charged one.
Sun Dec 08, 2019 6:46 pm
Forum: Sigma & Pi Bonds
Topic: Ionic bond --> sigma and pi bonds
Replies: 8
Views: 355

### Re: Ionic bond --> sigma and pi bonds

NaCl is an ionic compound and therefore doesn't involve the sharing of electrons. So, there is no bond formed because a bond is the overlapping of orbitals.
Sun Dec 08, 2019 6:45 pm
Forum: Amphoteric Compounds
Topic: Amphiprotic
Replies: 7
Views: 192

### Re: Amphiprotic

An amphiprotic molecule can act as both an acid and a base.
Sun Dec 01, 2019 3:28 pm
Forum: Sigma & Pi Bonds
Topic: Ionic bond --> sigma and pi bonds
Replies: 8
Views: 355

### Re: Ionic bond --> sigma and pi bonds

Sigma or pi bonds are not formed in an ionic compound because sigma and pi bonds are the result of the sharing (and therefore overlapping) of electrons in only covalent compounds.
Sun Dec 01, 2019 3:25 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Strong vs Weak Acids
Replies: 7
Views: 141

### Re: Strong vs Weak Acids

Strong acids almost completely dissociate into the ions, whereas weak acids only partially dissociate into the respective ions.
Sun Dec 01, 2019 3:20 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Kb
Replies: 2
Views: 41

### Re: Kb

Kb is the base dissociation constant, so the higher the value is, the stronger the base is. Kb multiplied by Ka should give Kw, the dissociation constant for water (at equilibrium). So, Kb = Kw/Ka.
Sun Dec 01, 2019 3:17 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: What is kA value?
Replies: 5
Views: 95

### Re: What is kA value?

The value of kA is the acid disassociation constant for a reaction at equilibrium. Essentially, this means that kA is the ratio of concentration of products (multiplied) to concentration of reactants (multiplied) when these values are in the equilibrium state.
Sun Dec 01, 2019 3:05 pm
Forum: Calculating the pH of Salt Solutions
Topic: pH of acids
Replies: 13
Views: 678

### Re: pH of acids

The lower the pH is, the stronger the acid is. This is because pH decreases with the increase of H+ ion concentration, and a greater presence of H+ when compared to OH- indicates base-like properties.
Sun Dec 01, 2019 3:03 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Value of pH
Replies: 8
Views: 96

### Re: Value of pH

Yes, this is possible when the H+ concentration is greater than 1.
Sat Nov 23, 2019 9:06 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Interaction Potential Energy
Replies: 5
Views: 60

### Re: Interaction Potential Energy

Interaction potential energy relies on the charges of the two molecules and the distance between them. As distance increases, potential energy decreases. As charges of the molecules increase, potential energy also increases. This can be seen by the relationships in the equation.
Sat Nov 23, 2019 9:02 pm
Forum: Sigma & Pi Bonds
Topic: How to Find Sigma Bonds and Pi Bonds
Replies: 15
Views: 444

### Re: How to Find Sigma Bonds and Pi Bonds

A single bond is a sigma bond. A double bond is one sigma bond and one pi bond. A triple bond is one sigma bond and two pi bonds.
Sat Nov 23, 2019 9:01 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: Best Approach to Find IMFs
Replies: 11
Views: 218

### Re: Best Approach to Find IMFs

I start out by drawing a Lewis structure and determining whether the compound is polar. If it's polar, it will experience dipole-dipole interactions. If it has an H bonded to an F, O, or N, it experiences H-bonding. If it's non polar, it only experiences London Dispersion Forces.
Sat Nov 23, 2019 9:00 pm
Forum: Resonance Structures
Topic: Resonance and Naming
Replies: 11
Views: 298

### Re: Resonance and Naming

No, because it is the same compound and resonance isn't reality. Reality is the intermediate of all the resonance structures.
Sat Nov 23, 2019 8:59 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 bond Strength
Replies: 3
Views: 68

### Re: Hydrogen bond Strength

Hydrogen bonding is the strongest form of dipole-dipole interaction. London dispersion forces are the weakest form in a sense as it is the result of two induced dipoles interacting.
Sat Nov 16, 2019 4:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: All VSEPR structures or just ones from class?
Replies: 11
Views: 197

### Re: All VSEPR structures or just ones from class?

Try not to memorize but to visualize all the VSEPR structures. Understand the mechanisms behind each structure and it'll be easier to remember all of them.
Sat Nov 16, 2019 4:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent or Angular
Replies: 13
Views: 343

### Re: Bent or Angular

"Bent" and "angular" are the same shape, but I believe "angular" is the preferred term for this class since the solutions manual refers to the shape as "angular."
Sat Nov 16, 2019 4:32 pm
Forum: Lewis Structures
Topic: Balanced Lewis Structures
Replies: 6
Views: 98

### Re: Balanced Lewis Structures

It doesn't matter if an atom is bonded vertically or horizontally to the central atom per say, but those could be the different resonance structures for the same molecule. The structure that is most stable is the one with formal charges closest to zero and the negative formal charges being on the mo...
Sat Nov 16, 2019 4:17 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: polar vs nonpolar
Replies: 6
Views: 80

### Re: polar vs nonpolar

You usually cannot simply look at the molecular formula and determine its polarity. It's important to look at the lewis structure, and even the molecular shape. For example, the lewis structure for CH2Cl2 seems symmetrical from a 2-D perspective; however, because it is tetrahedral, the dipoles don't...
Sat Nov 16, 2019 4:15 pm
Forum: Ionic & Covalent Bonds
Topic: Polarity
Replies: 6
Views: 87

