Search found 55 matches

by Sarah Salam 1J
Sun Feb 14, 2021 11:58 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity
Replies: 6
Views: 18

Re: Heat Capacity

The specific heat capacity depends on knowing the mass, heat capacity doesn't so we use that when we don't know the mass.
by Sarah Salam 1J
Sun Feb 07, 2021 9:56 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Sapling #8 Week3/4
Replies: 6
Views: 44

Sapling #8 Week3/4

Could someone explain how they solved for the amount of CS2 produced? I've tried a couple of different ways and I'm not getting the right answer, I was using the heat abosorbed = moles * standard enthalpy equation to solve for moles, then grams.
by Sarah Salam 1J
Sun Jan 31, 2021 11:55 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Solving for Cubic Equations
Replies: 13
Views: 33

Re: Solving for Cubic Equations

I believe we were given an example where the X was negligible in a quadratic equation. It just depends on whether X is small enough, under 10^-4.
by Sarah Salam 1J
Sun Jan 31, 2021 11:51 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pka vs ka
Replies: 18
Views: 60

Re: pka vs ka

You add pKa and pKb because they are logarithmic values, and based on their properties adding them is like multiplying Ka and Kb.
by Sarah Salam 1J
Sun Jan 31, 2021 11:41 pm
Forum: Ideal Gases
Topic: How can we identify when to use the ideal gas law?
Replies: 11
Views: 43

Re: How can we identify when to use the ideal gas law?

You'll have to look at the equation PV=nRT and see if the question is asking you to solve for one of these variables using what you are given. That would mean you are given or can solve for the rest of the variables.
by Sarah Salam 1J
Sun Jan 24, 2021 11:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling #3
Replies: 8
Views: 29

Re: Sapling #3

Use an ICE table to solve for x, and use -logx to find the pH, and use x/concentration X 100 to find percentage.
by Sarah Salam 1J
Sun Jan 24, 2021 11:56 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Base/Acid Scale
Replies: 4
Views: 12

Re: Base/Acid Scale

Like Michael said, strong acids and bases dissociate completely, so one important thing to keep in mind would be that weak ones don't dissociate completely, and we can calculate the percentage that it did, which we did in the homework.
by Sarah Salam 1J
Sun Jan 24, 2021 11:38 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Sapling Week 2 #5
Replies: 3
Views: 21

Re: Sapling Week 2 #5

When you set your equation equal to Kb, did you arrange it like x^2/M-x (this is how I thought of it)? And when you solved it, did you use the M value to divide the x value when you were getting the percentage? That's the only thing I could think of when I compared my work to yours.
by Sarah Salam 1J
Sun Jan 24, 2021 11:24 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Week 2 Sapling #5
Replies: 6
Views: 35

Re: Week 2 Sapling #5

The way I solved this question is by finding the pOH since we have the Kb by subtracting the pH from 14. Then I found x by finding 10 to the power of the negative pOH. I used that and the Kb we were given to find molarity, and used the x and molarity value to find the percentage protonated.
by Sarah Salam 1J
Sun Jan 24, 2021 11:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka and Kb Formula
Replies: 15
Views: 72

Re: Ka and Kb Formula

What key words should we look for in order to determine if we should be using Ka and Kb? This concept caused me a few issues with the homework In the homework, you'd need to use Ka when solving for a weak acid, and Kb when solving for weak bases. You solve for one by dividing 1x10^-14 by the other....
by Sarah Salam 1J
Sun Jan 24, 2021 11:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Clarification for Sampling #7
Replies: 10
Views: 49

Re: Clarification for Sampling #7

Yes, because they are asking about the pH of the weak base, you'll need to find Kb first, and then solve the way you would have with Ka.
by Sarah Salam 1J
Sun Jan 10, 2021 11:52 pm
Forum: Ideal Gases
Topic: Pressure and partial pressure
Replies: 12
Views: 62

Re: Pressure and partial pressure

Partial pressure is for each gas present, the total pressure is all pressures combined.
by Sarah Salam 1J
Sun Jan 10, 2021 11:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Favors
Replies: 10
Views: 57

Re: Favors

A reaction that produces more products than reactants favors the right side. A reaction that has more reactants than products favors the left.
by Sarah Salam 1J
Sun Jan 10, 2021 11:30 pm
Forum: Ideal Gases
Topic: Inert Gases
Replies: 7
Views: 46

