Search found 107 matches
- Sat Mar 14, 2020 12:15 am
- Forum: Balancing Redox Reactions
- Topic: OH vs H
- Replies: 12
- Views: 873
Re: OH vs H
I actually use H+ to help balance my basic equations, except an extra step would have to be taken. When I have H+, I convert that to OH- by adding OH- to both sides. H+ and OH- neutralize to H2O so H+ never appears in my final equation I learned this method in this video: https://www.youtube.com/wat...
- Sat Mar 14, 2020 12:13 am
- Forum: Balancing Redox Reactions
- Topic: Test 2 Return
- Replies: 20
- Views: 1150
Re: Test 2 Return
Test 2 is available in your TA's mailbox in Young Hall.
- Sat Mar 14, 2020 12:11 am
- Forum: Balancing Redox Reactions
- Topic: Ecell values
- Replies: 12
- Views: 790
Re: Ecell values
along with the responses above, I also try to consider which assignment of the cathode or anode will result in a positive Eº cell value
- Sat Mar 14, 2020 12:09 am
- Forum: Balancing Redox Reactions
- Topic: Oxidation number
- Replies: 12
- Views: 1147
Re: Oxidation number
Elements with positive oxidation numbers will generally gain electrons whereas elements with negative oxidation numbers will generally lose electrons. This can change depending on if you're dealing with a reduction or oxidation reaction.
- Sat Mar 14, 2020 12:03 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts
- Replies: 2
- Views: 215
Catalysts
Does the presence of a catalyst change the value of rate constants?
- Sun Mar 08, 2020 4:51 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: linear plots
- Replies: 7
- Views: 527
Re: linear plots
I think we should be able to determine the rate law based off of what the axes are labeled and what gives us a linear line or not.
- Sun Mar 08, 2020 4:48 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: the intermediate in a reaction
- Replies: 10
- Views: 681
Re: the intermediate in a reaction
Intermediates are included in the elementary rate laws but not the overall rate-law since they cancel out.
- Sun Mar 08, 2020 4:47 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: intermediates
- Replies: 5
- Views: 376
Re: intermediates
I believe Dr. Lavelle said that we will never have to determine the intermediates ourselves since they are experimentally proposed/recorded
- Sun Mar 08, 2020 4:45 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Rate Laws
- Replies: 3
- Views: 257
Re: Rate Laws
I believe you include whatever reactant is lost/decreased.
- Sun Mar 08, 2020 4:44 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: 7B.13
- Replies: 1
- Views: 170
Re: 7B.13
I initially did the same thing, but I found that by using the second-order half-life to find k and using that in the integrated rate law, you could find t by using [A]0 and [A] as whatever amount of [A]0 is remaining.
- Sun Mar 01, 2020 8:12 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Rules for Writing Cell Diagrams
- Replies: 2
- Views: 144
Re: Rules for Writing Cell Diagrams
I don't believe you include the stoichiometric coefficients when writing the cell diagram. As for H+ being included, I have always written it in my cell diagrams if it is involved in the half-reactions and that's been pretty consistent with my homework answers and the book.
- Sun Mar 01, 2020 8:09 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Adding an inert electrode
- Replies: 3
- Views: 253
Re: Adding an inert electrode
Adding on to the answers above, you use an inert electrode if there is no solid METAL. An example is Iodine, I2(s). You would still have to use an electrode for half-reactions involving solid iodine since it is technically a gas/nonmetal.
- Sun Mar 01, 2020 8:07 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Anode vs Cathode
- Replies: 5
- Views: 344
Re: Anode vs Cathode
If given Eº values, you can decide which ones are the cathode and anode if Eº is positive when subtracting them (if you aren't given a cell diagram)
- Sun Mar 01, 2020 8:05 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6L.3 D
- Replies: 1
- Views: 147
Re: 6L.3 D
You first start off with
O2 --> H+
balance with oxygen with water
O2 --> H+ + 2H2O
balance hydrogen with protons
5H+ + O2 --> H+ + 2H2O
cancel protons
4H+ + O2 --> 2H2O
balance charges
4H+ + 4e- + O2 --> 2H2O
To balance OH-, you use the basic method.
