## Search found 117 matches

Tue Mar 17, 2020 12:31 am
Forum: General Rate Laws
Topic: unique average reaction rate change
Replies: 1
Views: 88

### Re: unique average reaction rate change

If the coefficients in a chemical equation are doubled, the unique reaction rate would decrease by a factor of 2.
Sat Mar 14, 2020 7:04 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: In Class Review Question
Replies: 1
Views: 98

### Re: In Class Review Question

From your question I think Gr means Gibbs Free Energy of the entire reaction. Gr can be calculated by doing Gf(products) - Gf(reactants).
Sat Mar 14, 2020 7:01 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: order of reaction
Replies: 6
Views: 158

### Re: order of reaction

If there are two reactants, the order of a reaction is by adding up the two exponents in the rate law (rate = k[A]^n [B]^M, so the rate law is n + m). How do you find n and m? Usually they give you a bunch of experimental trials where they used different or same amounts of A and B to find different ...
Wed Mar 11, 2020 12:31 am
Forum: Ideal Gases
Topic: Acids and Basis: Salts
Replies: 9
Views: 167

### Re: Acids and Basis: Salts

You would have to use an ice table and find the concentration of H3O+ (sometimes you will have to used the quadratic equation to find it). Then you plug in the concentration of H3O+ to get the pH.
Wed Mar 11, 2020 12:28 am
Forum: Environment, Ozone, CFCs
Topic: stoichiometric coefficients
Replies: 9
Views: 153

### Re: stoichiometric coefficients

Sometimes you want one of the species in your equation to be 1 mol, which is why other species have fractions as coefficents.
Wed Mar 11, 2020 12:23 am
Forum: General Rate Laws
Topic: Help on 7A.15(d)
Replies: 1
Views: 43

### Re: Help on 7A.15(d)

Yeah, you're right.. To solve for part d, all you need to find is the rate constant and the exponents for each reactant (which you found in the previous parts already). Then you just plug everything back into the rate order equation and find the rate.
Wed Mar 11, 2020 12:20 am
Forum: General Rate Laws
Topic: Help on 7A.13
Replies: 1
Views: 44

### Re: Help on 7A.13

So the way I answered this question was by looking at all three of the rate laws we know (0 order, 1st order, and 2nd order). Rate laws usually only include the reactants, so I knew the rate law was something like this: rate = k x [CH3Br]^n x [OH-]^m. The first part of the question says when we doub...
Wed Mar 11, 2020 12:11 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Difference between catalyst and intermediate
Replies: 9
Views: 146

### Re: Difference between catalyst and intermediate

An intermediate is produced and used up. The catalyst appears as a reactant in the first step (which means it must have been in the original experiment) and is then later reproduced.
Mon Mar 09, 2020 12:59 am
Forum: First Order Reactions
Topic: equation derivations
Replies: 5
Views: 61

### Re: equation derivations

I don't think so, but maybe you can ask him during office hours. I feel like Dr. Lavelle cares more about using the equation correctly than just memorizing an equation.
Mon Mar 09, 2020 12:58 am
Forum: Balancing Redox Reactions
Topic: Reversing the anode
Replies: 10
Views: 195

### Re: Reversing the anode

The anode reaction is always reversed because usually when you look at the table, you get the reduction reaction the standard reduction potential. Since the anode is where oxidation occurs, you want the oxidation reaction. Therefore you would flip the reduction reaction to get the oxidation reaction...
Mon Mar 09, 2020 12:54 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Adding Pt(s) to a Cell Diagram
Replies: 14
Views: 211

### Re: Adding Pt(s) to a Cell Diagram

Platinum is an inert electrode which is why you add that to a cell diagram when you need an electrode. In addition, you can also use graphite (Cgraphite) because it is also an inert electrode.
Mon Mar 09, 2020 12:52 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: n=2
Replies: 7
Views: 108

### Re: n=2

n is the moles of electrons and can be found by looking at the overall balanced redox reaction.
Mon Mar 09, 2020 12:51 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Ecell
Replies: 5
Views: 57

