Search found 50 matches
- Sat Dec 07, 2019 1:31 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: Marshmallow Questions
- Replies: 2
- Views: 266
Re: Marshmallow Questions
Both K+ and Na+ are derived from strong bases so they are extremely stable and will not form their strong bases in water, so they do not affect the pH.
- Thu Dec 05, 2019 2:34 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: 6B.5 and example 6B.1
- Replies: 2
- Views: 166
Re: 6B.5 and example 6B.1
You can do it both ways. If you multiply the H+ and OH- concentrations you should always get 1*10^-14, so they chose to solve for the OH- concentration that way but it is the same answer.
- Thu Dec 05, 2019 2:26 am
- Forum: Naming
- Topic: HW Problem 9C 3d
- Replies: 1
- Views: 170
Re: HW Problem 9C 3d
Normally you would write out the formula with the ligands in alphabetical order.
- Thu Dec 05, 2019 2:22 am
- Forum: Lewis Acids & Bases
- Topic: 6A.13
- Replies: 5
- Views: 282
Re: 6A.13
BF3 is an acid because the boron atom can still complete the octet by accepting another electron pair.
- Thu Dec 05, 2019 2:21 am
- Forum: Lewis Acids & Bases
- Topic: Hw 6.5
- Replies: 4
- Views: 301
Re: Hw 6.5
In the SO3 molecule, the sulfur atom has space to accept another electron pair so that in the molecule there are 4 regions of electron density in the molecule. Thus, as the electron pair acceptor it is the Lewis acid.
- Thu Dec 05, 2019 2:17 am
- Forum: Conjugate Acids & Bases
- Topic: HW 6D #11
- Replies: 1
- Views: 315
Re: HW 6D #11
The first equation you wrote is correct. For the second part of the problem, look at both of the ions. Br- is the conjugate base of a strong acid so it is a weak base. NH4+ is the conjugate acid of a weak base so it is a strong acid. Thus the solution will be acidic.
- Thu Dec 05, 2019 2:14 am
- Forum: Conjugate Acids & Bases
- Topic: HW 6A.3 Part C
- Replies: 2
- Views: 283
Re: HW 6A.3 Part C
They want you to write the equations as if the acid they give you is the acid. If you treat H2PO4 as the acid, HPO42- will be the conjugate base.
- Thu Dec 05, 2019 2:09 am
- Forum: Identifying Acidic & Basic Salts
- Topic: 6D.11
- Replies: 1
- Views: 269
Re: 6D.11
d is neutral as the salt is formed from a strong acid and strong base. e and f are both acidic because the copper and aluminum ions react with water to form Cu(OH)2 and Al(OH)3 leaving behind H+ ions that do not react with Cl- or NO3- ions as those stay completely dissociated. Thus, there are H+ ion...
- Thu Dec 05, 2019 2:06 am
- Forum: Identifying Acidic & Basic Salts
- Topic: Weak acid and base
- Replies: 2
- Views: 151
Re: Weak acid and base
Usually you would have to compare something like the strengths of the conjugate acid/base, but since we can't really do that now I doubt we'll see a salt like that.
- Thu Dec 05, 2019 2:01 am
- Forum: Lewis Acids & Bases
- Topic: HW 6.A.1 #9
- Replies: 1
- Views: 159
Re: HW 6.A.1 #9
Look at which species lose a hydrogen atom (the acid) and which species gain a hydrogen atom (the base).
- Thu Dec 05, 2019 2:00 am
- Forum: Lewis Acids & Bases
- Topic: HW 6.B #3
- Replies: 1
- Views: 147
Re: HW 6.B #3
Because HCl is a strong acid, you can assume 100% of the ions are ionized into H+ and Cl- ions. They give you the concentration of the solution which is also the concentration H+ ions which you can plug into the pH=-log(H+) equation. Then you solve for the pH of the solution with the same moles of H...
- Thu Dec 05, 2019 1:53 am
- Forum: Lewis Acids & Bases
- Topic: 6.13
- Replies: 1
- Views: 144
6.13
The conjugate base for B(OH)3 is B(OH)4. Is there a reason it wouldn't be B(OH)2H instead? Why does boric acid gain a hydroxide group instead of just donating a hydrogen proton?
- Wed Dec 04, 2019 11:10 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Types of ligands
- Replies: 1
- Views: 131
Types of ligands
The outline mentions we need to know the types of ligands, what are the types?
OH2
In the textbook, all the coordination compounds with water molecules are written as OH2 rather than H20, why is this? And do we have to write it the same way on the test?
- Wed Dec 04, 2019 9:02 pm
- Forum: Lewis Acids & Bases
- Topic: HF
- Replies: 4
- Views: 272
HF
Why is HF not a strong acid like HCl or HI?
- Mon Nov 18, 2019 11:58 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: AXE formula
- Replies: 9
- Views: 511
Re: AXE formula
AX2E is bent shaped.
