## Search found 102 matches

Fri Mar 13, 2020 8:22 am
Forum: Phase Changes & Related Calculations
Topic: phase change
Replies: 6
Views: 126

### Re: phase change

Usually the problem will tell you when a phase change occurs, or if on a phase diagram the temperature remains constant but enthalpy increases, the energy in crease was used for the phase change of the compound.
Fri Mar 13, 2020 8:20 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6.57
Replies: 1
Views: 23

### 6.57

I'm having trouble understanding the half reactions of question 6.57. How do I derive the second half reaction from the first half reaction the problem gives?
Mon Mar 09, 2020 2:13 pm
Forum: Environment, Ozone, CFCs
Topic: Catalysts and angular dependence
Replies: 2
Views: 51

### Catalysts and angular dependence

Since the catalyst (more specifically an enzyme) is holding the reactant(s) in the proper position for the reacting bonds to be weakened and accessed easier, then does a catalyst also increase the a angular dependence constant (A)?
Sun Mar 08, 2020 12:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5.57
Replies: 1
Views: 37

### 5.57

Question 5.57 b asks to find the amount of NO you should add to a flask of 0.245 moles of SO3 and 0.240 moles of SO2. The K value is 6,000. The reaction is SO3 + NO --> NO2 + SO2. I'm confused as to how to set this problem up, since we're missing the concentration of NO2 and NO. Can someone help me ...
Sun Mar 08, 2020 12:17 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 5.35
Replies: 1
Views: 76

### 5.35

Question 5.35 asks to find the balanced equation from the graph it gives. Can someone explain how we would go about solving this problem?
Sun Mar 08, 2020 12:09 pm
Forum: General Rate Laws
Topic: Graphs of rate laws
Replies: 8
Views: 74

### Re: Graphs of rate laws

A first order rate law forms a linear relationship when the natural log of [A] is plotted over time. A second d order rate law forms this relationship when 1/[A] is graphed over time. We derive these relationships from the integrated rate laws of each order of reaction. Since a 0th order rxn doesn't...
Mon Mar 02, 2020 2:14 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Platinum
Replies: 2
Views: 35

### Re: Platinum

Platinum is a noble metal, meaning it is inert in electrochemical conducting. It can be used as both a cathode and an anode. We use platinum anodes/cathodes when the solution involves an aqueous product or reactant, or both in some cases. For example, a platinum conductor would be used for the half ...
Mon Mar 02, 2020 2:11 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: text problem 4J.5
Replies: 2
Views: 98

### Re: text problem 4J.5

the (1/2) N2 revers to only using a half mole of N2 (literally only one nitrogen molecule) to make one mole of NH3, which makes sense. Same applies with using (3/2) of the diatomic hydrogen to make one mole of NH3 (since 2x3=6 and 6/3=3, which lines up with the 3 hydrogen molecules in one mole of NH3)
Mon Mar 02, 2020 2:09 pm
Forum: Balancing Redox Reactions
Topic: Electrochemical series.
Replies: 4
Views: 49

### Re: Electrochemical series.

An electrochemicalical series is a list of standard potential series in order from least (most negative) to greatest (most positive)
Mon Mar 02, 2020 2:08 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Standard energy H
Replies: 1
Views: 26

### Re: Standard energy H

Since diatomic hydrogen is a stable compound, researchers chose to make this measurement equal to 0. since standard potential energy is an intensive property, we only really need to know the change in potential energy, not necessarily what the actual values are
Sun Mar 01, 2020 10:50 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6.61
Replies: 1
Views: 43

### 6.61

for question 6.61, it asks us to calculate the potential of a neuron if the ions entering the cell is 20-30x greater than the rate out. The answer book makes the assumption that the standard potential of the cell is equal to 0. Why is this assumption made?
Sun Mar 01, 2020 10:41 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6.53 of the homework
Replies: 1
Views: 25

### 6.53 of the homework

6.53 question c asks if the mass of the anode in a concentration cell were to be increased, what would the affect on the potential of the cell be. Can someone explain to me what the correct answer is. I believe the cell potential wouldn't change since the anode isn't aqueous, but I don't know If thi...
Sat Feb 29, 2020 10:16 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: No Salt Bridge
Replies: 7
Views: 86

