Search found 77 matches

Sun Jan 17, 2021 11:51 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: When to use ICE chart?
Replies: 10
Views: 20

Re: When to use ICE chart?

Usually when you need to find the concentration of a compound, use the ice chart. When finding the Kc value you'll need the concentrations in order to plug your values.
Sun Jan 17, 2021 9:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Homework #5
Replies: 9
Views: 56

Re: Sapling Homework #5

The most common mistake on this one is forgetting to inverse the function if it is in the wrong order! You need to find the reciprocal to do this.
Sun Jan 17, 2021 9:40 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Sapling Week 1 #6
Replies: 7
Views: 36

Re: Sapling Week 1 #6

Make sure that the p/r, the values are the power of the coefficient in the chem rxn! This is essential to solve the problem.
Sun Jan 17, 2021 9:39 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q and K
Replies: 44
Views: 140

Re: Q and K

Being more general, Q is the more specific term compared to K which specifies a specific instance in the rxn!
Sun Jan 17, 2021 9:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Week 1 #6
Replies: 10
Views: 30

Re: Sapling Week 1 #6

When doing the problem, make sure you know Q= products/reactants. The coefficients turn into powers and just plug in the values they give for the compounds!
Sun Jan 10, 2021 10:25 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Stability
Replies: 8
Views: 43

Re: Stability

In terms of pure stability, q and k have no effect on one another because they are separate variables that assess different values of the reaction.
Sun Jan 10, 2021 10:23 pm
Forum: Ideal Gases
Topic: inert gas and pressure changes
Replies: 9
Views: 33

Re: inert gas and pressure changes

Since the factor affecting the concentration is not the volume, and volume changes concentration, then it will have no effect!
Sun Jan 10, 2021 10:22 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Effects of temperature
Replies: 6
Views: 23

Re: Effects of temperature

The exact effect would require calculations and since we are just doing general trends it will not be tested!
Sun Jan 10, 2021 10:20 pm
Forum: Ideal Gases
Topic: Non-Ideal gases?
Replies: 26
Views: 106

Re: Non-Ideal gases?

Non-ideal gases are not tested for this course because it isn't on the syllabus or lecture!
Sun Jan 10, 2021 10:18 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure and Volume
Replies: 16
Views: 40

Re: Pressure and Volume

Pressure and volume always have an inverse relationship.
Sun Jan 10, 2021 10:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K Favors Products or Reactants
Replies: 20
Views: 67

Re: K Favors Products or Reactants

The large k value is usually for 10^3 while small k value is 10^-3!
Sun Jan 10, 2021 10:15 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: H2O
Replies: 44
Views: 276

Re: H2O

Only include it for gases because solids and liquids are not a part of the ice table!
Sun Jan 10, 2021 10:14 pm
Forum: Ideal Gases
Topic: T variable in pv=nrt [ENDORSED]
Replies: 38
Views: 269

Re: T variable in pv=nrt[ENDORSED]

I personally never keep my units in celsius for the t variable as its just easier to remember!
Sat Dec 12, 2020 10:24 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Character
Replies: 33
Views: 202

Re: Covalent Character

I think it's just the opposite of the ionic character!
Sat Dec 12, 2020 10:22 pm
Forum: Hybridization
Topic: Electron Density
Replies: 6
Views: 44

Re: Electron Density

Count lone pairs and regions of electron density. A double bond is still 1 region of electron density as is a single or triple bond.
Sat Dec 12, 2020 10:21 pm
Forum: Lewis Structures
Topic: Tips on drawing Lewis structures
Replies: 20
Views: 141

Re: Tips on drawing Lewis structures

I make sure to count the electrons and remember that the charge of the overall molecule matters for adding/subtracting electrons!
Sat Dec 12, 2020 10:19 pm
Forum: Limiting Reactant Calculations
Topic: Testing with a periodic table
Replies: 16
Views: 172

Re: Testing with a periodic table

Its the same table as the one we used for the 2 midterms!
Sat Dec 12, 2020 10:18 pm
Forum: Air Pollution & Acid Rain
Topic: Why does acid rain exist
Replies: 13
Views: 147

Re: Why does acid rain exist

It exists because of naturally existing chemicals in the atmosphere (CO2,SO2) forming acids in the presence of water, making the rain slightly acidic.
Thu Dec 10, 2020 8:28 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Thionyl Chloride
Replies: 1
Views: 20

