Search found 61 matches
- Sun Jan 24, 2021 3:37 am
- 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
You can use the strength of bonds and bond energies to determine if a reaction is endothermic or exothermic by comparing the sum of the bond energies on the reactants side and that of the products side and then comparing the two. If the reactants have a higher total bond energy or have stronger bond...
- Sun Jan 24, 2021 3:31 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Diatomic Molecules
- Replies: 6
- Views: 31
Re: Diatomic Molecules
I think diatomic molecules are just molecules that involve two atoms in total while the diatomic elements allude to the elements that pretty much only exist in a homogenous diatomic arrangement such as O2 and H2.
- Sun Jan 24, 2021 3:29 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat released/ gained
- Replies: 17
- Views: 157
Re: Heat released/ gained
Bonded atoms are stable so it requires energy to break these bonds and move them into a less stable state. Atoms forming bonds go into a more stable state, therefore releasing energy.
- Sun Jan 24, 2021 3:26 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: specific vs molar
- Replies: 4
- Views: 412
Re: specific vs molar
Molar heat capacity alludes to the amount of energy required to change the temperature of one mole of the substance while specific heat alludes to the same concept but for one gram of the substance.
- Sun Jan 24, 2021 3:24 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Kinetic energy and particle motion
- Replies: 4
- Views: 12
Re: Kinetic energy and particle motion
Temperature is commonly defined as the average kinetic energy of the molecules. This derives from the increase of heat and temperature as the observed molecules move fast and increase their speed.
- Sun Jan 17, 2021 3:41 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kw constant
- Replies: 25
- Views: 53
Re: Kw constant
H2O is in excess amounts on both sides of the equation and can therefore be neglected as its minimal changes would not have any considerable effects
- Sun Jan 17, 2021 3:39 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE table and Molarity units
- Replies: 18
- Views: 41
Re: ICE table and Molarity units
As said above, I think using molarity (mol/L) is the most convenient that volume is already taken care of. However, it can be used with moles and other units of pressure as long as the units throughout the table are consistent.
- Sun Jan 17, 2021 3:37 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: When x is negligible in Equilibrium constant
- Replies: 34
- Views: 105
Re: When x is negligible in Equilibrium constant
According to Lavelle, the safest would be below 10^-4
- Sun Jan 17, 2021 3:35 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling HW #2
- Replies: 6
- Views: 44
Re: Sapling HW #2
Yep, just use the ice box and the molar ratios for the "change" column. Then use the equilibrium value given to solve for those x's and then plug them back in to get the actual mole values at equilibrium. Then divide by the volume to get M, and then plug it in to the eq. expression.
- Sun Jan 17, 2021 3:32 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: hw question #3
- Replies: 10
- Views: 41
Re: hw question #3
On the right side of the equation, both the numerator and the denominator have a square (once you combine the like terms in the denominator), meaning the entire fraction can be squared. That way, you can square root both sides of the equation and solve with algebra from there.
- Sun Jan 10, 2021 10:37 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: How to choose R
- Replies: 6
- Views: 41
Re: How to choose R
Make sure the units for pressure and volume match(:
- Sun Jan 10, 2021 10:35 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Solids and Concentration
- Replies: 8
- Views: 37
Re: Solids and Concentration
Their volume does not change and they do not dissolve in solution
- Sun Jan 10, 2021 10:33 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: change in K
- Replies: 22
- Views: 67
Re: change in K
Yep just temp in K
- Sun Jan 10, 2021 10:27 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K vs. Q
- Replies: 53
- Views: 170
Re: K vs. Q
Yep, Q is just the expression anytime during the expression wheres as K is the value for when it is in equilibrium.
- Sun Jan 10, 2021 10:25 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Units
- Replies: 27
- Views: 105
Re: Units
bars and atm, so make sure you have the right constant (:
- Sun Dec 06, 2020 10:27 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Polarity
- Replies: 14
- Views: 89
Re: Polarity
You can't know simply from that. You would need the other bonded atoms as well as the shape of the molecule in order to see if the dipole moments remain or cancel out.
- Sun Dec 06, 2020 10:26 pm
- Forum: Hybridization
- Topic: Unhybridized orbitals
- Replies: 3
- Views: 43
Re: Unhybridized orbitals
Carbon has 4 valence electrons that can form bonds. In CO2, there are 2 regions of electron density in which the sp hybrid orbitals participate. There are still two more electrons, therefore there are two non hybridized orbitals.
