Search found 102 matches
- Sun Mar 14, 2021 11:38 pm
- Forum: Phase Changes & Related Calculations
- Topic: Steam v. Water
- Replies: 4
- Views: 356
Re: Steam v. Water
When steam touches the skin and cools down, it must go through 2 processes: it must go through a phase change from gas to liquid, which requires a lot of energy (aka a lot of heat), and it must also cool down further to the temperature of the skin (releasing even more heat). Meanwhile, the boiling w...
- Sun Mar 14, 2021 11:34 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chem community points
- Replies: 19
- Views: 1228
Re: Chem community points
We need at least 50 chem community posts by today midnight (100 posts if you had him last quarter).
- Sun Mar 14, 2021 11:33 pm
- Forum: Administrative Questions and Class Announcements
- Topic: points on final?
- Replies: 8
- Views: 761
Re: points on final?
140 points, with 24 questions and a combo of 4pt and 10 pt questions :)
- Sun Mar 14, 2021 11:32 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: 0 Entropy
- Replies: 4
- Views: 311
Re: 0 Entropy
Entropy approaches zero as temperature approaches absolute zero.
- Sun Mar 14, 2021 11:31 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies
- Replies: 6
- Views: 443
Re: Bond Enthalpies
Bond enthalpies are the energy required to break a bond, therefore you are always inputting energy, and that means the enthalpy will be positive.
- Sun Mar 07, 2021 11:51 pm
- Forum: Balancing Redox Reactions
- Topic: Studying for finals?
- Replies: 47
- Views: 2004
Studying for finals?
Does anyone have any tips for studying for finals? I'm so stressed and there seems to be so much to do, I don't know where to start :(
- Sun Mar 07, 2021 11:49 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: nernst equation
- Replies: 20
- Views: 776
Re: nernst equation
You find the number of moles after balancing the two redox reactions (oxidation and reaction).
- Sun Mar 07, 2021 11:44 pm
- Forum: Ideal Gases
- Topic: K and Q
- Replies: 57
- Views: 3076
Re: K and Q
K is the concentrations of the products over reactants AT EQUILIBRIUM, but Q is the concentrations of the products over reactants NOT AT EQUILIBRIUM.
- Sun Mar 07, 2021 11:39 pm
- Forum: Balancing Redox Reactions
- Topic: Redox Tips
- Replies: 5
- Views: 356
Redox Tips
Any tips on how to balance redox reactions? or anything tricky I need to watch out for?
- Sun Mar 07, 2021 11:17 pm
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: pH
- Replies: 17
- Views: 861
Re: pH
A pH meter measures the acidity of things, and the scale goes up by multiples of 10. It measures the hydrogen ion concentration, and ranges from 1-14, with 7 being neutral, and anything above 7 basic, and any below 7 acidic.
- Sun Feb 28, 2021 11:59 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt bridge
- Replies: 10
- Views: 533
Re: Salt bridge
The salt bridge helps maintain neutrality in each of the half reaction solutions, so the reaction will continue to work. Otherwise, the reactions will stop.
- Sun Feb 28, 2021 11:57 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Arranging elements with best reduction ability
- Replies: 9
- Views: 534
Arranging elements with best reduction ability
How can we tell whether an element has the best oxidizing or reducing power based on the reduction cell potential?
- Sun Feb 28, 2021 11:55 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Anodes and Cathodes
- Replies: 22
- Views: 967
Re: Anodes and Cathodes
The half reaction that undergoes oxidation is always at the anode, and the half reaction that undergoes reduction is always at the cathode.
- Sun Feb 28, 2021 11:53 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Max cell potential
- Replies: 4
- Views: 285
Max cell potential
What does it mean when the cell is at max potential?
- Sun Feb 28, 2021 11:52 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Redox
- Replies: 16
- Views: 831
Balancing Redox
When balancing redox, how does one find out how many electrons to put on each side of the equation?
- Sun Feb 21, 2021 11:57 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gas Constant R
- Replies: 43
- Views: 3720
Re: Gas Constant R
It depends on the units, but usually yes, we use 8.314!
- Sun Feb 21, 2021 11:55 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Q and K
- Replies: 40
- Views: 2642
Re: Q and K
If Q>K, the reaction shifts towards the reactants. If Q<K, the reaction shifts toward the products.