Re: Inert Gases

They're noble gases! And they're different because they don't react, so they aren't affecting the equilibrium reaction like other gases would.
by Sarah Salam 1J
Sun Jan 10, 2021 11:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solids and Concentration
Replies: 8
Views: 60

Re: Solids and Concentration

They don't dissolve or change volume, and so they don't affect equilibrium, so their concentration doesn't matter.
by Sarah Salam 1J
Sun Jan 10, 2021 10:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: How to choose R
Replies: 6
Views: 62

Re: How to choose R

It depends on the units that are given in the question. One R value is in J/K*mol and the other is L*atm/K*mol, so you would look at what units are present or that you could convert to and use the corresponding R value.
by Sarah Salam 1J
Sun Jan 10, 2021 10:36 pm
Forum: Ideal Gases
Topic: Chemical Equilibrium Part 1A Post-Module Assessment
Replies: 4
Views: 39

Re: Chemical Equilibrium Part 1A Post-Module Assessment

It's D because the will not stop, but equilibrium means the reactions will produce equal amounts of products and reactants at same time.
by Sarah Salam 1J
Sun Dec 06, 2020 10:49 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: en and others
Replies: 2
Views: 26

en and others

I know that en is C2H4(NH2)2, and I believe that there are two other compounds with similar abbreviations. What are those, and what is important to know about these compounds?
by Sarah Salam 1J
Sun Dec 06, 2020 10:27 pm
Forum: Electronegativity
Topic: Acidity
Replies: 4
Views: 25

Acidity

In the Friday's lecture, electronegativity was mentioned with acid bonds. How do they relate to increasing electronegativity?
by Sarah Salam 1J
Sun Dec 06, 2020 9:56 pm
Forum: Naming
Topic: Roman numeral
Replies: 5
Views: 41

Roman numeral

How do we find the oxidation number of a metal to get the Roman numeral when naming a compound?
by Sarah Salam 1J
Sun Dec 06, 2020 4:45 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: tetradentate
Replies: 8
Views: 73

Re: tetradentate

Lily Mohtashami wrote:So is tetradentate different than tetrahedron and square-planar complex?

Kind of, tetradentate refers to the binding sites of the ligand, while tetrahedral and square planar are molecular geometries. Denticity can determine possible geometries.
by Sarah Salam 1J
Sun Dec 06, 2020 4:30 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Sapling #3
Replies: 7
Views: 46

Sapling #3

Why is the octahedral geometry the only one with a coordination number of 6?
by Sarah Salam 1J
Sun Nov 29, 2020 11:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: electronic geometry vs molecular geometry
Replies: 9
Views: 57

Re: electronic geometry vs molecular geometry

Hi, this confused me too, but from what I saw I believe electron geometry groups can include molecular geometry shapes based off of bond angles.
by Sarah Salam 1J
Sun Nov 29, 2020 11:56 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Determining Type of Bond from Shape
Replies: 12
Views: 58

Re: Determining Type of Bond from Shape

No, you will need to draw the Lewis structure to determine if the bonds are single, double or triple.
by Sarah Salam 1J
Sun Nov 29, 2020 11:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Easiest Way to Memorize Shape Names
Replies: 9
Views: 90

Re: Easiest Way to Memorize Shape Names

Is there a full list of shapes we could use to practice each one? Should I just write down what Dr. Lavelle went over in lecture, or are there more?
by Sarah Salam 1J
Sun Nov 29, 2020 11:43 pm
Forum: Dipole Moments
Topic: Dipole arrows
Replies: 8
Views: 46

Dipole arrows

One of the sapling questions suggested using dipole arrows to solve it. I solved it without them, but how could we use dipole arrows? What do they show?
by Sarah Salam 1J
Sun Nov 29, 2020 11:38 pm
Forum: Sigma & Pi Bonds
Topic: Delocalized pi bonds
Replies: 2
Views: 37

Delocalized pi bonds

How can we recognize a delocalized pi bond?
by Sarah Salam 1J
Sun Nov 29, 2020 11:31 pm
Forum: Hybridization
Topic: Sigma and Pi bonds
Replies: 21
Views: 191

Re: Sigma and Pi bonds

Sigma bonds are single bonds, pi bonds are double or triple bonds. All bonds include sigma bonds.
by Sarah Salam 1J
Sun Nov 22, 2020 11:54 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic and Covalent bonds in respect to boiling point
Replies: 8
Views: 50

Re: Ionic and Covalent bonds in respect to boiling point

Generally ionic bonds are going to have a higher melting point because of their stronger bonds and bond energy, but if I'm not mistaken there are a few exceptions based on other factors.
by Sarah Salam 1J
Sun Nov 22, 2020 10:49 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic vs. Covalent Compounds
Replies: 7
Views: 90