Thionyl Chloride

How do you determine the shape of this molecule? Also, how do you know that the compound's formula is SOCl2 from the name of the compound? This was a sapling problem
Thu Dec 10, 2020 12:42 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Shapes on Exam
Replies: 3
Views: 39

VSEPR Shapes on Exam

What VSEPR shapes do we have to memorize for the exam?
Sun Dec 06, 2020 10:54 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Oxidation state vs. oxidation number
Replies: 4
Views: 31

Re: Oxidation state vs. oxidation number

I always thought they are interchangeable. Wikipedia says "The oxidation state, sometimes referred to as oxidation number," so I think they are the same!
Sun Dec 06, 2020 10:51 pm
Forum: Properties of Light
Topic: Photoelectric Effect
Replies: 14
Views: 138

Re: Photoelectric Effect

The excess energy is thought of as kinetic energy because excess energy is transferred into the electron to give it the energy to move from the metal. Hence, it is kinetic.
Sun Dec 06, 2020 10:46 pm
Forum: Photoelectric Effect
Topic: exciting electrons
Replies: 3
Views: 29

Re: exciting electrons

The photoelectric effect was focused on electrons emitting from metals, but there could be a correlation with the structure of the metals (with different alloys and so on) which can have an effect on the amount of electron emission. It's a stretch, though.
Sun Dec 06, 2020 10:42 pm
Forum: Sigma & Pi Bonds
Topic: Pi and Sigma Bonds Positions
Replies: 2
Views: 42

Pi and Sigma Bonds Positions

In a double or triple bond, where would the sigma bond be in relation to the pi bond, and vice versa?
Sun Dec 06, 2020 10:40 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Definition of Ligand
Replies: 8
Views: 53

Re: Definition of Ligand

Yes, along with others the main point is that it would be bound to a transition metal for it to be called a ligand.
Sun Dec 06, 2020 10:38 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Tips for Coordination #
Replies: 4
Views: 18

Tips for Coordination #

How would coordination numbers work for more complex and lengthy ions? For example Ba[FeBr4]2?
Sun Nov 29, 2020 10:54 pm
Forum: Hybridization
Topic: Confused on hybridization conceptually
Replies: 9
Views: 74

Re: Confused on hybridization conceptually

Also,w remember that the types of bonds in a real molecule are not actually there; the atoms are just arranged to maximize efficiency. A molecule with a single and double bond in its lewis structure has the same bond lengths in real life!
Sun Nov 29, 2020 10:51 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Determining Molecular Shape
Replies: 9
Views: 49

Re: Determining Molecular Shape

Types of bonds do not change the shape of the molecule! It would only be for lone pairs or the number of separate bonds.
Sun Nov 29, 2020 10:50 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: H2O VSEPR
Replies: 27
Views: 147

Re: H2O VSEPR

Because of the lone pairs forming electron repulsion, it takes on a bent shape.
Sun Nov 29, 2020 10:49 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AsO43-
Replies: 9
Views: 61

Re: AsO43-

Even though it is an ion, the charges cancel so it is nonpolar.
Sun Nov 29, 2020 10:48 pm
Forum: Hybridization
Topic: Single Bonds and Sigma Bonds
Replies: 23
Views: 110

Re: Single Bonds and Sigma Bonds

Yes, you are correct but also note that for double and triple bonds they would also have pi bonds.
Sun Nov 29, 2020 10:47 pm
Forum: Hybridization
Topic: Sapling #11
Replies: 19
Views: 109

Re: Sapling #11

Hybridization is usually for a specific atom, so you have to look at phosphorous first!
Sun Nov 29, 2020 10:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape Names
Replies: 50
Views: 297

Re: Shape Names

It would be angular!
Sun Nov 29, 2020 10:45 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Resonance Structure Definition
Replies: 9
Views: 67

Re: Resonance Structure Definition

In other words, it is pretty much like resonance!
Sun Nov 22, 2020 5:03 pm
Forum: Electronegativity
Replies: 8
Views: 44

Yes, and the larger the atom the more polarizable because its electrons are further from the nucleus
Sun Nov 22, 2020 5:01 pm
Forum: Lewis Structures
Topic: Expanded Valence
Replies: 6
Views: 97

Re: Expanded Valence

The expanded octet rule cannot be applied to period 2 elements as well!
Sun Nov 22, 2020 5:00 pm
Forum: Dipole Moments
Topic: Polarity
Replies: 30
Views: 152

