Here's a couple more differences:
- T is constant in a reversible pathway but changes along an irreversible pathway
- V increases and P decreases during a reversible run but for irreversible work is done against a constant P
- more work is done in a reversible reaction than irreversible
Search found 101 matches
- Mon Mar 09, 2020 8:56 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Reversible vs Irreversible
- Replies: 3
- Views: 261
- Mon Mar 09, 2020 8:54 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Question on Midterm
- Replies: 4
- Views: 378
Re: Question on Midterm
i'm not 100% sure why but I think it has to do with that option being the most concentrated.
- Mon Mar 09, 2020 8:52 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Pre-Equilibrium Approach
- Replies: 2
- Views: 199
Re: Pre-Equilibrium Approach
in examples in the book if its important its always given so I assume it will be.
- Mon Mar 09, 2020 8:51 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: 7E7
- Replies: 1
- Views: 128
Re: 7E7
Catalysits are not soncumed. Intermediates are consumed. For intermediates you see it as the product in one of the steps and reactant in another step, so it cancels out. This is not the case for catalysts, they don't "cancel out" in this way.
- Mon Mar 09, 2020 8:50 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: ln(A) Arrhenius Equation
- Replies: 3
- Views: 245
ln(A) Arrhenius Equation
How do you find what A is in the term ln(A) in the Arrhenius equation. Like if you are using the Arrhenius equation to solve for Ea or K how do you know what to plug in for ln(A)? Is there some sort of table that has A values for different runs in the book? Or do we solve for that algebraically?
- Sat Mar 07, 2020 8:04 pm
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: 6O.1 b
- Replies: 1
- Views: 234
Re: 6O.1 b
Yes we assume standard conditions
- Sat Mar 07, 2020 8:02 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: E- Chem Equations
- Replies: 4
- Views: 292
Re: E- Chem Equations
I believe so. The constants and equations link on his website takes you to the constants and equations paper that will be provided on the final.
- Sat Mar 07, 2020 8:00 pm
- Forum: Second Order Reactions
- Topic: 7B.13
- Replies: 5
- Views: 456
Re: 7B.13
I think the only difference is that in the book they round 0.0236 to 0.024 before plugging it into the last equation which slightly changes the answer from 756 seconds to 744 seconds (which using sig figs and scientific notation is 7.4 * 10^2).
- Sat Mar 07, 2020 7:57 pm
- Forum: General Rate Laws
- Topic: 7A.17
- Replies: 5
- Views: 364
Re: 7A.17
I don't think it matters which one because B is 1.25 in experiment 1 and 2
- Sat Mar 07, 2020 7:54 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Homework 7D5
- Replies: 1
- Views: 205
Homework 7D5
In homework problem 7D5 how do you know ln(A)=-0.59?
- Tue Mar 03, 2020 11:43 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: 6N.13 part a
- Replies: 3
- Views: 243
Re: 6N.13 part a
I am getting the same answer as well. I think it is an error in the solution manual.
- Tue Mar 03, 2020 11:41 am
- Forum: Second Order Reactions
- Topic: [A] v. Time
- Replies: 27
- Views: 1139
Re: [A] v. Time
For a second order reaction it gives a straight line.
- Sun Mar 01, 2020 12:55 pm
- Forum: Van't Hoff Equation
- Topic: Van't Hoff
- Replies: 2
- Views: 260
Van't Hoff
One of the bullets on the thermodynamics outline says "Use a ‘Chemisty’ van't Hoff analysis to calculate ∆H°, ∆S° and ∆G°." Can someone explain this?
- Sun Mar 01, 2020 12:55 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Reaction Free Energy
- Replies: 2
- Views: 274
Reaction Free Energy
One of the bullets on the second pager of the thermodynamics outline says "Understand why reaction free energy depends on pressure and the equilibrium constant." Can someone explain this?
- Wed Feb 26, 2020 10:41 pm
- Forum: General Science Questions
- Topic: Test 2
- Replies: 16
- Views: 951
Test 2
After thermodynamics, what is test 2 going to cover up to?
- Sat Feb 22, 2020 6:48 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Using Pt
- Replies: 7
- Views: 428
Using Pt
When is it necessary to use Pt(s) in the skeletal equation of a redox reaction?
