## Search found 87 matches

Sun Jan 24, 2021 12:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook Problem 6B.11
Replies: 2
Views: 15

### Re: Textbook Problem 6B.11

The original solution is 100 times more concentrated than the diluted solution. You can use this information to find the pH of the original solution and the concentration of hydroxide from there. This information should also help you with part B by manipulating the concentration and using the molar ...
Sun Jan 24, 2021 12:25 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: acidic or basic salts?
Replies: 3
Views: 14

### Re: acidic or basic salts?

In water, salts decompose into their constituent anions and cations. If one (and only one) of these parts is a strong acid or a strong base, the salt will act as a strong base or strong acid, respectively. If both the cation and the anion are a strong acid and a strong base, then the salt will be ne...
Sun Jan 24, 2021 12:23 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: figuring out whether salts are acidic or basic
Replies: 4
Views: 14

### Re: figuring out whether salts are acidic or basic

Bases take H+ (protons) from the water surrounding them, turning some of the water into OH-. This is why bases increase the OH- concentration of a solution and thereby decrease the pOH.
Sun Jan 24, 2021 12:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Problem 5I.29
Replies: 4
Views: 21

### Re: Problem 5I.29

If K on the order of 10-4 or smaller, it is safe to approximate that an expression like (0.22-2x)2 is about (0.22)2.
Sat Jan 23, 2021 11:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Difference between K and Kc
Replies: 13
Views: 30

### Re: Difference between K and Kc

K is just used as shorthand for Kc or Kp. K can be used interchangeably with Kc or Kp.
Sat Jan 23, 2021 11:06 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.29 Question
Replies: 1
Views: 4

### Re: 5I.29 Question

Yes, you can use the ICE table to solve this. If the volume were not 1 L, as long as the partial pressure was given, you would not have to do an extra step. If for example moles were given, then you would have to divide moles by the volume to find moles per liter.
Sun Jan 17, 2021 12:56 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ice Box Method
Replies: 14
Views: 40

### Re: Ice Box Method

If the concentration of something is decreasing, you should use a negative sign for x, and vise versa. For example, in a problem where you add one reactant into a vessel and the chemical reaction produces products, the sign for the reactant should be negative and the sign for the products should be ...
Sun Jan 17, 2021 12:55 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: How do we know a compound is a weak acid or base?
Replies: 6
Views: 23

### Re: How do we know a compound is a weak acid or base?

Acids donate protons, while bases accept protons. You can often figure out whether a compound is an acid or a base by drawing its molecular structure. Some strong acids and bases you just need to memorize, however.
Sun Jan 17, 2021 12:53 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Adding together two equilibrium equations
Replies: 5
Views: 16

### Re: Adding together two equilibrium equations

If you added two equilibrium concentrations, the equilibrium constants would also be added together. However, most of the time when you modify existing equilibrium equations to find a new K value, you will multiply or divide the equilibrium equations because this allows you to remove terms from the ...
Sun Jan 17, 2021 12:51 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook 5G3
Replies: 1
Views: 9

### Re: Textbook 5G3

Since all the reactants and products are gases, you should give the answer in terms of partial pressures. Also, if the values you are given are in terms of partial pressure, giving the answer in terms of partial pressure should be much easier since you will not have to convert between concentration ...
Sun Jan 17, 2021 12:50 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Focus 5 Exercise 61
Replies: 2
Views: 7

### Re: Focus 5 Exercise 61

Since water is present in large amounts in photosynthetic plant cells, the water is assumed to be in large excess for this reaction. Whenever a reactant is in large excess, you do not need to include it in the K value and thus changing the concentration of water will not affect the equilibrium compo...
Sun Jan 17, 2021 12:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Focus 5 Exercise 57
Replies: 1
Views: 6

