Search found 111 matches

by Maaria Abdel-Moneim 2G
Wed Mar 03, 2021 2:25 pm
Forum: Second Order Reactions
Topic: Slope =k
Replies: 3
Views: 22

Re: Slope =k

I'm not sure if I'm understanding your question correctly but slope=k because if you look at the equation 1/[A]=kt+1/[A]o it matches the format of y=mx+b. In that equation m is the slope therefore k is the slope in the second-order integrated rate law.
by Maaria Abdel-Moneim 2G
Wed Mar 03, 2021 2:22 pm
Forum: First Order Reactions
Topic: order of a reaction
Replies: 6
Views: 118

Re: order of a reaction

By just looking at the written reaction you can't figure out the order of the reaction. However if you have experimental data or concentration values you should be able to figure it out.
by Maaria Abdel-Moneim 2G
Mon Mar 01, 2021 2:08 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Reverse Reactions
Replies: 6
Views: 16

Re: Reverse Reactions

I believe it was referring to if we weren't studying the initial rates then we would have to look at the rate of the forward reaction and that of the reverse reaction. In the table we were given initial rates so there is no need to look at the rate of the reverse reaction.
by Maaria Abdel-Moneim 2G
Mon Mar 01, 2021 2:07 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Value of k throughout Experiments
Replies: 5
Views: 14

Re: Value of k throughout Experiments

k is constant for the reaction you are studying at a certain temperature. Once you calculate k for the reaction at a temperature it can be applied to any period of time in the reaction.
by Maaria Abdel-Moneim 2G
Sun Feb 28, 2021 11:17 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Adding Pt(s) to the cell diagram
Replies: 13
Views: 30

Re: Adding Pt(s) to the cell diagram

To add on, sometimes the reaction is taking place only in an aqueous solution and you would therefore need the Pt to conduct the electrons.
by Maaria Abdel-Moneim 2G
Wed Feb 24, 2021 1:44 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Sapling 7/8 Question 17 [ENDORSED]
Replies: 4
Views: 125

Sapling 7/8 Question 17 [ENDORSED]

In the solution for question 17 I was wondering why for the Q value can be calculated by doing the partial pressure of H2 divided by the concentration of H+. I was under the impression the units had to be the same when calculating Q.
by Maaria Abdel-Moneim 2G
Wed Feb 24, 2021 1:29 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Ion-selective electrode
Replies: 4
Views: 29

Re: Ion-selective electrode

I believe ion-selective electrode have a set concentration of an ion inside of them and it measures the Ecell when it is inserted in a different solution. In that sense, it has every value in the nernst equation except the concentration of the solution it is inside of so it can solve for it.
by Maaria Abdel-Moneim 2G
Wed Feb 24, 2021 1:27 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Ion selective Electrodes
Replies: 2
Views: 16

Re: Ion selective Electrodes

I believe you are correct. From my understanding in Ion selective electrodes there is only one ion you are focusing on like H+ or Na+ and therefore you just plug in concentrations of the ion that is present.
by Maaria Abdel-Moneim 2G
Wed Feb 24, 2021 1:25 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Question about Monday lecture (2/22/21)
Replies: 5
Views: 32

Re: Question about Monday lecture (2/22/21)

Since the equation has the term Q when the concentration of the products or reactants changes it is going to affect Ecell. You can also look at it in terms of the reaction shifting towards the anode or the cathode and use the equation Ecell=Ecathode-Eanode.
by Maaria Abdel-Moneim 2G
Mon Feb 22, 2021 1:37 pm
Forum: Balancing Redox Reactions
Topic: Salt Bridge Diagram
Replies: 8
Views: 21

Re: Salt Bridge Diagram

The anode doesn't necessarily have to be on the left but most of the time it is. You really want to just pay attention to which species is losing the electrons and which one is gaining the electrons and therefore be able to determine the direction of the electron flow. In knowing that direction you ...
by Maaria Abdel-Moneim 2G
Mon Feb 22, 2021 1:34 pm
Forum: Balancing Redox Reactions
Topic: salt bridge?
Replies: 8
Views: 23

Re: salt bridge?

The salt bridge allows the spectator ions to flow throughout the cell in order for the reaction to stay neutral. Without the addition of the salt bridge the electron flow will stop and the cell will continue to run.
by Maaria Abdel-Moneim 2G
Fri Feb 19, 2021 11:50 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Negative Symbol
Replies: 4
Views: 36

Negative Symbol

I find myself getting confused on when to put the negative in calorimetry problems. I know when you are doing heat given=-heat absorbed calculations you include it but when you are just doing q=mcdeltaT when should a negative be included?
by Maaria Abdel-Moneim 2G
Thu Feb 18, 2021 11:15 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Residual Entropy
Replies: 8
Views: 25

Residual Entropy

When a problem asks to calculate the residual entropy that means to just use the equation S=kB*lnW, correct?
by Maaria Abdel-Moneim 2G
Wed Feb 17, 2021 9:09 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Phase Change
Replies: 3
Views: 24

