## Search found 60 matches

Sun Jan 17, 2021 6:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Amphiprotic
Replies: 8
Views: 23

### Re: Amphiprotic

amphiprotic molecules are molecules that can act as a either a base or an acid such as water which can either give off a proton or accept one.
Sun Jan 17, 2021 6:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE table calculations and X
Replies: 3
Views: 10

### Re: ICE table calculations and X

yes I believe that the only situation when we can approximate for X is when K is smaller than or equal to 10^-4
Sun Jan 17, 2021 6:06 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure Rule
Replies: 29
Views: 183

### Re: Pressure Rule

i believe that you should only look at the moles of gas since they are the ones that will be affected by the change in pressure.
Sun Jan 17, 2021 5:59 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: endothermic vs exothermic
Replies: 11
Views: 24

### Re: endothermic vs exothermic

a reaction is endothermic if the reaction requires heat and its exothermic when the reaction gives off heat. A good way to tell the difference in a problem is whether the change in enthalpy is positive (endothermic) or negative (exothermic). I hope this helps!!
Sun Jan 17, 2021 5:55 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ice Box Method
Replies: 14
Views: 37

### Re: Ice Box Method

to determine the change and whether it will increase or decrease, you have to look at the context of the question and determine which way the reaction is going. if the reaction is going forward then you will be adding to products and if the reaction is going backwards then you will be adding to the ...
Sun Jan 10, 2021 3:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K vs. Q
Replies: 53
Views: 157

### Re: K vs. Q

Yes, you are correct! Q is found the same way as K and you use Q when the reaction has not reached equilibrium.
Sun Jan 10, 2021 3:19 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homogeneous and Heterogeneous Equilibrium
Replies: 13
Views: 57

### Re: Homogeneous and Heterogeneous Equilibrium

I agree! I believe that you have to look at the entire reaction to determine if the equilibrium is either homogenous or heterogeneous.
Sun Jan 10, 2021 3:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentration
Replies: 12
Views: 40

### Re: Concentration

Concentrations cannot be negative since it is moles divided by liters and you can't measure negative amounts of either.
Sun Jan 10, 2021 3:06 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Picking Value when doing Quadratic Equation
Replies: 10
Views: 28

### Re: Picking Value when doing Quadratic Equation

you should pick the x value that is possible in the context of the problem so it should be positive and a smaller value than the initial concentrations.
Sun Jan 10, 2021 3:01 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Reactions at Equilibrium
Replies: 6
Views: 22

### Re: Reactions at Equilibrium

Yes, you are right to assume that! the reason that the concentrations of reactants and products do not change is because the forward and reverse reactions are occurring at the same rate.
Thu Dec 10, 2020 3:08 am
Forum: Lewis Acids & Bases
Topic: Lewis vs Bronsted Definition
Replies: 7
Views: 56

### Re: Lewis vs Bronsted Definition

the way that I remember the definition of both the lewis and bronsted acid/base is that if a molecule is accepting either a proton or lone pair then it will be a donor of the alternate definition. So the "acceptor" and "donor" will switch for the lewis and bronsted definition of ...
Thu Dec 10, 2020 3:00 am
Forum: Dipole Moments
Topic: Determining if a molecular is polar/np based on dipoles
Replies: 3
Views: 25

### Re: Determining if a molecular is polar/np based on dipoles

I found that using arrows to draw out the dipole moments is the best way of determining if a molecule is polar or nonpolar because it is the one way to find out for sure if the dipoles will cancel out since you can also look at the molecule's structure as well.
Thu Dec 10, 2020 2:52 am
Forum: Polyprotic Acids & Bases
Topic: Proton vs H+
Replies: 14
Views: 101

### Re: Proton vs H+

Yes! proton and H+ are interchangeable since H+ does not have any electrons
Thu Dec 10, 2020 2:47 am
Forum: Conjugate Acids & Bases
Topic: Alkaline
Replies: 15
Views: 84