- Sat Feb 22, 2020 6:41 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Finding n
- Replies: 6
- Views: 405
Finding n
How do you find n? does it have to do with moles like the variable n has in the past or is it the number of electrons being transferred?
- Sat Feb 22, 2020 6:39 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Clarifying from textbook
- Replies: 2
- Views: 206
Re: Clarifying from textbook
In Galvanic cells the electrodes flow from cathode to anode.
- Sat Feb 22, 2020 6:23 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Standard Cell Potentials
- Replies: 2
- Views: 181
Re: Standard Cell Potentials
Yeah so E^o(cell) is given to be -0.689V. In the table 6M1 E^o of the anode half reaction Cu2+ + 2e- -> Cu is given as +0.34. So the equation would be:
E^o(cell)=E^o(cathode)-E^o(anode) which is -0.689=E^o(cathode)+0.34. Then you solve for E^o(cathode)
E^o(cell)=E^o(cathode)-E^o(anode) which is -0.689=E^o(cathode)+0.34. Then you solve for E^o(cathode)
- Sat Feb 22, 2020 6:19 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell diagrams
- Replies: 2
- Views: 189
Re: Cell diagrams
Yeah you assume there is water so the half reactions are:
O2+2H2O+4e- -> 4OH-
o2+4H+4e- -> 2H2)
O2+2H2O+4e- -> 4OH-
o2+4H+4e- -> 2H2)
- Sat Feb 22, 2020 6:16 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Textbook progress
- Replies: 3
- Views: 268
Re: Textbook progress
I don't think we have finished 6N. I think we're in the middle of it
- Tue Feb 11, 2020 2:48 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Pizza Rolls 6
- Replies: 3
- Views: 242
Re: Pizza Rolls 6
delta S and delt U are 0 because the final and initial state of the system is the same (ends up being 100.0L and 1.0atm in the end again) and because U and S are state functions it means the change is 0. As for q and w, I have no idea i need help with those too
- Tue Feb 11, 2020 2:07 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Constant R
- Replies: 15
- Views: 1005
Constant R
When do you use the constant R=8.314 vs 8.206x10^-2 and what are the units for each
- Mon Feb 10, 2020 11:20 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Pizza Rolls Answers Explained
- Replies: 1
- Views: 215
Pizza Rolls Answers Explained
Does someone want to be a life saver and post an attachment that shows their work for the pizza rolls worksheet because only the final answers were posted. It would be greatly appreciated!
- Sun Feb 09, 2020 8:22 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: spontaneity
- Replies: 18
- Views: 671
Re: spontaneity
A reaction is spontaneous of S is positive and G is negative. If the product is more stable than the reactant.
- Sun Feb 09, 2020 7:12 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: state function mnemonic device
- Replies: 3
- Views: 1616
Re: state function mnemonic device
Its just saying that all of those are state variables.
- Sun Feb 09, 2020 7:10 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Entropy QUestion
- Replies: 2
- Views: 158
Re: Entropy QUestion
Entropy is basically the randomness and disorder of molecules in a system and is based on the different arrangements available to the molecules.
- Sun Feb 09, 2020 7:08 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Second Law Thermodynamics
- Replies: 4
- Views: 229
Re: Second Law Thermodynamics
Yes. In simpler terms, it essentially means that entropy always increases.
- Wed Feb 05, 2020 8:10 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 4F.9
- Replies: 2
- Views: 105
Re: 4F.9
because in the ideal gas equation: PV=nrT P and V are inverses (as one increases the other decreases)
- Sun Feb 02, 2020 2:56 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Standard Enthalpy of Formation
- Replies: 4
- Views: 222
Standard Enthalpy of Formation
Do we need to memorize the standard enthalpy of formation for different molecules??
- Sat Feb 01, 2020 1:58 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 4C.3
- Replies: 2
- Views: 92
4C.3
In the text book problem 4C.3 why is nCp=5/2*8.314? Where does the 5/2 come from?