Re: Polarity

Yes because the dipoles cancel
Sun Nov 22, 2020 4:59 pm
Forum: Bond Lengths & Energies
Topic: electron repulsion
Replies: 15
Views: 131

Re: electron repulsion

It can be any 2 electrons that repel each other!
Sun Nov 22, 2020 4:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Memorizing Shape Names
Replies: 12
Views: 63

Re: Memorizing Shape Names

Quizlet is a life saver!
Tue Nov 17, 2020 7:30 pm
Forum: Lewis Structures
Topic: Tetrahydridoborate
Replies: 1
Views: 16

Re: Tetrahydridoborate

That is the charge for the individual atoms if they were to lose or gain electrons. For the BH4- ion, if you draw the lewis structure and calculate formal charges, the total charge is -1.
Fri Nov 13, 2020 7:43 pm
Forum: Lewis Structures
Topic: Recognizing lowest formal charge
Replies: 11
Views: 50

Re: Recognizing lowest formal charge

I think the general tip is that the more symmetrical the lewis structure is, it will probably be the lowest formal charge. Of course, you can check each structures' formal charges and the one with the most formal charges of 0 would be the lowest.
Fri Nov 13, 2020 3:54 pm
Forum: Ionic & Covalent Bonds
Topic: 2D.3
Replies: 2
Views: 14

Re: 2D.3

BaBr2 is more ionic because the difference in electronegativity is the greatest. Be is more electronegative than Ba so when bonded with Br it's less ionic. FOr example, F2 is covalent even though F is the most electronegative. It's about the difference in electronegativity, not the atoms that add up...
Thu Nov 12, 2020 8:38 pm
Forum: Octet Exceptions
Topic: Textbook 2C.3 question
Replies: 3
Views: 41

Re: Textbook 2C.3 question

The lewis structure should just be the same as the lewis structures for phosphate and clo3- with a hydrogen attached to the oxygen. This cancels the -1 formal charge for the oxygen so instead of po4(3-) it would be hpo4(2-) and hclo3 instead of clo3-.
Thu Nov 12, 2020 8:30 pm
Forum: Ionic & Covalent Bonds
Topic: Midterm 2
Replies: 6
Views: 79

Re: Midterm 2

From end of mt1 to chemical bonding
Thu Nov 12, 2020 8:28 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum States
Replies: 1
Views: 26

Quantum States

What exactly is a quantum state?
Fri Nov 06, 2020 10:55 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic Bonds with Covalent Characters
Replies: 5
Views: 22

Re: Ionic Bonds with Covalent Characters

that's a good visualizer, thanks!
Fri Nov 06, 2020 10:48 pm
Forum: Bond Lengths & Energies
Topic: Bond Length
Replies: 22
Views: 350

Re: Bond Length

x-ray diffraction is used to determine the bond length.
Fri Nov 06, 2020 10:45 pm
Forum: Electronegativity
Topic: Noble Gases
Replies: 40
Views: 1726

Re: Noble Gases

They are omitted because they are inert and don't need any more e-
Fri Nov 06, 2020 10:44 pm
Forum: Ionic & Covalent Bonds
Topic: Homework due date
Replies: 49
Views: 336

Re: Homework due date

Sunday 11:59 pst
Fri Nov 06, 2020 10:40 pm
Forum: Resonance Structures
Topic: Bond lengths
Replies: 20
Views: 142

Re: Bond lengths

No, you don't need to draw the bonds shorter or longer!
Fri Nov 06, 2020 10:39 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic Bonds with Covalent Characters
Replies: 5
Views: 22

Re: Ionic Bonds with Covalent Characters

I would assume a the more covalent the character, the smaller the ionization energy because it would be easier to remove an electron since the electron is further away from the nucleus.
Fri Nov 06, 2020 10:35 pm
Forum: Dipole Moments
Topic: Water and NaCl Solubility
Replies: 4
Views: 18

Water and NaCl Solubility

How do the water molecules interact with NaCl to dissociate them?
Fri Nov 06, 2020 10:27 pm
Forum: Properties of Electrons
Topic: Electron Spin
Replies: 7
Views: 82

Electron Spin

Why do electrons have spin? Are we just supposed to take this as a truth because of experimental data, or is there deeper reasoning behind electrons having spin properties?
Fri Oct 30, 2020 10:48 pm
Forum: Properties of Light
Topic: Electromagnetic Spectrum
Replies: 7
Views: 70

