Search found 73 matches

Sat Jan 23, 2021 6:57 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Week 3 Sapling #5
Replies: 4
Views: 30

Week 3 Sapling #5

Can someone please explain how they did the problem below? I understand the general steps to getting the resulting heat enthalpy: 1) manipulate the given equations so that you get the amount of reactant or product for the equation you want 2) apply those numerical manipulations to the corresponding ...
Sat Jan 23, 2021 6:16 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Strength of Bonds
Replies: 7
Views: 20

Re: Strength of Bonds

Thanks for your response! What if the two reactants seem to be neutral and balance each other out? How would you use the products to determine the type of reaction?
Sat Jan 23, 2021 5:48 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Strength of Bonds
Replies: 7
Views: 20

Strength of Bonds

How do you use the strength of bonds to determine whether a reaction will be endothermic or exothermic?
Sat Jan 23, 2021 5:47 pm
Forum: Phase Changes & Related Calculations
Topic: bonds and energy
Replies: 13
Views: 49

Re: bonds and energy

When a bond is broken, it requires energy and is an endothermic reaction because you are basically making the bond less stable. Whereas when a bond is formed, it releases energy and is, therefore, an exothermic reaction because you are making the bond stable.
Sat Jan 23, 2021 5:28 pm
Forum: Phase Changes & Related Calculations
Topic: Steam causing severe burns
Replies: 19
Views: 68

Re: Steam causing severe burns

When you are using a pressure cooker and release the steam, it would cause more severe burns than when coming into contact with water because it turned into vapor from boiling water through an increase in temperature.
Fri Jan 15, 2021 9:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling week 2 #9
Replies: 1
Views: 8

Sapling week 2 #9

Hi can someone explain why the answer is charged? Below is the question. A monoprotic weak acid, HA , is ionized according to the reaction HA(aq)+H2O(l)↽−−⇀A−(aq)+H3O+(aq) pKa=3.84 where A− is the conjugate base to HA. For this weak monoprotic acid, the predominant species present at pH 5.64 is
Fri Jan 15, 2021 7:44 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Week 2 HW
Replies: 8
Views: 41

Re: Week 2 HW

Can someone show me step by step how exactly they solve for x when using the quadratic formula for Wk 2 Sapling #3? I can never get the right answer and the number inside the square root is always negative somehow.
Fri Jan 15, 2021 7:41 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Week 2 HW
Replies: 8
Views: 41

Re: Week 2 HW

What are the steps to find the percent ionization of a solution?
Fri Jan 15, 2021 7:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Percent ionization
Replies: 6
Views: 19

Percent ionization

What is a simple definition of percent ionization?
Fri Jan 15, 2021 7:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Molecular phases
Replies: 6
Views: 17

Molecular phases

What is the difference between (aq) and (l)? Why do we exclude H2O when calculating equilibrium?
Fri Jan 15, 2021 7:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Week 2 Sapling #1
Replies: 2
Views: 17

Week 2 Sapling #1

How do you know if a concentration change is small compared to the given initial condition?
Fri Jan 08, 2021 8:32 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Change in Pressure
Replies: 9
Views: 40

Re: Change in Pressure

Why does inert gas not apply to the same rule of the effect of changing the pressure on the concentration?
Fri Jan 08, 2021 8:25 pm
Forum: Ideal Gases
Topic: Kc vs Kp
Replies: 109
Views: 936

Re: Kc vs Kp

You use Kp when you are dealing with gases, but use Kc when you are dealing with molarity.
Fri Jan 08, 2021 8:19 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling #3
Replies: 11
Views: 82

Re: Sapling #3

How do you set up the ICE chart for this? Will H2 end up with 0.4M-X and I2 with 0.4M-X and 2HI with +2X as the equilibriums?
Fri Jan 08, 2021 8:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling #3
Replies: 11
Views: 82

Re: Sapling #3

I had the same problem as Darren. I just set up my equation as [HI^2}/{H2][I2] but the answer I got, in the end, was wrong. Why is this?
Fri Jan 08, 2021 7:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling #2
Replies: 1
Views: 32

Sapling #2

The problem is:
At a certain temperature, 0.860 mol SO3 is placed in a 5.00 L container.
2SO3(g)↽−−⇀2SO2(g)+O2(g)
At equilibrium, 0.190 mol O2 is present. Calculate Kc.