- Sun Feb 21, 2021 11:54 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3008739
Re: Post All Chemistry Jokes Here
The noble gases walk into a bar. No one reacts. XD
- Sun Feb 21, 2021 11:52 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidizing vs Reducing
- Replies: 55
- Views: 2258
Re: Oxidizing vs Reducing
The oxidizing agent is being reduced (aka gaining electrons) and is DOING the oxidizing, thus taking the electrons from another element (which is being oxidized). The reducing agent is the opposite.
- Sun Feb 21, 2021 11:37 pm
- Forum: Ideal Gases
- Topic: Temperature
- Replies: 99
- Views: 5710
Re: Temperature
Yep! Usually the question will say "standard room temperature" if they do not specify a temperature, meaning that it is at 25˚C or 298K.
- Sun Feb 21, 2021 11:35 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Thermodynamically Stable or Unstable
- Replies: 8
- Views: 769
Re: Thermodynamically Stable or Unstable
A system is thermodynamically unstable when Gibbs free energy is positive, and thus not spontaneous.
- Mon Feb 15, 2021 12:04 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Open vs closed
- Replies: 31
- Views: 2788
Open vs closed
What's the difference between open, closed, and isolated systems? And would it matter what kind of system it is when solving problems?
- Mon Feb 15, 2021 12:02 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Reversible vs Irreversible
- Replies: 4
- Views: 237
Reversible vs Irreversible
How can we tell whether a reaction is reversible or irreversible? And what are the different equations that we need to know in terms of reversible/irreversible?
- Mon Feb 15, 2021 12:01 am
- Forum: Calculating Work of Expansion
- Topic: Ideal gas constant
- Replies: 9
- Views: 774
Re: Ideal gas constant
In short, you look at the units that the question provided you, and choose the R based off of the units that you are given.
- Mon Feb 15, 2021 12:00 am
- Forum: Calculating Work of Expansion
- Topic: Sign of work
- Replies: 25
- Views: 859
Re: Sign of work
If work is done ON the system, the system is gaining energy, thus it will be positive. If the system does work, they lose energy. to express this in mathematics, we change the sign of the work to be either positive or negative.
- Sun Feb 14, 2021 11:57 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Equations for Midterm
- Replies: 2
- Views: 124
Equations for Midterm
There are so many equations and concepts that are floating around in my head, does anyone have a list of which equations we need for the midterm? Thank you!
- Mon Feb 08, 2021 3:49 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: work
- Replies: 9
- Views: 485
work
How does knowing whether a system is endo/exothermic help determine the direction of work? Or do they have no correlation?
- Mon Feb 08, 2021 3:47 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Entropy
- Replies: 6
- Views: 321
Entropy
What do we use entropy to calculate? And how is entropy different from enthalpy (in terms of calculation)?
- Mon Feb 08, 2021 3:45 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Sapling #20
- Replies: 2
- Views: 98
Sapling #20
A 0.721 mol sample of SO2(g) initially at 298 K and 1.00 atm is held at constant volume while enough heat is applied to raise the temperature of the gas by 16.9 K. Assuming ideal gas behavior, calculate the amount of heat (q) in joules required to affect this temperature change and the total change ...
- Mon Feb 08, 2021 2:48 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Sapling #18 Week 3/4
- Replies: 1
- Views: 107
Sapling #18 Week 3/4
A 0.669 mol sample of CO2(g), initially at 298 K and 1.00 atm, is held at constant pressure while enough heat is applied to raise the temperature of the gas by 14.1 K. Calculate the amount of heat q required to bring about this temperature change, and find the corresponding total change in the inter...
- Mon Feb 08, 2021 1:59 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: work and pos/neg
- Replies: 9
- Views: 474
work and pos/neg
I'm still kind of confused, how can we tell whether work is positive or negative?
- Mon Feb 01, 2021 12:47 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy reactions
- Replies: 9
- Views: 429
Enthalpy reactions
If a problem gives us bond enthalpies, how can you use that to find the reaction enthalpy? And is the reaction enthalpy different from the standard reaction enthalpy?
- Mon Feb 01, 2021 12:46 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Reaction enthalpies and bond enthalpies
- Replies: 4
- Views: 229
Reaction enthalpies and bond enthalpies
I know that there are three methods for finding enthalpies, but I'm confused on what they are used on. Are they used to find bond enthalpies, or reaction enthalpies? Or neither?