### Re: Ecell

E cell naught is calculated in standard conditions and can be calculated by the standard reduction potentials. E cell is the cell potential when it's not under standard conditions and can be calculated from the equation: Ecell = Ecell(naught) -RT/(nF)lnQ.
Sun Mar 01, 2020 12:56 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Flipping the sign
Replies: 10
Views: 134

### Re: Flipping the sign

Usually they give you the reduction potential for a half reaction in the table, so if you want the oxidation potential, all you do is flip the half reaction which switches the sign for E (naught).
Sun Mar 01, 2020 12:52 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Finding N
Replies: 6
Views: 134

### Re: Finding N

n is moles of electrons, and you find it by looking at the overall balanced redox reaction for the cell.
Sat Feb 29, 2020 10:37 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Anode vs Cathode
Replies: 5
Views: 66

### Re: Anode vs Cathode

In addition, you want a galvanic cell with a positive E (naught) for the reaction. So after you see the the E (naught) of the two half reactions, you can figure out which reaction will be the reduction and which reaction will be the oxidation.
Sat Feb 29, 2020 10:34 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Corrosion
Replies: 1
Views: 19

### Re: Corrosion

I know that for test 2, it will just be on the 2nd page of the thermodynamics outline page and on electrochemistry. So no kinetics.
Sat Feb 29, 2020 10:32 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Phases in cell diagrams
Replies: 1
Views: 25

### Re: Phases in cell diagrams

No, I don't think the order of the of the two molecules of the same phase matters. As long as you have anode and then cathode, and then have the electrodes at the beginning and end of the cell notation, you should be fine.
Sun Feb 23, 2020 1:32 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Finding n
Replies: 6
Views: 78

### Re: Finding n

"n" means moles of electrons and can easily be found by looking at your balanced redox reaction and looking at the number of electrons that were transferred.
Sun Feb 23, 2020 1:28 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Using Pt
Replies: 7
Views: 130

### Re: Using Pt

Lavelle told us in class that Pt and C(gr) are both good inert conductors, but that Pt is more commonly used.
Sun Feb 23, 2020 1:24 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: work and cell potential
Replies: 4
Views: 57

### Re: work and cell potential

Another way Lavelle related work and cell potential was this equation:

w = -nFE

where w = maximum work, n = moles of electrons (which is found in the balanced redox reaction), and E = cell potential of the cell.
Sun Feb 23, 2020 1:17 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Voltage Energies
Replies: 3
Views: 56

### Re: Voltage Energies

When you reverse a reaction, the voltage does change sign.

When you multiply or divide the reaction, the reason E naught doesn't change is because E naught in an intensive property since you're using two standard electrodes.
Sun Feb 23, 2020 1:11 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Anode vs Cathode
Replies: 6
Views: 96

### Re: Anode vs Cathode

Anode and cathode are just terms used to describe parts of the galvanic cell. The anode is the part of the half-cell where oxidation occurs and the cathode is the part of the half cell where reduction occurs.
Sun Feb 23, 2020 1:08 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: porous disc
Replies: 5
Views: 94

### Re: porous disc

I believe the porous disc is just another way to keep the charges of both cells to be neutral.
Sun Feb 16, 2020 2:14 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Midterm Curve
Replies: 45
Views: 625

### Re: Midterm Curve

Yeah, my TA said the same thing about how midterms will be given back to us after lecture on Wednesday.
Sun Feb 16, 2020 2:11 am
Forum: Calculating Work of Expansion
Topic: work = 0
Replies: 14
Views: 286

### Re: work = 0

The work would be zero because in this vacuum the external pressure is zero. The system is not using any energy to push the piston up.
Sun Feb 16, 2020 2:08 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Equilibrium
Replies: 15
Views: 207

### Re: Equilibrium

So when a reaction is at equilibrium, delta G is equal to 0. The only way delta G naught is also equal to zero is if K = 1.
Sun Feb 16, 2020 1:54 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta G naught
Replies: 2
Views: 64

