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by sarahwu3a
Sat Dec 07, 2019 1:31 pm
Forum: Calculating the pH of Salt Solutions
Topic: Marshmallow Questions
Replies: 2
Views: 98

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.
by sarahwu3a
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: 1
Views: 33

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.
by sarahwu3a
Thu Dec 05, 2019 2:26 am
Forum: Naming
Topic: HW Problem 9C 3d
Replies: 1
Views: 47

Re: HW Problem 9C 3d

Normally you would write out the formula with the ligands in alphabetical order.
by sarahwu3a
Thu Dec 05, 2019 2:22 am
Forum: Lewis Acids & Bases
Topic: 6A.13
Replies: 5
Views: 55

Re: 6A.13

BF3 is an acid because the boron atom can still complete the octet by accepting another electron pair.
by sarahwu3a
Thu Dec 05, 2019 2:21 am
Forum: Lewis Acids & Bases
Topic: Hw 6.5
Replies: 4
Views: 57

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.
by sarahwu3a
Thu Dec 05, 2019 2:17 am
Forum: Conjugate Acids & Bases
Topic: HW 6D #11
Replies: 1
Views: 31

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.
by sarahwu3a
Thu Dec 05, 2019 2:14 am
Forum: Conjugate Acids & Bases
Topic: HW 6A.3 Part C
Replies: 1
Views: 33

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.
by sarahwu3a
Thu Dec 05, 2019 2:09 am
Forum: Identifying Acidic & Basic Salts
Topic: 6D.11
Replies: 1
Views: 52

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...
by sarahwu3a
Thu Dec 05, 2019 2:06 am
Forum: Identifying Acidic & Basic Salts
Topic: Weak acid and base
Replies: 2
Views: 35

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.
by sarahwu3a
Thu Dec 05, 2019 2:01 am
Forum: Lewis Acids & Bases
Topic: HW 6.A.1 #9
Replies: 1
Views: 28

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).
by sarahwu3a
Thu Dec 05, 2019 2:00 am
Forum: Lewis Acids & Bases
Topic: HW 6.B #3
Replies: 1
Views: 23

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...
by sarahwu3a
Thu Dec 05, 2019 1:53 am
Forum: Lewis Acids & Bases
Topic: 6.13
Replies: 1
Views: 35

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?
by sarahwu3a
Wed Dec 04, 2019 11:10 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Types of ligands
Replies: 1
Views: 21

Types of ligands

The outline mentions we need to know the types of ligands, what are the types?
by sarahwu3a
Wed Dec 04, 2019 10:41 pm
Forum: Naming
Topic: OH2
Replies: 1
Views: 27

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?
by sarahwu3a
Wed Dec 04, 2019 9:02 pm
Forum: Lewis Acids & Bases
Topic: HF
Replies: 4
Views: 34

HF

Why is HF not a strong acid like HCl or HI?
by sarahwu3a
Mon Nov 18, 2019 11:58 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AXE formula
Replies: 9
Views: 82

Re: AXE formula

AX2E is bent shaped.
by sarahwu3a
Mon Nov 18, 2019 11:25 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: I3-
Replies: 1
Views: 22

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?
by sarahwu3a
Mon Nov 18, 2019 11:16 pm
Forum: Dipole Moments
Topic: Cancelling dipole moments
Replies: 9
Views: 204

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.
by sarahwu3a
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: 3410

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.
by sarahwu3a
Mon Nov 18, 2019 10:49 pm
Forum: Dipole Moments
Topic: Dipole Moment Arrows
Replies: 1
Views: 47

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.
by sarahwu3a
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: 99

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.
by sarahwu3a
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: 138

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.
by sarahwu3a
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: 41

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?
by sarahwu3a
Sat Nov 09, 2019 11:39 am
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 4
Views: 71

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?
by sarahwu3a
Wed Nov 06, 2019 2:04 pm
Forum: Bond Lengths & Energies
Topic: Bond strengths
Replies: 9
Views: 86

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?
by sarahwu3a
Wed Oct 30, 2019 4:18 pm
Forum: Lewis Structures
Topic: Charges on Lewis Structures
Replies: 7
Views: 96

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.
by sarahwu3a
Wed Oct 30, 2019 4:13 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 8
Views: 66

Electron Affinity

What is the trend for electron affinity? Does it just go horizontally or is it diagonally like the other trends?
by sarahwu3a
Wed Oct 30, 2019 4:11 pm
Forum: Ionic & Covalent Bonds
Topic: ionic vs covalent bonds
Replies: 6
Views: 82