### Re: Polarity

A molecule is polar if there are dipoles that don't cancel each other out, making a specific part of the molecule more prone to having a higher electron density (usually near a more electronegative atom). A simpler way to look at this is determining whether the molecule is symmetrical (the element o...
Sun Nov 03, 2019 9:18 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic vs Covalent
Replies: 14
Views: 217

### Re: Ionic vs Covalent

An electronegativity difference of more than 2.5 indicates that the bond is ionic. An electronegativity difference less than 1.5 indicates that the bond is covalent. An electronegativity difference between 1.5 and 2.5 indicates that the bond has ionic and covalent character.
Sun Nov 03, 2019 9:09 pm
Forum: Quantum Numbers and The H-Atom
Topic: Rules for n, l,m
Replies: 11
Views: 180

### Re: Rules for n, l,m

n is the energy level of the electron. l is the number of subshells and describes the shape of the orbital, and can have the value of 0, 1,...(n-1). ml describes the orientation of the orbital, and its values range from -l to l. ms describes the direction of spin of the electron, and can be 1/2 or -...
Sun Nov 03, 2019 8:55 pm
Forum: Ionic & Covalent Bonds
Topic: middle atom
Replies: 13
Views: 105

### Re: middle atom

The central atom is typically the least electronegative atom.
Sun Nov 03, 2019 8:36 pm
Forum: Sigma & Pi Bonds
Topic: Quantum Numbers
Replies: 9
Views: 150

### Re: Quantum Numbers

The four quantum numbers are used to essentially describe an electron. 'n' describes its energy shell, 'l' describes the shape that electron density can be found in, 'ml' describes its orientation, and 'ms' describes spin state.
Sun Nov 03, 2019 8:22 pm
Forum: Lewis Structures
Topic: Resonance Structure
Replies: 4
Views: 60

### Re: Resonance Structure

Yes, usually you have to draw all the resonance structures and indicate the most stable one, or the one with the least formal charge.
Sun Oct 27, 2019 12:43 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 6
Views: 101

### Re: Electron Affinity

When electron affinity is negative, it indicates that energy was released which means an electron was added. When electron affinity is positive, it indicates that energy was absorbed, which is required when actually producing an anion.
Sun Oct 27, 2019 12:39 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Ionization Energy
Replies: 4
Views: 47

### Re: Ionization Energy

It is harder to remove a second electron because removing the first electron gave the atom (now ion) a positive charge. This indicates that the pull of the nucleus is strong because less electrons means less electron-electron repulsion, resulting in the radii slightly decreasing, and therefore causi...
Sun Oct 27, 2019 12:35 pm
Forum: Hybridization
Topic: Electrons
Replies: 13
Views: 677

### Re: Electrons

Electron promotion occurs when an electron is excited (absorbs energy from a photon) and jumps to a higher energy level.
Sun Oct 27, 2019 12:30 pm
Forum: Trends in The Periodic Table
Replies: 11
Views: 148

Yes - essentially, the more electrons there are, the more electron repulsion there is. This inherently increases the radius. However, there are more factors affecting this than the number of electrons, such as the pull of the nucleus which is determined by the number of protons and the number of cor...
Sun Oct 27, 2019 12:29 pm
Forum: Lewis Structures
Topic: Expanded Octet
Replies: 6
Views: 74

### Re: Expanded Octet

An atom (ex: P, S) is said to have an expanded valence shell if it has more than an octet (8 valence electrons). This is only possible when the valence shell has enough orbitals to "make space" for the extra electrons.
Sun Oct 20, 2019 11:24 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Multi-electron atoms
Replies: 7
Views: 86

### Re: Multi-electron atoms

Yes, the one-electron model is only applicable to H-atoms. All other atoms will have more than 1 electron, rendering it a multi-electron atom.
Sun Oct 20, 2019 11:21 pm
Forum: Properties of Light
Topic: speed of light and velocity
Replies: 6
Views: 77

### Re: speed of light and velocity

"c" (speed of light) can never be replaced by "v" (velocity) because "c" is a constant which is known and "v" is a variable which is unknown.
Sun Oct 20, 2019 11:08 pm
Forum: Einstein Equation
Topic: energy emitted by H electrons
Replies: 5
Views: 113

### Re: energy emitted by H electrons

Yes, that equation is specific to a "one-electron" model, and this model is only possible with a hydrogen atom.
Sun Oct 20, 2019 11:07 pm
Forum: Properties of Light
Topic: What are the units of hertz
Replies: 41
Views: 516

### Re: What are the units of hertz

Hertz essentially indicates how many "cycles" of the wave have passed a certain point in one second. In simple terms, 1Hz = 1cycle/second. The "cycle" is implied.
Sun Oct 20, 2019 11:05 pm
Forum: Photoelectric Effect
Topic: Speed of Light
Replies: 29
Views: 340

### Re: Speed of Light

Yes, the speed of light (2.998*10^8 m/s) is always a constant, as long as this light is traveling in a vacuum-like medium.
Sun Oct 13, 2019 9:45 pm
Forum: Photoelectric Effect
Topic: Waves
Replies: 4
Views: 47

### Re: Waves

Wavelength and frequency have an inverse relationship. Amplitude is unrelated, but an increase in amplitude indicates an increase in the intensity of the energy.
Sun Oct 13, 2019 9:41 pm
Forum: Properties of Light
Topic: Frequency vs. Intensity
Replies: 4
Views: 37

### Re: Frequency vs. Intensity

The intensity of light, when looking at the wave model, depends on how large the amplitude of the wave is. When looking at it based on the quantum model of light, a higher intensity means more photons are involved.
Sun Oct 13, 2019 9:39 pm
Forum: Properties of Light
Topic: Speed of light.
Replies: 10
Views: 111

### Re: Speed of light.

Speed of light is a constant depending on the medium it travels through. The "c" speed of light constant indicates the speed of light in a vacuum.