### Re: Focus 5 Exercise 57

You have been given two values, the initial concentration of SO3 and the equilibrium concentration of SO2. Using these values, you can make an ICE table, solve for the x values using the given K value, and plug that x value back into the term for initial NO concentration. Good luck!
Sun Jan 17, 2021 12:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook 5.35
Replies: 2
Views: 10

### Re: Textbook 5.35

All you should need to write the balanced equation is the chemical formulas of each of the gases. Writing the balanced equation is as simple as placing stoichiometric coefficients in front of each of the reactants and products. Hope this helps.
Sun Jan 10, 2021 10:50 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Textbook 5J #5 Part D?
Replies: 6
Views: 24

### Re: Textbook 5J #5 Part D?

If the problem simply says that there is an increase in pressure, you could assume that equal amounts (in moles) are being added to each of the gases in the equation. If you add equal amounts in moles to all the gases, there would be no change in equilibrium. However, "increase in pressure"...
Sun Jan 10, 2021 10:48 pm
Forum: Student Social/Study Group
Topic: Answering Questions with Responses
Replies: 5
Views: 34

### Re: Answering Questions with Responses

Yes, you do. However, this is not very helpful if you're simply repeating what everyone else has said, try to add at least one new thing (for example, another way of thinking about the problem) to your answer.
Sun Jan 10, 2021 10:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling #2
Replies: 4
Views: 20

### Re: Sapling #2

You need to make a table. Write down the initial values that you are given and the equilibrium values that you are provided, then define the changes in concentration in terms of x, and finally plug all your equilibrium values into the equation and solve for x.
Sun Jan 10, 2021 9:45 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Conditions of Equilibrium
Replies: 4
Views: 25

### Re: Conditions of Equilibrium

Another condition given in an equilibrium problem might be the volume of the container, so remember to divide given moles by volume before you start the problem.
Sun Jan 10, 2021 7:40 pm
Forum: Ideal Gases
Topic: Equation Constant
Replies: 5
Views: 43

### Re: Equation Constant

In math, proportional equations mean that the equation is equal except for a constant missing from one or both sides. Adding a constant changes the equation from a proportional equation to an real equation, i.e., the two sides are equal.
Sun Jan 10, 2021 6:51 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling HW 1 Question 2
Replies: 8
Views: 49

### Re: Sapling HW 1 Question 2

You forgot to divide the moles by the volume of the container, so the correct value of x is four times smaller than the one you found (x=0.035). Hope this helps!
Sun Jan 10, 2021 6:45 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Increasing the Yield of the Product.
Replies: 5
Views: 24

### Re: Increasing the Yield of the Product.

To answer this question in another way, removing the product would reduce the Qc of the reaction, since the concentration of product will decrease. Now that Q is lower than K, the reaction will move in the forward direction until Q = K once again and chemical equilibrium is restored.
Wed Dec 16, 2020 6:07 pm
Forum: Student Social/Study Group
Topic: New Year Resolutions?
Replies: 54
Views: 174

### Re: New Year Resolutions?

I want to develop my communication and scheduling skills, as these things are a lot more difficult in the era of COVID and as a college student.
Wed Dec 16, 2020 6:07 pm
Forum: Student Social/Study Group
Topic: New Year Resolutions?
Replies: 54
Views: 174

### Re: New Year Resolutions?

I want to develop my communication and scheduling skills, as these things are a lot more difficult in the era of COVID and as a college student.
Tue Dec 15, 2020 9:34 pm
Forum: Hybridization
Topic: Hybridization of CO2
Replies: 5
Views: 52

### Re: Hybridization of CO2

Just to add to your answer, the non-hybrid 2p orbitals also play a part in bonding in this molecule, forming the second (pi) bond between each oxygen and the carbon.
Tue Dec 15, 2020 9:29 pm
Forum: Lewis Structures
Topic: Most Stable Structure
Replies: 23
Views: 119