- Mon Nov 18, 2019 11:25 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: I3-
- Replies: 1
- Views: 115
I3-
Why is the I3- molecule linear? Shouldn't it follow the pattern that the lone pairs have more repulsion and make the molecule bent?
- Mon Nov 18, 2019 11:16 pm
- Forum: Dipole Moments
- Topic: Cancelling dipole moments
- Replies: 11
- Views: 4578
Re: Cancelling dipole moments
Another example of dipoles cancelling out is in CO2. The dipoles point in opposite directions and as they are the same magnitude, cancel out and CO2 is nonpolar.
- Mon Nov 18, 2019 11:11 pm
- Forum: Administrative Questions and Class Announcements
- Topic: KAREN SUN 5-7PM WORKSHOP - DOWNLAOD WORKSHEETS HERE
- Replies: 53
- Views: 5711
Re: KAREN SUN 5-7PM WORKSHOP - DOWNLAOD WORKSHEETS HERE
for 2(b) if you draw out the Lewis Structure for the molecule, the carbon atom is single bonded to a hydrogen and an oxygen and double bonded to another oxygen atom. Thus, it has 3 regions of electron density and is sp2 hybridized, which is trigonal planar.
- Mon Nov 18, 2019 10:49 pm
- Forum: Dipole Moments
- Topic: Dipole Moment Arrows
- Replies: 1
- Views: 251
Dipole Moment Arrows
What direction should we draw the arrows for dipole moments? The textbook says to draw it towards the more electropositive one but I've seen it both ways.
- Sat Nov 09, 2019 11:52 am
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Hydrogen bonding
- Replies: 8
- Views: 407
Re: Hydrogen bonding
Hydrogen only forms hydrogen bonds with N, O, and F because they are the only elements with high enough electro negativities to attract it.
- Sat Nov 09, 2019 11:50 am
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Boiling Points
- Replies: 6
- Views: 867
Re: Boiling Points
Yes, usually more electrons makes stronger bonds but in this case AsF3 has a long pair compared to AsF5 with no lone pairs. This gives the molecule a strong negative dipole and as a result the molecule has both london and dipole-dipole IMF.
- Sat Nov 09, 2019 11:48 am
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: hydrogen vs london
- Replies: 2
- Views: 130
hydrogen vs london
How would you go about comparing a very small molecule with hydrogen bonds vs a very large molecule with only london forces? Are hydrogen bonds always stronger?
- Sat Nov 09, 2019 11:39 am
- Forum: Lewis Structures
- Topic: Lewis Structures
- Replies: 4
- Views: 336
Lewis Structures
For molecules with only 2 atoms and a single charge, how do you determine which atom gets the charge and which atom has a formal charge of zero?
- Wed Nov 06, 2019 2:04 pm
- Forum: Bond Lengths & Energies
- Topic: Bond strengths
- Replies: 9
- Views: 501
Bond strengths
Is it possible to have a bond that is both longer and stronger in comparison to another bond? Or should we assume that if a bond is longer, it is weaker than the bond in comparison?
- Wed Oct 30, 2019 4:18 pm
- Forum: Lewis Structures
- Topic: Charges on Lewis Structures
- Replies: 7
- Views: 441
Re: Charges on Lewis Structures
If the compound is negatively charged the electrons should indicate so, the only thing you have to add are a minus sign and brackets around the molecule.
- Wed Oct 30, 2019 4:13 pm
- Forum: Trends in The Periodic Table
- Topic: Electron Affinity
- Replies: 8
- Views: 239
Electron Affinity
What is the trend for electron affinity? Does it just go horizontally or is it diagonally like the other trends?
- Wed Oct 30, 2019 4:11 pm
- Forum: Ionic & Covalent Bonds
- Topic: ionic vs covalent bonds
- Replies: 6
- Views: 250
Re: ionic vs covalent bonds
Yes, the textbook says that if the difference between the two elements is about 2, the bond is ionic.
- Wed Oct 30, 2019 4:09 pm
- Forum: Ionic & Covalent Bonds
- Topic: 2A 19b
- Replies: 3
- Views: 140
Re: 2A 19b
Sn will have 8 valence electrons.
- Tue Oct 29, 2019 1:39 pm
- Forum: Resonance Structures
- Topic: Bond Order
- Replies: 2
- Views: 92
Bond Order
How do you calculate bond order between a pair of atoms?
- Fri Oct 25, 2019 10:55 am
- Forum: Electronegativity
- Topic: Nonmetals?
- Replies: 6
- Views: 704
Re: Nonmetals?
Nonmetals are usually more electronegative than metals as they're located further to the right on the period table and they tend to want to gain electrons rather than lose them.
- Fri Oct 25, 2019 10:41 am
- Forum: Electronegativity
- Topic: Molecular Geometry
- Replies: 4
- Views: 197
Molecular Geometry
Are we going to have to memorize molecular geometry for the midterm?
- Fri Oct 25, 2019 10:29 am
- Forum: Electronegativity
- Topic: Electronegativity
- Replies: 6
- Views: 894
Re: Electronegativity
Oxygen is more electronegative as Chlorine is down a period so it has less pull on the outer shell of electrons.