### Re: Delta G naught

Another way of finding delta g naught is by using the equation delta G = delta G naught + RTlnQ.
Sun Feb 16, 2020 1:50 am
Forum: Balancing Redox Reactions
Topic: simplifying half reactions
Replies: 3
Views: 54

### Re: simplifying half reactions

In addition, besides canceling out species when they are present on both sides of a reaction, you can also cancel electrons if there are the same number of electrons on both sides.
Sun Feb 09, 2020 9:11 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Is heat capacity an extensive or intensive property?
Replies: 2
Views: 32

### Re: Is heat capacity an extensive or intensive property?

Heat capacity is an extensive property, but specific heat capacity is an intensive property. The reason why is because specific heat capacity is defined as per 1 gram.
Sun Feb 09, 2020 9:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pressure change
Replies: 3
Views: 57

### Re: Pressure change

When a question tells you there s a change in pressure, you need to know more than that to see which side the reaction will shift to. If there was an increase in pressure because there was a decrease in volume, then the reaction favors the side with the fewer moles of gas. If there was an increase i...
Sun Feb 09, 2020 9:04 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Reversible expansion
Replies: 3
Views: 43

### Re: Reversible expansion

An irreversible free expansion tells you that there will be constant pressure, so work = -P x delta V.
Sun Feb 09, 2020 9:01 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy
Replies: 5
Views: 63

### Re: Gibbs Free Energy

To calculate Gibb's free energy, you can use the same method as Hess's law. You can also use the equation: delta G = delta H - T(delta S).
Sun Feb 09, 2020 8:56 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Le Chatelier's Principle
Replies: 5
Views: 52

### Re: Le Chatelier's Principle

When you increase the volume, which decreases the pressure of the gas molecules and changes the concentration of the gas molecules, the reaction will shift to the side with more moles of gas.
Sun Feb 09, 2020 8:46 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: spontaneity
Replies: 18
Views: 207

### Re: spontaneity

Also, to find out what delta g is and to figure out if the reaction is spontaneous, you use the equation: delta G = delta H - T(delta S).
Fri Jan 31, 2020 1:54 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: state property
Replies: 8
Views: 59

### Re: state property

Distance traveled is a great example of a nonstate property because lets say you take 20 steps forward and then 10 steps backward. How many steps did you take? If distance traveled was a state property you would do final minus initial which would be 10 - 0 = 10 (we are saying your starting point is ...
Fri Jan 31, 2020 1:42 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta G° vs Delta G
Replies: 2
Views: 29

### Re: Delta G° vs Delta G

Just to add on the standard conditions for Delta G° are 1 atm for pressure and 25 degrees Celsius.
Tue Jan 28, 2020 6:05 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Enthalpy of Formation
Replies: 4
Views: 74

### Re: Standard Enthalpy of Formation

The standard enthalpy of formation is 0 when elements are in their stable form. For example, since the most stable form of oxygen is O2, then the standard enthalpy of formation is 0. Another example, is zinc(s). The standard enthalpy of formation for zinc in its solid state is 0 because zinc's most ...
Tue Jan 28, 2020 6:00 pm
Forum: Phase Changes & Related Calculations
Topic: Cv and Cp
Replies: 9
Views: 99

### Re: Cv and Cp

Since enthalpy change is usually under constant pressure, maybe that's why only Cp equals enthalpy change.
Tue Jan 28, 2020 5:58 pm
Forum: Phase Changes & Related Calculations
Topic: Burns
Replies: 4
Views: 66

### Re: Burns

Steam would cause more severe burns because if you look at the heating curve, you will see that steam will have more enthalpy than boiling water at 100 degrees Celsius. More enthalpy means more heat which means worse burns.
Sun Jan 26, 2020 7:54 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy is said to be additive
Replies: 10
Views: 120

### Re: Enthalpy is said to be additive

One of the examples that Dr. Lavelle gave for another state property is altitude. For altitude, the path doesn't matter. What matters is where the hiker ends up.
Sat Jan 25, 2020 3:27 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Using different methods
Replies: 4
Views: 44