### Re: Most Stable Structure

The original poster mentioned not using trial and error, so in order to save time, while drawing the structure try to make sure that the formal charges are as close to zero as possible. In order to achieve this, you can follow trends like nitrogen forming three bonds, oxygen forming two bonds, and f...
Tue Dec 15, 2020 9:27 pm
Forum: Student Social/Study Group
Topic: Study music
Replies: 32
Views: 171

### Re: Study music

I agree with lots of people that listening to music without lyrics can make studying very easy! My favorite album to listen to while studying is Raise Your Skinny Fists Like Antennas to Heaven by Godspeed You! Black Emperor. It won't be for everyone but I find it so conducive to focus.
Tue Dec 15, 2020 9:24 pm
Forum: General Science Questions
Topic: Chemistry Behind Mosquito Bites
Replies: 6
Views: 72

### Re: Chemistry Behind Mosquito Bites

Interesting question. I generally don't use mosquito spray because of the chemicals in it, but I don't think said chemicals are very dangerous to humans in the amount they're present in bug spray. Also, in areas where mosquitos carry diseases like malaria, mosquito spray is definitely justified and ...
Tue Dec 15, 2020 9:22 pm
Forum: Student Social/Study Group
Topic: Plans for Relaxing After Finals
Replies: 98
Views: 457

### Re: Plans for Relaxing After Finals

I am planning to play lots of video games while I have time!
Sun Dec 06, 2020 7:13 pm
Forum: Lewis Acids & Bases
Topic: sapling #6
Replies: 19
Views: 108

### Re: sapling #6

The COOH group gives away a proton in the form of a positively charged hydrogen atom, which makes it an acid.
Sun Dec 06, 2020 7:10 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Tips on determining coordination number
Replies: 5
Views: 32

### Re: Tips on determining coordination number

You are correct, coordination number is just the number of bonds from the central atom to ligands.
Sun Dec 06, 2020 7:09 pm
Forum: Naming
Topic: Oxidation number
Replies: 5
Views: 59

### Re: Oxidation number

You can usually tell by the chemical formula of a coordination compound what the oxidation number of the metal cation is. For example, in the coordination compound [Co(NH 3 ) 4 Cl 2 ]Cl, you can see that there are three chlorines, each with an oxidation number of -1. Since the compound is neutral ov...
Sun Dec 06, 2020 7:06 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Sapling Question #2
Replies: 7
Views: 50

### Re: Sapling Question #2

The oxidation state is the positive charge of the metal atom, so oxidation state + oxidation states of other atoms in the compound must equal overall charge of the compound. Since this compound has an overall charge of -1, and each chlorine atom has an oxidation state of -1, the oxidation state of c...
Sun Dec 06, 2020 7:03 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Sapling #6
Replies: 3
Views: 21

### Re: Sapling #6

The oxidation state is +2 because the overall charge of the molecule is neutral, and you know each chlorine atom has a charge of -1, so since there are two chlorine atoms, the charge of the cobalt must be +2 to result in a neutrally charged molecule.
Sun Dec 06, 2020 7:02 pm
Forum: Naming
Topic: Sapling Week 9 #1
Replies: 6
Views: 46

### Re: Sapling Week 9 #1

The name is composed of ligands in alphabetical order with greek number prefixes, then the name of the transition metal, then any atoms outside. So this molecule would be tetramminecholocobalt (III) dichloride.
Sun Dec 06, 2020 6:58 pm
Forum: Naming
Topic: Cl & Br3
Replies: 7
Views: 52

### Re: Cl & Br3

Bromide specifically refers to Br-, Br3 is named tribromide.
Sun Dec 06, 2020 6:57 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sapling Week 9 HW #3
Replies: 5
Views: 61

### Re: Sapling Week 9 HW #3

To exlplain further, a coordination number of six means there are six bonds between the transition metal and the ligand. Six bonds arrange themselves in an octahedral geometry with four ligands in the plane at 90 degrees and one ligand above and below the plane.
Sun Dec 06, 2020 6:37 pm
Forum: Naming
Topic: Naming [Co(CN)5(OH2)]2-
Replies: 5
Views: 36