- Sat Feb 01, 2020 1:57 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy of Rxn
- Replies: 9
- Views: 389
Re: Enthalpy of Rxn
Multiply
- Sat Feb 01, 2020 1:56 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Test 1 #5
- Replies: 3
- Views: 229
Re: Test 1 #5
You can use the pKb to find the Kb and then use the Kb to find the Ka. Then create your ICE table and set that equal to the Ka you found to solve for x which equals [H30+]. The use [H30+] to find pH and use pH to find pOH.
- Tue Jan 28, 2020 4:05 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 4A7
- Replies: 4
- Views: 169
4A7
In problem 4A7 where does the constant 4.18J/(Cg) come from? (this constant is used in the solution manual but not given in the problem)
- Tue Jan 28, 2020 3:46 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Calculating Work
- Replies: 3
- Views: 90
Calculating Work
Do you use a different equations to calculate work done in a reversible or irreversible expansion?
- Mon Jan 27, 2020 9:50 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy and Heat
- Replies: 6
- Views: 196
Enthalpy and Heat
What is the difference between enthalpy and heat?
- Mon Jan 27, 2020 9:44 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: 4B.5 and 4B.13 part a
- Replies: 2
- Views: 153
Re: 4B.5 and 4B.13 part a
So in the case of 4B 5 the units of w are L atm so you have to multiply it by 8.31447 J/mol K and then divide it by 0.08206 L atm/mol K in order to get the units to be J.
- Tue Jan 21, 2020 10:08 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Prep for Test 1
- Replies: 16
- Views: 603
Prep for Test 1
Do we need to memorize any Ka or Kb values for Test 1?
- Sun Jan 19, 2020 1:21 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Step Up Sessions
- Replies: 71
- Views: 6712
Step Up Sessions
Does anyone know if the normal step-up up sessions and workshops that are held on Mondays are still being held tomorrow despite it being MLK Day???
- Tue Jan 14, 2020 8:45 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Module 3 #19
- Replies: 2
- Views: 184
Module 3 #19
Can someone explain how to solve this and what the answer is:
0.482 mol N2 and 0.933 mol O2 are placed in a 10.0 L reaction vessel and form N2O (dinitrogen oxide): 2N2(g) + O2(g) ⇌ 2N2O(g) KC = 2.0 x 10-37 What is the composition of the equilibrium mixture?
0.482 mol N2 and 0.933 mol O2 are placed in a 10.0 L reaction vessel and form N2O (dinitrogen oxide): 2N2(g) + O2(g) ⇌ 2N2O(g) KC = 2.0 x 10-37 What is the composition of the equilibrium mixture?
- Mon Jan 13, 2020 9:55 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Module 2 Question 27
- Replies: 1
- Views: 154
Module 2 Question 27
27. A mixture of 2.5 moles H2O and 100 g of C are placed in a 50 L container and allowed to come to equilibrium subject to the following reaction: C(s) + H2O (g) ⇌ CO (g) + H2 (g) The equilibrium concentration of hydrogen is found to be [H2] = 0.040 M. What is the equilibrium concentration of water,...
- Mon Jan 13, 2020 2:00 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Textbook question 5J.5
- Replies: 2
- Views: 120
Re: Textbook question 5J.5
Part E is different from part D (no change) because there is 1 mole of the gas on the reactant side but two moles on the product side (looking at the sum of the coefficients, not the sum of the total number of elements) and therefore the reactants would be favored if the pressure was increased becau...
- Mon Jan 13, 2020 1:56 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equilibrium constant for water
- Replies: 3
- Views: 112
Equilibrium constant for water
when writing the equilibrium constant for water, why do we omit [H20] from the expression?
- Fri Jan 10, 2020 1:44 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Pressure and Volume
- Replies: 8
- Views: 201
Pressure and Volume
do changes in pressure and volume affect K? if not, why not? if it does, how does it affect it?
- Fri Jan 10, 2020 1:42 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Le Chatelier's Principle
- Replies: 7
- Views: 279
Le Chatelier's Principle
I'm a little confused on Le Chatelier's Principle, can someone define exactly what it is and explain why the in class example Lavelle gave with it? N2+3H2=2NH3 He said that if N2 were increased, NH3 was increased, and H2 was decreased, the only way to increase the yield of NH3 without adding more re...