### Re: Using different methods

I think it depends on what information is given to you in the equation. For example, it the question only gives you bond enthalpies then you should use bond enthalpies for your calculations, even though bond enthalpies is the most inaccurate.
Sat Jan 25, 2020 3:16 pm
Forum: Phase Changes & Related Calculations
Topic: Phase changes
Replies: 7
Views: 56

### Re: Phase changes

Temperature remains constant during these phase changes because the heat is actually breaking the intermolecular forces.
Wed Jan 22, 2020 12:35 pm
Forum: Ideal Gases
Topic: Inert Gases and Equilibrium
Replies: 6
Views: 78

### Re: Inert Gases and Equilibrium

Because even though by adding the inert gas the pressure inside is increasing, the equilibrium constant is a ratio of the concentration of the products and reactants. The inert gas is not a product or reactant, and the moles and volume of the products and reactants are still the same. Concentration ...
Wed Jan 22, 2020 12:32 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pKa and pKb
Replies: 2
Views: 43

### Re: pKa and pKb

A strong acid would have a higher Ka. For example, a strong acid could have Ka = 10^-1. The formula for pKa is pKa = -logKa. If you do -log(10^-1), you get pKa = 1. Therefore this strong acid has a low pKa. I like to first think about Ka and then work backwards. A higher Ka means 10^-x where x is a ...
Tue Jan 21, 2020 12:13 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Noble Gases
Replies: 1
Views: 8

### Re: Noble Gases

Noble gases are very stable on their own because their outer orbital is already filled up with the max number of electrons (8). They wouldn't need or want to form covalent bonds.
Tue Jan 21, 2020 12:09 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating pH from Concentration of Strong Acid/Base
Replies: 2
Views: 43

### Re: Calculating pH from Concentration of Strong Acid/Base

When Ba(OH)2 is placed in water, it dissociates into Ba^2+ and 2OH-. So the reaction would be Ba(OH)2 + H2O -> H2O + Ba^2+ + 2OH- For every 1 mole of Ba(OH)2, there are 2 moles of OH-.
Thu Jan 16, 2020 9:25 pm
Forum: Administrative Questions and Class Announcements
Topic: test 1/homework
Replies: 4
Views: 86

### Re: test 1/homework

Yes, I believe so.
Thu Jan 16, 2020 8:53 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Replies: 6
Views: 57

### Re: ice table/quadratic

There's a possibility where you get two x values that are both positive, but when you do initial concentration of reactant minus one of the x values, you get a negative value. It's important to check to see if the equilibrium concentrations turn out positive.
Thu Jan 16, 2020 8:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: equilibrium concentration
Replies: 1
Views: 22

### Re: equilibrium concentration

I think your mistake is that when you were trying to change the equilibrium constant to a quadratic equation you accidentally did 85 x .0008 = .68, when the actual answer is 85 x .008 = .068. This difference of 10^-1 probably was the reason why you were getting the wrong answer.

I hope this helps.
Thu Jan 16, 2020 8:39 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: inert gas added
Replies: 4
Views: 54

### Re: inert gas added

No, adding an inert gas does not change the equilibrium constant or cause any side to be favored.
Thu Jan 16, 2020 8:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: strong/weak acids and bases
Replies: 2
Views: 25

### Re: strong/weak acids and bases

Also, if the question gives you a Ka value, then you know that the acid is weak because only weak acids have a Ka value. The same goes for bases with their Kb value.
Sun Jan 12, 2020 1:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentrations and the K value.
Replies: 7
Views: 120

### Re: Concentrations and the K value.

The way I explain it to myself is that these stoichiometric coefficients are just telling us more than one of these species was formed. For example, in the balanced chemical equation to form water, 2H2 + O2 <-> 2H2O, the equation is telling us that two H2O species were created. Another way of writin...
Fri Jan 10, 2020 1:20 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.1.C explanation (SSM)
Replies: 2
Views: 30

