Search found 55 matches

by Edwin Liang 1I
Sun Jan 10, 2021 3:10 pm
Forum: Ideal Gases
Topic: Advice on how to navigate Chem Community
Replies: 17
Views: 62

Re: Advice on how to navigate Chem Community

You can go through the Board Index to find topics that correspond to each course. Clicking on a topic will lead to a subsection with many questions and answers about that topic. You can click "Post a Reply" to answer a question on a post.
by Edwin Liang 1I
Sun Jan 10, 2021 3:08 pm
Forum: Ideal Gases
Topic: Bars to atm [ENDORSED]
Replies: 22
Views: 115

Re: Bars to atm [ENDORSED]

We are allowed to approximate 1 bar = 1 atm! There is a very small difference, though.
by Edwin Liang 1I
Sun Jan 10, 2021 3:03 pm
Forum: Ideal Gases
Topic: Non-Ideal gases?
Replies: 22
Views: 85

Re: Non-Ideal gases?

I think it would be much later in the series, or in upper-division courses.
by Edwin Liang 1I
Sun Jan 10, 2021 2:48 pm
Forum: Ideal Gases
Topic: value of R
Replies: 24
Views: 72

Re: value of R

Each value of R is different because different units are used. Use the value of R that corresponds to your problem.
by Edwin Liang 1I
Sun Jan 10, 2021 2:43 pm
Forum: Ideal Gases
Topic: Kc vs Kp
Replies: 106
Views: 882

Re: Kc vs Kp

Kc is used for problems with molarity and Kp for calculating pressures of gas.
by Edwin Liang 1I
Wed Dec 16, 2020 1:21 am
Forum: Naming
Topic: Ligand use -ate
Replies: 18
Views: 100

Re: Ligand use -ate

Hi! -ate is used when there is an overall negative charge
by Edwin Liang 1I
Fri Dec 11, 2020 2:27 pm
Forum: Bronsted Acids & Bases
Topic: HClO3 Strong Acid
Replies: 4
Views: 49

Re: HClO3 Strong Acid

This is really confusing. I think it is because of the three oxygens attached.
by Edwin Liang 1I
Fri Dec 11, 2020 2:22 pm
Forum: Bronsted Acids & Bases
Topic: Strong and Weak Acids/Bases
Replies: 5
Views: 43

Re: Strong and Weak Acids/Bases

Yes, it would be best. Sapling provides a very concise list of these acids and bases.
by Edwin Liang 1I
Fri Dec 11, 2020 2:10 pm
Forum: Industrial Examples
Topic: Chemotherapy
Replies: 18
Views: 376

Re: Chemotherapy

As mentioned in lecture, cisplatin is one of them.
by Edwin Liang 1I
Fri Dec 11, 2020 2:05 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Sapling Week 9 HW Question 2
Replies: 11
Views: 94

Re: Sapling Week 9 HW Question 2

The coordination number is the amount of atoms bonded to the transition metal atom, so in this case, it would be 4.
by Edwin Liang 1I
Thu Dec 10, 2020 3:02 pm
Forum: Properties of Light
Topic: Minimum Energy
Replies: 4
Views: 42

Re: Minimum Energy

The work function determines the amount of energy to remove an electron from a surface. The threshold frequency is the minimum amount of radiation needed for the work function
by Edwin Liang 1I
Thu Dec 10, 2020 2:58 pm
Forum: General Science Questions
Topic: Textbook Questions on the Final
Replies: 11
Views: 89

Re: Textbook Questions on the Final

It will most likely follow a similar format to the previous midterms
by Edwin Liang 1I
Thu Dec 10, 2020 2:56 pm
Forum: Administrative Questions and Class Announcements
Topic: Final Content
Replies: 18
Views: 146

Re: Final Content

My TA said that there would be more of an emphasis on topics we spent more time on.
by Edwin Liang 1I
Thu Dec 10, 2020 2:55 pm
Forum: Administrative Questions and Class Announcements
Topic: Naming on Final
Replies: 9
Views: 75

Re: Naming on Final

Yes, memorizing them would most likely benefit greatly
by Edwin Liang 1I
Thu Dec 10, 2020 2:54 pm
Forum: Ionic & Covalent Bonds
Topic: CO2 vs CS2
Replies: 8
Views: 101

Re: CO2 vs CS2

It is because the oxygen is much more electronegative
by Edwin Liang 1I
Fri Dec 04, 2020 7:50 pm
Forum: Resonance Structures
Topic: Resonance
Replies: 9
Views: 40