- Fri Jan 10, 2020 1:38 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Change in k
- Replies: 11
- Views: 492
Re: Change in k
a change in concentration of a reactant causes the concentration of the product to change (and vice versa) so the ration of P/R does not change because both P and R change, meaning K does not change.
- Thu Jan 09, 2020 5:51 pm
- Forum: Ideal Gases
- Topic: Solving for K when only given balanced equation [ENDORSED]
- Replies: 6
- Views: 216
Re: Solving for K when only given balanced equation [ENDORSED]
partial pressure is used for gasses. for aqueous things you don't need partial pressure.
- Thu Jan 09, 2020 11:45 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5G.9
- Replies: 4
- Views: 142
Re: 5G.9
a. the second situation will have more O2 because the only thing changing is the moles of O3 (not the volume of the flask) so the concentration of O3 is greater so the concentration of O2 must also be greater. For b. the partial pressure of O2 will be higher in the second situation because if there ...
- Sat Dec 07, 2019 11:38 am
- Forum: Administrative Questions and Class Announcements
- Topic: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]
- Replies: 115
- Views: 12181
Re: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]
When will the marshmallow answer key be posted?
- Mon Dec 02, 2019 11:22 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Marshmallow
- Replies: 1
- Views: 112
Marshmallow
When will the marshmallow answers be posted?
- Mon Dec 02, 2019 9:43 pm
- Forum: General Science Questions
- Topic: Final test locations
- Replies: 4
- Views: 279
Re: Final test locations
Yes it can be found on his website.
- Mon Dec 02, 2019 8:46 pm
- Forum: Amphoteric Compounds
- Topic: Oxides in Water
- Replies: 1
- Views: 92
Oxides in Water
How do you know if an oxide will form an acid or base when added to water?
- Mon Dec 02, 2019 8:41 pm
- Forum: Amphoteric Compounds
- Topic: Oxides
- Replies: 1
- Views: 99
Oxides
How do you know if an oxide is basic, acidic, or amphoteric?
- Mon Dec 02, 2019 8:01 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Stronger Acid than another
- Replies: 5
- Views: 332
Re: Stronger Acid than another
The acid with the lower PkA is always stronger.
- Mon Dec 02, 2019 7:46 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polarity and electronegativity
- Replies: 2
- Views: 225
Re: Polarity and electronegativity
Because if one is more electronegative than the other it will cause there to be a partial negative where the more electronegative element is and a partial positive where the less electronegative element is.
- Mon Nov 25, 2019 8:42 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: complexes
- Replies: 3
- Views: 246
Re: complexes
Because Lavelle sent an email of ligand names we should know and those were included, I think we need to memorize them.
- Mon Nov 25, 2019 8:29 pm
- Forum: Ionic & Covalent Bonds
- Topic: Intra vs Inter molecular forces
- Replies: 7
- Views: 1306
Re: Intra vs Inter molecular forces
Intramolecular forces involve the sharing or exchange of electrons while intermolecular forces involve fluctuating electron distribution.
- Mon Nov 25, 2019 8:27 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Online Textbook
- Replies: 6
- Views: 352
Re: Online Textbook
I typed in the link in my textbook into my computer but the page said error. I am going home for thanksgiving and really didn't want to have to take the textbook with me in my backpack.
- Mon Nov 25, 2019 8:25 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: 9C.5
- Replies: 1
- Views: 127
Re: 9C.5
The ligand is polydentate if it has more than 1 atom with a lone pair that can bind to a metal central atom. The number of atoms with a lone pair is the number of sites it can bind to the central metal atom.
- Mon Nov 25, 2019 7:54 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Online Textbook
- Replies: 6
- Views: 352
Online Textbook
Is there a way to access the chemistry textbook online?
- Mon Nov 25, 2019 7:54 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Radicals
- Replies: 3
- Views: 192
Radicals
Some of the problems in the assigned homework for the coordination compound unit asks about radicals. Do we need to know what that is and if so can anyone explain it?