Phase Change

Is a phase change always at equilibrium? In other words can we assume that deltaS total is 0 and delta G is also 0 during a phase change?
by Maaria Abdel-Moneim 2G
Tue Feb 16, 2021 6:58 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Cp vs. Specific Heat Capacity
Replies: 1
Views: 7

Cp vs. Specific Heat Capacity

I was just wondering when we use the Cp value for water/ice versus when we use the specific heat capacity value. Is it just a matter of if we are using moles or grams because specific heat is in moles and Cp is molar heat capacity?
by Maaria Abdel-Moneim 2G
Tue Feb 16, 2021 2:57 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Textbook 4.17
Replies: 3
Views: 26

Re: Textbook 4.17

I believe that q = -w only when delta U = 0. This is because delta U = q + w, so 0 = q + w and q = -w. In this problem, delta U is not equal to zero (and we actually must calculate it in part f of the problem). Since we cannot assume that delta U is zero, we must use a different method to calculate...
by Maaria Abdel-Moneim 2G
Mon Feb 15, 2021 3:06 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Textbook 4.17
Replies: 3
Views: 26

Textbook 4.17

In this problem part e asks for how much enthalpy was exchanged in the reaction. The answer solution uses standard enthalpies of formation to solve for delta H. However I was wondering why we couldn't say that q=-w because the temperature is staying constant and it is at constant pressure meaning q=...
by Maaria Abdel-Moneim 2G
Sat Feb 13, 2021 2:34 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Assumption on type of system
Replies: 10
Views: 41

Assumption on type of system

Do we usually assume that a system is closed if it doesn't say otherwise?
by Maaria Abdel-Moneim 2G
Thu Feb 11, 2021 10:08 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Difference between constants
Replies: 4
Views: 18

Difference between constants

I'm not sure if these are completely unrelated but what is the difference between the specific heat capacity and the Cp value. On the equation sheet they are different values so I was just wondering what the difference between them is.
by Maaria Abdel-Moneim 2G
Wed Feb 10, 2021 2:13 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Temperature
Replies: 7
Views: 48

Re: Temperature

I believe he was referring to specifically a phase change. In a phase change, the heat of the system is changing because energy is breaking/forming bonds however the external temperature is staying the same.
by Maaria Abdel-Moneim 2G
Wed Feb 10, 2021 1:54 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy of Surroundings
Replies: 4
Views: 24

Re: Entropy of Surroundings

I think that T in this case is the temperature of the surroundings after the reaction has fully gone to completion, it should be a constant value.
by Maaria Abdel-Moneim 2G
Tue Feb 09, 2021 4:09 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Sapling #6 Week 5/6
Replies: 4
Views: 34

Re: Sapling #6 Week 5/6

So your first calculation should be the equation mol*R*ln(v2/v1) you multiplied by the CV,m in the first equation when it should have been the R constant, 8.314 J/K*mol. Your second calculation should be Cv,m*ln(T2/T1). Once you do these two calculations then you should add them together to get the...
by Maaria Abdel-Moneim 2G
Tue Feb 09, 2021 3:49 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Sapling #6 Week 5/6
Replies: 4
Views: 34

Sapling #6 Week 5/6

Hello, I am having trouble with number 6 on the sapling the question says: A particular container holds 3.30 mol of neon gas. The volume of this container can be altered by sliding a piston in or out. The volume is changed from 8.40 L to 4.70 L while at the same time the temperature is changed from ...
by Maaria Abdel-Moneim 2G
Mon Feb 08, 2021 2:11 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy changes during phase changes
Replies: 3
Views: 14

Re: Entropy changes during phase changes

During an actual phase change the temperature is not changing so you would use the deltaS=qrev/T. However when there is a temperature change you use the deltaS=nCln(T2/T1).
by Maaria Abdel-Moneim 2G
Mon Feb 08, 2021 2:05 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: dT versus ΔT
Replies: 8
Views: 27

Re: dT versus ΔT

Delta T is the overall change in temperature and it is much larger. dT is infinitely small changes in temperature that are so small the system essentially is unchanged.
by Maaria Abdel-Moneim 2G
Fri Feb 05, 2021 1:35 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Application of Second Law
Replies: 3
Views: 37

Application of Second Law

I was just wondering whether or not the second law of thermodynamics (deltaS=q/T) can be applied to all systems or if it can only be applied to an isothermal reversible expansion like in the lecture?
by Maaria Abdel-Moneim 2G
Wed Feb 03, 2021 2:56 pm
Forum: Calculating Work of Expansion
Topic: Integral Work Equation
Replies: 3
Views: 29

Integral Work Equation

Hello, I was just wondering if we have gone over when to use the work equation with the integral or if it was just a conceptual set up for w=pdeltaV? What situations would we use the work equation with the integral?
by Maaria Abdel-Moneim 2G
Wed Feb 03, 2021 2:13 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Delta S total
Replies: 6
Views: 144