O2 --> H+
balance with oxygen with water
O2 --> H+ + 2H2O
balance hydrogen with protons
5H+ + O2 --> H+ + 2H2O
cancel protons
4H+ + O2 --> 2H2O
balance charges
4H+ + 4e- + O2 --> 2H2O
To balance OH-, you use the basic method.
- Tue Feb 25, 2020 2:24 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6M.3
- Replies: 1
- Views: 165
6M.3
For predicting the voltage of galvanic cells for b: Ag(s)|AgI(s)|I-(aq)||Cl-(aq)|AgCl(s)|Ag(s) The anode reaction is: AgI + e- --> Ag + I- The cathode reaction is: Cl- + Ag --> AgCl + e- I reversed these reactions and assigned them negative values since oxidation occurs at the anode and reduction oc...
- Sun Feb 23, 2020 12:45 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6L.5b
- Replies: 2
- Views: 209
6L.5b
For the galvanic cell diagram Pt(s)|I2(s)|2I-(aq)||Ce4+(aq) ,Ce3+(aq)|Pt(s), why is platinum included at the anode even though the iodine being oxidized is a solid?
- Fri Feb 21, 2020 8:36 pm
- Forum: Balancing Redox Reactions
- Topic: balancing half reactions in a basic solution
- Replies: 7
- Views: 412
Re: balancing half reactions in a basic solution
Jessica Esparza 2H wrote:Do you add the same amount of OH-?
Yes, the OH- will neutralize the H+ and leave you with water and OH-
- Fri Feb 21, 2020 8:35 pm
- Forum: Balancing Redox Reactions
- Topic: Homework problem 6K.1
- Replies: 5
- Views: 343
Re: Homework problem 6K.1
Start by identifying the oxidized and reduced species. The oxidation number for Cr changes from +6 to +3, indicating reduction (gain of 3 electrons). The oxidation number for C changes from -2 to -1, indicating oxidation (loss of 1 electron). You now have the skeleton for your half-reactions: (Cr2O...
- Fri Feb 21, 2020 8:28 pm
- Forum: Balancing Redox Reactions
- Topic: Redox Proton Transfer
- Replies: 3
- Views: 185
Re: Redox Proton Transfer
Protons aren't transferred, only electrons. Protons are used to balance redox reactions in acidic solutions, however.
- Fri Feb 21, 2020 8:27 pm
- Forum: Balancing Redox Reactions
- Topic: oxidation
- Replies: 3
- Views: 304
Re: oxidation
Oxidation numbers are the theoretical charge of the molecule. Many follow patterns: group 1 is +1, group 2 is +2. H is 0 or +1 and O is 0 or -2. A molecule that breaks this rule is H2O2 where the oxygens are actually -1
- Fri Feb 21, 2020 8:25 pm
- Forum: Balancing Redox Reactions
- Topic: Homework 6K1
- Replies: 4
- Views: 354
Re: Homework 6K1
The overall charge is 0 on both but the charge of C changes.
- Mon Feb 10, 2020 5:18 pm
- Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Topic: Entropy
- Replies: 3
- Views: 310
Entropy
Why do molecules and atoms with greater mass have more molar entropy?
- Sat Feb 08, 2020 4:36 pm
- Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Topic: Degeneracy
- Replies: 1
- Views: 112
Degeneracy
When counting positions on a complex molecule, would we count lone pairs as their own position? For example, would NH3 have 4 possible positions?
- Sat Feb 08, 2020 3:10 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 4F.11
- Replies: 1
- Views: 106
4F.11
I'm confused as to why neither (3R/2) or (5R/2) are used for nitrogen; they just used R by itself as N2's ideal heat capacity.
Another general question I have is when to use 3R/2 and 5R/2 for heat capacities when calculating entropy.
Another general question I have is when to use 3R/2 and 5R/2 for heat capacities when calculating entropy.
- Sat Feb 08, 2020 2:46 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Entropy equations
- Replies: 2
- Views: 109
Entropy equations
Will the entropy equations for isothermal expansion/compression, pressure change, and heat change be on the midterm?