### Re: Alkaline

Yes! I believe that alkaline and basic are synonymous with each other
Thu Dec 10, 2020 2:45 am
Forum: Determining Molecular Shape (VSEPR)
Topic: wedge and dash
Replies: 14
Views: 94

### Re: wedge and dash

the wedges and dashes are used to help us visualize the 3D structures so wedge means that it is coming towards you and the dash means that it is going away from you. I hope this helps!!
Sun Dec 06, 2020 2:49 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number Question
Replies: 12
Views: 110

### Re: Coordination Number Question

you can determine the coordination compound by adding up all the bonds that the ligands can form with the TM. Usually, when I am finding the coordination compound, I will always identify how many bonding sites each ligand has and then note how many of each ligand there is. So in your example, I woul...
Sun Dec 06, 2020 2:16 pm
Forum: Dipole Moments
Topic: Dipole canceling
Replies: 13
Views: 78

### Re: Dipole canceling

yes, a nonpolar molecule can have polar bonds but that means that it has an overall dipole moment of zero since its dipoles will cancel out.
Sun Dec 06, 2020 2:13 pm
Forum: Administrative Questions and Class Announcements
Topic: Final
Replies: 21
Views: 133

### Re: Final

I agree with what is being said above, the final will likely be the same set up as the midterms where we will need the secondary device to be running a zoom call.
Sun Dec 06, 2020 2:11 pm
Forum: Shape, Structure, Coordination Number, Ligands
Replies: 8
Views: 54

Dentate refers to the bonding sites that a ligand has. So in a tetradentate ligand, there are 3 bonding sites.
Sun Dec 06, 2020 2:07 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: porphyrin ligand
Replies: 3
Views: 33

### Re: porphyrin ligand

I believe that right now all we need to know is that the porphyrin ligand is square planar because Dr. Lavelle had made the distinction in the lecture. For the other ligands where he has not explicitly stated if it was either square planar or tetrahedral we just need to know that it can be either on...
Sun Nov 29, 2020 5:31 pm
Forum: Hybridization
Topic: Sapling Week 7/8 HW #11
Replies: 13
Views: 73

### Re: Sapling Week 7/8 HW #11

you can determine the hybridization of phosphorus by adding up the regions of electron density of that atom which includes lone pairs and bonds. I hope this helps!!
Sun Nov 29, 2020 5:29 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Textbook Problem 2F3
Replies: 4
Views: 17

### Re: Textbook Problem 2F3

After drawing out the lewis structures, you would identify the amount of bonds between the atoms and if there is one bond, it will be a sigma bond, and if there are two bonds, then it will be one sigma and one pi bond. For triple bonds, it is one sigma bond and 2 pi bonds. I hope this helps!!
Sun Nov 29, 2020 5:24 pm
Forum: Sigma & Pi Bonds
Topic: Sapling Q #16
Replies: 14
Views: 102

### Re: Sapling Q #16

to approach this problem you would look for the molecules that has resonance structures since it indicates that electrons are spread throughout the molecule, thus the electrons are delocalized.
Sun Nov 29, 2020 5:18 pm
Forum: Hybridization
Topic: Sapling #12
Replies: 27
Views: 171

### Re: Sapling #12

to find the hybrized orbital you would count up all the regions of electron density that the oxygen has and use that to determine its hybridization. Since oxygen has 2 lone pairs and 2 bonds, it has 4 regions of electron density so its hybridization is sp^3
Sun Nov 29, 2020 5:13 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: dipole moments
Replies: 10
Views: 54

### Re: dipole moments

I would follow what Dr. Lavelle said and have the arrows point toward the more electronegative atoms. I hope this helps!!
Sun Nov 22, 2020 11:01 pm
Forum: Ionic & Covalent Bonds
Topic: Ionization Energy
Replies: 19
Views: 141