Re: Delta S total

The total entropy of a system would S1+S2 and in the equation it would be kB*ln(W1*W2)
by Maaria Abdel-Moneim 2G
Wed Feb 03, 2021 2:09 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: delta U versus delta H
Replies: 5
Views: 17

Re: delta U versus delta H

Delta U is the change in internal energy of a system. Delta H is the change in enthalpy of a reaction. Delta U is the same as Delta H if the pressure and volume are constant because the equation DeltaU=DeltaH-P*DeltaV.
by Maaria Abdel-Moneim 2G
Mon Feb 01, 2021 2:28 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Qp = ΔH
Replies: 6
Views: 41

Re: Qp = ΔH

The definition of delta H is the change in heat at a constant pressure which is Qp
by Maaria Abdel-Moneim 2G
Thu Jan 28, 2021 10:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook 6D.17
Replies: 1
Views: 23

Re: Textbook 6D.17

You have to use the water complex that forms with Al3+ which is Al(H2O)6^3+ and add it to water in the reaction. In this case the Al-water compound is behaving like an acid so the reaction would yield Al(H2O)5OH^2+ and H3O+.
by Maaria Abdel-Moneim 2G
Thu Jan 28, 2021 10:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: textbook problem 6D.19
Replies: 2
Views: 23

Re: textbook problem 6D.19

Yes you would still have to use the Cl when calculating the molar mass of the compound in order to convert to moles. The molar mass should come out to be 67.52 g/mol.
by Maaria Abdel-Moneim 2G
Wed Jan 27, 2021 9:33 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Biological Examples
Replies: 2
Views: 34

Biological Examples

In the bullet pointed learning objectives for the Chemical Equilbirum section it says to know biological examples of equilibrium like ATP hydrolysis and osmotic pressure. I was wondering if anyone knew what we actually have to know about these.
by Maaria Abdel-Moneim 2G
Mon Jan 25, 2021 1:54 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Molar heat Capacity
Replies: 3
Views: 28

Re: Molar heat Capacity

From my understanding in the heat capacity units you can interchange kelvin and celsius since a change in the degrees of celsius would equal a change in the degrees of kelvins. For example if you go from 10 to 15 degrees celsius you are going from 283.15 to 288.15 Kelvin and the net change for both ...
by Maaria Abdel-Moneim 2G
Mon Jan 25, 2021 1:52 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Exothermic rxn
Replies: 9
Views: 58

Re: Exothermic rxn

He was referring to the change in heat of the surroundings. Since the reaction is giving off heat the surroundings are gaining heat therefore the change in heat for the surroundings would be positive but negative for the change in heat of the system.
by Maaria Abdel-Moneim 2G
Sun Jan 24, 2021 4:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook Problem 5.35
Replies: 1
Views: 18

Textbook Problem 5.35

I was wondering why on textbook 5.35 the solution manual has the unit conversion of everything being divided by 100 instead of 1000 because the graph in the problem says P/kPa. This was what the question reads: The following plot shows how the partial pressures of reactant and products vary with tim...
by Maaria Abdel-Moneim 2G
Fri Jan 22, 2021 1:12 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies of Diatomic Molecules
Replies: 3
Views: 40

Bond Enthalpies of Diatomic Molecules

In today's lecture Dr. Lavelle mentioned a point about how the bond enthalpies of diatomic molecules are accurate and I was just wondering if anyone could clarify what this point actually means?
by Maaria Abdel-Moneim 2G
Wed Jan 20, 2021 2:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Number 5
Replies: 3
Views: 44

Sapling Number 5

On number 5 on sapling for the acids and bases assignment it says in the solution that in order to calculate the percent protonated of a generic weak base you would have to take [BH+]/([BH+]+[B]). I was just wondering why we have to divide by that sum instead of just doing [BH+]/[B] like when we cal...
by Maaria Abdel-Moneim 2G
Wed Jan 20, 2021 1:48 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Identifying Strong & Weak Acids/Bases
Replies: 7
Views: 64

Re: Identifying Strong & Weak Acids/Bases

There is a mnemonic to help remember the strong acids. It is "So I Brought No Clean Clothes." The So corresponds to H2SO4, the I corresponds to HI, the Brought corresponds to HBr, the No corresponds to HN03, the Clean corresponds to HClO3 and HClO4, and Clothes corresponds to HCl. Hope thi...
by Maaria Abdel-Moneim 2G
Wed Jan 20, 2021 1:41 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: pH in relation to pKa
Replies: 6
Views: 38

Re: pH in relation to pKa

From my understanding, if the pH is lower than the pKa of the reaction then the acid will be predominantly neutral because the environment is too acidic causing less charged molecules. It is the opposite for the pH is higher than the pKa. You can also look at it with Le Chatelier's principle which w...
by Maaria Abdel-Moneim 2G
Wed Jan 20, 2021 1:34 pm
Forum: Phase Changes & Related Calculations
Topic: Lecture #7 Question
Replies: 7
Views: 36