- Fri Feb 07, 2020 1:59 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Discussion 4I
- Replies: 1
- Views: 118
Discussion 4I
Hey everyone, I left my black Ray bans in Bunche 3211 in the back row of the classroom for discussion 4I (Friday’s 12-12:50) on Friday 2/7. If you have them, would you mind returning them? My name is Simon Dionson and I have lectures MWF from 3-3:50.
- Fri Feb 07, 2020 12:59 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 4F.9
- Replies: 2
- Views: 46
Re: 4F.9
Sean Cheah 1E wrote:Because the process is isothermal, q = -w. Decreasing pressure must mean that volume is increasing, therefore work is negative. Then q is positive and delta S = q/T is also positive.
Oh, that makes sense. Thank You! I think I interpreted decreasing pressure as decreasing volume.
- Fri Feb 07, 2020 11:20 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 4F.9
- Replies: 2
- Views: 46
4F.9
If the pressure of a gas in a container is decreased isothermally, wouldn't the entropy change be negative? The answer key is saying that it is positive.
- Fri Feb 07, 2020 11:09 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 4f.7
- Replies: 1
- Views: 135
4f.7
How do we know to use 5/2R and 3/2R for constant pressure and volume?
- Fri Feb 07, 2020 10:50 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 4f.1
- Replies: 2
- Views: 91
4f.1
Is it incorrect to report the entropy change in Celcius rather than kelvin?
- Sat Feb 01, 2020 2:29 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat capacity
- Replies: 2
- Views: 69
Heat capacity
Is it possible for a heat capacity to be negative?
- Sat Feb 01, 2020 1:12 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calorimeter
- Replies: 3
- Views: 154
Calorimeter
Why is there a negative in: q = -C(cal)ΔT. What is this indicating/what is losing heat and gaining heat?
- Sat Feb 01, 2020 1:01 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: reaction enthalpy
- Replies: 14
- Views: 447
Re: reaction enthalpy
Elizabeth Harty 1A wrote:What is the difference between enthalpy and entropy?
Entropy is the disorder of a system, Enthalpy is the measure of heat/energy related to a substance when it is changed.
- Sat Feb 01, 2020 12:56 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 4E.5
- Replies: 3
- Views: 79
Re: 4E.5
Benzene has a special value for bond enthalpy that is noted in the table; I also made the same mistake.
- Sat Feb 01, 2020 12:53 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase Changes
- Replies: 17
- Views: 672
Re: Phase Changes
Phase changes are constant to change intermolecular forces. Sloped lines can indicate heat capacities.
- Thu Jan 30, 2020 3:17 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond enthalpies
- Replies: 4
- Views: 225
Bond enthalpies
When calculating a reaction using bond enthalpies, will the answer always be negative (exothermic)?
- Thu Jan 30, 2020 2:45 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calorimeter q
- Replies: 2
- Views: 100
Calorimeter q
How do we know if q is negative or positive for q(system) when analyzing a bomb calorimeter?
- Fri Jan 24, 2020 2:50 pm
- Forum: General Science Questions
- Topic: Fall 2019 final
- Replies: 7
- Views: 206
Fall 2019 final
If we took Chem 14A with Lavelle last quarter does anyone know when the final is handed out/if it was already?
- Thu Jan 23, 2020 1:15 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 5J.13
- Replies: 5
- Views: 453
Re: 5J.13
At 700k less ammonia is formed since the K value is smaller. The K value being smaller indicates that there is more reactant that product at equilibrium
- Thu Jan 23, 2020 1:13 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 5J 5: increase in pressure
- Replies: 4
- Views: 146
Re: 5J 5: increase in pressure
Increasing pressure will favor the side with fewer mols of gas
B) 1mol of H2O vs 1mol of H2 + 1mol CO --> reactants favored
D) 2mol of HD vs 1 mol of H2 + 1mol of D2 --> neither favored since both have 2 mols of gases
B) 1mol of H2O vs 1mol of H2 + 1mol CO --> reactants favored
D) 2mol of HD vs 1 mol of H2 + 1mol of D2 --> neither favored since both have 2 mols of gases
- Thu Jan 23, 2020 1:07 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Acids and Bases pka and pkb
- Replies: 8
- Views: 290
Re: Acids and Bases pka and pkb
the -log means that the higher the number, the lower the value. Higher numbers result in stronger acids/bases for pka and pkb.