How do you find the concentration of SO2 to then calculate Kc?
Wed Dec 09, 2020 2:51 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: UA Question
Replies: 1
Views: 27

UA Question

How would you do this problem?
Tue Dec 08, 2020 11:47 pm
Forum: Identifying Acidic & Basic Salts
Topic: acidic/basic solution of salts
Replies: 4
Views: 37

Re: acidic/basic solution of salts

How would you identify the pH level of a molecule just by looking at its chemical formula?
Tue Dec 08, 2020 11:34 pm
Forum: Identifying Acidic & Basic Salts
Topic: Sapling #8
Replies: 2
Views: 12

Sapling #8

How would you identify aqueous solutions as acidic or basic by their H+ or OH- concentrations?
Tue Dec 08, 2020 10:09 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Sapling Week 10 question
Replies: 6
Views: 58

Re: Sapling Week 10 question

I notice that all the problems above are labeled to be at 25 degrees Celsius. How would the temperature affect the pH of substances?
Tue Dec 08, 2020 9:55 pm
Forum: Conjugate Acids & Bases
Topic: Conjugate Acids and Bases
Replies: 4
Views: 47

Re: Conjugate Acids and Bases

So basically to find the conjugate acid of a molecule, we add a hydrogen to it and give it a positive charge, and to find the conjugate base of a molecule, we take a hydrogen away from the molecule and make it a negative charge?
Tue Dec 08, 2020 9:32 pm
Forum: Amphoteric Compounds
Topic: How to determine amphoteric compounds
Replies: 5
Views: 16930

Re: How to determine amphoteric compounds

Could someone elaborate more on Kyle's process of easily identifying the amphoteric substance out of a list of substances that you are given? I still do not quite understand. Are there any patterns we should look out for?
Sat Dec 05, 2020 2:44 pm
Forum: Calculating the pH of Salt Solutions
Topic: pH formula?
Replies: 46
Views: 934

Re: pH formula?

What is the difference between pH=-log[H3O+] and pH=-log[H+]?
Sat Dec 05, 2020 2:42 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: coordination number
Replies: 13
Views: 80

Re: coordination number

Can someone explain more in detail of what bidentate means in a coordination compound and how it is different from a monodentate?
Sat Dec 05, 2020 2:39 pm
Forum: Naming
Topic: Naming
Replies: 6
Views: 65

Re: Naming

Any tips for remembering how to name coordination compounds and remembering which suffixes to use?
Sat Dec 05, 2020 2:36 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: chelate
Replies: 7
Views: 55

Re: chelate

What is a chelating ligand?
Sat Dec 05, 2020 2:35 pm
Forum: Naming
Topic: Polydentate
Replies: 8
Views: 58

Re: Polydentate

How would you identify a monodentate and a bidentate?
Sun Nov 29, 2020 1:22 pm
Forum: Hybridization
Topic: Sapling #18
Replies: 10
Views: 100

Sapling #18

What does it mean when the atoms lie in the same plane? The problem is below: Select the correct statement about the relative positions of the hydrogen atoms in the three structures. The hydrogen atoms of H2CCH2 and H2CCCH2 lie in the same plane. The hydrogen atoms of H2CCCH2 and H2CCCCH2 lie in the...
Sun Nov 29, 2020 12:36 pm
Forum: Sigma & Pi Bonds
Topic: sapling #15
Replies: 24
Views: 136

Re: sapling #15

What are delocalized pi bonds?
Sat Nov 28, 2020 3:37 pm
Forum: Sigma & Pi Bonds
Topic: Sigma and Pi Bonds
Replies: 9
Views: 69

Re: Sigma and Pi Bonds

Are there any other types of bonds other than sigma and pi bonds?
Sat Nov 28, 2020 3:32 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordinate Compounds
Replies: 5
Views: 55