Re: Electromagnetic Spectrum

I don't have a mnemonic device to memorize the EM spectrum, but I just remember counting even powers down from 10^-10 being x rays, 10^-8 UV, 10^-6 and 10^-4 infrared, and then 10^-2 microwaves. This is in meters.
Fri Oct 30, 2020 8:33 pm
Forum: DeBroglie Equation
Topic: Electron Affinity Sapling
Replies: 6
Views: 94

Electron Affinity Sapling

For the electron affinity of thulium given 1064 nm and an energy of .137 ev, I'm confused how to find the electron affinity in ev/atom. I know it has something to do with debroglies equation, but I cant find the right units to solve it. Thanks in advance!
Fri Oct 30, 2020 8:24 am
Forum: Photoelectric Effect
Topic: Kinetic Energy
Replies: 10
Views: 106

Re: Kinetic Energy

Id say its true because with the equation E(photon)-work function=Kinetic energy, the higher the frequency, the larger the energy of photon, so the larger the kinetic energy.
Sun Oct 25, 2020 7:28 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Calculating Speed Uncertainty
Replies: 1
Views: 43

Calculating Speed Uncertainty

The hydrogen atom has a radius of approximately 0.05 nm. Assume that we know the position of an electron to an accuracy of 1 % of the hydrogen radius, calculate the uncertainty in the speed of the electron using the Heisenberg uncertainty principle. Comment on your value obtained. I solved using the...
Fri Oct 23, 2020 10:30 pm
Forum: Properties of Light
Topic: Midterm
Replies: 42
Views: 390

Re: Midterm

It's still a bit unclear about the amount of material we are able to use for the midterm; I thought I heard he was going to provide a printout sheet for the formulas, but I have not gotten an email about this.
Fri Oct 23, 2020 10:28 pm
Forum: Properties of Light
Topic: N2 vs N1
Replies: 6
Views: 67

Re: N2 vs N1

I was confused initially, but remember to also square the values of the energy levels if you use the Rydberg equation.
Fri Oct 23, 2020 7:21 pm
Forum: Limiting Reactant Calculations
Topic: Textbook M5
Replies: 2
Views: 46

Textbook M5

Solve this exercise without using a calculator. The reaction 6 ClO 2 (g) + 2 BrF 3 (l) → 6 ClO 2 F (s) + Br 2 (l) is carried out with 12 mol ClO 2 and 5 mol BrF 3 . (a) Identify the excess reactant. (b) Estimate how many moles of each product will be produced and how many moles of the excess reactan...
Fri Oct 23, 2020 11:56 am
Forum: Molarity, Solutions, Dilutions
Topic: Molar Bridge Conversions
Replies: 2
Views: 25

Molar Bridge Conversions

When given problems like how to calculate the volume of solution to obtain mol of Na in Na2CO3, the molar bridge conversion is 1 mol Na2CO3/2 mol Na+, so you would divide by 2. However, in other problems like the number of moles of nitrogen atoms a plant can receive, the bridge conversion is 2 mol N...
Fri Oct 23, 2020 11:08 am
Forum: DeBroglie Equation
Topic: Sapling Question #10
Replies: 8
Views: 108

Re: Sapling Question #10

As a good baseline, whenever I run into problems involving the velocity/speed of something, I think of the De Broglie equation!
Wed Oct 21, 2020 11:41 am
Forum: Properties of Light
Topic: Sapling Q 11,13,15,16,17,18
Replies: 2
Views: 44

Sapling Q 11,13,15,16,17,18

Professor Lavelle said that the midterm material will cover all lectures until Wednesday week 3, and he also said that these include all sapling problems until Q19. However, all the problems from Sapling stated above are material we have not covered. Will we still be expected to know these?
Wed Oct 21, 2020 11:23 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: dx^2-y^2 orbital
Replies: 4
Views: 38

dx^2-y^2 orbital

Out of all the orbital structures in the d orbital, this one is the only structure that has the -y value in it. I was wondering about the reason for this.
Tue Oct 20, 2020 9:54 pm
Forum: Properties of Light
Topic: Sapling #10
Replies: 8
Views: 159

Sapling #10

The average speed of a diatomic fluorine molecule at 25 ∘C is 442.4 m⋅s−1 . What is the average wavelength of a fluorine molecule at this temperature? Assume that the molecule acts like a single particle. Having trouble finding the mass for the single fluorine molecule. If it is diatomic do I use do...
Tue Oct 20, 2020 5:26 pm
Forum: Student Social/Study Group
Topic: How are you studying?
Replies: 203
Views: 1284

Re: How are you studying?