- Thu Jan 23, 2020 12:59 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5% rule
- Replies: 13
- Views: 580
Re: 5% rule
In my experience, I usually use this rule in weak acid/base equilibria.
- Thu Jan 23, 2020 12:52 pm
- Forum: Ideal Gases
- Topic: Equilibrium Constant
- Replies: 7
- Views: 226
Re: Equilibrium Constant
Since reactants are represented at the bottom, if the number is smaller than 10^-3 then more reactants are present at equilibrium
- Thu Jan 23, 2020 12:51 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Water in K constant
- Replies: 6
- Views: 230
Re: Water in K constant
Water is only not included if it is a solvent (liquid) or a solid.
- Thu Jan 16, 2020 7:41 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: 6D.3
- Replies: 3
- Views: 110
6D.3
Does anyone have the answers for both parts?
For part a, I calculated: K(a) = 0.09, pKa = 1.0
Part b, I calculated: K(b) = 5.7*10^-4, pKb = 3.2
I can't find the solutions so I wanna make sure these are right
For part a, I calculated: K(a) = 0.09, pKa = 1.0
Part b, I calculated: K(b) = 5.7*10^-4, pKb = 3.2
I can't find the solutions so I wanna make sure these are right
- Thu Jan 16, 2020 3:29 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Approximating -x
- Replies: 3
- Views: 119
Approximating -x
When can we approximate x when expressing K(a) or K(b)
i.e. when (x)(0.10+x)/(0.10 - x)
can be approximated to
(x)(0.10 + x)/(0.10)
i.e. when (x)(0.10+x)/(0.10 - x)
can be approximated to
(x)(0.10 + x)/(0.10)
- Wed Jan 15, 2020 7:12 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Strong acids/weak acids
- Replies: 3
- Views: 143
Strong acids/weak acids
Do strong acids have K(a) values like weak acids do? Or is there even a distinction between K and K(a)?
- Tue Jan 14, 2020 6:59 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 5J.13
- Replies: 4
- Views: 99
Re: 5J.13
Tracy Tolentino_2E wrote:Do we not have to calculate anything?
I didn't do any math, I used the K values to base my answers. Since K at the lower temperature was smaller, I assumed more products were formed at 600K vs 700K.
- Tue Jan 14, 2020 6:57 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 5J.3
- Replies: 5
- Views: 174
Re: 5J.3
Removal of a product will cause the equilibrium to shift to the right, meaning there will be more reactants consumed to reach equilibrium again.
- Tue Jan 14, 2020 6:40 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 5J.9b
- Replies: 8
- Views: 288
5J.9b
If p(NH3) is decreased will O2 increase?
3NH3 + 5O2 = 4NO + 6H2O
My initial answer is yes because the reaction will shift to the left, is this explanation correct?
3NH3 + 5O2 = 4NO + 6H2O
My initial answer is yes because the reaction will shift to the left, is this explanation correct?
- Sat Jan 11, 2020 1:48 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5I.19
- Replies: 1
- Views: 80
5I.19
For H2 + I2 <=> 2HI
If 60% of 0.133M H2 has reacted at equilibrium, do I represent the change as - 60% of H2 and the equilibrium concentration as the remaining 40%?
If 60% of 0.133M H2 has reacted at equilibrium, do I represent the change as - 60% of H2 and the equilibrium concentration as the remaining 40%?
- Thu Jan 09, 2020 9:19 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5I.15
- Replies: 1
- Views: 95
5I.15
To set up the quadratic equation, there would actually be no denominator correct?
NH4HS(s) = NH3(g) + H2S(g)
We would only use NH3 and H2S in the ICE table?
NH4HS(s) = NH3(g) + H2S(g)
We would only use NH3 and H2S in the ICE table?
- Thu Jan 09, 2020 8:58 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Stability
- Replies: 5
- Views: 452
Re: Stability
You can also look at the product formed. F2 -> 2F has more atoms formed than Cl2 -> 2Cl, F atoms form more than Cl atoms at the same conditions, so they are more stable.