### Re: No Salt Bridge

Since the anode is losing electrons, it will gradually build up a positive charge. As for the cathode, it is receiving electrons from the anode, and therefore gaining a negative charge
Thu Feb 27, 2020 12:19 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Additional resources: Thermodynamics
Replies: 5
Views: 141

### Re: Additional resources: Thermodynamics

Honestly for thermo, I just do as many of the cumulative questions at the end of the unit that I can. Usually they offer a wide variety of question types, and are very helpful and challenging. If you want more resources, I've used Khan academy simply to gather some more scenario practice since this ...
Thu Feb 27, 2020 12:18 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Hg and Cell Diagrams
Replies: 3
Views: 36

### Re: Hg and Cell Diagrams

I believe that liquid mercury itself can conduct electrons and act as an electrode, so it doesn't need a solid metal to act as an electrode
Sat Feb 22, 2020 4:22 pm
Forum: Balancing Redox Reactions
Topic: Balancing charge when balancing redox reactions
Replies: 1
Views: 29

### Re: Balancing charge when balancing redox reactions

I'm pretty sure the entire side gets multiplied, since what you do to one portion of the reaction should be done to the rest in order to ensure the entire reaction remains balanced
Sat Feb 22, 2020 4:21 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6N.3
Replies: 6
Views: 101

### 6N.3

I am confused at how the solution book worked this problem, specifically the making of the reaction quotient (Q). Also, the book doesn't use Faraday's constant in the Nernst Equation. Why is this, or is this suppose to happen?
Sat Feb 22, 2020 3:30 pm
Forum: Balancing Redox Reactions
Topic: Finding moles of the reaction
Replies: 4
Views: 55

### Finding moles of the reaction

I'm having trouble calculating for the moles (n) of the reaction when referring to the equation delta G= -nFE. Can someone explain how the solution book gets these numbers for the moles?
Sat Feb 22, 2020 2:50 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 5J.15
Replies: 2
Views: 55

### Re: 5J.15

Once you find delta G, you can use the delta G= delta G0 + RTln(Q) equation, or more specifically, the delta G0= -RTln(K)
Sat Feb 22, 2020 2:49 pm
Forum: Van't Hoff Equation
Topic: Van't Hoff Equation
Replies: 3
Views: 42

### Re: Van't Hoff Equation

I believe they correlate, as K1 has a specific temperature it occurs at, being T1. Same goes for K2 and T2
Mon Feb 17, 2020 8:58 am
Forum: Phase Changes & Related Calculations
Topic: Van't Hoff Eq
Replies: 8
Views: 193

### Van't Hoff Eq

For the Van't Hoff equation, should we study the relationship between how the Van 't Hoff was derived, or is it okay to simply understand the equation's relationships and assumptions with delta H and delta S?
Mon Feb 17, 2020 8:56 am
Forum: Phase Changes & Related Calculations
Topic: delta G0 versus delta G
Replies: 15
Views: 359

### delta G0 versus delta G

What Is the difference between delta G0 and delta G, and why are they both in the delta G= delta GO+RTln(K equation?
Mon Feb 17, 2020 8:54 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: sign of delta G
Replies: 9
Views: 132

### Re: sign of delta G

delta G has a relationship with the equilibrium constant through the equation delta G= -RTln(K. This means that with delta G we will be able to make calculations and therefore determine which way the equilibrium leans by analyzing the eqwuilibrium constant relative to Q
Thu Feb 13, 2020 2:02 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: reversible entropy and irreversible entropy
Replies: 1
Views: 41

### reversible entropy and irreversible entropy

I understand that for a reversible reaction, entropy change is calculated using the equation nRln(v2/v1). However, I do not know how to calculate for an irreversible reaction, or frankly what an irreversible change in entropy would involve. Can someone explain this concept?
Wed Feb 12, 2020 2:35 pm
Forum: Calculating Work of Expansion
Topic: Pizza Rolls review number 6
Replies: 2
Views: 120

### Pizza Rolls review number 6

For number 6a of the pizza rolls review, they said both the entropy and the internal energy change of the process remains at 0. Why is that?
Sun Feb 09, 2020 11:53 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Calculating q when U is not 0
Replies: 1
Views: 18