### Re: Naming [Co(CN)5(OH2)]2-

You just need to replace hydro with aqua, as indicated on the ligand naming sheet from discussion. Since aqua starts with an a and there is only one water molecule, the molecule begins with "aqua" and then the rest of the name follows.
Wed Dec 02, 2020 1:27 pm
Forum: Hybridization
Topic: Pi Bonds Cannot Rotate
Replies: 23
Views: 166

### Re: Pi Bonds Cannot Rotate

Pi bonds cannot rotate because they are p-orbitals overlapping side-by-side, so that both electron density areas are "touching." Hope this helps.
Sun Nov 29, 2020 7:44 pm
Forum: Student Social/Study Group
Topic: Expanded Octet
Replies: 4
Views: 25

### Re: Expanded Octet

Since As is in the 4th period of the periodic table, it can use d-orbitals to form an expanded octet. Any elements with atomic number > 20 can use d-orbitals to form an expanded octet.
Sun Nov 29, 2020 7:41 pm
Forum: Lewis Structures
Topic: Expanded Valence Shells
Replies: 7
Views: 62

### Re: Expanded Valence Shells

Jaden Haskins 2F wrote:What is the reason that p-block elements can have an expanded valence shell? Why do elements with an atomic number >20 want more electrons?

These elements can have an expanded valence shell because they can use d-orbitals for bonding, meaning they can have more than an octet of electrons.
Sun Nov 29, 2020 7:39 pm
Forum: Coordinate Covalent Bonds
Topic: Do C.C. bonds have expanded octet?
Replies: 3
Views: 32

### Re: Do C.C. bonds have expanded octet?

I think that the professor mentioned that most transition metals are more stable with an expanded octet, just like some p-block elements. Additionally, the transition metal had an expanded octet in each example he provided.
Sun Nov 29, 2020 7:37 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Diamagnetism, Paramagnetism
Replies: 3
Views: 28

### Re: Diamagnetism, Paramagnetism

No, I don't think either of these concepts are mentioned in any of the lectures.
Sun Nov 29, 2020 7:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: How to determine negative poles? (Week 8 Sapling Q10)
Replies: 9
Views: 51

### Re: How to determine negative poles? (Week 8 Sapling Q10)

The negative poles are located closer to the more electronegative atom in the compound, since that atom attracts electrons more strongly. For example, in H2O, the negative pole is located closer to the oxygen than the hydrogens.
Sun Nov 29, 2020 7:34 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligands
Replies: 5
Views: 25

### Re: Ligands

Yes, I believe that all Lewis bases are ligands and vise versa because both definitions define a compound that can give away two electrons to form a coordinate bond.
Sun Nov 29, 2020 6:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Linear Shape and Lone Pairs
Replies: 8
Views: 79

### Re: Linear Shape and Lone Pairs

Yes, a molecule like O2 has both lone pairs and is linear. However, a molecule with three atoms would not be linear if the central atom had any lone pairs.
Sun Nov 29, 2020 6:43 pm
Forum: Hybridization
Topic: Hybridization of Carbon
Replies: 10
Views: 83

### Re: Hybridization of Carbon

The number 3 comes from the fact that there are three separate p-orbitals used to form the sp3 hybridization,
Sun Nov 29, 2020 5:25 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Textbook Problem 2F3
Replies: 4
Views: 18

### Re: Textbook Problem 2F3

The first bond between any two atoms will always be a sigma-bond, while the second and third bonds between the atoms (in a double or triple bond) will be pi-bonds. You should be able to figure out which atoms have single, double, and triple bonds from the Lewis structure and then use that informatio...
Sun Nov 29, 2020 5:21 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Textbook Problem 2E27
Replies: 4
Views: 9