- Tue Jan 07, 2020 7:16 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: P(k) and P(q)
- Replies: 2
- Views: 120
P(k) and P(q)
If we were calculating a reaction with multiple phases (i.e. solid, liquid, aqueous, gas), will calculating P(q) and P(k) only deal with the gases?
- Tue Jan 07, 2020 7:14 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Constant Q
- Replies: 2
- Views: 93
Constant Q
When calculating Q, do we apply the same rules of not including the concentrations of solids and solvents?
- Sat Dec 07, 2019 2:03 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Marshmallow Packet pH
- Replies: 3
- Views: 462
Re: Marshmallow Packet pH
I don't see the answer key for the marshmallow practice problems so can someone tell me if the answer to 34 is a pH of 2.1? I'm not sure if it's 2.1 or 2.3. CaO + H2O --> Ca(OH)2. There are 2 hydroxides produced for every 1 CaO. If you double the moles of OH-, the answer comes out to 2.276 vs 2.1 i...
- Sat Dec 07, 2019 11:39 am
- Forum: Properties of Electrons
- Topic: Mass of an electron
- Replies: 9
- Views: 744
Re: Mass of an electron
It will be provided on the front sheet along with other constants and equations.
- Sat Dec 07, 2019 11:37 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: orbitals past f
- Replies: 5
- Views: 287
Re: orbitals past f
The only possible l values are 0, 1, 2, 3 (s, p, d, f respectively)
- Sat Dec 07, 2019 11:36 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Listing quantum numbers
- Replies: 3
- Views: 274
Re: Listing quantum numbers
I think as long as you know the values, you should be fine. I also don't think they'll explicitly mark you down if you assign a random ml value to an atom since they can be in any orientation in a given moment.
- Sat Dec 07, 2019 11:34 am
- Forum: Properties of Light
- Topic: Light Absorbed/ emitted
- Replies: 4
- Views: 374
Re: Light Absorbed/ emitted
If light is absorbed, a system is receiving an input of energy, so the value is positive. If light is emitted, a system is releasing energy (essentially losing it), so the value is negative.
- Mon Dec 02, 2019 5:35 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: 6D.11b
- Replies: 1
- Views: 119
6D.11b
If we were to dissolve Na2CO3 in water, would CO3 2- be completely or partially protonated by the water?
i.e.
CO3 2- + 2H2O -> H2CO3 + 2OH-
vs
CO3 2- + H2O -> HCO3- + OH-
Could the same be said for bases with a negative charge greater than 1? thanks.
i.e.
CO3 2- + 2H2O -> H2CO3 + 2OH-
vs
CO3 2- + H2O -> HCO3- + OH-
Could the same be said for bases with a negative charge greater than 1? thanks.
- Sun Dec 01, 2019 5:04 pm
- Forum: Bronsted Acids & Bases
- Topic: Bronsted Acids and Bases
- Replies: 3
- Views: 186
Re: Bronsted Acids and Bases
water is amphoteric since it can form H3O+ or OH- if it accepts or donates a proton respectively. Another amphoteric molecule is HCO3- (bicarbonate)
It can accept a proton to form H2CO3 (carbonic acid)
It can also donate a proton to form CO3 2- (carbonate ion)
It can accept a proton to form H2CO3 (carbonic acid)
It can also donate a proton to form CO3 2- (carbonate ion)
- Sun Dec 01, 2019 4:59 pm
- Forum: Bronsted Acids & Bases
- Topic: Distinguishing between the different definitions of acids and bases
- Replies: 2
- Views: 155
Re: Distinguishing between the different definitions of acids and bases
Arrhenius acid: a compound that supplies H+ in water
Arrhenius base: a compound that supplies OH- in water
Brønsted acid: a compound that donates protons
Brønsted base: a compound that accepts protons
Lewis acid: an electron pair acceptor (i.e. H+)
Lewis base: an electron pair donor
Arrhenius base: a compound that supplies OH- in water
Brønsted acid: a compound that donates protons
Brønsted base: a compound that accepts protons
Lewis acid: an electron pair acceptor (i.e. H+)
Lewis base: an electron pair donor
- Sun Dec 01, 2019 1:22 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: 6c.21
- Replies: 1
- Views: 72
6c.21
Why is acetic acid considered a weaker acid than formic acid? I thought carbon is more electronegative than hydrogen.
