Search found 49 matches
- Mon Dec 09, 2019 1:29 am
- Forum: Calculating the pH of Salt Solutions
- Topic: pH vs. pOH
- Replies: 17
- Views: 2312
Re: pH vs. pOH
What is the relationship between pka and ph? Which equation do we use to go between them? Thank you.
- Mon Dec 09, 2019 1:25 am
- Forum: Student Social/Study Group
- Topic: heme complex
- Replies: 5
- Views: 616
Re: heme complex
Hemoglobin should be tetra dentate. Problem 21 on marshmallow is helpful for visualizing the structure of hemoglobin.
- Mon Dec 09, 2019 1:21 am
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Strength
- Replies: 4
- Views: 409
Re: Strength
Maddie wrote:does this have to do with determining the strength of the acid
Yes, if the inductive effect withdraws electron density, say from an OH- bond, the acidity of the compound will increase.
- Mon Dec 09, 2019 1:12 am
- Forum: Administrative Questions and Class Announcements
- Topic: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]
- Replies: 115
- Views: 12370
Re: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]
In problem #21, why is the charge of the central Iron 2+? How do we interact with the surrounding N molecules, and what do the dotted bonds signify again? Thank you.
- Mon Dec 02, 2019 1:53 am
- Forum: Conjugate Acids & Bases
- Topic: conjugate acids/bases
- Replies: 4
- Views: 444
Re: conjugate acids/bases
Let's look at an example: HBr + H2O --> H3O+ + Br- Here, HBr is the acid and H2O acts as the base. H3O+ is the conjugate acid as it is the species that is protonated, and Br- is the conjugate base because it is the species from which a proton is donated. The formula for the conjugate base of HBr is ...
- Mon Dec 02, 2019 1:43 am
- Forum: Industrial Examples
- Topic: For the Final
- Replies: 3
- Views: 803
Re: For the Final
In the textbook, look at section 3H.2 for the formation of synthetic industrial diamonds and box 4D.1 for the production of industrial hydrogen. Hope this helps :)
- Mon Dec 02, 2019 1:21 am
- Forum: *Stereochemistry
- Topic: stereochemistry reference
- Replies: 6
- Views: 973
Re: stereochemistry reference
Stereochemistry refers to the spatial arrangement of atoms. It involves isomerism--stereoisomerism, constitutional isomerism. If you would like I can send you a powerpoint I made on the subject! :)
- Mon Dec 02, 2019 1:18 am
- Forum: Biological Examples
- Topic: Cisplatin
- Replies: 15
- Views: 638
Re: Cisplatin
If you memorize why cisplatin is able to stop DNA replication, and by extension cell division, you should also be able to apply this information to the final. I feel like in the context of the final, the application and memorization of this information is more or less synonymous.
- Mon Dec 02, 2019 1:08 am
- Forum: Amphoteric Compounds
- Topic: Determining Acidic or Basic
- Replies: 2
- Views: 221
Re: Determining Acidic or Basic
I think you would leave it as amphoteric, unless the question specifies otherwise.
- Mon Nov 25, 2019 6:28 am
- Forum: Conjugate Acids & Bases
- Topic: Cojugate Acids and Bases
- Replies: 10
- Views: 2047
Re: Cojugate Acids and Bases
A conjugate ion is the molecule/ion formed when a proton is added to a base.
A conjugate base is what remains of an acid molecule/ion when a proton is lost.
Example:
HCl + NH3 --> NH4+ + Cl-
Here, NH4+ is the conjugate acid, and Cl- is the conjugate base.
A conjugate base is what remains of an acid molecule/ion when a proton is lost.
Example:
HCl + NH3 --> NH4+ + Cl-
Here, NH4+ is the conjugate acid, and Cl- is the conjugate base.
- Mon Nov 25, 2019 6:23 am
- Forum: Ionic & Covalent Bonds
- Topic: Ionic and Covalent character
- Replies: 4
- Views: 462
Re: Ionic and Covalent character
Will we need to memorize values of electronegativity at any point?
- Mon Nov 25, 2019 6:21 am
- Forum: Dipole Moments
- Topic: benzene polarity
- Replies: 4
- Views: 453
Re: benzene polarity
Benzene is non polar, as it is a hydrocarbon only containing c-c and c-h bonds, and hydrocarbons are generally non polar. The c-h bond, though, is slightly polar, as c is more electronegative than h, giving it a small dipole moment.