Re: Ionic vs. Covalent Compounds

Ionic bonds are formed by nonmetals and metals, since metals usually have few valence electrons, they will give their electrons to nonmetals. Covalent bonds are when an electron is being shared between two atoms, usually these are nonmetals.
by Sarah Salam 1J
Sun Nov 08, 2020 11:17 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Ground state
Replies: 1
Views: 17

Ground state

I think it was mentioned in a lecture that Pauli's exclusion principle and Hund's rule can be used to find the ground state electron configuration. I'm still a little confused by finding configurations, so what is this process and how are these involved?
by Sarah Salam 1J
Sun Nov 08, 2020 11:14 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Study material
Replies: 2
Views: 53

Study material

I'm still confused by the different orbitals, and how to make configurations with them, even though I remember them from high school. Does anyone have any resources that I could use to practice and understand these on a basic level?
by Sarah Salam 1J
Sun Nov 08, 2020 10:47 pm
Forum: Electronegativity
Topic: polyatomic ions
Replies: 4
Views: 33

Re: polyatomic ions

You'll want to use periodic table trends to determine the electronegativity of the atom in question and what it is bonded to.
by Sarah Salam 1J
Sun Nov 08, 2020 9:57 am
Forum: Lewis Structures
Topic: Expanded octet
Replies: 4
Views: 21

Re: Expanded octet

Oh, that clears it up, thank you!
by Sarah Salam 1J
Sun Nov 08, 2020 8:32 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Parallel electrons
Replies: 7
Views: 61

Parallel electrons

When would electrons be parallel? I'm a bit confused on what Hund's rule is saying about this.
by Sarah Salam 1J
Sun Nov 08, 2020 8:24 am
Forum: Ionic & Covalent Bonds
Topic: atomic radius
Replies: 7
Views: 49

Re: atomic radius

We use the idea of neighboring atoms for reference, or it could be atoms that they are bonded to, in the case of ionic and covalent radius.
by Sarah Salam 1J
Sun Nov 08, 2020 8:21 am
Forum: Lewis Structures
Topic: Expanded octet
Replies: 4
Views: 21

Expanded octet

Do we always make an expanded octet if we can? Also, the professor explained why they are ok, but I didn't fully understand the explanation. What does it have to do with orbitals?
by Sarah Salam 1J
Sun Nov 08, 2020 8:02 am
Forum: Ionic & Covalent Bonds
Topic: Octet rule exceptions
Replies: 15
Views: 77

Re: Octet rule exceptions

Be has 2 valence electrons, and Li tends to lose an electron and go down to two instead of going up to 8, so they do not form an octet.
by Sarah Salam 1J
Sun Nov 08, 2020 7:51 am
Forum: Octet Exceptions
Topic: Boron Trifluoride Example
Replies: 2
Views: 43

Re: Boron Trifluoride Example

The point of making it into BF4 was to show how the octet can be completed with a coordinate covalent bond, since BF3 usually behaves as a Lewis acid.
by Sarah Salam 1J
Sun Nov 08, 2020 7:44 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Distortion
Replies: 8
Views: 75

Distortion

What does it mean for something to be highly distorted? I know that it relates to polarization, and the model with the ion and cation in the lecture helped me understand what is happening, but I don't understand what is making that happen or how to recognize it. Does this only refer to electrons and...
by Sarah Salam 1J
Sun Oct 25, 2020 10:33 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectra Post Assessment
Replies: 3
Views: 32

Re: Atomic Spectra Post Assessment

Could someone please walk me through this problem using the deltaE = -hR/n^2-(-hR/n^2) method that he showed in the lecture? I've used the deltaE=hv equation to solve for the total change in energy, which I got to be 7.55*10^-20 J. I then substituted that into the equation with the necessary consta...
by Sarah Salam 1J
Sun Oct 25, 2020 10:30 pm
Forum: SI Units, Unit Conversions
Topic: Can someone explain Avogrado's #?
Replies: 8
Views: 93

Re: Can someone explain Avogrado's #?