Re: ionic vs covalent bonds

Yes, the textbook says that if the difference between the two elements is about 2, the bond is ionic.
by sarahwu3a
Wed Oct 30, 2019 4:09 pm
Forum: Ionic & Covalent Bonds
Topic: 2A 19b
Replies: 3
Views: 43

Re: 2A 19b

Sn will have 8 valence electrons.
by sarahwu3a
Tue Oct 29, 2019 1:39 pm
Forum: Resonance Structures
Topic: Bond Order
Replies: 2
Views: 37

Bond Order

How do you calculate bond order between a pair of atoms?
by sarahwu3a
Fri Oct 25, 2019 10:55 am
Forum: Electronegativity
Topic: Nonmetals?
Replies: 6
Views: 363

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.
by sarahwu3a
Fri Oct 25, 2019 10:41 am
Forum: Electronegativity
Topic: Molecular Geometry
Replies: 4
Views: 78

Molecular Geometry

Are we going to have to memorize molecular geometry for the midterm?
by sarahwu3a
Fri Oct 25, 2019 10:29 am
Forum: Electronegativity
Topic: Electronegativity
Replies: 6
Views: 419

Re: Electronegativity

Oxygen is more electronegative as Chlorine is down a period so it has less pull on the outer shell of electrons.
by sarahwu3a
Fri Oct 25, 2019 10:03 am
Forum: Electronegativity
Topic: Trend of Electronegativity
Replies: 18
Views: 2938

Re: Trend of Electronegativity

Yes both electronegativity and ionization energy increase as you go up the periodic table and down the period.
by sarahwu3a
Fri Oct 25, 2019 9:57 am
Forum: Ionic & Covalent Bonds
Topic: Ionization Energy
Replies: 5
Views: 56

Ionization Energy

Why is that IE decreases diagonally down the periodic table and not straight down?
by sarahwu3a
Fri Oct 18, 2019 2:02 am
Forum: Quantum Numbers and The H-Atom
Topic: 1D 13 Part A
Replies: 2
Views: 67

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.
by sarahwu3a
Fri Oct 18, 2019 2:00 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Problem 1E.7
Replies: 2
Views: 35

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.
by sarahwu3a
Fri Oct 18, 2019 1:57 am
Forum: Einstein Equation
Topic: Mass of a proton and neutron
Replies: 3
Views: 49

Re: Mass of a proton and neutron

The mass of a proton/neutron is a 1.67 × 10-27 kg
by sarahwu3a
Fri Oct 18, 2019 1:55 am
Forum: *Particle in a Box
Topic: Particle in a box
Replies: 1
Views: 125

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?
by sarahwu3a
Fri Oct 18, 2019 1:53 am
Forum: Properties of Light
Topic: atomic spectra
Replies: 2
Views: 31

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.
by sarahwu3a
Fri Oct 11, 2019 3:54 am
Forum: Properties of Light
Topic: Speed of light
Replies: 9
Views: 85

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.
by sarahwu3a
Fri Oct 11, 2019 3:52 am
Forum: Properties of Light
Topic: Electromagnetic Spectrum
Replies: 4
Views: 61

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!
by sarahwu3a
Fri Oct 11, 2019 2:46 am
Forum: Einstein Equation
Topic: Planack's constant
Replies: 8
Views: 196

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.
by sarahwu3a
Fri Oct 11, 2019 2:43 am
Forum: Einstein Equation
Topic: Kinetic Energy
Replies: 3
Views: 73

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.
by sarahwu3a
Fri Oct 11, 2019 2:27 am
Forum: Photoelectric Effect
Topic: Ejecting electrons with no KE
Replies: 3
Views: 46

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?
by sarahwu3a
Fri Oct 04, 2019 2:26 am
Forum: Significant Figures
Topic: Lab Sig Figs
Replies: 2
Views: 51

Lab Sig Figs

Is there any time during a lab that a value does not have sig figs that contribute to a calculation?
by sarahwu3a
Fri Oct 04, 2019 2:24 am
Forum: SI Units, Unit Conversions
Topic: Homework
Replies: 9
Views: 210

Re: Homework

As long as it's legible I think it doesn't matter if it's pen or pencil!
by sarahwu3a
Fri Oct 04, 2019 2:22 am
Forum: Limiting Reactant Calculations
Topic: Limiting Reactants
Replies: 2
Views: 61

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?
by sarahwu3a
Fri Oct 04, 2019 2:19 am
Forum: Significant Figures
Topic: Sig Figs
Replies: 3
Views: 55

Sig Figs

Are there 3 or 4 sig figs in 8340?
by sarahwu3a
Fri Oct 04, 2019 2:16 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Moles
Replies: 3
Views: 97

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.

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