### Re: Textbook Problem 2E27

During exams, we will always be provided with the molecular formula for a compound when determining its shape in addition to the name of the compound. Thus, I think it would be reasonable to look up the formulas of these molecules.
Sun Nov 29, 2020 5:19 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Textbook Problem 2E11
Replies: 3
Views: 20

### Re: Textbook Problem 2E11

I think that VSEPR formula refers to finding the placement of lone pairs and paired electrons and using that information to determine the overall shape of the molecule.
Sun Nov 29, 2020 5:14 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Textbook Problem 2E5
Replies: 3
Views: 28

### Re: Textbook Problem 2E5

I think that the shape of an ion depends on the location of its unpaired electron, which affect its regions of electron density and therefore its shape. The bond angle of OClO would be affected by the lone pairs on the chlorine atom, giving the molecule a "bent" shape.
Sun Nov 15, 2020 7:11 pm
Forum: Dipole Moments
Topic: Strength of Dipole-Dipole vs Induced Dipole-Dipole
Replies: 4
Views: 16

### Re: Strength of Dipole-Dipole vs Induced Dipole-Dipole

Dr. Lavelle stated in the lecture that both types of dipole intramolecular forces have an energy of -2kJ/mol. I agree that dipole-dipole seem intuitively stronger, but I believe they are the same.
Sun Nov 15, 2020 7:04 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge and Ions
Replies: 7
Views: 81

### Re: Formal Charge and Ions

I believe that the concept of formal charges only applies to covalent bonds. I wrote in my notes that the definition of formal charge is "gain or loss of electrons of an atom when forming a covalent bond." Thus, formal charge does not apply to ionic compounds. This also makes sense because...
Sun Nov 15, 2020 7:02 pm
Forum: Dipole Moments
Topic: Dipole or Ion
Replies: 4
Views: 30

### Re: Dipole or Ion

To further clarify, "dipole" is a characteristic of a covalent bond in which electrons are unequally shared, so one atom is slightly positive and the other atoms is slightly negative (hence the name). Ionic bonds form when a cation "gives" an electron to an anion, creating one fu...
Sun Nov 15, 2020 6:59 pm
Forum: Dipole Moments
Topic: Sapling #13
Replies: 9
Views: 52

### Re: Sapling #13

Also, each lone pair on an atom like nitrogen can form a hydrogen bond, as long as you ignore that the space might not be enough for two water molecules. Thus, the answer might be more than you originally thought. Hope this helps!
Sun Nov 15, 2020 6:57 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sapling #20
Replies: 12
Views: 93

### Re: Sapling #20

This molecule has no hydrogen bonded to a highly electronegative atom, so it cannot form hydrogen bonds. It could form hydrogen bonds with water because of the oxygen bonded to the carbon, but it cannot make hydrogen bonds with itself.
Sun Nov 08, 2020 5:23 pm
Forum: Lewis Structures
Topic: Layout of Lewis Structures
Replies: 2
Views: 19

### Re: Layout of Lewis Structures

Nitrogen has the lowest ionization energy of the elements listed, so it would be the central atom in the Lewis structure. I think that this is a more important consideration than formal charge.
Sun Nov 08, 2020 5:21 pm
Forum: Properties of Electrons
Topic: Orbital Energies
Replies: 5
Views: 95

### Re: Orbital Energies

As far as I know, orbitals are math functions which represent the likelihood of an electron being at any given point at any given time. They are math functions because they are three dimensional sine waves.
Sun Nov 08, 2020 5:17 pm
Forum: Quantum Numbers and The H-Atom
Topic: Pauli Exclusion Principle
Replies: 6
Views: 23

### Re: Pauli Exclusion Principle

Electrons have unique quantum numbers, meaning no two electrons can exist in an atom with the same quantum numbers. Within each suborbital, the first three quantum numbers are the same, meaning the fourth quantum number can either be -1/2 or 1/2. Thus, one "spin down" electron and one &quo...
Sun Nov 08, 2020 5:14 pm
Forum: Formal Charge and Oxidation Numbers
Topic: formal charge
Replies: 11
Views: 42