### Calculating q when U is not 0

I encountered a few problems in the book where delta U was not 0 and I was tasked with finding q, w, and delta U. For work I k now to use the equations for either a reversible or irreversible system, but I'm experiencing some confusion on how to solve for q without knowing what delta U is. Can anyon...
Sun Feb 09, 2020 11:46 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Entropy units
Replies: 7
Views: 126

### Entropy units

So for a lot of the calculations I've been seeing in the book, the solutions book plugs in the entropy value in Joules and leaves the Enthalpy value in kilojoules. The units don't match, so I'm assuming you change them to match either in joules of kJ. Is this correct?
Thu Feb 06, 2020 4:05 pm
Forum: Phase Changes & Related Calculations
Topic: 4.1
Replies: 3
Views: 30

### 4.1

For question 4.1 in the book, the question asks to calculate the energy needed to vaporize ice at -5.042 degrees C to a vapor at 150.33 degrees C. I understand how to calculate for the phases where the water is increasing in temperature, but for the phase changes, the solution book multiplies the mo...
Tue Feb 04, 2020 3:27 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D.9
Replies: 1
Views: 30

### 4D.9

For this problem, I know conceptually that I need to find the net change of the enthalpy of reaction and apply that to the 1.65g/cm^3 of TNT's density, but I don't understand how to set this up. Can someone help me out?
Tue Feb 04, 2020 3:25 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D.7
Replies: 1
Views: 22

### 4D.7

I'm having trouble understanding how to solve this problem. I understand that w=-P deltaV can be translated to w=-delta nRT, but the answer I got from this was much different than the solution.
Sat Feb 01, 2020 11:42 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated systems
Replies: 4
Views: 50

### Isolated systems

When differentiating between a closed system and an isolated system, do we assume that the insulation of a calorimeter is close to 100% effective, or should we analyze if the system's insulator will leak heat into the surroundings?
Sat Feb 01, 2020 11:39 am
Forum: Calculating Work of Expansion
Topic: The integral of pressure and the derivative of volume equation
Replies: 1
Views: 27

### The integral of pressure and the derivative of volume equation

Is the more complex equation of w=-P delta V involving reserved to reactions at equilibrium?
Sat Feb 01, 2020 11:36 am
Forum: Calculating Work of Expansion
Topic: ∆H = ∆U
Replies: 1
Views: 18

### Re: ∆H = ∆U

We get that delta H is equal to internal energy because of the equation internal energy (U)=qp+w. However, if we look at a system at constant volume, that makes qv. Therefore, we cannot make delta U equal to delta H because a system at constant volume will have a pressure change.
Tue Jan 28, 2020 2:06 pm
Forum: Phase Changes & Related Calculations
Topic: 4A.9
Replies: 4
Views: 29

### 4A.9

Cab someone explain how to work this problem? I believe one would need to figure out the amount of energy released by the copper to find out the amount of energy absorbed by the water, but I'm confused as how to perform these steps.
Tue Jan 28, 2020 2:04 pm
Forum: Phase Changes & Related Calculations
Topic: Cv and Cp
Replies: 9
Views: 94

### Cv and Cp

Dr. Lavelle said that Cp is equivalent to enthalpy change, but why is Cv not included in this?
Sat Jan 25, 2020 12:24 pm
Forum: Phase Changes & Related Calculations
Topic: 4A.1
Replies: 1
Views: 13

### Re: 4A.1

A closed system will be addressed in the problem. For example, they'll say the system has a lid or is being performed inside a sealed container. Either way, a closed system is susceptible to pressure change since the volume could change or the moles of gas could change. In an open system, pressure i...
Sat Jan 25, 2020 12:21 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: biological examples
Replies: 7
Views: 113

### Re: biological examples

I think this asks us to know about the production of ATP and its use. For example, ATP is less stable than its conjugate component, ADP. Therefore, it requires energy to make ATP, an endothermic process. I believe that's the point of the "biological examples"
Sat Jan 25, 2020 12:19 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy
Replies: 2
Views: 25

### Re: Enthalpy

Enthalpy is the change in a system's energy, typically measured as heat or work. For example, if a reaction required 500 KJ of energy to make its reactants into products, then the net change of enthalpy of the reaction would be around 500 KJ, since we used that energy purposefully to create the prod...
Sat Jan 25, 2020 12:16 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4B.1
Replies: 1
Views: 22