- Mon Feb 01, 2021 12:39 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Entropy [ENDORSED]
- Replies: 1
- Views: 95
Entropy [ENDORSED]
Can the entropy of the system decrease, of does it always increase? (I'm kind of confused about the second law of thermodynamics and what it applies to).
- Mon Feb 01, 2021 12:33 am
- Forum: Ideal Gases
- Topic: Temperature
- Replies: 99
- Views: 5710
Re: Temperature
Yeo, we assume the reaction is at standard temperature and pressure.
- Mon Feb 01, 2021 12:32 am
- Forum: Phase Changes & Related Calculations
- Topic: Why does steam cause severe burns?
- Replies: 22
- Views: 1630
Re: Why does steam cause severe burns?
Steam is water vapor, and since gas-->liquid is when the gas molecules are forming bonds, thus releasing energy (exothermic reaction), the energy is given off as heat. This results in severe burns. Note that since it is changing states, even more energy is released.
- Mon Feb 01, 2021 12:04 am
- Forum: Phase Changes & Related Calculations
- Topic: Endothermic vs exothermic
- Replies: 24
- Views: 1647
Re: Endothermic vs exothermic
Water condensing means it's going from gas to a liquid state, meaning the gas molecules are forming bonds and becoming a liquid. When bond formation happens, it is releasing energy, therefore it is exothermic.
- Sun Jan 24, 2021 11:58 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Weak acid vs strong acid
- Replies: 4
- Views: 293
Weak acid vs strong acid
I still don't really understand how a weak acid is different from a strong acid in terms of calculations? If the question gives a molarity for an acid, it doesn't matter whether it is weak or strong, you still use that molarity to solve right?
- Sun Jan 24, 2021 11:53 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ka and pH calculation
- Replies: 4
- Views: 200
Ka and pH calculation
How does one convert from Ka to pH?
- Sun Jan 24, 2021 11:53 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ka to pH
- Replies: 2
- Views: 105
Ka to pH
What is the relationship between Ka and pH?
- Sun Jan 24, 2021 11:51 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Definition of a monoprotic acid
- Replies: 3
- Views: 206
Definition of a monoprotic acid
Can someone explain what a monoprotic acid is and how that changes the reaction?
- Sun Jan 24, 2021 11:49 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Salt and whether it is acidic or basic
- Replies: 1
- Views: 76
Salt and whether it is acidic or basic
Can some explain why NH4ClO4, when placed in water, becomes acidic?
- Sun Jan 17, 2021 11:55 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE Box
- Replies: 10
- Views: 494
Re: ICE Box
If the question gives you an initial concentration, then the change would have to be negative. If the question does not give an initial concentration, then it is zero, and thus it can only increase the concentration, and the change will then be positive.
- Sun Jan 17, 2021 11:52 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Enthalpy: exo/endo and how it will affect K
- Replies: 5
- Views: 161
Enthalpy: exo/endo and how it will affect K
If the enthalpy is positive, meaning the reaction is endothermic, how would that affect the equilibrium constant? And how about for an exothermic reaction?
- Sun Jan 17, 2021 11:50 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: equilibrium shifts: left of right?
- Replies: 13
- Views: 664
equilibrium shifts: left of right?
If the question gives you the initial concentration of the products and reactants, then they add more moles to the reactants and let it go to equilibrium, which way does it shift and why?
- Sun Jan 17, 2021 11:47 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: When to use ICE chart?
- Replies: 10
- Views: 590
When to use ICE chart?
How do we know when to use an ICE chart, and when to just do the normal equilibrium equation K=[products]/[reactants]?
- Sun Jan 17, 2021 11:45 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kc and Kp and Keq and Q
- Replies: 6
- Views: 1218
Kc and Kp and Keq and Q
What's the difference between Kc, Kp, Keq, and Q? Thank you!
- Sun Jan 10, 2021 11:11 pm
- Forum: Ideal Gases
- Topic: Pressure and partial pressure
- Replies: 12
- Views: 434
Re: Pressure and partial pressure
Partial pressure would just be part of the total pressure. There can be multiple partial pressures of different gases in a mixture, which can add up to a total pressure.
- Sun Jan 10, 2021 11:09 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: States that affect K
- Replies: 5
- Views: 240
States that affect K
Can someone explain to me why solids and liquids don't affect K? Thank you!