Re: Coordinate Compounds

What is a coordinate compound and examples of it?
Sat Nov 28, 2020 3:32 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape vs Polarity
Replies: 11
Views: 72

Re: Shape vs Polarity

How can you determine if a bond is polar or nonpolar? And from looking at the polarity of the bonds, how would you judge whether the molecule as a whole is polar or nonpolar?
Sat Nov 28, 2020 3:10 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape vs Polarity
Replies: 11
Views: 72

Re: Shape vs Polarity

How do you identify dipoles?
Sat Nov 28, 2020 3:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity and Shape
Replies: 13
Views: 93

Re: Polarity and Shape

How do you know if a molecule is polar?
Wed Nov 18, 2020 9:05 pm
Forum: Bond Lengths & Energies
Topic: Comparing Strengths of Interactions Between Ions
Replies: 2
Views: 34

Comparing Strengths of Interactions Between Ions

Can someone go through step by step how they would go about solving this?
Wed Nov 18, 2020 8:42 pm
Forum: Ionic & Covalent Bonds
Topic: Ionization energy
Replies: 4
Views: 827

Re: Ionization energy

Can someone explain the different parts of the expression for the Coulomb potential energy?
Wed Nov 18, 2020 7:49 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic & Covalent Character
Replies: 3
Views: 32

Re: Ionic & Covalent Character

Can someone explain what lattice energy is and what causes it?
Wed Nov 18, 2020 7:14 pm
Forum: Ionic & Covalent Bonds
Topic: Electronegativity difference
Replies: 12
Views: 89

Re: Electronegativity difference

Can someone explain what the difference is between electron affinity, ionization, and electronegativity? I keep getting so confused.
Wed Nov 18, 2020 11:32 am
Forum: Octet Exceptions
Topic: Octet Rule Exceptions
Replies: 20
Views: 170

Re: Octet Rule Exceptions

I am slightly confused about drawing lewis structures, and specifically the octet rule. Do elements with 1 or 2 valence electrons have to fill an octet? For example, when drawing out a compound that contains the element Na (which has one valence electron), is it ever possible for it to fill the octet?
Mon Nov 09, 2020 8:56 pm
Forum: Bond Lengths & Energies
Topic: Van der Waals
Replies: 7
Views: 92

Van der Waals

What is the Van der Waals interaction between ions and molecules?
Mon Nov 09, 2020 8:53 pm
Forum: Bond Lengths & Energies
Topic: Dissociation Energy
Replies: 4
Views: 26

Dissociation Energy

How is the dissociation energy found for the strength of bonds?
Mon Nov 09, 2020 8:51 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic/Covalent
Replies: 8
Views: 43

Re: Ionic/Covalent

How is a polar covalent bond different from an ionic bond?
Mon Nov 09, 2020 8:51 pm
Forum: Bond Lengths & Energies
Topic: Bond length
Replies: 11
Views: 41

Re: Bond length

How do you calculate Debye? Is it just the electronegativity difference between two atoms?
Mon Nov 09, 2020 8:49 pm
Forum: Dipole Moments
Topic: q for charge
Replies: 5
Views: 50

Re: q for charge

Can someone explain what this equation (u=|q|d) means? Why is there an absolute value sign? What does the q stand for?
Mon Nov 09, 2020 8:47 pm
Forum: Bond Lengths & Energies
Topic: Electron Pairs Interacting
Replies: 3
Views: 26

Electron Pairs Interacting

Can someone explain why lone pairs on neighboring atoms repel each other?
Wed Nov 04, 2020 11:29 am
Forum: Octet Exceptions
Topic: Radicals
Replies: 5
Views: 61

Re: Radicals

Can someone elaborate more on what radicals are? From what I understand, they are just atoms that are electron-deficient, but if I am missing another essential part of its definition, please let me know!
Tue Nov 03, 2020 2:28 pm
Forum: Properties of Electrons
Topic: Orbital Energies
Replies: 5
Views: 95