### Re: 4B.1

I'm assuming since energy is supplied, therefore the reaction is endothermic. Work should be an exothermic process because like releasing heat, energy is being released. In this case, the energy is being released through performing a task versus escaping as heat. I'd say the 524 KJ supplied is a pos...
Tue Jan 21, 2020 12:50 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Question 6.19
Replies: 1
Views: 24

### Question 6.19

In this problem, part a asks if lactic acid were to increase, what would happen to HbO2 in the reaction H3O+HbO2->HHb+H2O+O2 I said that HbO2 would decrease since more H3O would be produced when lactic acid dissociates. However, is my statement accurate since we don't know the Ka of lactic acid and ...
Fri Jan 17, 2020 12:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Why is there Negative pH
Replies: 1
Views: 35

### Why is there Negative pH

I understand that if your concentration of strong acid is large enough relative to the solvent, you will receive a negative pH. Why does this occur mathematically?
Fri Jan 17, 2020 12:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Negative pH
Replies: 2
Views: 28

### Re: Negative pH

You can receive a negative pH if the molarity of the strong acid is large enough. However, I do not know the mathematical reasons as to why this occurs.
Thu Jan 16, 2020 2:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka/Kb of 10^-4
Replies: 3
Views: 28

### Ka/Kb of 10^-4

I know Dr. Lavelle said to be careful with K values of 10^-4 and using the assumption rule. When is it "safer" to use the assumption rule for values of K equal to 10^-4?
Thu Jan 16, 2020 2:50 pm
Forum: Ideal Gases
Topic: 5I.15
Replies: 5
Views: 128

### Re: 5I.15

Solids are not included in the ICE table, since they aren't included in the K equation anyway. Basically for a solid and a liquid omit them from the ICE table
Fri Jan 10, 2020 12:31 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Calculating eq with percentages of reaction
Replies: 3
Views: 20

### Calculating eq with percentages of reaction

How do you use the percentages of reactions to find the eq constant?
Fri Jan 10, 2020 12:29 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Calculating eq constants with only one variable
Replies: 3
Views: 26

### Calculating eq constants with only one variable

While taking the online exams, I experienced trouble with the problems asking to calculate the eq constant with initial values and only one value at eq. Can anyone help me with this issue?
Thu Jan 09, 2020 5:49 pm
Forum: Ideal Gases
Topic: Solving for K when only given balanced equation [ENDORSED]
Replies: 6
Views: 73

### Re: Solving for K when only given balanced equation[ENDORSED]

Partial pressures can be calculated since we know the total pressure of the system.
Thu Jan 09, 2020 5:46 pm
Forum: Ideal Gases
Topic: converting Kc to Kp
Replies: 13
Views: 136

### converting Kc to Kp

when using the ideal gas equation to convert Kp to Kc, do we need to know the volume, or do we just keep our value in molar and omit knowing the volume?
Thu Jan 09, 2020 5:44 pm
Forum: Ideal Gases
Topic: Solving for K (coefficients)
Replies: 11
Views: 109

### Re: Solving for K (coefficients)

The coefficients need to be assigned to their specific molecules/compounds
Thu Jan 09, 2020 5:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K values and stability of product
Replies: 2
Views: 20

### K values and stability of product

If the K value is closer to 1 or larger, does that mean the product is more stable than the reactants?
Sat Dec 07, 2019 2:46 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: stability of conj. base oxo acids and electronegativity
Replies: 1
Views: 82

### stability of conj. base oxo acids and electronegativity

Is it okay to assume that with oxo acids, as electronegativity of the conj. base increases, the stability of the conj. base also increases?
Sat Dec 07, 2019 2:44 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelating compounds and structure
Replies: 1
Views: 46

### Chelating compounds and structure

If a compound is defined as chelating, will it always have a 2D geometry, or can it be 3D? Most chelating examples I've seen have all been square planar so I was wondering if all chelating molecules were limited to 2D.
Thu Dec 05, 2019 1:22 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate compounds
Replies: 1
Views: 54

### Polydentate compounds

When assigning the number of "dentate" bonds a compound can form, I always seem to be one off. I began to assume that one lone pair will not be counted since it'll be already bound to the metal in the compound, and started getting answers right. Is this an incorrect assumption and am I jus...
Thu Dec 05, 2019 12:44 pm
Forum: Naming
Topic: water and coord. compounds
Replies: 1
Views: 42