- Sun Dec 06, 2020 10:20 pm
- Forum: Hybridization
- Topic: Unhybridized orbitals
- Replies: 5
- Views: 37
Re: Unhybridized orbitals
I think you would look at the number of regions of electron density vs the number of valence electrons available to that atom. For example, a carbon that has three regions of electron density would have 3 sp3 hybridized orbitals and 1 sp that isn't. Carbon has 4 valence electrons.
- Sun Dec 06, 2020 10:18 pm
- Forum: Hybridization
- Topic: Pi Bonds Cannot Rotate
- Replies: 23
- Views: 167
Re: Pi Bonds Cannot Rotate
In a pi bond orbitals are overlapping outside of the intermolecular axis. Thus, rotating the bond about that axis would break the pi bond. On the other hand, sigma bonds overlap along this axis and thus allowing rotation.
- Sun Dec 06, 2020 10:16 pm
- Forum: Hybridization
- Topic: pi bonds
- Replies: 6
- Views: 90
Re: pi bonds
Anything that is additional to the single bond would be the pi bond, so you would have to look at the lewis structure.
- Sun Nov 29, 2020 11:50 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Remembering Bond Degrees
- Replies: 7
- Views: 75
Re: Remembering Bond Degrees
I cement the visualization of the shape and then the associated bond angles using flashcards and I'd say it helped a lot
- Sun Nov 29, 2020 11:46 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: H2O VSEPR
- Replies: 27
- Views: 147
Re: H2O VSEPR
2 lone pairs and 2 bonding domains on the central atom in O for H2O forms a "bent" shape
- Sun Nov 29, 2020 11:45 pm
- Forum: Bond Lengths & Energies
- Topic: Hydrogen Bonds
- Replies: 16
- Views: 124
Re: Hydrogen Bonds
Nope because hydrogen bonding denotes an intermolecular force
- Sun Nov 29, 2020 11:43 pm
- Forum: Octet Exceptions
- Topic: Phosphate
- Replies: 7
- Views: 39
Re: Phosphate
Phosphate has access to the 3d state, which means it can add extra valence electrons
- Sun Nov 29, 2020 11:42 pm
- Forum: Octet Exceptions
- Topic: Question on Radicals
- Replies: 7
- Views: 55
Re: Question on Radicals
yep it seems like it, probably synonymous as long as the specie has one unpaired electron making it unstable and existing only for a short amount of time
- Sun Nov 22, 2020 11:40 pm
- Forum: Dipole Moments
- Topic: Dipole-dipole and london-dispersion IMF
- Replies: 7
- Views: 55
Re: Dipole-dipole and london-dispersion IMF
Dipole-dipole interactions occur between the partial positive and partial negative ends of two polar molecules. London-Dispersion Forces occur as a result of temporary and arbitrary electron position within its density, which means it occurs in all molecules.
- Sun Nov 22, 2020 11:26 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pair E-
- Replies: 47
- Views: 271
Re: Lone Pair E-
Yep, thus affecting the shape of the molecule. Their repulsion is stronger than bonding pairs.
- Sun Nov 22, 2020 11:22 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Non-Polar Bonds
- Replies: 3
- Views: 41
Re: Non-Polar Bonds
Keep in mind that though some molecules have polar bonds, these molecules can be non polar still based on their shape.
- Sun Nov 22, 2020 11:11 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 25
- Views: 133
Re: Bond Angles
I think it would be safe to know the bond angles with the common shapes and geomteries.
- Sun Nov 22, 2020 11:09 pm
- Forum: Coordinate Covalent Bonds
- Topic: Just to clear it up
- Replies: 13
- Views: 239
Re: Just to clear it up
Yep because Lewis Bases are defined to donate electrons.
- Sun Nov 15, 2020 4:55 am
- Forum: Resonance Structures
- Topic: lewis base or acid
- Replies: 15
- Views: 119
Re: lewis base or acid
Izamary Marquez 2L wrote:Would this make cations and anions more likely to be acids or donors? Is there a correlation?
Cations donate electrons, resulting in their positive charge, making them Lewis bases. Anions accept electrons and then become negatively charged, making them Lewis acids.
- Sun Nov 15, 2020 4:52 am
- Forum: Bond Lengths & Energies
- Topic: Covalent Bond Length
- Replies: 13
- Views: 133
Re: Covalent Bond Length
Electronegativity, atomic radius, and either being a single, double, triple bond contributes to bond length.
- Sun Nov 15, 2020 4:51 am
- Forum: Octet Exceptions
- Topic: Identifying Radicals
- Replies: 24
- Views: 176
Re: Identifying Radicals
Having a single unpaired electron would form a radical.