Re: Lecture #7 Question

When 100 degrees steam is going back to liquid at room temperature it releases a lot more heat compared to liquid water at 100 degrees going down to room temperature therefore causing more severe burns.
by Maaria Abdel-Moneim 2G
Wed Jan 20, 2021 1:32 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy vs heat
Replies: 20
Views: 88

Re: Enthalpy vs heat

From my understanding, heat is the actual flow of energy when there is a temperature change whereas enthalpy is the change in heat absorbed or emitted at a constant pressure.
by Maaria Abdel-Moneim 2G
Mon Jan 18, 2021 2:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Moles vs Concentrations in ICE Box
Replies: 21
Views: 77

Re: Moles vs Concentrations in ICE Box

Using molar concentrations makes things more consistent especially if you are using or solving for the K value which uses molar concentrations in its equation.
by Maaria Abdel-Moneim 2G
Wed Jan 13, 2021 1:55 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Concentrations and Solubility
Replies: 3
Views: 24

Re: Equilibrium Concentrations and Solubility

You can use the equilibrium concentrations to calculate the K value. The larger the K value the more the reaction is preceding to the right meaning whatever substance is more soluble. When something is very soluble it turns into its products easily therefore by knowing the K value you can assess the...
by Maaria Abdel-Moneim 2G
Wed Jan 13, 2021 1:53 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka (Acidity Constant)
Replies: 5
Views: 51

Re: Ka (Acidity Constant)

The Acidity constant is also called the ionization constant because when an acid is dissociating it dissociates into its respective ions therefore coining the term ionization. A strong acid ionizes (dissociates) completely whereas a weak acid doesn't.
by Maaria Abdel-Moneim 2G
Mon Jan 11, 2021 1:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Effect of Catalyst
Replies: 7
Views: 42

Re: Effect of Catalyst

A catalyst just allows the reaction to move along faster and therefore reach equilibrium faster. This means that the K value isn't changing, the equilibrium concentrations are just being reached faster than they would without the catalyst.
by Maaria Abdel-Moneim 2G
Mon Jan 11, 2021 1:51 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K in relation to shifting right/left
Replies: 8
Views: 56

Re: K in relation to shifting right/left

Yes reactions with really small K values always lie to the left because since K is [products]/[reactants] if the K value is small that means the concentration of reactants is much larger than the concentration of the products. This also applies the opposite way when the K value is large.
by Maaria Abdel-Moneim 2G
Tue Jan 05, 2021 5:43 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Changes in Concentration
Replies: 8
Views: 339

Re: Changes in Concentration

If you increase the concentration of the reactants then the equilibrium reaction will shift towards the product's side. If you decrease the concentration of the reactants then the equilibrium reaction will shift towards the reactant's side. Essentially the reaction is always trying to compensate for...
by Maaria Abdel-Moneim 2G
Tue Jan 05, 2021 5:41 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: How does K change during compression/expansion?
Replies: 6
Views: 185

Re: How does K change during compression/expansion?

The equilibrium constant K does not change when pressure changes, only temperature can change K. However when the pressure increases in a reaction because the volume has decreased the reaction will shift towards the side with less moles of gas. When volume is increased and pressure decreases the rea...
by Maaria Abdel-Moneim 2G
Tue Jan 05, 2021 5:39 pm
Forum: Ideal Gases
Topic: Units of Temperature
Replies: 82
Views: 368

Re: Units of Temperature

You would want it to be in Kelvin since the constant R has Kelvins and you want the units to cancel.
by Maaria Abdel-Moneim 2G
Tue Jan 05, 2021 9:12 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium is shifted to the right/left
Replies: 9
Views: 42

Re: Equilibrium is shifted to the right/left

When it says the reaction is shifted to the right this essentially means that there are more products being created than reactants. The same goes for if it says the reaction is shifted to the left (there will be more reactants created compared to products). In terms of how this relates to K, I don't...
by Maaria Abdel-Moneim 2G
Tue Jan 05, 2021 9:07 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Temperature/Pressure Effect on Equilibirum (Le Chatlier)
Replies: 4
Views: 39

Re: Temperature/Pressure Effect on Equilibirum (Le Chatlier)

In terms of temperature and its effect on equilibrium, if a reaction is endothermic and the temperature increases the reactions will shift to the right. On the other hand if the reaction is exothermic and the temperature increases the reaction will shift to the left. It is the opposite for both of t...
by Maaria Abdel-Moneim 2G
Sat Dec 12, 2020 10:48 pm
Forum: Naming
Topic: Cobalt vs Cobaltate
Replies: 12
Views: 79

Re: Cobalt vs Cobaltate

If the whole complex has a negative charge you simply just add -ate to the end of the name.
by Maaria Abdel-Moneim 2G
Sat Dec 12, 2020 10:44 pm
Forum: Identifying Acidic & Basic Salts
Topic: What is a Salt?
Replies: 9
Views: 70

Re: What is a Salt?