- Sun Jan 10, 2021 11:08 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K Favors Products or Reactants
- Replies: 20
- Views: 576
Re: K Favors Products or Reactants
K>1 = products favored, since K=[products]/[reactants]. By the same logic, K<1 = reactants favored
- Sun Jan 10, 2021 11:06 pm
- Forum: Ideal Gases
- Topic: Does temperature matter?
- Replies: 19
- Views: 538
Does temperature matter?
Sometimes, the question will give a chemical equation with the molarity and the temperature of the reaction, and tell us to solve for K. Does temperature matter in this case?
- Wed Dec 16, 2020 9:56 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polar bonds
- Replies: 3
- Views: 230
Re: Polar bonds
You look at the electronegativity and the bond formation. If the molecule has uneven electronegativity, as in the different bonded atoms have different electronegativity and thus more electrons are pulled to one side, then the molecule is polar. If the bonds are symmetrical however, the charges canc...
- Wed Dec 16, 2020 9:54 pm
- Forum: Naming
- Topic: coordination compounds with aqua
- Replies: 12
- Views: 689
Re: coordination compounds with aqua
Both are allowed, it doesn't matter which order you put it in. However, it's better to put the atom that is being bonded to first, which is oxygen, so OH2 is more preferred.
- Wed Dec 16, 2020 9:36 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Saying Thank You to Dr. Lavelle
- Replies: 490
- Views: 513925
Re: Saying Thank You to Dr. Lavelle
Hi Dr. Lavelle!! Thank you for the fun chem music and chem jokes at the end of each lecture :)) I really appreciated the fact that you tried to record the lectures in the lecture hall to let us experience what it would be like at school. Thank you so much for being our teacher!!
- Wed Dec 16, 2020 6:58 pm
- Forum: Sigma & Pi Bonds
- Topic: Bond length [ENDORSED]
- Replies: 13
- Views: 793
Bond length [ENDORSED]
How do you calculate bond length? (assuming you have drawn out the Lewis structure)
- Wed Dec 16, 2020 6:55 pm
- Forum: Sigma & Pi Bonds
- Topic: Pi Bonds
- Replies: 18
- Views: 768
Re: Pi Bonds
Pi bonds are only applicable to covalent bonds, since ions don't share electrons and form bonds.
- Sun Dec 06, 2020 10:31 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Oxidation #
- Replies: 6
- Views: 385
Re: Oxidation #
1) The oxidation number of a free element is 0
2) The number for the cation/anion is usually just their charge
3) the number for H is usually +1
4) the oxidation number for O is -2 unless it's in peroxides
That's what I have so far :D
2) The number for the cation/anion is usually just their charge
3) the number for H is usually +1
4) the oxidation number for O is -2 unless it's in peroxides
That's what I have so far :D
- Sun Dec 06, 2020 10:15 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3008739
Re: Post All Chemistry Jokes Here
Did you know that you can cool yourself to -273.15˚C and still be 0 k?
en
Are there any other bidentate ligands we need to know besides en?
Re: Sapling 1
I'm pretty sure the answer is triamminetrichlorocobalt(III)!! Someone double check me though :D
- Sun Dec 06, 2020 9:51 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Prefixes
- Replies: 9
- Views: 1029
Prefixes
Does anyone have any tips for memorizing prefixes? Like do we need to know all of the prefixes?
- Sun Dec 06, 2020 9:48 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polarity
- Replies: 7
- Views: 204
Re: Polarity
Yep, I believe so! The bonds and the structure do not really correlate. You can have polar bonds, but the polarity can cancel out due to the non-polar structure.
- Sun Nov 29, 2020 5:57 pm
- Forum: Dipole Moments
- Topic: Dipole moment definition/calculation [ENDORSED]
- Replies: 3
- Views: 313
Dipole moment definition/calculation [ENDORSED]
Can someone explain what a dipole moment is, and what it depends on? I know a dipole dipole attraction depends on the polarity of the atom (the electronegativity). What's the difference between this and a dipole moment? And will we ever need to calculate this?
- Sun Nov 29, 2020 5:55 pm
- Forum: Ionic & Covalent Bonds
- Topic: Lewis structure
- Replies: 13
- Views: 638
Lewis structure
Is there a way to tell which is an ionic and which is a covalent, or even an acid, based off the lewis structure alone? Thank you!