Avogadro's constant is the number of something in a mole. It can be the number of atoms in something, molecules in something, it is just a number without units.
by Sarah Salam 1J
Sun Oct 25, 2020 10:21 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Minimum vs Maximum Confusion
Replies: 3
Views: 31

Re: Minimum vs Maximum Confusion

For better conceptual understanding, what is the maximum?
by Sarah Salam 1J
Sun Oct 25, 2020 9:32 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Focus Topics Question
Replies: 1
Views: 19

Focus Topics Question

Can someone explain the process for solving #27 in the atomic spectra post module? The meter was defined in 1963 as 1,650,763.73 wavelengths of radiation emitted by krypton-86 (it has since been redefined). What is the wavelength of this krypton-86 radiation? To what region of the electromagnetic sp...
by Sarah Salam 1J
Sun Oct 25, 2020 8:37 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Minimum vs Maximum Confusion
Replies: 3
Views: 31

Minimum vs Maximum Confusion

Some Heisenberg uncertainty questions ask about the minimum uncertainty and some ask about the maximum. Is there a difference in the way we solve for this or the answers? What is the maximum referring to?
by Sarah Salam 1J
Sun Oct 18, 2020 9:27 pm
Forum: Einstein Equation
Topic: unexpected outcome of wave-particle experiment
Replies: 8
Views: 55

Re: unexpected outcome of wave-particle experiment

I believe it was that increasing the intensity of the light did not eject electrons, like it should have with only wave properties.
by Sarah Salam 1J
Sun Oct 18, 2020 9:13 pm
Forum: Photoelectric Effect
Topic: Kinetic energy equation
Replies: 3
Views: 36

Kinetic energy equation

What is the m in Ek=1/2mv^2 equation? Where does this come from?
by Sarah Salam 1J
Sun Oct 18, 2020 9:07 pm
Forum: Properties of Light
Topic: Chemistry Community Points
Replies: 10
Views: 92

Re: Chemistry Community Points

I believe your comment counts, but as far as the email somebody else mentioned goes you will want to make sure you are posting your questions in the right topic sections to get points for your posts.
by Sarah Salam 1J
Sun Oct 18, 2020 8:29 pm
Forum: Properties of Light
Topic: Study Advice
Replies: 50
Views: 308

Re: Study Advice

As far as understanding goes, that's up to how comfortable you are with the bookwork. I found the workshops I've went to very helpful because the UA will go through the problem after letting you work on it, so if you get stuck that will hopefully clarify the problem immediately. You don't need to do...
by Sarah Salam 1J
Sun Oct 18, 2020 8:01 pm
Forum: Properties of Light
Topic: Kinetic Energy of Electron
Replies: 4
Views: 45

Re: Kinetic Energy of Electron

According to the video modules, kinetic energy is the energy of the photon or light minus the work function. Also called excess energy.
by Sarah Salam 1J
Sun Oct 11, 2020 8:44 pm
Forum: Balancing Chemical Reactions
Topic: Balancing Combustion Reactions
Replies: 6
Views: 76

Re: Balancing Combustion Reactions

I believe Prof. Lavelle mentioned in either a video module or a lecture that combustion specifically is a reaction with O2 to make H2O and CO2, so I think it is safe to assume that a question asking about combustion will be that equation.
by Sarah Salam 1J
Sun Oct 11, 2020 8:21 pm
Forum: SI Units, Unit Conversions
Topic: Showing Work
Replies: 8
Views: 51

Re: Showing Work

I'm not sure but using units throughout the question may help you get partial credit if you were to mess up the final answer. Otherwise, I've found it at least helps you keep track of your work if you need to fix something.
by Sarah Salam 1J
Sun Oct 11, 2020 8:17 pm
Forum: SI Units, Unit Conversions
Topic: Textbook
Replies: 22
Views: 183

Re: Textbook

I can get to the homework problems through CCLE but how do I get to the textbook with the free trial?
by Sarah Salam 1J
Sun Oct 11, 2020 7:34 pm
Forum: Empirical & Molecular Formulas
Topic: Sapling Wk 1 Question 10
Replies: 4
Views: 54

Re: Sapling Wk 1 Question 10

What do the 1-bromopropane and the magnesium represent in the equation as pictured in the problem? Because as far as I've solved it I did not reference those elements In this particular question we were told the 1-bromopropane was in excess, so I think those elements were just there to complete the...
by Sarah Salam 1J
Sat Oct 10, 2020 9:30 pm
Forum: Empirical & Molecular Formulas
Topic: Finding empirical formula process
Replies: 2
Views: 52

Finding empirical formula process

In questions where we are trying to find the empirical formula from given masses, like Sapling question #9 or the nicotine example, where we have found the moles of the molecule and we multiply it by the amount of atoms in that molecule, can someone explain the next steps and why they work?

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