A salt is essentially an ionic compound with a cation and an anion. You are correct that they are formed in acid+base reactions but they are not only limited to those types of reactions. Any ionic compound is a salt.
by Maaria Abdel-Moneim 2G
Thu Dec 10, 2020 3:28 pm
Forum: Lewis Acids & Bases
Topic: Lewis Acids and Bases
Replies: 2
Views: 21

Lewis Acids and Bases

Hello! I was just wondering if when classifying lewis acids and bases you only look at the central atom so if the central atom has a lone pair it can be a lewis base or if it doesn't have a full octet it can be a lewis acid. You don't look at the lone pairs on the surrounding atoms correct?
by Maaria Abdel-Moneim 2G
Thu Dec 10, 2020 3:18 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Sapling Number 5
Replies: 1
Views: 14

Re: Sapling Number 5

(en) is bidentate so there's two bonds each to the Co atom in the center making it a total of 6: 2 Cl and 4 (en). Hope this helps!
by Maaria Abdel-Moneim 2G
Tue Dec 08, 2020 3:57 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Square Planar vs. Tetrahedral
Replies: 15
Views: 134

Square Planar vs. Tetrahedral

Hello! In lecture, Dr. Lavelle explained that with coordination compounds the 3 main shapes we will see are octahedral, tetrahedral, and square planar. I was just wondering how we are supposed to tell the difference between square planar and tetrahedral since both have them have 4 surrounding ligands.
by Maaria Abdel-Moneim 2G
Sat Dec 05, 2020 7:14 pm
Forum: Naming
Topic: Diatomic Molecules
Replies: 4
Views: 44

Diatomic Molecules

I had a quick question regarding naming coordination compounds with diatomic molecules. There was an example in the textbook that said that [Fe(OH)(OH2)5]Cl2 was called Pentaaquahydroxidoiron(III) chloride. I just wanted to make sure that since Cl2 is a diatomic molecule when you say chloride it aut...
by Maaria Abdel-Moneim 2G
Sat Dec 05, 2020 2:48 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AX3E2
Replies: 1
Views: 32

AX3E2

I had a quick question regarding the molecular shape for a molecule with the AX3E2 formula. I know that it is T-shaped but I was wondering why the shape doesn't become trigonal planar because don't the lone pairs have the highest repulsion so why wouldn't the lone pairs go to the axial positions whe...
by Maaria Abdel-Moneim 2G
Fri Dec 04, 2020 1:23 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Stability based on Resonance
Replies: 4
Views: 50

Stability based on Resonance

In today's lecture I was a little confused by what Dr. Lavelle meant that resonance results in a more stable structure. Did he mean generally that if a structure has resonance it is more stable than a structure without resonance?
by Maaria Abdel-Moneim 2G
Thu Dec 03, 2020 8:55 pm
Forum: Coordinate Covalent Bonds
Topic: cyanide
Replies: 3
Views: 42

Re: cyanide

Because cyanide has a triple bond it cannot orient in a way where both lone pairs can bond to the transition metal. In order for something to be polydentate it has to be able to orient where each lone pair can bond easily.
by Maaria Abdel-Moneim 2G
Wed Dec 02, 2020 3:23 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted Acids vs Strong Acids
Replies: 4
Views: 43

Re: Bronsted Acids vs Strong Acids

My understanding is that the definition of a Bronsted acid (which is a proton donor) is characteristic of all acids, weak and strong.
by Maaria Abdel-Moneim 2G
Wed Dec 02, 2020 3:18 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Strength of Acids
Replies: 8
Views: 76

Re: Strength of Acids

HBr is the stronger acid. Since Br is larger than Cl the bond length of HBr is larger making it a weaker bond. This allows the bond to break much easier and therefore it can more easily donate H+ compared to HCl.
by Maaria Abdel-Moneim 2G
Wed Dec 02, 2020 3:15 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Determining Coordination Numbers
Replies: 5
Views: 48

Re: Determining Coordination Numbers

The coordination number is the number of bonds bound to the center transition metal. You wouldn't take into account the transition metal.
by Maaria Abdel-Moneim 2G
Wed Dec 02, 2020 3:14 pm
Forum: Lewis Structures
Topic: Lone Pair placement
Replies: 10
Views: 73

Re: Lone Pair placement

You always want to place the electron lone pairs in the spot that will minimize the electron repulsion so you want the lone pairs to be as far away from eachother as possible. The different shapes of H20 and XeF4 are what give arise to the difference in where the electron lone pairs are placed.
by Maaria Abdel-Moneim 2G
Tue Nov 24, 2020 5:34 pm
Forum: Administrative Questions and Class Announcements
Topic: Chem 14B
Replies: 9
Views: 93