### water and coord. compounds

what is the difference between a compound that's hydrated and one that has the prefix "aqua?" They both have water, and I'm really confused
Thu Dec 05, 2019 12:40 pm
Forum: Naming
Topic: Iron compounds
Replies: 1
Views: 56

### Iron compounds

Are we suppose to use the name iron or ferrous when referring to a coord. compound containing iron?
Thu Dec 05, 2019 12:32 pm
Forum: Octet Exceptions
Topic: Valence Electrons for d-block Elements (Transition Metals)
Replies: 1
Views: 131

### Re: Valence Electrons for d-block Elements (Transition Metals)

Oxidation numbers tell you the charge of the metal and this how many electrons it's missing. So if you have Fe(II), you know that the iron atom is missing 2 more electrons than normal. As far as valence electrons, the transition metals have 3 orbitals (s, p, d). So you can know how many valence elec...
Thu Dec 05, 2019 12:30 pm
Forum: Conjugate Acids & Bases
Topic: buffer solutions
Replies: 5
Views: 261

### Re: buffer solutions

Since buffer solutions are technically calculating for weak acids, I don't think so. That should be a chem 14B topic.
Thu Dec 05, 2019 12:27 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg Equation use
Replies: 2
Views: 122

### Rydberg Equation use

Will we lose points on the Final if we use the Rydberg equation for potential atomic spectra problems?
Thu Dec 05, 2019 12:24 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Strength of Acids
Replies: 2
Views: 35

### Re: Strength of Acids

Electronegativity comes into play when comparing acids along a period and/or for polyatomic acids. For instance, HClO3 is stronger than HClO2 because the combine electronegativities of the oxygens in ClO3 create a more polar dipole, making the proton easier to remove. Bond length is for comparing sa...
Thu Dec 05, 2019 12:21 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Listing quantum numbers
Replies: 3
Views: 119

### Listing quantum numbers

Does it matter the order I list the quantum numbers in one descriptor?
For instance, when I list the possible L numbers, I list from positive to negative (1,0,-1). The book lists them oppositely (-1,0,1). Will I lose points for listing them "backwards?"
Fri Nov 22, 2019 11:17 am
Forum: Hybridization
Topic: sp hybridization
Replies: 4
Views: 46

### Re: sp hybridization

Since a linear molecule deals with the double bonding of 2 other atoms to the central atom, the central atom must hybridize its orbitals to include the available amount of bonding electrons. For example, CO2 has 2 c double bonded o regions. Since carbon needs 4 electrons to perform this task, it mus...
Wed Nov 20, 2019 3:28 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Boiling Point
Replies: 7
Views: 101

### Re: Boiling Point

O3 should have a higher boiling point because the bond between oxygen-oxygen is stronger than the bond between oxygen and sulfur. This is because the oxygen molecule has a smaller diameter than the sulfur atom due to having one less shell of electrons. This allows the bonding electrons to revolve cl...
Tue Nov 19, 2019 10:50 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Dissociation Energy?
Replies: 2
Views: 35

### Re: Dissociation Energy?

Dissociation energy is the energy needed to disrupt an IMF or intermolecular force, such as a hydrogen bond etc... Hydrogen bonds take more energy to disrupt than Van Der Waal's for example because hydrogen bonding involves intense dipole interactions, versus Van Der Waal's force momentary dipoles. ...
Mon Nov 18, 2019 11:12 am
Forum: Hybridization
Topic: 2.29
Replies: 1
Views: 22

### 2.29

Part b asks for the hybridization of the carbon-oxygen bond in the molecule CH4O. I understand why the carbon atom is sp3, but don't understand why the oxygen atom is also sp3 hybridized. Can someone provide an explanation?
Mon Nov 18, 2019 11:10 am
Forum: Hybridization
Topic: 2.19
Replies: 1
Views: 40

### 2.19

Part d asks for which compound (1 or 2) has a higher lattice energy and why. Compound 1 is composed of Tl2O3 and compound 2 is composed of Tl2O. I picked compound 2 as the molecule with a higher lattice energy and this is correct, but I don't understand why. Can someone help me out?
Fri Nov 15, 2019 11:08 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: nonpolar molecules
Replies: 5
Views: 42