- Mon Nov 25, 2019 6:17 am
- Forum: Properties of Light
- Topic: Frequency vs. Velocity
- Replies: 8
- Views: 823
Re: Frequency vs. Velocity
Yes, the velocity of light is always a constant, as far as we are concerned.
- Mon Nov 25, 2019 6:16 am
- Forum: Student Social/Study Group
- Topic: test 2
- Replies: 2
- Views: 263
Re: test 2
We will receive our tests during week 10 discussion--the time at which they are posted on MyUCLA is dependent on TA. :)
- Sun Nov 17, 2019 7:50 pm
- Forum: Dipole Moments
- Topic: Ion-dipole molecular force
- Replies: 3
- Views: 225
Re: Ion-dipole molecular force
It occurs when either an anion or cation attracts the partially negative end of a neutral polar molecule. The force becomes strong as either the ionic charge increases, or as the magnitude of the dipole of the polar molecule increases. Ex: NaCl dissociates--Na+ and Cl-, in the presence of water, due...
- Sun Nov 17, 2019 7:44 pm
- Forum: Student Social/Study Group
- Topic: What will Test 2 be on?
- Replies: 8
- Views: 537
Re: What will Test 2 be on?
Do we need to know about the relative magnitudes of intermolecular forces and hydrogen bonds.
- Sun Nov 17, 2019 7:37 pm
- Forum: Student Social/Study Group
- Topic: Test 2 Topics
- Replies: 3
- Views: 291
Re: Test 2 Topics
You will need to know intermolecular forces, sigma/pi bonds, VSPER theory, resonance hybridity, Lewis acids and bases, polarizability.
- Sun Nov 17, 2019 7:35 pm
- Forum: Student Social/Study Group
- Topic: Chem 14B
- Replies: 10
- Views: 710
Re: Chem 14B
Is there a lot of overlap between chem 14A and chem 14B; is it more learning in depth what we have previously learned or are we learning entirely new material?
- Sun Nov 17, 2019 7:34 pm
- Forum: Student Social/Study Group
- Topic: Curve?
- Replies: 50
- Views: 6054
Re: Curve?
Once a class average is determined at the end, the grades will be adjusted, I think.
- Sun Nov 10, 2019 6:35 pm
- Forum: Ionic & Covalent Bonds
- Topic: London Dispersion
- Replies: 13
- Views: 653
Re: London Dispersion
London dispersion is dictated by the proximity of electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. This force induces a dipole-dipole attraction and is what causes condensation into liquids and freezing into solids.
- Sun Nov 10, 2019 6:32 pm
- Forum: *Black Body Radiation
- Topic: What do I really need to know?
- Replies: 6
- Views: 731
Re: What do I really need to know?
You don't need to know much about black body radiation for chem 14A. I am not sure about the rest of the series though. Regardless, here is a link that explores the topic more in relation to chemistry than physics: https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_M...
- Sun Nov 10, 2019 6:27 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Shape of Orbitals
- Replies: 2
- Views: 308
Re: Shape of Orbitals
In chem 14A I think we will only need to know the general shape of s, p, and d orbitals, and that too, only in order to graph them. This is a link that I found really helpful:).
https://ch301.cm.utexas.edu/section2.ph ... shape.html
https://ch301.cm.utexas.edu/section2.ph ... shape.html
- Sun Nov 10, 2019 6:21 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Quantum Numbers
- Replies: 6
- Views: 495
Re: Quantum Numbers
Are there any equations that use ms? Will we only ever need to know its application as we have learned it before, or will we need to apply it somehow?
- Sun Nov 10, 2019 6:19 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 1E.1
- Replies: 3
- Views: 342
Re: 1E.1
'l' value regards the shape of the orbital--as it changes from spherical to polar when an electron goes from an s to a p orbital, the 'l' value changes from 0 to 1.
- Sun Nov 03, 2019 8:05 pm
- Forum: Dipole Moments
- Topic: Dipole moment
- Replies: 2
- Views: 98
Re: Dipole moment
https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&ved=2ahUKEwj5gc2h1s_lAhVRtZ4KHacwACAQjRx6BAgBEAQ&url=https%3A%2F%2Fch301.cm.utexas.edu%2Fsection2.php%3Ftarget%3Dimfs%2Fpolar%2Fdipole-moment.html&psig=AOvVaw1xFoXkNQUKXNPadlW7uZNF&ust=1572926577393...