Re: Resonance

Resonance is where a molecule's Lewis structure could be expressed in multiple ways. This is due to interchanging double bonds or triple bonds.
by Edwin Liang 1I
Fri Dec 04, 2020 7:30 pm
Forum: Lewis Structures
Topic: Lone Pair placement
Replies: 10
Views: 66

Re: Lone Pair placement

The lone pairs want to be in the areas where there is least electron repulsion, so the two lone pairs on H2O try to be furthest away from each other
by Edwin Liang 1I
Fri Dec 04, 2020 5:48 pm
Forum: Electronegativity
Topic: Periodic Table Trend
Replies: 37
Views: 385

Re: Periodic Table Trend

Electronegativity increases from the lower left side of the table to the top right and the ionization energy increases as you go from the bottom left to top right.
by Edwin Liang 1I
Fri Dec 04, 2020 5:43 pm
Forum: Ionic & Covalent Bonds
Topic: Polar and Nonpolar
Replies: 28
Views: 163

Re: Polar and Nonpolar

Drawing the molecule and seeing whether there is a difference in dipoles helps too
by Edwin Liang 1I
Fri Dec 04, 2020 5:37 pm
Forum: Bond Lengths & Energies
Topic: London Dispersion Forces/ van der Waal forces
Replies: 8
Views: 64

Re: London Dispersion Forces/ van der Waal forces

The two are both essentially the same type of force!
by Edwin Liang 1I
Fri Dec 04, 2020 3:50 pm
Forum: Hybridization
Topic: Sigma/pi bonds
Replies: 6
Views: 45

Re: Sigma/pi bonds

I don't think the order matters, as long as we can identify the bonds.
by Edwin Liang 1I
Thu Nov 26, 2020 1:53 am
Forum: Ionic & Covalent Bonds
Topic: Valence in d-block
Replies: 4
Views: 32

Re: Valence in d-block

For most d-block elements in period 4, you would add have [Ar] 4s2 and some number of electrons in 3d orbital. As you go along the d block, add one electron to 3d. There are exceptions, such as Cr and Cu in which the 4s orbital is missing one electron. Cr is [Ar]4s1 3d5 and Cu is [Ar]4s1 3d10
by Edwin Liang 1I
Wed Nov 25, 2020 11:20 pm
Forum: DeBroglie Equation
Topic: De broglie equation versus E=hv
Replies: 9
Views: 104

Re: De broglie equation versus E=hv

The De Broglie Equation is used to find wavelengths with a mass while E=hv finds the energy of a photon at a given wavelength
by Edwin Liang 1I
Wed Nov 25, 2020 11:12 pm
Forum: Administrative Questions and Class Announcements
Topic: Grade Adjustment after Final
Replies: 2
Views: 74

Re: Grade Adjustment after Final

Dr. Lavelle will hopefully curve the grades, but it would be dependent on the final grade distribution.
by Edwin Liang 1I
Wed Nov 25, 2020 10:45 pm
Forum: Administrative Questions and Class Announcements
Topic: Final exam (fall 2020 quarter)
Replies: 20
Views: 212

Re: Final exam (fall 2020 quarter)

Dr. Lavelle will most likely discuss it in the upcoming weeks, but I believe it is cumulative. My guess is that it might have an emphasis on material after Midterm 2
by Edwin Liang 1I
Wed Nov 25, 2020 10:18 pm
Forum: Administrative Questions and Class Announcements
Topic: 14B Enrollment [ENDORSED]
Replies: 26
Views: 1073

Re: 14B Enrollment [ENDORSED]

I think the lectures are recorded again because it saids "Online - Recorded"
by Edwin Liang 1I
Wed Nov 25, 2020 10:02 pm
Forum: Limiting Reactant Calculations
Topic: Combustion
Replies: 10
Views: 96

Re: Combustion

Hi,
In combustion reactions, the Oxygen is usually in excess unless its specific amount is given
by Edwin Liang 1I
Sun Nov 08, 2020 8:39 pm
Forum: Trends in The Periodic Table
Topic: Tips for learning the trends in the Periodic table
Replies: 11
Views: 69

Re: Tips for learning the trends in the Periodic table

I personally quiz myself on the trends of atomic radii, ionic radii, etc by looking at different elements. I find that it helps identifying trends after short practice.
by Edwin Liang 1I
Sun Nov 08, 2020 8:34 pm
Forum: Coordinate Covalent Bonds
Topic: Group 13 Elements
Replies: 4
Views: 43

Re: Group 13 Elements

Many metal cations are also able to be in Lewis reactions
by Edwin Liang 1I
Sun Nov 08, 2020 8:27 pm
Forum: Ionic & Covalent Bonds
Topic: Classifying Distortion
Replies: 4
Views: 37