- Sun Nov 15, 2020 4:45 am
- Forum: Resonance Structures
- Topic: Resonance
- Replies: 19
- Views: 100
Re: Resonance
Resonance structures are just different Lewis structures of the same molecule. The most stable resonance structures would have the least number of atoms with a formal charge and most especially a sum closest to 0 for formal charges of the whole molecule.
- Sun Nov 15, 2020 4:43 am
- Forum: Coordinate Covalent Bonds
- Topic: When do we use it
- Replies: 9
- Views: 59
Re: When do we use it
When only one of the atoms in a covalent bond donates both electrons that are shared, that bond is considered a coordinate covalent bond.
- Sun Nov 08, 2020 11:31 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge Equation
- Replies: 16
- Views: 72
Re: Formal Charge Equation
L is the number of unpaired electrons. In other words, count the number of electrons around an atom that is not participating in a bond.
- Sun Nov 08, 2020 11:30 pm
- Forum: Resonance Structures
- Topic: Valence Electrons [ENDORSED]
- Replies: 43
- Views: 328
Re: Valence Electrons [ENDORSED]
Based on the group that the element falls under on the periodic table, you can determine the number of valance electrons. On the S block, Group 1 (alkali metals) have 1 valence electron and Group 2 (alkali earth metals) have 2 valence electrons. Skipping all the way to the p block, the Boron group h...
- Sun Nov 08, 2020 11:24 pm
- Forum: Lewis Structures
- Topic: central atom
- Replies: 2
- Views: 19
Re: central atom
Keep track of the number of valence electrons it has by looking at what group it is under in the periodic table. The number of bonds can surpass that however if that central element is passed period 3 because these elements can use their 3d state to accommodate extra valence electrons past 8.
- Sun Nov 08, 2020 11:22 pm
- Forum: Ionic & Covalent Bonds
- Topic: formal charge
- Replies: 8
- Views: 39
Re: formal charge
The formal charge of an atom in a molecule will tells you the charge associated with it. We use them to determine the best Lewis Structure for a molecule that has different possibilities. We want the lowest energy, and separating charges takes energy, therefore we want FC's of 0 ideally.
- Sun Nov 08, 2020 11:20 pm
- Forum: Ionic & Covalent Bonds
- Topic: Octet rule exceptions
- Replies: 15
- Views: 75
Re: Octet rule exceptions
These atoms do not have up to 8 protons and therefore do not have enough to fullfill 8 valence electrons in its outer shell.
- Sun Nov 01, 2020 5:03 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?
I think you can choose either. In the lecture, he clearly showed that using the empirical formula twice and then subtracting worked just as well as using the ryderberg equation but it helps teach the concepts. Just be careful with the Ryderberg constant
- Sun Nov 01, 2020 4:59 pm
- Forum: Trends in The Periodic Table
- Topic: ionic radius
- Replies: 14
- Views: 68
Re: ionic radius
Cations would be smaller than their normal atoms because there are more protons than there are electrons, reducing electron repulsion as well allowing the protons to pull tighter on the lesser number of electrons, making that ionic radius smaller.
- Sun Nov 01, 2020 4:57 pm
- Forum: Trends in The Periodic Table
- Topic: Electron Affinity vs Electronegativity
- Replies: 7
- Views: 55
Re: Electron Affinity vs Electronegativity
While they can be used to imply one another, they directly mean two different things. One has to do with energy changes once electrons are accepted while the other deals with the ability of an atom to attract other atoms.
- Sun Nov 01, 2020 4:54 pm
- Forum: Trends in The Periodic Table
- Topic: Atomic Radius
- Replies: 30
- Views: 421
Re: Atomic Radius
The decrease of atomic radius as you travel across the periodic table horizontally is a result of increasing number of protons, pulling the electrons closer without the electrons jumping further away as they would down a group.
- Sun Nov 01, 2020 4:50 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Ground State vs. Excited State Question
- Replies: 8
- Views: 62
Re: Ground State vs. Excited State Question
This post really helped me a lot! The way I tend to look at it is as if an electron isn't where it's supposed to be because in the configuration, it appears as if an energy level has been skipped, which is kind of what the electron does during its excited state.
- Sun Nov 01, 2020 4:48 pm
- Forum: Einstein Equation
- Topic: E=hv vs E=hf
- Replies: 15
- Views: 120
Re: E=hv vs E=hf
I think the distinction is based mostly on context.
- Sun Nov 01, 2020 4:47 pm
- Forum: Properties of Light
- Topic: rydberg's constant
- Replies: 11
- Views: 95
Re: rydberg's constant
It depends on which equation you plug it into because like they said, same value but different units and the relation is based on the light energy equaiton.