- Sun Nov 03, 2019 7:59 pm
- Forum: Sigma & Pi Bonds
- Topic: Versus
- Replies: 3
- Views: 127
Re: Versus
A single bond is a sigma bond. A double bond is a sigma bond and a pi bond. A triple bond is one sigma and two pi bonds. A sigma bond is covalent and shows no resonance. A pi bond is a covalent bond between orbitals perpendicular to the bond direction. https://www.google.com/url?sa=i&rct=j&q...
- Sun Nov 03, 2019 7:38 pm
- Forum: Ionic & Covalent Bonds
- Topic: Figuring out the Lewis Structure
- Replies: 3
- Views: 180
Re: Figuring out the Lewis Structure
Also for salts (like NH4Cl), we can assume their complete dissociation! :)
- Sun Nov 03, 2019 7:25 pm
- Forum: Lewis Structures
- Topic: Question 2B.3 Part d
- Replies: 2
- Views: 85
Re: Question 2B.3 Part d
You have a reserve of 28 valence electrons. Once you single bond each fluorine and provide them with full octets, 2 pairs of non-bonding electrons will remain, and you would draw these around the central bromine. Each fluorine should have an octet...if the answer key is showing one fluorine to have ...
- Sun Nov 03, 2019 4:32 pm
- Forum: Ionic & Covalent Bonds
- Topic: middle atom
- Replies: 13
- Views: 508
Re: middle atom
The central atom is the one with the comparatively lower electronegativity because an atom in the central position shares more of its electrons than does a terminal atom. :)
- Mon Oct 28, 2019 5:18 pm
- Forum: Balancing Chemical Reactions
- Topic: When are atoms lost or created?
- Replies: 14
- Views: 1737
Re: When are atoms lost or created?
Atoms are not lost or created either:) It is a lot like recycling--there is more information on the conservation of matter on Professor Lavelle's website (I would recommend watching the video of his lecture on this topic).
- Mon Oct 28, 2019 5:13 pm
- Forum: Einstein Equation
- Topic: Used for Photons Only
- Replies: 6
- Views: 323
Re: Used for Photons Only
Will we also be provided these constant values on the midterm? Thank you.
- Mon Oct 28, 2019 5:11 pm
- Forum: Properties of Light
- Topic: 1.31
- Replies: 4
- Views: 210
Re: 1.31
Work = threshold energy. First, you need to convert the work from ev to joules: 2.93eV * (1.602*10^-19J/eV) = 4.69*10^-19J Second, convert each wavelength of given into energy using E=hc/(wavelength): 2.86*10^-19 (red ruby) and 4.91*10^-19 J (GaN) Third, compare the energies you calculated to the t...
- Mon Oct 28, 2019 4:57 pm
- Forum: DeBroglie Equation
- Topic: Homework 1B.15
- Replies: 3
- Views: 283
Homework 1B.15
1B.15: The velocity of an electron that is emitted from a metallic surface by a photon is 3.6 3 103 km?s21. (a) What is the wavelength of the ejected electron? (b) No electrons are emitted from the surface of the metal until the frequency of the radiation reaches 2.50 3 1016 Hz. How much energy is r...
- Mon Oct 28, 2019 4:52 pm
- Forum: Limiting Reactant Calculations
- Topic: Showing Work for Limiting Reactant Calculations on Tests [ENDORSED]
- Replies: 68
- Views: 6661
Re: Showing Work for Limiting Reactant Calculations on Tests [ENDORSED]
In addition to showing all units, it would be helpful to clearly split the limiting reaction question into 3 parts: (1) the type of amount for which you are calculating, (2) the dimensional analysis to compare amounts for compounds (3) determination of excess after determining limiting reactant.
- Sun Oct 20, 2019 10:04 pm
- Forum: Trends in The Periodic Table
- Topic: Atomic Radius
- Replies: 7
- Views: 443
Re: Atomic Radius
Atomic radius refers to the distance between the nuclei of two identical atoms. I don't think atomic radius is something you can easily calculate unless already given distance (use equation r=d/2 where r is radius and d is internuclear distance); you would need to use x-ray/spectroscopic methods oth...
- Sun Oct 20, 2019 9:45 pm
- Forum: DeBroglie Equation
- Topic: Unit Conversion
- Replies: 5
- Views: 170
Re: Unit Conversion
Unless the problem specifies to use mHz (megahertz), you should always be using Hz.
- Sun Oct 20, 2019 9:42 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Order or orbitals
- Replies: 5
- Views: 208
Re: Order or orbitals
Orbital filling concerns Aufbau's principle. Essentially, in their ground state electrons fill orbitals in order of increasing energy, lower first, and higher last. The energy of orbitals follows the (n+l) rule. The 4s orbital has n=4 and l=0, 4+0=4, and the 3d orbital has n=3 and l=2, 3+2=5. Thus, ...