Its a mix of watching all the lectures, notes, and reviewing some old chem material from high school for the fundamentals for me!
Sat Oct 17, 2020 8:18 am
Forum: Properties of Light
Topic: "Intensity"
Replies: 20
Views: 133

Re: "Intensity"

I think a good way of thinking about the photons' intensity is that the frequency and the wavelength have to be in proportion to each other since they are equal to the speed of light. So if you increase the intensity, you are still not increasing the frequency so that electrons are ejected by the wa...
Sat Oct 17, 2020 8:14 am
Forum: Significant Figures
Topic: Sig Figs and Constants on Exams
Replies: 9
Views: 104

Re: Sig Figs and Constants on Exams

I don't think the constant matter as much as just making sure you do not round your calculator when doing a problem, and just make sure to keep everything in the calculator until the final calculation where you can round the answer to the proper sig fig.
Sat Oct 17, 2020 8:12 am
Forum: Photoelectric Effect
Topic: Excess energy
Replies: 20
Views: 135

Re: Excess energy

I believe in Lavelle's lectures, he writes the excess energy as E(excess) and kinetic energy as EK, with the k being a subscript.
Sat Oct 17, 2020 8:09 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Finding the amount of molecules in compounds using mole conversions
Replies: 3
Views: 43

Re: Finding the amount of molecules in compounds using mole conversions

Along with Briannes reply, Avogadro's constant is exactly that, a constant that does not have specific units in terms of atoms, photons, molecules, or any other unit for measurement. This means it can be applied in many situations either to cancel out some units or to convert moles into molecules.
Sat Oct 17, 2020 8:02 am
Forum: Properties of Light
Topic: Energy Levels
Replies: 11
Views: 92

Re: Energy Levels

Yes, to add on to Margaret's point, the electrons' whereabouts can be thought of as in s,p,d, and f orbitals, but do not take this like they are in one spot in the orbital. Electrons are constantly moving around in their respective energy levels and Heisenberg's uncertainty principle complicates thi...
Thu Oct 08, 2020 8:13 pm
Forum: SI Units, Unit Conversions
Topic: Textbook
Replies: 2
Views: 37

Re: Textbook

I'm in the same situation, and yes you can access the textbook. It should be on the right-hand side when you open Sapling as an ebook. I had to make an account to use the textbook.
Thu Oct 08, 2020 8:00 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Reason for C-12 as base unit
Replies: 2
Views: 53

Reason for C-12 as base unit

During Lavelle's first lecture, he discusses how the Avogadro constant arose from the number of atoms in 12 grams of C-12. I was wondering why scientists chose C-12 element for using Avogadros number.
Thu Oct 08, 2020 7:50 pm
Forum: Properties of Light
Topic: Change in energy per mole of photons
Replies: 2
Views: 43

Change in energy per mole of photons

I was wondering how to properly solve this question since they do not give any units to work with. "What is the change in energy associated per mole of photons?"
Thu Oct 08, 2020 7:39 pm
Forum: Empirical & Molecular Formulas
Topic: Rounding up for Empirical Formulas?
Replies: 10
Views: 103

Rounding up for Empirical Formulas?

I was wondering what the usual cutoff point for rounding up empirical formulas is. For example, if the final moles of a compound containing C,H, and O are 2.67,2.67, and 1 you would multiply by 3, but what about numbers like 2.85,2.85, and 1, or any other variant for that matter.
Thu Oct 08, 2020 7:33 pm
Forum: Balancing Chemical Reactions
Topic: Sapling Wk1 Q10 Theoretical Yield and Actual Yield
Replies: 4
Views: 75

Sapling Wk1 Q10 Theoretical Yield and Actual Yield

I'm wondering for "A reaction was performed in which 0.60 mL of 2‑butanone was reacted with an excess of propyl magnesiumbromide to make 0.71 g of 3‑methyl‑3‑hexanol. Calculate the theoretical yield and percent yield for this reaction" if I would need to balance the given chemical equation...
Thu Oct 08, 2020 7:27 pm
Forum: Molarity, Solutions, Dilutions
Topic: Molar Mass Stated in Sapling HW
Replies: 10
Views: 66

Re: Molar Mass Stated in Sapling HW

Hey Meredith,

If I remember correctly I needed to multiply my answer by a factor of 2 to get within the set range of numbers. Have a good day!