### Re: 5G.1.C explanation (SSM)

I think the explanation is trying to say that even though you might start with an initial higher pressure of reactant, by the time the equation reaches equilibrium, the equilibrium constant K will still be the same. The only thing that changes the equilibrium constant is changing the temperature bec...
Thu Jan 09, 2020 1:37 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework Question 5I.13
Replies: 2
Views: 63

### Re: Homework Question 5I.13

The way I could tell Cl2 was more stable was the fact that the K for equation for Cl2 <-> 2Cl was smaller than the K for the F2. A smaller K, means that compared to the other reaction, the reactant (Cl2) is favored more. In addition, if you compare the equilibrium concentrations of Cl2 to F2, you se...
Thu Jan 09, 2020 1:29 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q vs K
Replies: 8
Views: 85

### Re: Q vs K

The difference between Q and K is that K is the equilibrium constant which in other words is when the reaction has reached equilibrium. Q, the reaction quotient, is something you can do during anytime of the reaction. By comparing Q to K, you can see the direction of the reaction. If Q=K, then you k...
Mon Jan 06, 2020 7:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Value of K
Replies: 1
Views: 41

### Re: Value of K

When K>1, that means the reaction favors the products or favors the right side. Also, if you think about the definition of K and how it's the concentration of products over the concentration of reactants, then when K is greater than 1, that means that there are more products than reactants when the ...
Mon Jan 06, 2020 7:27 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Determining Equilibrium Reaction Direction
Replies: 3
Views: 65

### Re: Determining Equilibrium Reaction Direction

To determine the direction of an equilibrium reaction you can just compare K to 1. If K <1, than the reaction favors the reactants and if K >1 then the reaction favors the products. Dr. Lavelle uses 10^3 or 10^-3 as comparison when he uses strongly favors. For example, if K<1, the reaction favors th...
Fri Dec 06, 2019 3:55 am
Forum: Lewis Acids & Bases
Topic: H2PO4-
Replies: 2
Views: 43

### Re: H2PO4-

H2PO4- can either accept or donate an H+. It's one of the examples of an amphiprotic molecule, where it can either give or receive a proton.
Fri Dec 06, 2019 3:50 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Sig Figs in 6B3
Replies: 3
Views: 87

### Re: Sig Figs in 6B3

Yeah, I also believe the answers should be 1.60 and 1.70.
Wed Dec 04, 2019 1:44 am
Forum: Identifying Acidic & Basic Salts
Topic: Classifying Salts
Replies: 5
Views: 76

### Re: Classifying Salts

You have to look at the cation and anion of the salt and determine if they are stable as cations and anions. If they are not stable as cations and anions, then they will probably affect the pH.

Yes, BaCl would not affect the pH because Ba+ is in group 2 and because Cl- is a stable anion.
Wed Dec 04, 2019 1:39 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: coordination number
Replies: 3
Views: 44

### Re: coordination number

I don't know if we can make that general statement that coordination number is synonymous with regions of electron density. I feel like most times that statement is true. I think the best way to calculate out the coordination number is to draw out the Lewis Diagram and count all the coordinate coval...
Wed Dec 04, 2019 1:32 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: How does anion stability contribute to relative acidity?
Replies: 6
Views: 116

### Re: How does anion stability contribute to relative acidity?

When we say that an acid is stronger, we mean that more of the products are formed. For example, the strong acid HCl dissociates into H+ and Cl-. Since we know that HCl is a strong acid, we know that Cl- is a stable anion because if it wasn't a stable anion it would want to combine back with H+ to b...
Sat Nov 30, 2019 4:30 pm
Forum: Naming
Topic: Iron
Replies: 1
Views: 26

### Re: Iron

When a complex has an overall negative charge, then you would add -ate to the end of the transition metal. So iron would become ironate, but there is a rule where you would use the latin name for a few of the elements. Thus it would be ferrate.
Wed Nov 27, 2019 11:44 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordinate covalent bonds
Replies: 4
Views: 61

### Re: Coordinate covalent bonds

The coordinate covalent bond is when 2 electrons, that came from one atom, are being shared between that same atom and another atom. An ionic bond is more about the attraction between the positive charge on the cation and the negative charge on the anion.
Wed Nov 27, 2019 11:39 pm
Forum: Lewis Acids & Bases
Topic: HCl vs HF
Replies: 19
Views: 274