- Thu Nov 21, 2019 3:49 pm
- Forum: Ionic & Covalent Bonds
- Topic: Bond Strengths
- Replies: 2
- Views: 234
Re: Bond Strengths
1. Ion-Ion
2. Hydrogen Bonds
3. Ion-Dipole
4. Dipole-Dipole, Dipole-Induced Dipole, Induced Dipole-Induced Dipole (these are all usually similar in strength, about -2KJ/mol)
2. Hydrogen Bonds
3. Ion-Dipole
4. Dipole-Dipole, Dipole-Induced Dipole, Induced Dipole-Induced Dipole (these are all usually similar in strength, about -2KJ/mol)
- Thu Nov 21, 2019 3:47 pm
- Forum: Dipole Moments
- Topic: Rod and Spherically Shaped Molecules
- Replies: 3
- Views: 116
Re: Rod and Spherically Shaped Molecules
Most molecules are spherical but molecules with multiple Carbon atoms often form chains with other atoms (usually Hydrogen) coming off each carbon which creates a rod shaped molecule. For example, Pentane (C5H12).
- Mon Nov 18, 2019 3:29 pm
- Forum: Lewis Structures
- Topic: HW 2E #13 A
- Replies: 1
- Views: 155
Re: HW 2E #13 A
They are two different shapes/structures but are both called linear just like there is a Bent for three regions of electron density and a Bent for four regions of electron density.
- Mon Nov 18, 2019 3:28 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Test
- Replies: 2
- Views: 134
Re: Test
I would just to be safe. I think you should know all the VSEPR shapes listed on the worksheet handed out in your discussion section which includes those.
- Mon Nov 18, 2019 3:27 pm
- Forum: Hybridization
- Topic: 2F.5 Homework
- Replies: 1
- Views: 143
2F.5 Homework
In the textbook the question 2F.5 asks: state the hybridization of the first atom in each of the following molecules and ions:
a) BeCl2 b) BH3 c) BH4-
Can someone explain how you solve these?
a) BeCl2 b) BH3 c) BH4-
Can someone explain how you solve these?
- Fri Nov 15, 2019 5:20 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E.17 D
- Replies: 1
- Views: 102
Re: 2E.17 D
In the Lewis structure the central O atom has one set of lone pair electrons and then three hydrogens. Since it has 4 areas of electron density it is tetrahedral which has bond angles of 109.5. But since one of the regions is a lone pair, this pushes the other atoms away a little bit (because it has...
- Fri Nov 15, 2019 5:15 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E.17 B
- Replies: 2
- Views: 99
Re: 2E.17 B
In the Lewis model the central N has no lone pairs (it is three Ns with the two outside Ns double bonded to the inner N) so it is Linear so the bond angles are 180.
- Tue Nov 12, 2019 8:42 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Quantum Numbers
- Replies: 5
- Views: 320
Re: Quantum Numbers
I think its n, l, and both of the m's (m sub l and m sub s)
- Tue Nov 12, 2019 8:39 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR Discussion worksheet
- Replies: 1
- Views: 148
VSEPR Discussion worksheet
Is there an answer key for the VSEPR worksheet we got during our discussion section? If not, does someone know the answer to d. and f.
- Tue Nov 12, 2019 8:37 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: Attractive Intermolecular Interactions
- Replies: 1
- Views: 105
Attractive Intermolecular Interactions
If a question asks you to identify the types of attractive intermolecular interactions that might arise between molecules of a substance (for example NH2OH) how do you know which ones? The answer for NH2OH is dipole-dipole and induced dipole-induced dipole but how do you know?
- Sat Nov 09, 2019 7:13 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polairzability characteristics
- Replies: 3
- Views: 213
Re: Polairzability characteristics
I think that the more polarizable the atom is, the more the covalent bond will have ionic characteristics, and ionic bonds are usually solid.
- Sat Nov 09, 2019 7:12 pm
- Forum: Bond Lengths & Energies
- Topic: Shape of Molecules and bond strength
- Replies: 5
- Views: 144
Re: Shape of Molecules and bond strength
Because, for example, rod-shaped molecules when they bond can be closer together than two spherical molecules and therefore their bond is stronger.
- Sat Nov 09, 2019 11:35 am
- Forum: Dipole Moments
- Topic: Interaction Potential Energy
- Replies: 2
- Views: 170
Re: Interaction Potential Energy
There is a negative sign because the EP is always negative because it is always an attractive force.