Chem 14B

In Dr.Lavelles email he said to keep chem 14b class time open because of exams. Does he mean just the discussion section needs to kept open and the lectures are recorded like this quarter in 14A?
by Maaria Abdel-Moneim 2G
Tue Nov 24, 2020 10:40 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Sampling Week 7/8 #6
Replies: 6
Views: 48

Re: Sampling Week 7/8 #6

It would only be linear if there were exactly two regions of electron density however the lone pairs add two more regions of electron density therefore it wouldn't be linear it would be a bent shape.
by Maaria Abdel-Moneim 2G
Tue Nov 24, 2020 10:38 am
Forum: Trends in The Periodic Table
Topic: Textbook Question 1F.3
Replies: 4
Views: 37

Re: Textbook Question 1F.3

In order from largest to smallest it would be P3-, S2-, P-. The atomic radius decreases as you go across a period so P is bigger in the first place. You are adding three electrons to P making it even larger than it was before. The same trend happens for S2- and P-
by Maaria Abdel-Moneim 2G
Tue Nov 24, 2020 10:35 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: isoelectronic
Replies: 12
Views: 93

Re: isoelectronic

Isoelectronic is when two atoms/ions have the same number of electrons. For example Ar and Ca2+ have the same number of electrons because Ca lost two electrons making it have 18 electrons exactly like Ar.
by Maaria Abdel-Moneim 2G
Mon Nov 23, 2020 1:58 pm
Forum: Hybridization
Topic: regions of electron density
Replies: 7
Views: 59

Re: regions of electron density

To figure out regions of electron density you essentially just have to look at the number of lone pairs and atoms around the atom you are looking at. Single, double, and triple bonds are all considered one region of electron density and each lone pair is considered one region of electron density.
by Maaria Abdel-Moneim 2G
Mon Nov 23, 2020 1:53 pm
Forum: Hybridization
Topic: Hybrid Bonds
Replies: 3
Views: 43

Re: Hybrid Bonds

I believe you need to see if the atom you are looking at has enough unpaired electrons to create the bonds evident in the lewis structure and if it doesn't have enough you have to look at the hybridized orbitals. For example with the carbon in CH4 it creates four single bonds meaning it has to have ...
by Maaria Abdel-Moneim 2G
Wed Nov 18, 2020 6:13 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: Number of Hydrogen Bond Sites on Guanine
Replies: 1
Views: 24

Number of Hydrogen Bond Sites on Guanine

I was doing the Week 6 Matthew Tran Worksheet and I was just wondering if anyone had the answer to the last question that asks how many hydrogen bonding sites guanine has. Thank you!
by Maaria Abdel-Moneim 2G
Wed Nov 18, 2020 5:16 pm
Forum: Trends in The Periodic Table
Topic: Metallic Character
Replies: 7
Views: 77

Metallic Character

I was going over one of the UA worksheets that asks to put the following in increasing order of metallic character: Si, Be, Mg, Na, P. In the answer key it had the order P, Si, Be, Mg, Na and I was a little confused why Be wouldn't have the lowest metallic character since metallic character increase...
by Maaria Abdel-Moneim 2G
Tue Nov 17, 2020 10:22 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polar and Nonpolar Molecules
Replies: 3
Views: 32

Polar and Nonpolar Molecules

I was wondering whether or not we need to know how to determine if a molecule is polar or nonpolar for midterm 2 because we didn't cover it in the reading or the lectures but for some of the 3F textbook problems you have to determine if the molecule is polar or nonpolar to decide which intermolecula...
by Maaria Abdel-Moneim 2G
Tue Nov 17, 2020 10:15 pm
Forum: Dipole Moments
Topic: textbook 3F.3
Replies: 3
Views: 44

Re: textbook 3F.3

I understood the word important as just another way of saying which of the following molecules exhibit dipole-dipole interactions or like you said if the dipole-dipole interactions are present.
by Maaria Abdel-Moneim 2G
Mon Nov 16, 2020 8:15 pm
Forum: Lewis Structures
Topic: Textbook Problem 2B.15
Replies: 2
Views: 20

Textbook Problem 2B.15

I had a question on textbook problem 2b.15 that asks to draw the resonance structures of ClNO2. In the answer key it showed the resonance structures will the double bond switching between the two oxygen atoms. How come the double bond can't also be from Cl to the N atom since it keeps the total char...
by Maaria Abdel-Moneim 2G
Mon Nov 16, 2020 7:05 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Problem 2A.17
Replies: 2
Views: 23

Problem 2A.17

I had a quick question on problem 2A.17 that says: Predict the number of valence electrons present for each of the following ions: (a) Mn4+ (b) Rh3+ (c) Co3+ (d)P3+. In the answers it listed the electrons that were listed after the most recent noble gas for example for (a) the electron configuration...
by Maaria Abdel-Moneim 2G
Wed Nov 11, 2020 11:56 am
Forum: Bond Lengths & Energies
Topic: Hydrogen Bonding
Replies: 6
Views: 73