### Re: HCl vs HF

Besides looking at the electronegativity, you can also look at the bond strengths. Since Cl has a larger atomic radius than F, the bond between HCl would be longer than the bond between HF. A longer bond means a weaker bond, so it would be easier for the H to be broken off the HCl than HF. Since it'...
Wed Nov 27, 2019 11:32 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate
Replies: 3
Views: 44

### Re: Polydentate

I think the best way to determine if a ligand is polydentate is to draw out the lewis diagram and to remember that the pattern for bonding sites is "atom - space - space - atom." For example, if you look at ligand edta, then you will see that pattern.
Wed Nov 27, 2019 11:29 pm
Forum: Naming
Topic: Naming coordination compound
Replies: 3
Views: 60

### Re: Naming coordination compound

I don't think the order of the ligands matter as much when writing out the chemical formula. If you're interested, the book tells you to put the ligands in alphabetical order base off their chemical symbols and single element ligands come first before molecular ligands.
Wed Nov 27, 2019 11:24 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Final Exam
Replies: 10
Views: 206

### Re: Final Exam

Yes, I believe the final will include everything we have learned this quarter.
Tue Nov 26, 2019 7:53 pm
Forum: Hybridization
Topic: s character
Replies: 2
Views: 39

### Re: s character

The way I imagine it is that hybridization is when orbitals are combined/mixed together. So for example, sp^3 is when 1 s-orbital and 3 p-orbitals combine together and sp^2 is when 1 s-orbital and 2 p-orbitals combine together. Since in the sp^2 hybrid orbital, it is only using 2 p orbitals, then sp...
Sun Nov 24, 2019 2:52 am
Forum: Sigma & Pi Bonds
Topic: Rotation
Replies: 3
Views: 46

### Re: Rotation

Pi bonds interact side to side, so when molecules rotate, the p-orbitals would no longer be side to side, which would break the pi bonds.
Sun Nov 24, 2019 2:49 am
Forum: Biological Examples
Topic: Biological Importance
Replies: 6
Views: 87

### Re: Biological Importance

I think understanding the molecules that have a biological importance that Lavelle went over in class like cisplatin and myglobins will be good to know. In addition, during lecture, he went over a bunch of elements in the first row of the d-block and went over their biological importance.
Sun Nov 24, 2019 2:46 am
Forum: Bronsted Acids & Bases
Topic: Bronsted vs. Lewis Acids
Replies: 4
Views: 71

### Re: Bronsted vs. Lewis Acids

Usually the Bronstead Acid in a chemical reaction is also the Lewis Acid of the same chemical equation.
Fri Nov 22, 2019 3:02 am
Forum: Determining Molecular Shape (VSEPR)
Topic: name?
Replies: 4
Views: 63

### Re: name?

Bent and anguler are the same shape, but a bent molecule might not have the same bond angles as another bent molecule. For example, for AX2E, it would be bent and would have bond angles a bit less than 120 degrees. For AX2E2, it would also be bent, but the bond angles would be less than 109.5 degress.
Fri Nov 22, 2019 2:59 am
Forum: Student Social/Study Group
Topic: Any tips on how to catch up in this class?
Replies: 16
Views: 320

### Re: Any tips on how to catch up in this class?

In addition, a great way to see if you fully understand the material is to go to Lavelle's office hours even if you don't have a question. Lavelle has his office hours where it's like a group discussion, so sometimes even sitting there and hearing other students ask questions will improve your learn...
Fri Nov 22, 2019 2:47 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape of Diatomic Molecules
Replies: 5
Views: 83

### Re: Shape of Diatomic Molecules

If you go by the definition of a bond angle which is the angle for three consecutive atoms, then there wouldn't be a bond angle for a diatomic molecule.
Fri Nov 15, 2019 8:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 6
Views: 99