- Sun Nov 29, 2020 5:53 pm
- Forum: Lewis Structures
- Topic: Octet Exceptions
- Replies: 4
- Views: 153
Octet Exceptions
Can we always assume that elements in the n=3 level or down can carry more than eight electrons? And if so, is there a set number to how many they can hold?
- Sun Nov 29, 2020 5:51 pm
- Forum: Hybridization
- Topic: Hybridization
- Replies: 2
- Views: 82
Hybridization
What is the definition of hybidization, and does formal charge play a role in determining this? Thank you!
- Sun Nov 29, 2020 5:50 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Knowing VESPR for final
- Replies: 5
- Views: 279
Knowing VESPR for final
Hi, I was wondering, to what extent do we have to memorize the different names for the VESPR models for the final? I know the basics, but there are so many combinations with lone pairs. Do we have to know all of them?
- Sun Nov 22, 2020 11:04 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Determining polar molecules
- Replies: 7
- Views: 310
Re: Determining polar molecules
Yes, if the molecule is symmetrical, then the molecule is nonpolar. To determine this, just draw out the vectors on the lewis structure.
- Sun Nov 22, 2020 10:44 pm
- Forum: Ionic & Covalent Bonds
- Topic: C-H bond polarity
- Replies: 10
- Views: 11591
C-H bond polarity
This always messes me up-- why is the C-H bond considered non-polar? They're really far apart on the periodic table, and if you follow the electronegativity trend on the periodic table, they should be different electronegativities? Unless this is an exception. If so, what are the other exceptions?
- Sun Nov 22, 2020 10:27 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: Polarizablity
- Replies: 10
- Views: 452
Re: Polarizablity
Polarizability is basically how much an atom's electron cloud can be manipulated and distorted. Thus, the polarizability trend usually follows the atomic radius trend-- the larger the radius, the more easy it is to manipulate the electrons (since the electrons are farther from the nucleus) and the m...
- Sun Nov 22, 2020 10:24 pm
- Forum: Dipole Moments
- Topic: Dipole-Dipole
- Replies: 10
- Views: 417
Re: Dipole-Dipole
Dipole dipole interaction are between two molecule with oppositely charged ends. You can tell when they are oppositely charged when the atoms in the molecule have different electronegativities. This means that one of the atom in the molecule has a greater tendency to attract electrons, thus even tho...
- Sun Nov 22, 2020 10:01 pm
- Forum: Lewis Structures
- Topic: Guidelines on Drawing Lewis Structures
- Replies: 4
- Views: 281
Re: Guidelines on Drawing Lewis Structures
The lower the ionization energy of an atom, the less of a hold that particular atom has on the electrons surrounding them, thus it will be easier for that atom to share its electrons and form a bond with other atoms. That's why the center atom always has the lower ionization energy.
- Fri Nov 13, 2020 5:44 pm
- Forum: Electronegativity
- Topic: C and H electronegativity
- Replies: 7
- Views: 177
C and H electronegativity
I remember a question on Sapling where C and H bonded together was said to be a neutral atom. How are their electronegative values the same, if they're so far apart on the periodic table?
- Fri Nov 13, 2020 5:42 pm
- Forum: Trends in The Periodic Table
- Topic: atomic radii
- Replies: 12
- Views: 502
Re: atomic radii
The midterm will definitely make it straightforward! Anything we need to know will be on the periodic table or the equation sheet they gave to us!
- Fri Nov 13, 2020 5:40 pm
- Forum: Lewis Acids & Bases
- Topic: Determining Lewis Acids and Bases
- Replies: 9
- Views: 526
Determining Lewis Acids and Bases
Can someone explain how to determine whether a molecule is a Lewis acid or base? In the sapling they talked about molecule structures and stuff in the answer, and I don't think we've gone over that yet... I know that a Lewis acid is an acceptor, but how do you know if it's an acceptor or now?