### Re: Ionization Energy

I believe that electrons from the outermost orbitals would be taken as it takes the least amount of energy to remove them and have a smaller effective nuclear charge.
Sun Nov 22, 2020 10:49 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pair E-
Replies: 47
Views: 257

### Re: Lone Pair E-

yes!! lone pairs do count as their own region of electron density so they affect the shape of the molecule.
Sun Nov 22, 2020 10:15 pm
Forum: Lewis Structures
Topic: Expanded Valence
Replies: 11
Views: 60

### Re: Expanded Valence

An atom can have an expanded octet if it is in row 3 or below so if you are drawing lewis structures and you have leftover electrons, then they may belong to an atom with an expanded octet.
Sun Nov 22, 2020 10:13 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: London Dispersion
Replies: 33
Views: 147

### Re: London Dispersion

london dispersion forces are always present in molecules, including when there are other forces occuring
Sun Nov 22, 2020 10:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: memorizing VSEPR models
Replies: 13
Views: 78

### Re: memorizing VSEPR models

I recommend looking at the images for each of the shapes and trying to quiz yourself on them. I also like to draw them out myself during lectures from the models that Professor holds up since it helps me to remember and understand it if I have drawn it out myself but this is just what works for me! ...
Sun Nov 15, 2020 8:44 pm
Forum: Quantum Numbers and The H-Atom
Topic: Clarification on the 4th quantum number
Replies: 5
Views: 37

### Re: Clarification on the 4th quantum number

we probably will just have to determine if a certain ms will be possible in a set of 4 quantum numbers and we already know it can either be +1/2 or -1/2
Sun Nov 15, 2020 7:31 pm
Forum: Resonance Structures
Topic: Formal Charge
Replies: 11
Views: 71

### Re: Formal Charge

when drawing lewis structures, I believe that its best when the central atom has a formal charge thats either 0 or close to it.
Sun Nov 15, 2020 7:05 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Sapling week 5 & 6 #5
Replies: 20
Views: 123

### Re: Sapling week 5 & 6 #5

the part that is incorrect about this problem is that Carbon's formal charge is -2 because it has 4 valence, 2 single bonds, and 4 lone electrons. When you plug all those numbers into the formal charge equation FC= valence- (bonds+ lone electrons), you get -2
Sun Nov 15, 2020 6:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sapling #20
Replies: 12
Views: 92

### Re: Sapling #20

hydrogen bonds arent present in CH3CHO because none of the hydrogens are bonded to the oxygen. In order for a H-bond to form Hydrogen must be covalently bonded to either N,F, or O
Sun Nov 15, 2020 6:56 pm
Forum: Coordinate Covalent Bonds
Topic: When do we use it
Replies: 9
Views: 59

### Re: When do we use it

we make covalent bonds between atoms when one of the atoms donates the 2 electrons to form the bond.
Sun Nov 08, 2020 6:39 pm
Forum: Resonance Structures
Topic: resonance structures
Replies: 8
Views: 66

### Re: resonance structures

resonance is the concept that some lewis strucutres have mulitple ways that you can draw certain bonds for it
Sun Nov 08, 2020 6:24 pm
Forum: Trends in The Periodic Table
Topic: Octet Rule
Replies: 6
Views: 42

### Re: Octet Rule

The reason that these elements are exceptions to the octet rule is that they can only have a maximum of 2 valence electrons
Sun Nov 08, 2020 6:15 pm
Forum: Ionic & Covalent Bonds
Topic: Coordinate Covalent Bond
Replies: 4
Views: 18

### Re: Coordinate Covalent Bond

What Professor Lavelle was discussing with BF3 was that Boron will complete its octet from an additional flourine that will form a coordinate covalent bond since it will be contributing the additional 2 electrons for the bond. I believe that is allowed since Boron does not have a full octet and can ...
Sun Nov 08, 2020 6:08 pm
Forum: Quantum Numbers and The H-Atom
Topic: Pauli Exclusion Principle
Replies: 6
Views: 22