Re: Hydrogen Bonding

Although the name says the opposite Hydrogen bonds aren't actual bonds, they are intermolecular forces that attract molecules to each other. The lone pairs become attracted to the delta positive H atom and therefore attract creating the Hydrogen bond.
by Maaria Abdel-Moneim 2G
Wed Nov 11, 2020 11:50 am
Forum: Dipole Moments
Topic: Ranking Strength of Interactions
Replies: 1
Views: 21

Re: Ranking Strength of Interactions

Yes like Dr. Lavelle said today the larger a molecule is the stronger the intermolecular attractions are. I am not 100% sure but I think the number of electrons impacts the strength of the forces more because the larger the atom and the more electrons it has the more polarizable it is.
by Maaria Abdel-Moneim 2G
Wed Nov 11, 2020 11:44 am
Forum: Ionic & Covalent Bonds
Topic: Covalent vs Dipole Dipole
Replies: 4
Views: 25

Re: Covalent vs Dipole Dipole

Covalent bonds are physical bonds that link two atoms together when they share electrons. Dipole dipole interactions are intermolecular forces so they are a force of attraction between different molecules. Essentially the covalent bonds hold the atoms of the molecule together and the dipole dipole i...
by Maaria Abdel-Moneim 2G
Wed Nov 11, 2020 11:43 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: Hydrogen Bond
Replies: 2
Views: 12

Re: Hydrogen Bond

I'm pretty sure the boiling and melting points listed were for H2O in general not just one H2O molecule because Hydrogen bonds are intermolecular forces so there has to be more than one H2O molecule present for the Hydrogen bond to be present.
by Maaria Abdel-Moneim 2G
Mon Nov 09, 2020 1:29 pm
Forum: Ionic & Covalent Bonds
Topic: interactions between ions and molecule [ENDORSED]
Replies: 3
Views: 23

Re: interactions between ions and molecule [ENDORSED]

I think it is the value of energy of attraction between the two molecules or ions.
by Maaria Abdel-Moneim 2G
Fri Nov 06, 2020 12:58 pm
Forum: Lewis Structures
Topic: Difference in ionic and covalent Lewis structures
Replies: 9
Views: 94

Re: Difference in ionic and covalent Lewis structures

Ionic compounds do not share electrons they are donated therefore in the lewis structures there aren't lines drawn connecting the atoms. However in a covalent bond the electrons are shared between the atoms therefore the bond lines have to be drawn.
by Maaria Abdel-Moneim 2G
Fri Nov 06, 2020 12:55 pm
Forum: Trends in The Periodic Table
Topic: Period Trends
Replies: 8
Views: 41

Re: Period Trends

I usually just try to think about it conceptually. The more protons there are in the nucleus the stronger pull they have therefore the atomic radius decreases but ionization energy increases because it would be harder to remove an electron being attracted by a stronger nucleus.
by Maaria Abdel-Moneim 2G
Fri Nov 06, 2020 12:52 pm
Forum: Electronegativity
Topic: Electronegativity
Replies: 4
Views: 34

Re: Electronegativity

Dr. Lavelle mentioned that the greater than 2 and less than 1.5 were rough values and if you have a value in between it would require more chemical analysis of the interactions of the atoms to figure out if it is ionic or covalent.
by Maaria Abdel-Moneim 2G
Wed Nov 04, 2020 1:04 pm
Forum: Octet Exceptions
Topic: Limit to octet exception
Replies: 2
Views: 34

Limit to octet exception

I just have a sort of hypothetical question regarding the octet exception. Is there a limit to the amount of extra electrons the octet exception atoms can hold? Is it just the amount of electrons in the d-orbital?
by Maaria Abdel-Moneim 2G
Wed Nov 04, 2020 12:37 pm
Forum: Octet Exceptions
Topic: PCl5 octet exception
Replies: 1
Views: 33

PCl5 octet exception

Hello! I had a quick question regarding what Dr. Lavelle said in his lecture today about PCl5 having 10 valence electrons because it has s2p6d2. How come it has the d2 included because in the electron configuration of P the do orbitals aren't included even though it is in the 3rd energy level? Also ...
by Maaria Abdel-Moneim 2G
Thu Oct 29, 2020 7:01 pm
Forum: Quantum Numbers and The H-Atom
Topic: Effective Nuclear Charge
Replies: 4
Views: 50

Re: Effective Nuclear Charge

Effective nuclear charge is basically the positive charge from the nucleus that the electrons feel. The higher the effective nuclear charge the higher the positive attractive positive charge is from the nucleus therefore the electrons are held more tightly. This is why atomic radius decreases and io...
by Maaria Abdel-Moneim 2G
Thu Oct 29, 2020 6:57 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: orbitals
Replies: 5
Views: 72