### Re: formal charge

To clarify further, formal charge is defined as the gain or loss of electrons of an atom when forming a covalent bond. Thus, an atom not forming a covalent bond could not have a formal charge.
Sun Nov 08, 2020 5:12 pm
Forum: Coordinate Covalent Bonds
Topic: formation of coordinate covalent bonds
Replies: 4
Views: 49

### Re: formation of coordinate covalent bonds

Hydrogen could not donate an electron pair because it only has one electron in its base state. Helium theoretically could donate an electron pair, but would not because both of its electrons are tightly held, explaining helium's non-reactive nature. Lithium only gives up one electron when forming an...
Sun Nov 01, 2020 4:55 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 1E.7
Replies: 6
Views: 22

### Re: 1E.7

Rohit, as far as I can tell your answer is mostly correct but (a) also does not follow Hund's rule.
Sun Nov 01, 2020 4:54 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 1E.7
Replies: 6
Views: 22

### Re: 1E.7

Remember, a ground state atom will follow Hund's rule. That is, electrons will fill a subshell by first occupying different orbitals with parallel spin and then filling in these orbitals only when more electrons are added. So the C electron configuration shown here is not the ground state. Also reme...
Sun Nov 01, 2020 4:44 pm
Forum: Quantum Numbers and The H-Atom
Topic: Sapling question 21
Replies: 11
Views: 69

### Re: Sapling question 21

At energy level n=2, an atom could have the s and p states. Therefore, there could be two atoms in the 2s state, and six atoms in the 2p state. In total, this atom could have eight electrons. This is represented on the periodic table, as Neon is the atom with the highest number of electrons (8) cont...
Sun Nov 01, 2020 4:36 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration For Calcium
Replies: 7
Views: 72

### Re: Electron Configuration For Calcium

The reason that 4s comes before 3d for K and Ca is that the 4s state has a lower energy level than the 3d state for these specific elements. In elements like scandium, the 3d state is once again a lower energy so 3d is written before 4s. Basically, K and Ca are exceptions. Hope this helps.
Sun Nov 01, 2020 4:14 pm
Forum: Trends in The Periodic Table
Topic: Isoelectronic atoms/ions Radii
Replies: 1
Views: 20

### Re: Isoelectronic atoms/ions Radii

O2- is slightly larger than F- because despite having the same number of electrons, O2- has a smaller nuclear charge and thus attracts the electrons less strongly than F-.
Sun Nov 01, 2020 3:12 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: [Ar]3d14s2 vs [Ar] Ar4s23d1
Replies: 3
Views: 27

### Re: [Ar]3d14s2 vs [Ar] Ar4s23d1

When the 4s2 is full and there is one electron in the 3d shell, the 3d shell is now a lower energy level than the 4s shell. Thus, you write the 3d shell before the 4s shell.
Sun Oct 25, 2020 4:18 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Clarification on the "uncertainty" part of this equation
Replies: 7
Views: 108

### Re: Clarification on the "uncertainty" part of this equation

Stated in words, the Heisenberg uncertainty equation is: the uncertainty in the position of an object times the uncertainty in its velocity is more than or equal to Planck's constant divided by 4*pi. The uncertainty (or as Professor Lavelle often refers to it, the indeterminacy) is a measure of the ...
Sun Oct 25, 2020 4:12 pm
Forum: Limiting Reactant Calculations
Topic: Textbook G.25
Replies: 4
Views: 60

### Re: Textbook G.25

To provide further clarification, your answer states that there is less than 1 molecule left, or really closer to 1 millionth of a molecule left. Molecules are indivisible (ignoring fission), so this small of a number indicates that there is no molecule remaining.
Sun Oct 25, 2020 2:14 pm
Forum: DeBroglie Equation
Topic: Detecting wavelike properties
Replies: 5
Views: 29