### Re: Pauli Exclusion Principle

there can only be 2 electrons per orbital because each will have opposite spins of either +1/2 or -1/2 that are paired together.
Sat Nov 07, 2020 11:12 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Why is the 4s state filled before the 3d state?
Replies: 14
Views: 122

### Re: Why is the 4s state filled before the 3d state?

Electrons will fill orbital levels of lowest energy first and 4s has a lower energy than 3d. I also agree with the post above about the chart on how to fill the orbitals, its super helpful!!
Sun Nov 01, 2020 1:55 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: General Heisenberg Question
Replies: 7
Views: 88

### Re: General Heisenberg Question

When you are given a percentage as your uncertainty you would have to multiply the percentage by the position value, to get your uncertainty. So in the example you gave, the uncertainty in position would be (.02)(5)= .1.
Sun Nov 01, 2020 1:50 pm
Forum: Einstein Equation
Topic: E=hv vs E=hf
Replies: 15
Views: 120

### Re: E=hv vs E=hf

I believe that E=hv is occasionally denoted as E=hf to avoid confusion as v can also mean velocity for other equations.
Sun Nov 01, 2020 1:42 pm
Forum: Properties of Light
Topic: How to remember what v is in equations
Replies: 46
Views: 258

### Re: How to remember what v is in equations

Hi! On our equation sheets "v" for frequency is italicized and "v" for velocity is not. One way that helps me remember is to look at the context of the problem, for example if you are dealing with kinectic energy or momentum, then "v" will be velocity. I hope this helps!!
Sun Nov 01, 2020 1:36 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Where should the Rydberg Equation be used?
Replies: 11
Views: 82

### Re: Where should the Rydberg Equation be used?

The Rydberg Equation is another method for finding the emitted or absorbed light following quantum level change and it's simliar to the Empirical Equation for hydrogen in that Rydberg is derived from it. Both of these equations can only be used for Hydrogen atoms and 1 electron systems.
Sun Nov 01, 2020 1:30 pm
Forum: Properties of Light
Topic: Is c always the speed of light?
Replies: 88
Views: 456

### Re: Is c always the speed of light?

For our purposes, I believe that "c" will always be the speed of light
Thu Oct 22, 2020 11:02 pm
Forum: Properties of Light
Topic: Units for wavelength/frequency
Replies: 18
Views: 93

### Re: Units for wavelength/frequency

HI!! wavelength is measured in meters and frequency is measured in Hertz (Hz). Hertz is also equal to (s/1). Some questions ask for the wavelength in nanometers so I would be careful of those and make sure to convert my answer at the end.
Thu Oct 22, 2020 10:55 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Clarification on the Rydberg constant
Replies: 5
Views: 36

### Re: Clarification on the Rydberg constant

I think that you should use the Rydberg constant (3.29 * 10^15) that we were given in class for any equation and then you can convert the answer you get into whatever units you need to later on but that's just what I find to be easiest for me!!
Thu Oct 22, 2020 10:47 pm
Forum: Limiting Reactant Calculations
Topic: General Limiting Question
Replies: 9
Views: 67

### Re: General Limiting Question

the limiting reactant will always limit the amount of product formed. The amount of product is dependant on how much reactants there are so if there is a limiting reactant, then it will affect the whole chemical equation.
Thu Oct 22, 2020 10:45 pm
Forum: Molarity, Solutions, Dilutions
Topic: What does mmol stand for?
Replies: 33
Views: 329

### Re: What does mmol stand for?

mmol means millimole which is 1/1000 of a mole
Wed Oct 21, 2020 9:06 pm
Forum: *Shrodinger Equation
Topic: X,Y,Z axis
Replies: 4
Views: 34

### Re: X,Y,Z axis

I believe that the axis work the same as normal x and y-axis that we have learned about in our previous classes. The z-axis is what takes the orbitals from 2 dimensional to 3 dimensional.
Sat Oct 17, 2020 7:42 pm
Forum: Einstein Equation
Topic: m vs nm
Replies: 66
Views: 433