- Fri Nov 29, 2019 1:40 pm
- Forum: Lewis Acids & Bases
- Topic: 6A.13
- Replies: 7
- Views: 338
6A.13
Why is Ag+ considered a Lewis acid and not a Lewis base? Doesn't it have several electron pairs it can donate?
HW 9c.9
Is [PtCl2(en)2]2+ coordination number 4 or 6? Does en form a chelate that binds to the platinum more than once?
- Sun Nov 24, 2019 11:33 pm
- Forum: Electronegativity
- Topic: water solubility
- Replies: 4
- Views: 233
Re: water solubility
Electrons with high electronegativity are likely to form polar bonds which interact with partial charges in water molecules.
- Sun Nov 24, 2019 11:17 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: resonance bond rules
- Replies: 2
- Views: 191
Re: resonance bond rules
I'm guessing resonance structures still apply to the idea that they're hybrids of the resonance structures, so the number of signature and pi bonds don't change based on what resonance structure you use.
- Sun Nov 24, 2019 10:44 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Hydrogen Bonding
- Replies: 13
- Views: 652
Re: Hydrogen Bonding
Yes, but the atom would have to have a partially positive on the hydrogen and there would have to be a strongly electronegative atom, like N, O, or F
- Sun Nov 24, 2019 10:40 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: melting point
- Replies: 8
- Views: 604
Re: melting point
Stronger bonds result in higher melting points, so if bonds were broken, the melting point would decrease
- Sun Nov 24, 2019 10:39 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond angles
- Replies: 7
- Views: 415
Re: Bond angles
Visually, it's similar to a trigonal bipyramidal but you would have to remove one bonding pair. So it would be 90, 180, 120
- Sun Nov 17, 2019 3:27 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Will polarizability/polarizing power be on test 2?
- Replies: 3
- Views: 273
Re: Will polarizability/polarizing power be on test 2?
He explicitly told us on Friday's lecture that only hybridization wouldn't be on the test. I think it would be safe to assume this will be on the test.
- Sun Nov 17, 2019 3:26 pm
- Forum: Sigma & Pi Bonds
- Topic: Hybridization shortcuts
- Replies: 1
- Views: 312
Hybridization shortcuts
Are there any shortcuts or quick ways of finding an atom's hybridized orbitals?
- Sun Nov 17, 2019 3:24 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Trend in polarisability and polarizing power?
- Replies: 3
- Views: 300
Re: Trend in polarisability and polarizing power?
Polarising power increases with an atom with fewer electrons and is more positively charged (up and left). Polarizability increases with an atom with more electrons and a more negatively charged nucleus (down and right)
- Sun Nov 17, 2019 3:22 pm
- Forum: Electronegativity
- Topic: Symbols for partial charge
- Replies: 4
- Views: 4365
Re: Symbols for partial charge
∂+ and ∂- represent partial charges due to difference in electronegavities. A dipole is indicated by ∂+ --> ∂-
- Sun Nov 17, 2019 3:21 pm
- Forum: Ionic & Covalent Bonds
- Topic: Bonds strength
- Replies: 4
- Views: 149
Re: Bonds strength
A double bond is stronger than a single bond due to its stability and distance between the bonding atoms. Shorter bond lengths allow attractive forces between atoms to be stronger.
- Fri Nov 08, 2019 6:13 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: Dispersion forces
- Replies: 6
- Views: 217
Re: Dispersion forces
Polarizability is how likely an electron cloud can be distorted in shape. Polarizability also increases with the size of atoms and how many electrons they have. If an atom has more electrons, there is a higher likelihood electrons can gather on one side and create an induced dipole.
- Fri Nov 08, 2019 6:09 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: Dispersion
- Replies: 3
- Views: 132
Re: Dispersion
The more electrons a molecule has, the stronger its induced dipole interactions are. If a molecule/atom has more electrons, they have increased probability of electrons creating a partial charge by gathering on one side of the electron cloud.