Orbital Energies

Can someone break down the symbols and explain to me how this equation is derived?
Tue Nov 03, 2020 2:26 pm
Forum: Administrative Questions and Class Announcements
Topic: Fall 2020 Midterm 1 Instructions
Replies: 20
Views: 1084

Re: Fall 2020 Midterm 1 Instructions

What is Midterm 2 going to cover?
Mon Nov 02, 2020 12:56 pm
Forum: Resonance Structures
Topic: Lecture 11/2
Replies: 5
Views: 40

Re: Lecture 11/2

In the SO4 molecule, I know the final charge is -2, but how does it all add up if sulfur's formal charge is 0 and all four oxygens formal charge is -1? So (4(-1)+0)=-4 but not -2. Can someone explain how summing up the total charge of the molecule works using formal charge?
Mon Nov 02, 2020 12:50 pm
Forum: Resonance Structures
Topic: Formal Charge Question
Replies: 16
Views: 378

Re: Formal Charge Question

Does formal charge have anything to do with oxidation numbers in the end?
Wed Oct 28, 2020 7:37 pm
Forum: Trends in The Periodic Table
Topic: Size of isoelectronic atoms/ions
Replies: 9
Views: 75

Re: Size of isoelectronic atoms/ions

How do you know if an atom is isoelectronic in the first place?
Mon Oct 26, 2020 11:19 pm
Forum: Properties of Electrons
Topic: rydberg equation
Replies: 8
Views: 64

Re: rydberg equation

Just to make sure, the Rydberg equation can be used for all series like the Lyman, Balmer, Pacshel, and Brackett, right?
Mon Oct 26, 2020 11:18 pm
Forum: Properties of Electrons
Topic: atomic spectra, absorption spectrums, and emission spectrums
Replies: 3
Views: 34

Re: atomic spectra, absorption spectrums, and emission spectrums

The problem is: In the spectrum of atomic hydrogen, several lines are generally classified together as belonging to a series (for example, Balmer series or Lyman series, as shown in Fig. 1A.10). What is common to the lines within a series that makes grouping them together logical? The answer to it i...
Mon Oct 26, 2020 10:31 pm
Forum: Properties of Electrons
Topic: What does this symbol mean?
Replies: 11
Views: 142

What does this symbol mean?

What does this symbol mean? I have not found anywhere in the book where it defines it.
Mon Oct 26, 2020 8:23 pm
Forum: Limiting Reactant Calculations
Topic: M9
Replies: 3
Views: 44

M9

Can someone explain how to write the net ionic equation? And what is the original equation?

Copper(II) nitrate reacts with sodium hydroxide to produce a precipitate of light blue copper(II) hydroxide. (a) Write the net ionic equation for the reaction.
Mon Oct 26, 2020 7:59 pm
Forum: Limiting Reactant Calculations
Topic: M.7
Replies: 6
Views: 78

Re: M.7

The book seems to use B2O3 as the LR because it uses that reactant to solve for the mass of boron produced. Problem: Solid boron can be extracted from solid boron oxide by reaction with magnesium metal at a high temperature. A second product is solid magnesium oxide. (a) Write a balanced equation fo...
Thu Oct 22, 2020 9:51 pm
Forum: Empirical & Molecular Formulas
Topic: L35
Replies: 4
Views: 2209

Re: L35

Why does this problem give us three chemical reaction equations and not just one?
Wed Oct 21, 2020 9:05 pm
Forum: Properties of Electrons
Topic: Calculating Wavelength of Spectral Line
Replies: 3
Views: 31

Calculating Wavelength of Spectral Line

How do you calculate the wavelength of a spectral line for the second part of the problem?
Wed Oct 21, 2020 12:04 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbitals
Replies: 4
Views: 173

Re: Orbitals

What is the donut in the atom orbital dz^2 diagram?
Wed Oct 21, 2020 12:02 pm
Forum: *Shrodinger Equation
Topic: schrodingers equation
Replies: 8
Views: 272

Re: schrodingers equation

Can someone explain Schrodinger's equation with an example problem?
Wed Oct 21, 2020 12:00 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg Diagram from Lecture
Replies: 5
Views: 56