### Re: m vs nm

It does not matter which unit you should use unless the problem specifically states so to use a specific unit. I believe that keeping your answer in meters should be fine for the most part.
Sat Oct 17, 2020 7:36 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Photon Frequency and Energy Between Ground States
Replies: 3
Views: 13

### Re: Photon Frequency and Energy Between Ground States

HI! I was confused about the same thing at first but the energy of the photon must match the difference in energy levels or else the electron will not move energy levels. This relates to the image on the lecture of the emission spectrum for the hydrogen atom where the wavelengths correspond to energ...
Thu Oct 15, 2020 9:50 pm
Forum: Photoelectric Effect
Topic: Definition of "Work"
Replies: 6
Views: 86

### Re: Definition of "Work"

"work" is the amount of energy required to remove an electron from metal, it is also referred to as the threshold energy. If the energy of the photon is not equal to or greater than the work function then no electrons will be emitted. You know whether to apply it in an equation when you ar...
Wed Oct 14, 2020 10:11 pm
Forum: General Science Questions
Topic: Balancing equations
Replies: 17
Views: 154

### Re: Balancing equations

there can be many approaches to balancing an equation! I always start with a chart that has how many elements are on each side of the equation and then update it as I go along to keep track. I usually start with the molecules that have the most elements, as those sometimes are the most complicated, ...
Wed Oct 14, 2020 10:06 pm
Forum: Photoelectric Effect
Topic: Excess energy
Replies: 20
Views: 135

### Re: Excess energy

the equation 1/2mv^2 is used for finding the kinetic or excess energy of electrons
Wed Oct 07, 2020 9:20 pm
Forum: SI Units, Unit Conversions
Topic: Rounding in Between Steps [ENDORSED]
Replies: 22
Views: 202

### Re: Rounding in Between Steps[ENDORSED]

Hi! You can do either but if you round in between steps then you run the risk that your final answer will be a little off so for me, I usually try to go as close to the exact number so my answer is as accurate as it can be. Although, there will be some cases where while you are doing the steps the a...
Tue Oct 06, 2020 11:12 pm
Forum: Molarity, Solutions, Dilutions
Topic: Sapling 6
Replies: 5
Views: 77

### Re: Sapling 6

Hi!! To find the moles of CuNO3, you start with the formula to find moles which is mass given (g) divided by molar mass (g.mol). This will give you the amount of moles of CuNO3 which you can plug into the molarity formula of Molarity= number of moles of solute/ volume in liters. Once you plug everyt...
Tue Oct 06, 2020 11:01 pm
Forum: Empirical & Molecular Formulas
Topic: Question Regarding F.23 in the Textbook
Replies: 3
Views: 57

### Re: Question Regarding F.23 in the Textbook

Hello, For this problem you would start by finding the molar mass of each compound. You then divide the mass of Carbon( 12.011) by each molar mass and then multiply by 100 to find the percent. This will be the mass percent composition of carbon and you can repeat this process with the other compound...
Tue Oct 06, 2020 9:26 pm
Forum: Balancing Chemical Reactions
Topic: Hmk. Problem H.3 (Fundamentals)
Replies: 6
Views: 53

### Re: Hmk. Problem H.3 (Fundamentals)

Hi!
You were correct in that the bonded molecules a mole of that molecule, however, in the product side of the box there are 8 moles of hydrogen so your balanced equation will be 2H4Si+ 4H2O ---> 2SiO2+ 8H2. I hope that this helps!
Tue Oct 06, 2020 9:16 pm
Forum: Balancing Chemical Reactions
Topic: Stoichiometric Coefficients
Replies: 20
Views: 147

### Re: Stoichiometric Coefficients

Hello,
There will be some cases where there will be stoichiometric coefficients given in the equation where they will still be unbalanced. I would just make sure to double-check each equation! hope this helps :)