Re: Classifying Distortion

I think it has to do with the charge of the cation(+1, +2, +3) and the electron density of the anion. There would be a higher distortion as the anion becomes larger as the electrons in the outer shell are held weakly compared to the inner shells. The greater the charge would mean a higher attraction...
by Edwin Liang 1I
Sun Nov 08, 2020 8:18 pm
Forum: Ionic & Covalent Bonds
Topic: Extra Valence Electrons
Replies: 10
Views: 52

Re: Extra Valence Electrons

Those three elements are exceptions to the octet rule. It's because of their d-orbitals.
by Edwin Liang 1I
Sun Nov 08, 2020 8:16 pm
Forum: Ionic & Covalent Bonds
Topic: Chemical Bonds
Replies: 12
Views: 63

Re: Chemical Bonds

Double bonds are stronger than single bonds, so it pulls atoms closer together
by Edwin Liang 1I
Sun Nov 01, 2020 7:45 pm
Forum: DeBroglie Equation
Topic: Sapling HW (Speed of Diatomic Hydrogen Molecule)
Replies: 2
Views: 22

Re: Sapling HW (Speed of Diatomic Hydrogen Molecule)

Hello! I started off with De Broglie's Equation, plugging in the speed of H for v and Planck's constant. To find the mass, multiply the mass of hydrogen(1.008 g/mol) by two, as it is a diatomic. Multiply this by Avogadro's Number and divide by 1000 to get Kg.(Kg is better because Planck's Constant h...
by Edwin Liang 1I
Sun Nov 01, 2020 7:40 pm
Forum: DeBroglie Equation
Topic: wrong equation?
Replies: 6
Views: 73

Re: wrong equation?

I believe you mistook two separate equations for De Broglie's. Lambda = h/mv would be the equation.
by Edwin Liang 1I
Sun Nov 01, 2020 7:37 pm
Forum: DeBroglie Equation
Topic: Avogadro's Number
Replies: 21
Views: 127

Re: Avogadro's Number

Avogadro's number is 6.02214 * 10^23 units. These units tell us the amount of "stuff" in a mole. For example, there are 6.02214 * 10^23 atoms of Nitrogen in a Mole of Nitrogen.
by Edwin Liang 1I
Sun Nov 01, 2020 7:34 pm
Forum: DeBroglie Equation
Topic: Sapling HW #17
Replies: 6
Views: 47

Re: Sapling HW #17

For this problem, utilize the De Broglie Equation. λ = h/mv. Insert Planck's Constant and the velocity of the diatomic fluorine for h and v, respectively. Mass could be found by multiplying the atomic mass of fluorine(18.998) by 2, then multiplying that by Avogadro's number. Then you would solve for...
by Edwin Liang 1I
Sun Nov 01, 2020 7:27 pm
Forum: DeBroglie Equation
Topic: energy of a photon
Replies: 3
Views: 30

Re: energy of a photon

Hello,

You would use the equations E = HV and c= λv. Convert the 2.4 μm to meters and insert that into c= λv for λ. Isolate for v, then use that to solve the E = HV equation
by Edwin Liang 1I
Sun Oct 25, 2020 5:35 pm
Forum: DeBroglie Equation
Topic: Derivation of Equations on Midterm?
Replies: 17
Views: 99

Re: Derivation of Equations on Midterm?

I do not believe so as the midterm is completely MCQ.
by Edwin Liang 1I
Sun Oct 25, 2020 5:30 pm
Forum: Einstein Equation
Topic: Einstein's Equation
Replies: 7
Views: 105

Re: Einstein's Equation

The equation Ek = HV - Φ represents the kinetic energy of the ejected electron. This is determined by finding the initial energy of the photon subtracting the threshold energy of the metal, which is the minimum energy required to eject an electron from the metal.
by Edwin Liang 1I
Sun Oct 25, 2020 5:14 pm
Forum: Einstein Equation
Topic: Usage of E=hv
Replies: 10
Views: 98

Re: Usage of E=hv

Those equations work for photons. De Broglie's equation is for electrons.
by Edwin Liang 1I
Sun Oct 25, 2020 5:09 pm
Forum: Einstein Equation
Topic: m vs nm
Replies: 66
Views: 432

Re: m vs nm

The question will most likely ask for specific units. Dr Lavelle has said either is fine unless specified.
by Edwin Liang 1I
Sun Oct 25, 2020 5:08 pm
Forum: Einstein Equation
Topic: Textbook Problem 1A.3
Replies: 9
Views: 55