- Fri Nov 08, 2019 8:10 pm
- Forum: Bond Lengths & Energies
- Topic: Bond Length
- Replies: 2
- Views: 195
Bond Length
Why does bond length increase with atom size?
- Fri Nov 08, 2019 7:17 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 bonds and Intermolecular Forces
- Replies: 4
- Views: 279
H bonds and Intermolecular Forces
So with hydrogen bonds and the intermolecular forces (ion-dipole, dipole-induced dipole, etc.) are electrons actually being transferred from one atom to another or shared between atoms or is it all just based on attraction?
- Sat Nov 02, 2019 5:41 pm
- Forum: Dipole Moments
- Topic: Interaction between ions and molecules
- Replies: 2
- Views: 166
Re: Interaction between ions and molecules
They are the attractive forces responsible for condensed phase (liquid and solid). They include:
ion-ion
ion-dipole
dipole-dipole
dipole-induced dipole
induced dipole-induced dipole
ion-ion
ion-dipole
dipole-dipole
dipole-induced dipole
induced dipole-induced dipole
- Sat Nov 02, 2019 4:42 pm
- Forum: Octet Exceptions
- Topic: Octet Exceptions
- Replies: 3
- Views: 220
Octet Exceptions
How do we know which elements/when they can have more than 8 valence electrons?
- Sat Nov 02, 2019 4:38 pm
- Forum: Ionic & Covalent Bonds
- Topic: Electronegativity difference >1.5 but <2
- Replies: 3
- Views: 225
Re: Electronegativity difference >1.5 but <2
If the electronegativity difference is between 1.5 and 2 then you can't say whether it is covalent or ionic.
- Sat Nov 02, 2019 4:33 pm
- Forum: Resonance Structures
- Topic: Resonance structure
- Replies: 4
- Views: 184
Re: Resonance structure
Resonance structure just shows all the possible lewis structure for a molecule. NH4 does not have resonance.
- Sat Nov 02, 2019 4:31 pm
- Forum: DeBroglie Equation
- Topic: Dino Nuggets 13a
- Replies: 1
- Views: 113
Re: Dino Nuggets 13a
electrons have such a small mass that the mass of the atom is essentially the same as the ion.
- Sat Nov 02, 2019 4:30 pm
- Forum: Trends in The Periodic Table
- Topic: Noble Gases
- Replies: 2
- Views: 72
Re: Noble Gases
The atomic radius trend and ionization energy applies to the noble gasses but electron affinity and electronegativity does not.
- Fri Nov 01, 2019 12:49 pm
- Forum: Octet Exceptions
- Topic: More than 8 e-
- Replies: 3
- Views: 141
Re: More than 8 e-
Unlike the p-shell, the d shell can fit 10 e-
- Fri Nov 01, 2019 12:24 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chemistry Community Posts
- Replies: 2
- Views: 85
Re: Chemistry Community Posts
Weekly, from one Sunday to the next.
- Fri Nov 01, 2019 12:23 pm
- Forum: Ionic & Covalent Bonds
- Topic: How does one find a most likely charge for ions for a given element?
- Replies: 6
- Views: 469
Re: How does one find a most likely charge for ions for a given element?
Count the valence electrons and if the number is closer to 8, it gains however many it needs to reach 8. If it is closer to 0, it loses however many necessary to get to 0. For d block elements, valence electrons in the s orbit move down to the d orbit and then it will gain however many electrons nee...
- Mon Oct 28, 2019 2:03 pm
- Forum: Ionic & Covalent Bonds
- Topic: Number of Chemistry Community Posts
- Replies: 3
- Views: 130
Number of Chemistry Community Posts
As of right now, if we've been posting at least 5 times each week, how many posts should we have made in total? Because I have been posting 5 times a week and have a total of 15 posts but I feel like we've been doing this for more than 3 weeks or is 15 correct?
- Mon Oct 28, 2019 1:59 pm
- Forum: Resonance Structures
- Topic: Resonance Hybrid
- Replies: 3
- Views: 99
Re: Resonance Hybrid
Yeah resonance is a blending of structures with the same arrangement of atoms but a different arrangement of electrons. It spreads multiple bond characteristics over a molecule and essentially "blends" the different Lewis Dot structures for that molecule.