- Fri Nov 13, 2020 5:33 pm
- Forum: Dipole Moments
- Topic: Dipole-dipole vs. ion-dipole vs. ion-ion
- Replies: 4
- Views: 253
Re: Dipole-dipole vs. ion-dipole vs. ion-ion
Dipole-Dipole: when two polar molecules are attracted through electrostatic attraction
Ion-Dipole: when an ion and a polar molecule attract each other
ion-ion: when a cation and anion bind together
Ion-Dipole: when an ion and a polar molecule attract each other
ion-ion: when a cation and anion bind together
- Fri Nov 13, 2020 5:29 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: H-F H-F Hydrogen Bonding vs Dipole-Dipole
- Replies: 11
- Views: 1393
Re: H-F H-F Hydrogen Bonding vs Dipole-Dipole
I believe both Hydrogen bonding and Dipole-Dipole forces are at work! Since one molecule is strongly polar (F), the polar ends of the molecule will attract the hydrogen. Because hydrogen only needs one pair of electrons, it can also form a hydrogen bond with F, which is strongly electronegative.
- Sun Nov 08, 2020 11:06 pm
- Forum: Properties of Electrons
- Topic: Elements with similar number of electrons
- Replies: 9
- Views: 303
Re: Elements with similar number of electrons
Hi! Elements in the periodic table are general group together, where they share similar properties such as electron number. So yes, electron number does matter.
- Sun Nov 08, 2020 10:31 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Can you have the same 3 quantem number but not the 4 same quantem numbers
- Replies: 12
- Views: 418
Re: Can you have the same 3 quantem number but not the 4 same quantem numbers
Yes, however the spin quantum number has to be +1/2 for one and -1/2 for the other electron.
- Sun Nov 08, 2020 10:14 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Subshell Definition
- Replies: 9
- Views: 394
Re: Subshell Definition
A subshell would be the "s,p,d,f", and the orbital is the magnetic quantum number.
- Sun Nov 08, 2020 10:06 pm
- Forum: Trends in The Periodic Table
- Topic: Ionization and electron affinity
- Replies: 6
- Views: 422
Ionization and electron affinity
Can someone explain exactly what ionization energy and electron affinity is? I'm still a bit confused on what is it and the trends on the periodic table.
- Sun Nov 08, 2020 9:59 pm
- Forum: Properties of Light
- Topic: Is c always the speed of light?
- Replies: 92
- Views: 4948
Re: Is c always the speed of light?
Yep, c in chemistry will always be known as the constant for the speed of light.
- Sun Nov 01, 2020 10:18 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Electron excitement
- Replies: 4
- Views: 197
Electron excitement
How can we tell whether an electron is excited or not through the electron configuration? And how can an electron be excited naturally?
- Sun Nov 01, 2020 9:59 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: The orbitals
- Replies: 8
- Views: 519
Re: The orbitals
We definitely need to know the basic information, such as where the spdf blocks are located on the periodic table, and how many orbitals are in each. s has 1 orbital, p has 3, d has 5, and f has 7. Each orbital can contain up to 2 electrons. "2s" stands for the 2nd line of the periodic tab...
- Sun Nov 01, 2020 9:52 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Atom Radius
- Replies: 6
- Views: 352
Atom Radius
Will we have to know in depth how to tell which atom has a smaller radius? I find it confusing how to determine which has a smaller radius between atoms (like oxygen) who experiences electron repulsion, atoms which has lost electrons (like Ne2-) or atoms which has gained electrons (like C2+), or lik...
- Sun Nov 01, 2020 9:36 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Electron affinity
- Replies: 4
- Views: 236
Electron affinity
I believe electron affinity is the energy that is released when and electron is added to an atom. Why is energy released, and not absorbed?
- Sun Oct 25, 2020 9:57 pm
- Forum: Properties of Light
- Topic: Amplitude
- Replies: 9
- Views: 489
Re: Amplitude
Yep, amplitude is only used in the wave model. Increasing the amplitude does not increase the amount of energy, thus, regardless of the amplitude (aka number of electrons), each electron can only react with another electron, so increasing amplitude does not make the electron eject off easier.
- Sun Oct 25, 2020 9:54 pm
- Forum: Photoelectric Effect
- Topic: Wavelength in Photoelectric Effect
- Replies: 7
- Views: 318
Re: Wavelength in Photoelectric Effect
This differs depending on the metal. Each metal requires different work, or "threshold energy" levels in order for an electron to be ejected.
- Sun Oct 25, 2020 9:50 pm
- Forum: Photoelectric Effect
- Topic: Photons vs electrons
- Replies: 2
- Views: 114
Photons vs electrons
Hi! So in number 6 on sapling, they asked me to find the max number of electrons that was ejected from the metal surface. I used stoichiometry and found the max number of photons. When I put that answer in, it was right. Does this mean that the max number of electrons is the same as the max number o...