- Fri Nov 08, 2019 6:05 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: Vapor Pressure
- Replies: 2
- Views: 219
Vapor Pressure
What is the relationship between the strength of intermolecular forces and vapor pressure?
- Fri Nov 08, 2019 6:00 pm
- Forum: Ionic & Covalent Bonds
- Topic: Polarizability
- Replies: 6
- Views: 418
Re: Polarizability
Polarizability increases with the size of the electron and how many electrons it has. For example, Iodine has high polarizability because it is a big atom with many electrons compared to something like sodium.
- Fri Nov 08, 2019 5:58 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionization of Nitrogen vs Oxygen
- Replies: 11
- Views: 1534
Re: Ionization of Nitrogen vs Oxygen
The orbitals of oxygen have one more electron in any of the p orbitals. These create electron-electron repulsions that make it easier to remove an electron than nitrogen.
- Sat Nov 02, 2019 8:15 pm
- Forum: Ionic & Covalent Bonds
- Topic: ionic vs. covalent
- Replies: 7
- Views: 353
Re: ionic vs. covalent
An ionic bond would be denoted as the cation being [M]+ with the anion having the donated electron(s) surrounding it with a charge [M]-. A covalent bond has a line for each bond its sharing electrons make. H2 is H-H because its electrons make a single bond
- Sat Nov 02, 2019 3:06 pm
- Forum: *Particle in a Box
- Topic: Nodes
- Replies: 1
- Views: 434
Nodes
Is there a relationship demonstrated between a particle in a box and nodes in an atom? If so, how can it be explained?
- Sat Nov 02, 2019 3:02 pm
- Forum: DeBroglie Equation
- Topic: Dino Nuggets Problem 8b
- Replies: 11
- Views: 929
Re: Dino Nuggets Problem 8b
To find the kinetic energy of the electron, you actually have to use 2 different equations. Use de Broglie's to find that lambda = h/mv and solve for v. Using the v from de Broglie's equation, find the kinetic energy using E(k) = 1/2(m)(v)^2. Note that m in both these equations is the mass of an ele...
- Sat Nov 02, 2019 2:49 pm
- Forum: Trends in The Periodic Table
- Topic: Ionization Energy from the Review
- Replies: 4
- Views: 136
Re: Ionization Energy from the Review
In the 2p orbital, all nitrogen's are half-filled with electrons whereas oxygen has one full orbital and two half-filled orbitals. This first full orbital in oxygen has greater electron repulsion than the first half-full orbital in nitrogen, which makes it easier to remove an electron
- Sat Nov 02, 2019 2:36 pm
- Forum: Photoelectric Effect
- Topic: Ionization Energy vs Threshold Energy
- Replies: 4
- Views: 302
Re: Ionization Energy vs Threshold Energy
Threshold energy is the minimum energy needed to remove an electron from a metal surface (photoelectric effect). Ionization energy is the energy needed to remove an electron from an element.
- Sun Oct 27, 2019 4:42 pm
- Forum: Trends in The Periodic Table
- Topic: Focus 1 1.31 Atoms
- Replies: 1
- Views: 94
Re: Focus 1 1.31 Atoms
Use E = hc/lambda to find the individual energies of the lasers. Convert the work function from eV to joules. Choose the laser that is greater the work function and from there you have the laser and can calculate the kinetic energy from E = (work function) - (kinetic energy).
- Sun Oct 27, 2019 4:11 pm
- Forum: Trends in The Periodic Table
- Topic: 1F.17
- Replies: 1
- Views: 103
1F.17
How can you tell exactly what pair of elements exhibit a diagonal relationship? Does it have to do with what ions they can readily form?
- Sun Oct 27, 2019 2:40 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: 1E.17
- Replies: 2
- Views: 80
1E.17
If an electron is removed from Mn, why is the electron removed from the 4s orbital instead of 3d orbital?
- Sun Oct 27, 2019 1:03 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: 1D.23
- Replies: 1
- Views: 74
1D.23
Would someone explain to me the answers of b and c? When m(l) in part b is given, is that talking about a specific orbital making the answer 2? For part c, I understand that 2p and 2s can exist, so are the orbitals of those two added together?