### Re: nonpolar molecules

Nonpolar covalent bonded molecules only exhibit induced dipole forces as long as they encounter a dipole or an induced dipole. So the only forces they experience are Van Der Waal's or London Dispersion forces.
Fri Nov 15, 2019 11:07 am
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E 11: Shapes for A and B
Replies: 3
Views: 45

### Re: 2E 11: Shapes for A and B

The easiest way to classify shape is to look at the lewis structure of the molecule and determine how many lone pairs and bonding regions there are. Since regions of electron density need to be spaced out symmetrically, this leads to the molecules shape. One you know the electron lone pairs and bond...
Mon Nov 11, 2019 2:16 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: 3F5C
Replies: 3
Views: 86

### Re: 3F5C

I would also think CHF3 has a higher melting point than CHI3, since the C-F bond is a closer and therefore stronger attraction than the C-I bond. The solution book could be incorrect?? However I concur with your statement.
Mon Nov 11, 2019 2:14 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: 3F.15
Replies: 3
Views: 40

### Re: 3F.15

I believe AsF3 is a non polar molecule. The highly electronegative fluorines will direct electron density around themselves, while the lone pair around the Arsenic non bonding domain will remain. Thus, the molecule will have a net negative charge surrounding its entirety.
Mon Nov 11, 2019 1:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.11
Replies: 1
Views: 24

### 2E.11

In part d, the molecule xenon trioxide is giving me some trouble. The central atom, xenon, is able to obtain 3 double bonds and a lone pair, but this puts the atom far above the octet rule's 8 electrons. Why can xenon hold this many electrons?
Tue Nov 05, 2019 11:01 am
Forum: Resonance Structures
Topic: resonance importance?
Replies: 7
Views: 97

### Re: resonance importance?

Resonance structures are more stable because they involve the delocalization of electrons. Therefore, they don't form negative/positive regions on the molecule, but are delocalized and neutral throughout the molecule. This in turn lowers the molecules energy state making it more stable.
Tue Nov 05, 2019 11:00 am
Forum: Electronegativity
Topic: 2D.13
Replies: 1
Views: 47

### 2D.13

I'm having trouble understanding why the CO bond in carbon monoxide forms a triple bond. Can anyone help me with this?
Tue Nov 05, 2019 9:03 am
Forum: Lewis Structures
Topic: 2C.15
Replies: 1
Views: 31

### Re: 2C.15

The lowest E structure has most, of not all, FC at 0. Only time you will have a charge is when the structure has a net charge. In that case, make sure the negative/positive FC is on the appropriate atom (electronegativity). Hopefully this helps
Mon Nov 04, 2019 11:28 am
Forum: Lewis Structures
Topic: Exceptions to the Octet Rule
Replies: 2
Views: 24

### Re: Exceptions to the Octet Rule

Basically atoms will experience an expanded octet when they have a degenerate d sub-shell available. For example, Sulfur's valence electrons have access to the d sub-shell since they are very similar in energy, so sulfur can therefore add extra electrons into that d sub-shell. Hopefully this helped.
Mon Nov 04, 2019 11:25 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration vs. Ground-state Electron Configuration
Replies: 2
Views: 71

### Re: Electron Configuration vs. Ground-state Electron Configuration

A ground state electron configuration means all electrons are in their lowest possible energy state. Basically meaning that there isn't a random electron excited into a more energetic sub-shell/shell.
Thu Oct 31, 2019 9:43 am
Forum: Octet Exceptions
Topic: Octet Exception
Replies: 3
Views: 53

### Re: Octet Exception

The octet exceptions occur when the element involved has a d-subshell available toehold electrons. Thus, elements in the p-block that have unoccupied d sub shells can achieve an expanded octet. An example is Sulfur, which has electrons in its p-subshell, and has a d-subshell available to hold electr...
Wed Oct 30, 2019 11:40 am
Forum: Bond Lengths & Energies
Topic: dissociation energy and bond length
Replies: 1
Views: 38

### dissociation energy and bond length

I have a few questions regarding dissociation energy and bond length relationships 1. Do all bond types have the same dissociation energy (all C-H bonds = 412 kJ/mol?) 2. Since double bonds have an increased dissociation energy than single bonds, can we assume shorter bonds have larger dissociation ...
Wed Oct 30, 2019 11:35 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability and Electronegativity
Replies: 2
Views: 47