- Sun Oct 25, 2020 9:47 pm
- Forum: Photoelectric Effect
- Topic: Frequency and energy
- Replies: 15
- Views: 508
Re: Frequency and energy
Yep! As seen in the equation E=hv, h is a constant (Planck's constant). Thus, when frequency increases, so does the energy, and vice versa.
- Sun Oct 25, 2020 9:45 pm
- Forum: Photoelectric Effect
- Topic: Sapling #4 how do I find the number of electrons
- Replies: 3
- Views: 158
Re: Sapling #4 how do I find the number of electrons
Hi! So in order to find the maximum amount of electrons that could be ejected by the metal, the kinetic energy has to equal zero (if KE=0, that means that there is no excess energy ejecting the electrons thus the max number of electrons are ejected). For the KE to equal zero, the energy of the photo...
- Sun Oct 18, 2020 11:18 pm
- Forum: Einstein Equation
- Topic: Particles with mass
- Replies: 5
- Views: 141
Re: Particles with mass
In the case of light, it is extremely fast moving compared to objects with mass, and the same laws for objects with mass cannot be applied to light. It is not the mass of the light that physically knocks electrons off, rather it is the energy of the particle that reacts with the electron. More speci...
- Sun Oct 18, 2020 10:54 pm
- Forum: Properties of Electrons
- Topic: The Quantum World
- Replies: 7
- Views: 133
Re: The Quantum World
According to my notes, the electron can still be ejected from the surface of the metal if the photon energy is equal to the energy needed to eject the electron from the metal.
- Sun Oct 18, 2020 10:52 pm
- Forum: Properties of Light
- Topic: Intensity of light
- Replies: 2
- Views: 143
Intensity of light
Will the question ever give you the "intensity of light", and if so, where would this number fit into the equations? I know that the intensity is proportional to the number of photons, but will we ever have to solve any questions where the intensity would be provided to us and we would hav...
- Sun Oct 18, 2020 10:50 pm
- Forum: Properties of Light
- Topic: Intensity vs amplitude
- Replies: 6
- Views: 343
Intensity vs amplitude
Is it safe to assume that if the problem gives us the "amplitude", they are talking about the intensity of light?
- Sun Oct 18, 2020 10:47 pm
- Forum: Properties of Electrons
- Topic: protons and electrons
- Replies: 33
- Views: 2502
Re: protons and electrons
Protons and electrons differ massively in size, whereas protons and neutrons have almost the same mass. Electrons weigh an extremely tiny amount compared to protons.
- Sun Oct 18, 2020 10:44 pm
- Forum: Properties of Light
- Topic: Remembering EM spectrum
- Replies: 6
- Views: 198
Re: Remembering EM spectrum
In Professor Lavelle's lecture, he mentioned that our class would be mainly dealing with the wavelengths of anything from microwave to x-ray. The order of the list from largest to smallest wavelength would be microwave (1 mm), infrared (1 micrometers), visible light (aka the ROYGBIV colors, from 700...
- Sat Oct 10, 2020 10:22 pm
- Forum: Empirical & Molecular Formulas
- Topic: Sapling Q10
- Replies: 4
- Views: 232
Re: Sapling Q10
Yep you ignore it! Once you figure out the limiting reactant, you ALWAYS use the limiting reactant to determine the moles in every other chemical in the equation. Thus, you ignore the other reactant, as that reactant will eventually be used up with extra reactant left over.
- Sat Oct 10, 2020 10:19 pm
- Forum: Empirical & Molecular Formulas
- Topic: Molecular formulas for organic chemical structures
- Replies: 3
- Views: 160
Molecular formulas for organic chemical structures
For week 1 Q10 on the sapling homework, I encountered a problem that depicted an organic chemical structure model, and it asked me to find the theoretical yield. I had to search up the formula for that structure. Will we be required to know how to find the molecular formulas for these structures, or...
- Sat Oct 10, 2020 10:15 pm
- Forum: Limiting Reactant Calculations
- Topic: Actual yield
- Replies: 20
- Views: 752
Re: Actual yield
The theoretical yield should always be 100%. As for the actual yield, if the number is not given, then the problem will always provide a method to solve for the actual yield. For example, the problem should usually tell you what the molar mass of the final product is, and using that number and the t...