### Re: Bond Angles

Usually when there is at least one lone pair on the central atom, then the bond angle is slightly less than the expected bond angle.
Fri Nov 15, 2019 8:41 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: regions of electron density
Replies: 7
Views: 145

### Re: regions of electron density

An electron density can either be a lone pair or a covalent bond.
Fri Nov 15, 2019 6:03 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T shape
Replies: 7
Views: 114

### Re: T shape

The reason why the molecule would not be a trigonal planar is because trigonal planar means that the bound atoms are about 120 degrees away from each other, but that would not make sense because there are 2 lone pairs which means there is very strong repulsion between the lone pairs and the lone pai...
Fri Nov 15, 2019 5:58 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 5
Views: 89

### Re: Bond Angles

Just know the basic bond angles for the shapes where there are no lone pairs attached to the central atom. The only bond angle that is a bit tricky to figure out is that for tetrahedral the bond angle is 109.5 degrees.
Fri Nov 15, 2019 5:53 pm
Forum: Dipole Moments
Topic: Polarity
Replies: 12
Views: 161

### Re: Polarity

Something that might help you determine if a molecule is polar is to consider it's shape according to the VSEPR.
Wed Nov 06, 2019 10:54 pm
Forum: Bond Lengths & Energies
Topic: Test 2 Topics
Replies: 40
Views: 980

### Re: Test 2 Topics

My TA told me test 2 will just be from the material after the midterm.
Wed Nov 06, 2019 10:46 pm
Forum: Photoelectric Effect
Topic: Wavelength to Frequency
Replies: 3
Views: 161

### Re: Wavelength to Frequency

For an e-, you can find the wavelength by using the de Broglie's equation lambda = planck's constant/momentum. You can't find the frequency of an e-.
Wed Nov 06, 2019 10:38 pm
Forum: Photoelectric Effect
Topic: Intensity in Photoelectric Effect
Replies: 6
Views: 232

### Re: Intensity in Photoelectric Effect

A simple way I think about the results of the photoelectric experiment is that increasing the intensity only increase the number of photons while increasing the frequency increases the strength/energy per photon.
Wed Nov 06, 2019 10:34 pm
Forum: Dipole Moments
Topic: Clarification on Dipole Moment
Replies: 3
Views: 47

### Re: Clarification on Dipole Moment

The easier way to calculate which atom has the partial positive charge and which atom has the partial negative charge is by looking at the eletronegativity for each atom. If the atom has a higher electronegativity then the other atom, then it will have the partial negative charge.
Wed Nov 06, 2019 10:32 pm
Forum: Dipole Moments
Topic: Hydrogen Dipoles
Replies: 3
Views: 32

### Re: Hydrogen Dipoles

Between any two different molecules, there is a dipole moment, so there will be dipole moment for H in CH3Br. But sometimes, the dipole moments are canceled out by equal dipole moments from the opposite direction.
Wed Nov 06, 2019 10:28 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Mo and Ag exceptions
Replies: 4
Views: 265

### Re: Mo and Ag exceptions

The two main exceptions to reading the periodic table for the electronic configuration are Chromium and Copper. Chromium will have a lower energy from a half filled d subshell so it's e- configuration is [Ar] 3d^5 4s^1. In addition, copper will have a lower energy with a full d subshell so it's e- c...
Thu Oct 31, 2019 11:38 pm
Forum: DeBroglie Equation
Topic: Confused about equations
Replies: 7
Views: 123

### Re: Confused about equations

The reason why you can only use c = λv for light is because pretty much everything else you need to find the wavelength for, has mass. For example, an electron has mass and mass is not considered in the c = λv. That's why if you want to find the wavelength (λ) for an electron you use the equation λ ...
Tue Oct 29, 2019 10:05 pm
Forum: Lewis Structures
Topic: Formal Charge
Replies: 2
Views: 29

### Re: Formal Charge

S = shared electrons. For example, if there is one bond between 2 atoms, then the s=2 (2 shared electrons).
Tue Oct 29, 2019 10:04 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 2A #5
Replies: 4
Views: 74