### Re: Detecting wavelike properties

The professor stated in lecture that 10^-15 m is the limit for detecting wavelike properties. Any value smaller than this, and wavelike properties will not be detected. 10^-38 meters is an incredibly small distance far beyond technology's capability to detect.
Sun Oct 25, 2020 2:10 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Rearranging uncertainty in velocity
Replies: 5
Views: 38

### Re: Rearranging uncertainty in velocity

This is an algebra question. When you have an equation of the form x=y*z, and you want to find the value of z, you would divide both sides by y, yielding x/y = z.
Sun Oct 25, 2020 2:07 pm
Forum: DeBroglie Equation
Topic: Using kg in DeBroglie Equation instead of g
Replies: 3
Views: 37

### Re: Using kg in DeBroglie Equation instead of g

Kg is the SI unit for mass, just as, for example, meters is the SI unit for distance and seconds is the SI unit for time. Mass is sort of unusual as it is one of the only SI units with a prefix. In fact, it might actually be the only SI unit with a prefix, but I'm not sure.
Sun Oct 25, 2020 2:05 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty in percentage
Replies: 8
Views: 73

### Re: Uncertainty in percentage

The delta-v is 4.5(0.01), as you guessed. Multiply the percentage uncertainty by the velocity to find the absolute uncertainty.
Sun Oct 25, 2020 2:04 pm
Forum: Photoelectric Effect
Topic: Calculating Maximum Kinetic Energy
Replies: 1
Views: 44

### Re: Calculating Maximum Kinetic Energy

The information given can be used to find the threshold energy of the metal, which will be needed to find the solution. A photon of wavelength 210 nm will have an energy of 9.47 * 10 -19 J, or 5.91 eV. 5.91 eV minus 1.25 eV tells us the threshold energy, 4.66 eV. The energy of a photon at a waveleng...
Sun Oct 25, 2020 1:54 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Paired vs. Parallel Spins
Replies: 5
Views: 66

### Re: Paired vs. Parallel Spins

"Parallel" spins would be two electrons with the same spin, for example in nitrogen where all three of the 2p orbitals are only half filled with spin "up" electrons. Paired spins would be for example in neon, where each of these 2p orbitals has now been filled with an additional ...
Sun Oct 25, 2020 11:14 am
Forum: Administrative Questions and Class Announcements
Topic: CCLE website
Replies: 12
Views: 79

### Re: CCLE website

I am experiencing the same issue right now. This is a wild guess, but it may have something to do with the planned power outages currently going on across California.
Sun Oct 25, 2020 11:14 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: P-, d-, f- Orbitals
Replies: 5
Views: 46

### Re: P-, d-, f- Orbitals

All these answers are correct. To provide some further information, the nodal planes of the p-, d-, and f-orbitals are the reason that these states are a higher energy level than the s-orbital when they are in the same shell, because the different arrangement means that the effective nuclear charge ...
Sun Oct 25, 2020 11:06 am
Forum: *Shrodinger Equation
Topic: The Hamiltonian
Replies: 8
Views: 125

### Re: The Hamiltonian

In the lecture about Schrodinger's wave function equation, Professor Lavelle mentioned that if one "operates a change on ψ(x,y,z), it would equal E*ψ(x,y,z)." The change operation was represented as H, meaning H*ψ = E*ψ. Therefore, H would be equal to the energy of the system. That being s...
Thu Oct 22, 2020 5:13 pm
Forum: *Shrodinger Equation
Topic: The Hamiltonian
Replies: 8
Views: 125

### Re: The Hamiltonian

Good explanation, Katarina. I would just like to clarify that the derivative of sin(x) is cos(x), but the derivative of cos(x) is -sin(x). The derivative of -sin(x) is -cos(x) and the derivative of -cos(x) is sin(x). It is a cycle, but it repeats every four derivatives instead of every two.
Thu Oct 15, 2020 9:24 pm
Forum: Quantum Numbers and The H-Atom
Topic: Atomic Spectra Post-Assessment #38
Replies: 1
Views: 42