- Fri Oct 25, 2019 1:42 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: 1D.19
- Replies: 1
- Views: 76
1D.19
This question is asking for the number of orbitals present in a given subshell. The answers in the answer guide are given in electrons, but wouldn't the answers be based on the value of 2l and 2l+1?
- Sat Oct 19, 2019 5:51 pm
- Forum: Properties of Electrons
- Topic: Textbook 1B.21
- Replies: 2
- Views: 104
Re: Textbook 1B.21
We can tell the de Broglie equation must be used because it's relating wavelength, mass, and velocity. The de Broglie uses SI units so you'll have to convert the values given.
- Sat Oct 19, 2019 4:43 pm
- Forum: Properties of Electrons
- Topic: Emission Spectrum
- Replies: 4
- Views: 134
Re: Emission Spectrum
Emission spectrums represent the energy an electron requires for it to jump up from a lower level to a higher level and back down (when it jumps back down, it releases energy as a photon, which is the line on the spectrum). Where there isn't a line, think of those regions as radiation not having eno...
- Sat Oct 19, 2019 4:31 pm
- Forum: Properties of Electrons
- Topic: parallel spins
- Replies: 3
- Views: 100
Re: parallel spins
Electron spins have a charge (denoted by + or - 1/2). If they spin in the same direction, they have similar charges and repel each other.
- Sat Oct 19, 2019 4:28 pm
- Forum: Properties of Electrons
- Topic: Photo and electron energy
- Replies: 4
- Views: 116
Re: Photo and electron energy
The threshold energy (work function) can be thought of as the energy needed to eject an electron from a metal. Any energy radiated that is higher than this will result in a higher kinetic energy. (That's what the equation E = (work function) + E(k) is is relating) In energy levels, electrons have to...
- Wed Oct 16, 2019 8:05 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: General question 1B.27
- Replies: 4
- Views: 201
General question 1B.27
I had a general question on what it means when the velocity is given as
5.00 + or - 5.0 m*s^-1. If we are using p=mv for momentum, how could I relate the + or - interval into ΔP?
5.00 + or - 5.0 m*s^-1. If we are using p=mv for momentum, how could I relate the + or - interval into ΔP?
- Sat Oct 12, 2019 6:11 pm
- Forum: DeBroglie Equation
- Topic: The Constant, h
- Replies: 2
- Views: 137
Re: The Constant, h
It's also important to note that Planck's constant, J * S, cancel out the bottom units in wavelength = h/mv (J = kg*m^2*s^-2) (mass = kg) (velocity = m*s^-1)
So wavelength = (kg)(m^2)(s^-2)(s)/(kg)(m^s)(s^-1) = wavelength in meters.
That's how I see it in the context of units like mass and seconds.
So wavelength = (kg)(m^2)(s^-2)(s)/(kg)(m^s)(s^-1) = wavelength in meters.
That's how I see it in the context of units like mass and seconds.
- Sat Oct 12, 2019 6:00 pm
- Forum: DeBroglie Equation
- Topic: Circular standing waves
- Replies: 4
- Views: 143
Circular standing waves
I'm having a hard time understanding what the wavy lines represent. Is it the path of an electron? Or is it representing a wavelength of an electron? Is it representing an electron as a wavelength at a certain energy level? (i.e. n=1, etc.)
- Sat Oct 12, 2019 5:49 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg Equation Alternatives?
- Replies: 4
- Views: 192
Re: Rydberg Equation Alternatives?
Dr. Lavelle's example problem on the 10/9/19 lecture is actually an alternative to way to use the Rydberg equation if both the initial n and final n are known and its possible to use the difference of the calculated energies. Unfortunately for this problem, I'm not sure it's possible since the final...
- Sat Oct 12, 2019 5:43 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: En = -hR/n2
- Replies: 1
- Views: 232
En = -hR/n2
I need some clarifying on the concept of: as n approaches infinity, E = 0. From what I understand it's because the difference between energy levels becomes smaller, but is the electron becoming less bound to the atom also a valid reason why E = 0?