### Re: 2A #5

You unfortunately did it wrong. Always remove electrons in the outermost energy level, which in this case is the 4s orbital. We know the original e- configruation is [Ar] 3d^10 4s^1, so when it become Cu^1+, the one electron in the 4s is removed, leaving behind an e- configuration of [Ar] 3d^10. I t...
Tue Oct 29, 2019 10:01 pm
Forum: Electronegativity
Topic: Exceptions to ionization energy trend?
Replies: 2
Views: 42

### Re: Exceptions to ionization energy trend?

The only exception to the ionization trend that was listed in the book (I think) was oxygen because the electron electron repulsion in one of 3p orbitals increases the energy and causes one of the two electrons to be removed from the atom a bit easier.
Tue Oct 29, 2019 9:51 pm
Forum: Lewis Structures
Topic: Lewis Structure structure
Replies: 4
Views: 55

### Re: Lewis Structure structure

Another great example of a lewis structure bent is H20. The reason for this bending is because the lone pair of electrons have little more repulsion and cause the bonded electrons to get a bit closer together.
Wed Oct 23, 2019 5:00 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 2A.5
Replies: 4
Views: 48

### Re: 2A.5

If you remember in class, Cu is an exception for telling the electron configuration from the periodic table. From reading the periodic table, we would expect the configuration to be [Ar]3d^9 4s^2, BUT through experiments, scientists have found that the e- configuration is actually [Ar]3d^10 4s^1 bec...
Wed Oct 23, 2019 4:54 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration
Replies: 2
Views: 44

### Re: Electron Configuration

Write the order of the electron configuration from increasing energy level (n=1, 2, 3, etc.). So that's why if you remember in class we put for element Sc's electron configuration the 3d shell before the 4s shell even though, if you read it based off the periodic table 3d comes after the 4s shell.
Wed Oct 23, 2019 4:48 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Hw Help 1A.11
Replies: 2
Views: 41

### Re: Hw Help 1A.11

The thing that is common to the lines within a series is that the lines in the same series all have to do with an electron falling down to the same energy level. For example, in the Balmer Series, those lines all have the electron fall down to n=2 energy level. In the Lyman Series, those lines have ...
Wed Oct 23, 2019 4:43 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: electron configurations
Replies: 2
Views: 31

### Re: electron configurations

The electron configuration in the periodic table is when the atom is in its ground state, which means that any other electronic configuration of that atom would be its excited state. So the ground state of Li is [Ar] 1s^2 2s^1, which means the example you gave in your post would be in the excited st...
Sat Oct 19, 2019 4:20 pm
Forum: Properties of Electrons
Topic: Photo and electron energy
Replies: 4
Views: 56

### Re: Photo and electron energy

For a photon's energy to be absorbed by an electron, the photon's energy must equal the energy difference between two energy levels. If the photon's energy is higher or lower than the energy difference between any two energy levels, then that the photon's energy is not absorbed and the photon just p...
Sat Oct 19, 2019 4:04 pm
Forum: Quantum Numbers and The H-Atom
Topic: Correlation Between n and l
Replies: 6
Views: 92

### Re: Correlation Between n and l

Since n=3, the electron is in the third energy level, which means the electron can be in the s orbital (l=0), p orbital (l=1), or d orbital (l=2).
Wed Oct 16, 2019 4:56 pm
Forum: Photoelectric Effect
Topic: Wavelength Emitted
Replies: 4
Views: 67

### Re: Wavelength Emitted

Electromagnetic radiation will only be emitted if the electrons move down from a higher transition level to a lower transition level (ground state). The reason why the energy for this electromagnetic radiation emitted is always positive is because there is a conservation of energy . So when an elect...
Wed Oct 16, 2019 4:48 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Magnetic Quantum Number
Replies: 3
Views: 34

### Re: Magnetic Quantum Number

In today's lecture, the reason why the electron was in 2p-base x state was because he was using the picture in his slides that showed the breakdown of l and m-base l for the first few energy levels. If you recall, in that specific picture, it labeled the 2p orbitals from left to right x, y, and z an...

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