### Re: Atomic Spectra Post-Assessment #38

We can use an equation derived from En = -hR/n^2. The derived equation, which Professor Lavelle briefly mentions in the video module, is v = -R[(1/ni^2 - 1/nf^2. In your example, it would be v = -R[(1/16-1/4). The resulting frequency is 6.169 * 10 ^14.
Thu Oct 15, 2020 9:15 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg Equation
Replies: 1
Views: 33

### Re: Rydberg Equation

As you said, the initial equation is En = (-hR/n^2). We can divide both sides by Planck's constant to get v = (-R/n^2). Now we can also say that v2 = (-R/n2^2). If we subtract the two, then v = (-R/n^2) + (R/n2^2). Remove the -R and we get v = -R[1/n1^2 - 1/n2^2]. In terms of which n is which, I fin...
Thu Oct 15, 2020 8:58 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: N2 vs N1
Replies: 4
Views: 72

### Re: N2 vs N1

If your final level is 1 and your initial level is 3, the equation would be: v = -R[1/9) - 1]. This gets you a frequency of 2.924 * 10^15 and a wavelength (wavelength = speed of light/frequency) of 102 nanometers. Hope this helps!
Thu Oct 15, 2020 8:48 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Determining Electron Energy Levels When Given Wavelength
Replies: 2
Views: 30

### Determining Electron Energy Levels When Given Wavelength

Hi, I am confused about question 6 on the Sapling homework for weeks 2 and 3. The question states: "A red line is observed at 656.3 nanometers in the spectrum of atomic hydrogen. Determine the values of n for the beginning and ending energy levels of the electron during the emission of energy t...
Thu Oct 15, 2020 8:37 pm
Forum: Photoelectric Effect
Topic: 1B #7 part b
Replies: 5
Views: 53

### Re: 1B #7 part b

In order to get part b, we first need to solve part a. If sodium emits light of a wavelength of 589 nanometers, we can divide the speed of light (3*10^8 m/s) by 589 nanometers (5.89 * 10^-7) to find the frequency, 5.09 * 10^14 Hz. We can multiply this number by Planck's constant to find the energy e...
Wed Oct 07, 2020 5:34 pm
Forum: Empirical & Molecular Formulas
Topic: Sampling Question #8
Replies: 5
Views: 78

### Re: Sampling Question #8

A chemical structure like the one in this problem will always represent the molecular formula, because the chemical structure shows every atom in the molecule.
Wed Oct 07, 2020 5:27 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: HW Problem E.9
Replies: 7
Views: 92

### Re: HW Problem E.9

The key to writing out the molecular formula of a molecule lies in its name. In this case, the name of the molecule is magnesium sulfate heptahydrate. Magnesium is represented by Mg, sulfate refers to the ion SO 4 . Since the charge of Mg is 2+ and the charge of sulfate is 2-, there would be one of ...
Wed Oct 07, 2020 4:48 pm
Forum: Empirical & Molecular Formulas
Topic: Outline #1 Topic
Replies: 2
Views: 49

### Re: Outline #1 Topic

Fundamentals F has several practice problems involving finding molecular formulas from visual representations of structures.
Wed Oct 07, 2020 4:43 pm
Forum: Student Social/Study Group
Topic: 2H GroupMe?
Replies: 1
Views: 17

### Re: 2H GroupMe?

Here is the link to the GroupMe for Discussion 2H: https://groupme.com/join_group/63039457/4Ltubrf4
Wed Oct 07, 2020 4:39 pm
Forum: Electronegativity
Topic: Electronegativity
Replies: 16
Views: 382

### Re: Electronegativity

Also, when the difference in electronegativity between the two atoms is greater than 1.7, the atoms will form an ionic bond instead of a covalent bond, since the atom with the higher electronegativity will "steal" one or more electrons from the other atom.

Go to advanced search