- Fri Oct 25, 2019 10:03 am
- Forum: Electronegativity
- Topic: Trend of Electronegativity
- Replies: 18
- Views: 4091
Re: Trend of Electronegativity
Yes both electronegativity and ionization energy increase as you go up the periodic table and down the period.
- Fri Oct 25, 2019 9:57 am
- Forum: Ionic & Covalent Bonds
- Topic: Ionization Energy
- Replies: 5
- Views: 166
Ionization Energy
Why is that IE decreases diagonally down the periodic table and not straight down?
- Fri Oct 18, 2019 2:02 am
- Forum: Quantum Numbers and The H-Atom
- Topic: 1D 13 Part A
- Replies: 2
- Views: 109
Re: 1D 13 Part A
The questions says when n=7, so l has the possible values of 0,1,2,3,4,5,6 which is 7 options.
- Fri Oct 18, 2019 2:00 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Problem 1E.7
- Replies: 2
- Views: 165
Re: Problem 1E.7
I believe the question is asking you to classify each of the options as ground or excited states, there shouldn't be one correct answer.
- Fri Oct 18, 2019 1:57 am
- Forum: Einstein Equation
- Topic: Mass of a proton and neutron
- Replies: 3
- Views: 177
Re: Mass of a proton and neutron
The mass of a proton/neutron is a 1.67 × 10-27 kg
- Fri Oct 18, 2019 1:55 am
- Forum: *Particle in a Box
- Topic: Particle in a box
- Replies: 1
- Views: 625
Particle in a box
For a particle in a box, the textbook mentions that the particle has zero potential energy inside the box and infinite potential energy outside of the box. Why is this?
- Fri Oct 18, 2019 1:53 am
- Forum: Properties of Light
- Topic: atomic spectra
- Replies: 2
- Views: 137
Re: atomic spectra
You can ignore the 60 W description. Use the wavelength of the light to calculate the the frequency, and then the energy of a photon of that wavelength of light. If there are 11 J total, divide 11J by the solved energy to get how many photons there are.
- Fri Oct 11, 2019 3:54 am
- Forum: Properties of Light
- Topic: Speed of light
- Replies: 9
- Views: 282
Re: Speed of light
If a question asks about speed of light not in a vacuum you should be able to calculate that speed using the index of that material.
- Fri Oct 11, 2019 3:52 am
- Forum: Properties of Light
- Topic: Electromagnetic Spectrum
- Replies: 4
- Views: 182
Re: Electromagnetic Spectrum
I don't think you need to memorize all the wavelengths for light but knowing that visible is about 400-700nm is definitely going to be necessary!
- Fri Oct 11, 2019 2:46 am
- Forum: Einstein Equation
- Topic: Planack's constant
- Replies: 8
- Views: 534
Re: Planack's constant
Plancks constant is essentially only used in Einstein's equation E=hv to find the energy of a photon with a given frequency.
- Fri Oct 11, 2019 2:43 am
- Forum: Einstein Equation
- Topic: Kinetic Energy
- Replies: 3
- Views: 129
Re: Kinetic Energy
You only need to use the equation for kinetic energy KE=1/2mv^2. I don't think the work function has anything to do with the answer.
- Fri Oct 11, 2019 2:27 am
- Forum: Photoelectric Effect
- Topic: Ejecting electrons with no KE
- Replies: 3
- Views: 261
Ejecting electrons with no KE
I remember in lecture Professor Lavelle mentioning how according to the photoelectric effect electrons can be emitted without having any KE (energy of photon is the same as the work function) but in an experiment, how would one detect that the electron was emitted?
- Fri Oct 04, 2019 2:26 am
- Forum: Significant Figures
- Topic: Lab Sig Figs
- Replies: 2
- Views: 70
Lab Sig Figs
Is there any time during a lab that a value does not have sig figs that contribute to a calculation?
- Fri Oct 04, 2019 2:24 am
- Forum: SI Units, Unit Conversions
- Topic: Homework
- Replies: 9
- Views: 456
Re: Homework
As long as it's legible I think it doesn't matter if it's pen or pencil!
- Fri Oct 04, 2019 2:22 am
- Forum: Limiting Reactant Calculations
- Topic: Limiting Reactants
- Replies: 2
- Views: 143
Limiting Reactants
When calculating for limiting reactants, does it matter which product you use as a final determination of the limiting reactant? Ex: combustion reactions can you find limiting reactants based on how much CO2 or H2O they produce?
- Fri Oct 04, 2019 2:19 am
- Forum: Significant Figures
- Topic: Sig Figs
- Replies: 3
- Views: 157
Sig Figs
Are there 3 or 4 sig figs in 8340?
- Fri Oct 04, 2019 2:16 am
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Moles
- Replies: 3
- Views: 241
Re: Moles
Hydrogen gas is in the form H2 so while the mole ratio of hydrogen gas to potassium is 1 to 1 the mole ratio of hydrogen atoms is 2 to 1.