- Sun Nov 01, 2020 4:40 pm
- Forum: Photoelectric Effect
- Topic: Lyman Series
- Replies: 30
- Views: 200
Re: Lyman Series
Yes, but for future references, keep in mind that this is for Hydrogen atom only.
- Sun Nov 01, 2020 4:39 pm
- Forum: DeBroglie Equation
- Topic: Sapling HW Question 25
- Replies: 8
- Views: 83
Re: Sapling HW Question 25
You can find the velocity based because you know the wavelength and mass values. So, isolate v in wavelength = h/mv and plug it into 1/2 mv^2.
- Sun Nov 01, 2020 11:21 am
- Forum: Properties of Light
- Topic: Is c always the speed of light?
- Replies: 88
- Views: 457
Re: Is c always the speed of light?
Yep, and it will always equal wavelength * frequency when taken from the EM spectrum
- Thu Oct 15, 2020 8:56 am
- Forum: Einstein Equation
- Topic: e=hv used for particles?
- Replies: 9
- Views: 225
Re: e=hv used for particles?
My understanding is that it is only applicable to photon energy for electromagnetic waves.
- Thu Oct 15, 2020 8:54 am
- Forum: Properties of Electrons
- Topic: protons and electrons
- Replies: 33
- Views: 191
Re: protons and electrons
Protons and neutrons have very similar mass. In fact, their masses together form the atomic mass of that element. Electrons however are so much smaller than them that the mass of electrons is neglected when dealing with atomic mass.
- Thu Oct 15, 2020 8:53 am
- Forum: Properties of Electrons
- Topic: Kinetic energy of electrons
- Replies: 3
- Views: 46
Re: Kinetic energy of electrons
Yep reference sheets for constants are useful! I imagine that our assessments in the future, we will be provided with these needed constants along with our periodic table.
- Thu Oct 15, 2020 8:48 am
- Forum: Properties of Light
- Topic: Calculator number meaning
- Replies: 6
- Views: 70
Re: Calculator number meaning
Like the previous replies said, e is used to mean "10 to the power of." You can even input your own "E" by pressing "2nd" and then "," (comma) on the TI-84 if you have one. This makes it a lot easier to input very low/high values without *10^x and adding all t...
- Thu Oct 15, 2020 8:34 am
- Forum: Properties of Light
- Topic: Photoelectric spectrum
- Replies: 24
- Views: 163
Re: Photoelectric spectrum
I think that it's safe to assume that we would be given an image or reference of the spectrum. But, I think it would probably be really helpful to be familiar with some of the ranges such as that of visible light.
- Thu Oct 08, 2020 8:57 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. Omg how did I not see the giant textbook on the right hand side of the screen I'm so blind HAHA. Thank you so much thi...
- Thu Oct 08, 2020 8:32 pm
- Forum: SI Units, Unit Conversions
- Topic: #10 in the sapling
- Replies: 6
- Views: 87
Re: #10 in the sapling
I just googled the molar masses of the molecules ahaha. I feel like in the future we would be given the molar masses of molecules that we aren't familiar with such as this.
- Thu Oct 08, 2020 8:08 pm
- Forum: SI Units, Unit Conversions
- Topic: Textbook
- Replies: 2
- Views: 37
Textbook
My textbook has yet to arrive along with my sapling code. However, I do have the free trial for sapling. Is it possible to access the book through the free trial of sapling?
- Thu Oct 08, 2020 8:06 pm
- Forum: Empirical & Molecular Formulas
- Topic: Sapling Hw Week 1 #10
- Replies: 20
- Views: 286
Re: Sapling Hw Week 1 #10
How do we know that the ratio for the problem is 1 to 1 to 1? Are we just assuming this or do we have to figure that out? If so, how do we find the ratio? I assumed that it would be 1:1 because there's no way would be expected to balance it even if it wasn't. Also if you work out the problem using ...
- Thu Oct 08, 2020 3:20 pm
- Forum: Limiting Reactant Calculations
- Topic: Sapling Question #10
- Replies: 9
- Views: 132
Re: Sapling Question #10
I googled the molar masses as well hahaha! I think it's clear that having prior understanding of what these organic compounds are is unrealistic for us to already know. It's safe to assume that for future tests or quizzes, we are most likely to be given these molar masses as well other information w...
- Thu Oct 08, 2020 3:09 pm
- Forum: Limiting Reactant Calculations
- Topic: Sapling Q #10-Balancing
- Replies: 3
- Views: 56
Re: Sapling Q #10-Balancing
I initially thought that the number before the organic compound was the number of moles but I realized that that was part of the name hahaha. Because I don't see how we can be expected to be familiar with these compounds and balance the equation, I think we should be safe to assume that they are all...