Heisenberg Diagram from Lecture

Why did Professor Lavelle draw two detectors and not just one in his diagram today when explaining how the path of the electron would be interrupted by the light source?
Wed Oct 21, 2020 11:58 am
Forum: DeBroglie Equation
Topic: DeBroglie Importance
Replies: 8
Views: 74

Re: DeBroglie Importance

I found the lecture a bit confusing. Can someone explain how the units of the De Broglie equation cancel out to get to meters?
Fri Oct 16, 2020 9:50 pm
Forum: Properties of Light
Topic: Spectral Lines
Replies: 11
Views: 115

Re: Spectral Lines

Professor Lavelle went over the atomic spectra today, and he mentioned something about gases when describing the spectral lines. Can someone explain how "gases" are related to the spectra?
Fri Oct 16, 2020 9:47 pm
Forum: Properties of Electrons
Topic: Sapling Homework
Replies: 4
Views: 51

Re: Sapling Homework

Can someone walk me through how to do the problem below? When a metal was exposed to photons at a frequency of 1.15×1015 s−1, electrons were emitted with a maximum kinetic energy of 3.20×10−19 J. What is the maximum number of electrons that could be ejected from this metal by a burst of photons (at ...
Fri Oct 16, 2020 9:38 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical and Molecular Formulas
Replies: 9
Views: 132

Re: Empirical and Molecular Formulas

How would you solve this?

In the following ball-and-stick molecular structures, dark gray indicates carbon; white, hydrogen; blue, nitrogen; and green, chlorine. Write the empirical and molecular formulas of each structure. Hint: It may be easier to write the molecular formula first.
Fri Oct 16, 2020 5:42 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: E1
Replies: 9
Views: 1238

Re: E1

Why should this answer be specifically three sig figs?
Wed Oct 14, 2020 9:06 pm
Forum: Properties of Electrons
Topic: Kinetic Energy of Electrons [ENDORSED]
Replies: 6
Views: 9740

Re: Kinetic Energy of Electrons[ENDORSED]

Can someone walk me through how to solve this problem? An electron was ejected from the surface of an unknown metal. The ejected electron had 2.35 x 10^-18 J of kinetic energy. The photon used to eject the electron had 4.19 x 10^-18 J of energy. Calculate the work function (or threshold energy) of t...
Wed Oct 07, 2020 8:14 pm
Forum: Limiting Reactant Calculations
Topic: Dis 1L Week 1 WS #6
Replies: 4
Views: 44

Re: Dis 1L Week 1 WS #6

Thanks! Your responses help me understand a whole lot better. How would you find the amount of excess reagent?
Tue Oct 06, 2020 10:28 pm
Forum: Properties of Light
Topic: Converting wavelength to Angstrom
Replies: 5
Views: 56

Converting wavelength to Angstrom

How do you convert the visible light of wavelength to Angstroms?
Tue Oct 06, 2020 10:25 pm
Forum: Bond Lengths & Energies
Topic: Bond Length
Replies: 22
Views: 360

Re: Bond Length

I have not learned anything about Angstroms and cannot find a lot about it online. Can someone walk me through how to solve the problem below?

All of the organic compounds contain C and H as their essential elements, the bond length of C-H is 110 pm. Express the C-H bond length in Angstrom.
Tue Oct 06, 2020 10:22 pm
Forum: Limiting Reactant Calculations
Topic: Dis 1L Week 1 WS #6
Replies: 4
Views: 44

Dis 1L Week 1 WS #6

How do you know which reactant is the limiting reactant?
Tue Oct 06, 2020 10:18 pm
Forum: Limiting Reactant Calculations
Topic: Sapling #10 Walkthrough
Replies: 6
Views: 69

Re: Sapling #10 Walkthrough

Also, what does the "d" below each of the reactants and products mean?
Tue Oct 06, 2020 10:12 pm
Forum: Limiting Reactant Calculations
Topic: Sapling #10 Walkthrough
Replies: 6
Views: 69

Re: Sapling #10 Walkthrough

How do you find the molar mass of 2‑butanone?

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