Re: Textbook Problem 1A.3

Since frequency and wavelength are directly related to one another( c = λ * v ), the slope on a wave with high frequency will be more than that with a lower frequency. This means the "extent of change" (slope) decreases as frequency decreases.
by Edwin Liang 1I
Sun Oct 25, 2020 4:43 pm
Forum: Einstein Equation
Topic: Scratch paper during the exam
Replies: 19
Views: 153

Re: Scratch paper during the exam

Yes I believe so. Run it through with the TA first ofcourse.
by Edwin Liang 1I
Sun Oct 18, 2020 10:13 pm
Forum: *Shrodinger Equation
Topic: Schrodinger for exam
Replies: 20
Views: 444

Re: Schrodinger for exam

I don't think so. Understanding basic principles that support what we have learned is enough I think.
by Edwin Liang 1I
Sun Oct 18, 2020 10:12 pm
Forum: Einstein Equation
Topic: e=hv used for particles?
Replies: 9
Views: 225

Re: e=hv used for particles?

E=hv is only usable for electromagnetic radiation.
by Edwin Liang 1I
Sun Oct 18, 2020 10:04 pm
Forum: Properties of Electrons
Topic: Ionizing Electrons vs Ejecting Electrons
Replies: 6
Views: 47

Re: Ionizing Electrons vs Ejecting Electrons

Hi! I think Professor Lavelle meant ionizing atoms, not electrons. To my understanding, ionizing atoms and electrons are different procedures.
by Edwin Liang 1I
Sun Oct 18, 2020 9:40 pm
Forum: Einstein Equation
Topic: unexpected outcome of wave-particle experiment
Replies: 8
Views: 53

Re: unexpected outcome of wave-particle experiment

The unexpected outcome of the photoelectric experiment was that increasing the intensity of a given light would not eject electrons from a metal surface. However, increasing the wavelengths(frequency) of the light would eject electrons. This is significant because it shows the wave-particle duality ...
by Edwin Liang 1I
Sun Oct 18, 2020 9:18 pm
Forum: Properties of Electrons
Topic: Electron Wave-Particle Duality
Replies: 10
Views: 98

Re: Electron Wave-Particle Duality

Wave-particle duality means that electronics are both waves and particles at the same time. It has properties of both. In response to your question, there would be no particle-like behavior in long wavelengths and no wave-like behaviors in short wavelengths, so it wouldn't make sense.
by Edwin Liang 1I
Sat Oct 17, 2020 4:59 pm
Forum: Properties of Electrons
Topic: Work function/Threshold Energy
Replies: 19
Views: 91

Re: Work function/Threshold Energy

The threshold energy and the work function are the exact same, only with different names. In the photoelectric effect experiment, the threshold energy is the amount of energy required to displace an electron from the metal.
by Edwin Liang 1I
Tue Oct 06, 2020 1:37 pm
Forum: Balancing Chemical Reactions
Topic: Periodic Table
Replies: 50
Views: 480

Re: Periodic Table

I think a periodic table will be given during exams, but understanding certain properties and elements of the table would be beneficial.
by Edwin Liang 1I
Mon Oct 05, 2020 9:40 pm
Forum: SI Units, Unit Conversions
Topic: Conversion of grams to moles and millimoles to moles.
Replies: 9
Views: 101

Re: Conversion of grams to moles and millimoles to moles.

Converting from grams to moles can be done by dividing the grams of substance divided by the molar mass of the substance. For the millimoles to moles, I think multiplying by 1000 would work
by Edwin Liang 1I
Mon Oct 05, 2020 7:37 pm
Forum: Empirical & Molecular Formulas
Topic: Sapling HW 9
Replies: 21
Views: 223

Re: Sapling HW 9

Yes, the empirical formula gives us the ratio of moles between each atom in the molecule, so converting the grams of products to moles would simplify it.
by Edwin Liang 1I
Mon Oct 05, 2020 7:23 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Determining Molar Mass
Replies: 19
Views: 210

Re: Determining Molar Mass

For rough estimates, 16 is fine, but for precise calculations, 15.999 is best.
by Edwin Liang 1I
Mon Oct 05, 2020 7:20 pm
Forum: Molarity, Solutions, Dilutions
Topic: G5 Molarity of Na
Replies: 6
Views: 95

Re: G5 Molarity of Na

Which question in the textbook are you looking at? You could take the moles of Na divided by the final volume of the solution of sodium carbonate to find the molarity.
by Edwin Liang 1I
Mon Oct 05, 2020 6:58 pm
Forum: SI Units, Unit Conversions
Topic: Chemistry 14A Exam format
Replies: 5
Views: 97

Re: Chemistry 14A Exam format

Dr. Lavelle spoke of partial credit for some problems during discussion, so there seems to be written and multiple choice questions for the exams.

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