### Polarizability and Electronegativity

Is there a relationship between polarizability and electronegativity, such that as electronegativity decreases, the polarizability of the anion increases? The book used the example about a large iodide anion being easily polarizable due to electron cloud being further from nucleus.
Tue Oct 29, 2019 5:55 pm
Forum: Resonance Structures
Topic: Expanded octets
Replies: 2
Views: 52

### Expanded octets

When drawing Lewis structures on the homework, I notices Sulfur structures forming multiple double bonding sites on the Sulfur atom, where the Sulfur atom would have 10 shared electrons. Is there a "max" amount of electron bonds an expanded octet atom can have?
Tue Oct 29, 2019 5:51 pm
Forum: Formal Charge and Oxidation Numbers
Topic: When would a compound not have FC=0?
Replies: 2
Views: 50

### Re: When would a compound not have FC=0?

If a compound has a charge, one or more of the atoms involved will have a formal charge not equalling 0. That being said, if this case scenario is encountered, make sure the charged atoms are energy stable. For example, If you have SO3 2 minus, the negative formal charges should be on the oxygens, s...
Thu Oct 24, 2019 1:11 pm
Forum: Resonance Structures
Topic: Delocalized electrons
Replies: 2
Views: 77

### Delocalized electrons

I am having trouble with the concept of the delocalized electrons exhibiting double/single bond qualities. Do these instances only occur with atoms of similar electronegativity, or are they more common? Also, would these delocalized electrons be stronger than single bonds, and weaker than double bon...
Thu Oct 24, 2019 1:07 pm
Forum: Trends in The Periodic Table
Topic: Relationship between Electronegativity and Ionization Energy?
Replies: 6
Views: 113

### Re: Relationship between Electronegativity and Ionization Energy?

An atom with a low IE (Ionization energy) typically has a low electronegativity. If an atom has a low electronegativity, it takes less energy to remove the electron since the effective nuclear charge the electron is experiencing is less. I believe the atom with the lowest IE is in the middle because...
Thu Oct 24, 2019 1:01 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Technique to Predict e- Configurations
Replies: 2
Views: 29

### Re: Technique to Predict e- Configurations

What I tend to do is I look at the "block" where the element falls (s block, p block, etc...). Usually that will let you know where an electron will be removed from. For example, Sodium is in the s block. If sodium were to be ionized, its electron would be removed from the 3s shell. Hopefu...
Wed Oct 23, 2019 11:15 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Spin Quantum Number
Replies: 6
Views: 79

### Re: Spin Quantum Number

the +1/2 and the -1/2 are used to signify the spin of the electron. So if you are only drawing the arrows, you probably don't need to use the ms numbers because the arrows signify spin direction already. It depends on what the problem asks of you.
Wed Oct 23, 2019 11:12 am
Forum: Properties of Light
Topic: Focus 1: 1. 27
Replies: 1
Views: 39

### Re: Focus 1: 1. 27

For part A using the equation c=(wavelength)(frequency), you should get a wavelength of 4.78x10^-7 m or 478 nm
For part B using the equation c=(wavelength)(frequency), your answer should be 7.12x10^14 Hz
Thu Oct 17, 2019 1:08 pm
Forum: Quantum Numbers and The H-Atom
Topic: 1D.25
Replies: 2
Views: 50

### 1D.25

What exactly is a subshell notation? Is that the "n,l,ml,ms" forma, or is it something else?
Thu Oct 17, 2019 1:06 pm
Forum: Quantum Numbers and The H-Atom
Topic: 1D. 11
Replies: 3
Views: 67

### 1D. 11

Problem: How many orbitals are in sub shells with l equal to 0,2,1,3?
When doing this problem for l=0, how many orbitals would there be?
Wed Oct 16, 2019 6:15 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: quantum numbers and orbital planes
Replies: 4
Views: 34

### Re: quantum numbers and orbital planes

In response to your second post, the 3 ml values are arbitrary. Basically, ml can be 3 values. If l is 1, ml can be 1,0,-1. These values correlate to the x,y,z planes. Since the values are arbitrary, the x axis can be represented as either 1 or -1. So for the ml=-1, Dr. Lavelle called chose -1 to de...
Wed Oct 16, 2019 6:12 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: quantum numbers and orbital planes
Replies: 4
Views: 34