Re: orbitals

Putting the [Ar] is just a shorter way of writing the electron configuration. Ar is the closest noble gas to Cr so writing the [Ar] just means that the electron configuration for Argon is the same up until the 4th level. It's just an easier and quicker way to write out the configuration.
by Maaria Abdel-Moneim 2G
Wed Oct 28, 2020 9:06 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Delta E and negative symbol
Replies: 3
Views: 40

Delta E and negative symbol

I had a quick question regarding the negative symbol when using the E=-hr/n^2 equation. If the problem was asking for the the energy of light emitted by the atom would you include the negative symbol in your final answer or would you convert it to positive since it's a value for energy. Thank you in...
by Maaria Abdel-Moneim 2G
Wed Oct 28, 2020 9:03 pm
Forum: Properties of Light
Topic: Regions of Electromagnetic Spectrum
Replies: 3
Views: 43

Re: Regions of Electromagnetic Spectrum

I'm not fully sure but I've seen that gamma rays start from 0.01 nm and get smaller from there.
by Maaria Abdel-Moneim 2G
Wed Oct 28, 2020 6:30 pm
Forum: Trends in The Periodic Table
Topic: Trends in Groups 15 and 16
Replies: 4
Views: 57

Re: Trends in Groups 15 and 16

I'm pretty sure you might have it backwards it is actually that O has a lower ionization energy than N because of the e- e- repulsion making it easier to remove an electron from the O atom. I'm pretty sure the trend goes down the periodic table in the same spot for example S has a lower ionization e...
by Maaria Abdel-Moneim 2G
Sat Oct 24, 2020 11:16 am
Forum: Properties of Electrons
Topic: Difference between two models
Replies: 1
Views: 70

Difference between two models

I was wondering what the difference between the circular standing wave model and the wave function is. Aren't they both modeling what the electron where the electron is around the atom or does the circular standing wave model not do that?
by Maaria Abdel-Moneim 2G
Sat Oct 24, 2020 10:15 am
Forum: Properties of Light
Topic: Application of Equations to Experiments
Replies: 2
Views: 38

Application of Equations to Experiments

Hello, many of the equations and concepts that Dr. Lavelle taught us had them applied to just one specific type of experiment, for example the experiment set up for Heisenberg's indeterminacy equation. I was just wondering if these equations and concepts can be applied to other scenarios or if they ...
by Maaria Abdel-Moneim 2G
Fri Oct 23, 2020 1:39 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum number ml
Replies: 3
Views: 68

Quantum number ml

In Dr.Lavelle's lecture he talked about how the quantum number ml is like a range of values from +l to -l. I was wondering if it is a range how do we know which quantum number it actually is?
by Maaria Abdel-Moneim 2G
Wed Oct 21, 2020 9:19 pm
Forum: Properties of Electrons
Topic: Calculating Wavelength of Spectral Line
Replies: 3
Views: 31

Re: Calculating Wavelength of Spectral Line

To calculate the wavelength you first must get the energy at that level using En=-hR/n^2 and then you can get the wavelength by using E=hv and c= λv. It is asking for a range so the largest energy gap is going to be between n=5 and n=1 and the lowest energy gap is going to be between n=5 and n=4 so ...
by Maaria Abdel-Moneim 2G
Wed Oct 21, 2020 6:42 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Negative Symbol
Replies: 2
Views: 24

Negative Symbol

Hello, I had a quick question regarding the negative symbol in the equation En=-hr/n^2. If the problem asks for just the delta E moving from one energy level to the other would we include the negative sign in our answer or would we not have it in the answer because it is only used to describe the re...
by Maaria Abdel-Moneim 2G
Wed Oct 21, 2020 6:23 pm
Forum: *Shrodinger Equation
Topic: Electron Density
Replies: 4
Views: 51

Re: Electron Density

This equation is basically saying the wave function squared is going to give you the electron density distribution. My understanding is that the electron density distribution is basically the probability you are going to find an electron in a specific area. The nodal plane which he mentioned is the ...
by Maaria Abdel-Moneim 2G
Wed Oct 21, 2020 6:20 pm
Forum: Properties of Light
Topic: N2 vs N1
Replies: 6
Views: 83

Re: N2 vs N1

N2 is the initial energy level that the electron is at and since it says it is an emission spectrum that means the electron is going from a higher energy level to a lower energy level. Therefore N2 will be 5 because it is starting at energy level 5 and N1 will be 2 because that is the lower energy l...
by Maaria Abdel-Moneim 2G
Wed Oct 21, 2020 1:00 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Electron behaving like a wave
Replies: 1
Views: 34

Electron behaving like a wave

Dr. Lavelle said in lecture today that the heisenberg indeterminacy equation reinforces the findings that an electron behaves like a wave but in the experiment isn't the electron behaving like a particle? In other words how does the heisenberg indeterminacy equation explain how an electron behaves l...

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