- Mon Oct 28, 2019 1:58 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm
- Replies: 3
- Views: 134
Re: Midterm
I think everything we have covered up to the midterm will be on it. So the high school review stuff, the quantum world, and chemical bonds.
- Wed Oct 23, 2019 9:48 pm
- Forum: Ionic & Covalent Bonds
- Topic: electron configuration for ions
- Replies: 3
- Views: 259
electron configuration for ions
how come when the book asks you to give the ground-state electron configuration for Ni^2+, the answer is [Ar]3d^8 and not [Ar]3d^64s^2?
- Wed Oct 23, 2019 9:43 pm
- Forum: Ionic & Covalent Bonds
- Topic: Understanding the electron affinity equation
- Replies: 3
- Views: 196
Re: Understanding the electron affinity equation
The Electron affinity= energy of the atom - the energy of the anion created when the atom gains a(n) electron(s)
- Wed Oct 23, 2019 3:24 pm
- Forum: Trends in The Periodic Table
- Topic: Trend in periodic table
- Replies: 6
- Views: 207
Re: Trend in periodic table
Yes, going down the table adds shells so the atomic radius gets bigger and the quantum number n increases.
- Sun Oct 20, 2019 3:20 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Valence electrons
- Replies: 4
- Views: 144
Re: Valence electrons
For chromium the valence electrons would be both the electrons in the 4s and 3d state because chromium has 6 valence electrons.
- Sun Oct 13, 2019 8:04 pm
- Forum: Properties of Electrons
- Topic: Mass of a neutron (1B.23)
- Replies: 2
- Views: 128
Mass of a neutron (1B.23)
For problem 1B.23 it gives the wavelength of a neutron and asks you to find the velocity. I used De Broglies Equation (wavelength= h/(mass x velocity) and plugged in h and wavelength to solve for velocity, but how do I find the mass of the neutron?
- Sun Oct 13, 2019 6:44 pm
- Forum: Properties of Electrons
- Topic: Balmer and Lyman Series (1A.11)
- Replies: 1
- Views: 162
Balmer and Lyman Series (1A.11)
Question 1A.11 asks what is common to the lines within a series that makes grouping them together logical (referring to the Balmer and Lyman series). I don't understand the explanation the solution manual gives. Can someone explain?
- Wed Oct 09, 2019 9:20 pm
- Forum: Properties of Light
- Topic: Constants in the Quantum World
- Replies: 6
- Views: 278
Re: Constants in the Quantum World
On the test we took the formulas were given but I would memorize them just in case and also understanding the formulas helps you understand the concepts. As for the constants- I think those will always be given.
- Wed Oct 09, 2019 9:17 pm
- Forum: Properties of Light
- Topic: HW Question #1A.15
- Replies: 6
- Views: 248
Re: HW Question #1A.15
Are there any other series like this other than the Lymen series that we need to memorize?
- Fri Oct 04, 2019 9:15 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Homework Grading
- Replies: 7
- Views: 347
Re: Homework Grading
I don't think rounding errors will be an issue as long as you are following the sig fig rules.
- Tue Oct 01, 2019 8:30 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Naming Compounds (F13)
- Replies: 7
- Views: 492
Naming Compounds (F13)
In problem F13 it asks you to name the compound PCL^5 (5 is a subscript) and the answer is Phosphorus Pentacholide. How do you know its chloride as opposed to chlorine/are there any other name-related things we should know?
- Tue Oct 01, 2019 4:36 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Dilution
- Replies: 9
- Views: 514
How to post a new topic on Chem Community
Hi this may be a dumb question but I can't figure out how to post a new topic/question? So far all of the questions I have asked I posted as replies to another persons question because I couldn't find any button that says "post a new topic" but I could find the "post a reply" but...
- Tue Oct 01, 2019 4:25 pm
- Forum: Significant Figures
- Topic: Sig Figs for Tests/Quizzes
- Replies: 7
- Views: 423
Sig Figs
For sig figs, do we round to the correct number of sig figs at the end or do we constantly round to the correct number as we go?