### Re: quantum numbers and orbital planes

the "ml" quantum number gives the relative orientation of the electron in the specific sub-shell. We derive the "ml" number from the "l" number, by following the given values "ml" can be, which are "l","l-1",or "-l". This means th...
Wed Oct 16, 2019 6:07 pm
Forum: Properties of Light
Topic: homework 1A.3
Replies: 8
Views: 99

### Re: homework 1A.3

when freq. decreases, the wavelength increases. This is because wavelength and frequency have an inverse relationship relative to the speed of light (c).
Tue Oct 15, 2019 1:29 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: 1D.4
Replies: 1
Views: 57

### 1D.4

Can someone assist me with this problem? I understand how to find the electron using the 0.83 angstrom measurement, but I don't understand the second portion of the problem "relative to finding it at the nucleus." "Evaluate the probability of finding an electron in a small region of a...
Thu Oct 10, 2019 12:36 pm
Forum: Trends in The Periodic Table
Replies: 16
Views: 286

Would an electron becoming excited increase the atomic radius of an atom, or is the radius only comnsidered when all electrons are in their ground states?
Thu Oct 10, 2019 12:30 pm
Forum: Properties of Electrons
Topic: Photoelectric Effect Experiment
Replies: 5
Views: 54

### Re: Photoelectric Effect Experiment

When the electron absorbs the incoming photon, it is given energy. The energy, allows the electron to move further from the positively charged nucleus, as the energy is converted into movement or kinetic energy. The metal has a certain threshold energy, which means the photons bombarding the metal m...
Thu Oct 10, 2019 12:17 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: ground/excited electron states
Replies: 2
Views: 96

### ground/excited electron states

Question 1E.7 is giving me a hard time. I don't understand why answer choice "d" is considered a ground state configuration, and why answer choice "a" is considered an excited state configuration.
Thu Oct 10, 2019 11:50 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Large Objects and Heisenberg Uncertainty
Replies: 1
Views: 31

### Large Objects and Heisenberg Uncertainty

I'm experiencing some confusion answering this question: For large everyday objects does Heisenberg's uncertainty (indeterminacy) principle play any measurable role? A. Yes, the uncertainties in position, speed, and momentum of a stationary object are noticeable or measurable. B. Yes, the uncertaint...
Tue Oct 08, 2019 8:07 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Using Heisenberg Uncertainty Eq. and finding energy per photon
Replies: 1
Views: 991

### Using Heisenberg Uncertainty Eq. and finding energy per photon

While taking the Pre/Post assessments for the "Heisenberg Uncertainty Equation" video module, I encountered this question, and experienced trouble figuring it out. Can anyone provide help? My answer from "part A" was Delta P= 3.1x10^-20 and Delta v= 3.4x10^10 "Use the above ...
Thu Oct 03, 2019 1:12 pm
Forum: Molarity, Solutions, Dilutions
Topic: Help on HW: Fundamentals G5
Replies: 3
Views: 106

### Re: Help on HW: Fundamentals G5

I'm going to use problem b for the example here. So how I began this problem: I figured out how many liters the .0796M sodium carbonate was in by using the moles of carbonate and the molarity of the solution. Use the equation "moles/volume=molarity." From there, I converted the liter measu...
Thu Oct 03, 2019 1:01 pm
Forum: Significant Figures
Topic: significant figures
Replies: 5
Views: 124

### Re: significant figures

Okay stupid question but I've been sitting here for a while trying to figure out how to make a new post. Do you mind walking me through the steps?
Thu Oct 03, 2019 12:54 pm
Forum: Significant Figures
Topic: significant figures
Replies: 5
Views: 124

### Re: significant figures

As far as I know, the 0's are ignored if they are place holding values without a decimal point. I believe you are correct with your examples
Thu Oct 03, 2019 12:50 pm
Forum: Empirical & Molecular Formulas
Topic: Finding a reactant from given products
Replies: 2
Views: 133

### Re: Finding a reactant from given products

the ratios are derived from how much reactant you will need to create the product. For example, in a water molecule, you need 2 moles of hydrogen and 1 mole of oxygen to create H2O. However, you typically don't see singular hydrogen, as it naturally forms as a diatomic molecule. The same goes for ox...

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