- Sun Oct 20, 2019 9:17 pm
- Forum: Einstein Equation
- Topic: 1B.9 help
- Replies: 4
- Views: 288
Re: 1B.9 help
A lamp rated at 32 W emits violet light of wavelength 420 nm. How many photons of violet light can the lamp generate in 2.0 s? How many moles of photons are emitted in that time interval? A watt is a unit of power, 1.00 J/s; we can rewrite 32 W as 32 J/s, so in 2 seconds: (32J/s)*(2s/1), the seconds...
- Sun Oct 20, 2019 8:59 pm
- Forum: Student Social/Study Group
- Topic: Midterm Review Material
- Replies: 5
- Views: 443
Re: Midterm Review Material
I would recommend doing all of the problems assigned, even if some may seem repetitive. Even the smallest of differences in wording/calculation can make a big impact when taking the midterm. I would also suggest not only knowing the equations used by memory, but the derivations behind some of the mo...
- Sun Oct 13, 2019 8:06 pm
- Forum: Balancing Chemical Reactions
- Topic: Writing out equations
- Replies: 9
- Views: 533
Re: Writing out equations
When writing out equations is it always necessary to include the states of matter (if not specified in the problem)? Thank you:)
- Sun Oct 13, 2019 7:54 pm
- Forum: Empirical & Molecular Formulas
- Topic: Nomenclature
- Replies: 11
- Views: 2263
Re: Nomenclature
I don't think we will need to know the formula for a compound so lengthy (and relatively uncommon in textbook material), but I would recommend knowing more common chemical compounds and their respective charges. Here is a quizlet that might be helpful for remembering compounds: https://quizlet.com/4...
- Sun Oct 13, 2019 7:42 pm
- Forum: Student Social/Study Group
- Topic: Grades
- Replies: 18
- Views: 1126
Re: Grades
You can also view your study list by visiting the MyFeatures on MyUCLA, and under each class, to the right (under class website), there is a link to grades. :)
- Sun Oct 13, 2019 6:59 pm
- Forum: General Science Questions
- Topic: Audio-Visual focus topics
- Replies: 4
- Views: 152
Re: Audio-Visual focus topics
It is mentioned on one of the links on the website that the following four modules should be completed before week 2: Photoelectric Effect, Atomic Spectra and the Bohr Frequency Condition, Wave Properties of Electrons and the De Broglie Equation, and Heisenberg Uncertainty Equation. There is no pena...
- Sun Oct 13, 2019 6:51 pm
- Forum: Student Social/Study Group
- Topic: Weekly Posts
- Replies: 6
- Views: 265
Re: Weekly Posts
Does it matter if a student's post echoes another? For example, after posting an explanation we realize that another student has already posted that explanation. Does our post still count? Thank you.
- Wed Oct 02, 2019 11:53 pm
- Forum: Significant Figures
- Topic: When are zeroes significant in calculations?
- Replies: 5
- Views: 1149
Re: When are zeroes significant in calculations?
Zeroes are significant when: They are found in-between significant digits, E.g. : 405, 20,001 (3 sig figs and 5 sig figs respectively) A final/trailing '0' after a decimal point and a non-zero value, E.g. : 0.00060, 1.40 x 10^2 (2 sig figs and 3 sig figs respectively). A decimal place after zeroes i...
- Wed Oct 02, 2019 11:38 pm
- Forum: Balancing Chemical Reactions
- Topic: Figuring Out State Symbols
- Replies: 3
- Views: 409
Re: Figuring Out State Symbols
I'm not sure it will always be possible to determine the states. Like Isabella said, you can look at the molecular formula for common compounds and use rules such as pure acids being liquids, and when the word 'insoluble' is used adjacent to a compound we can assume that compound to be a solid. Also...
- Wed Oct 02, 2019 11:27 pm
- Forum: Limiting Reactant Calculations
- Topic: Fundamentals M9 Part B
- Replies: 2
- Views: 169
Fundamentals M9 Part B
Problem: Copper(II) nitrate reacts with sodium hydroxide to produce a precipitate of light blue copper(II) hydroxide. (a) Write the net ionic equation for the reaction. (b) Calculate the maximum mass of copper(II) hydroxide that can be formed when 2.00 g of sodium hydroxide is added to 80.0 mL of 0....
- Wed Oct 02, 2019 10:54 pm
- Forum: Limiting Reactant Calculations
- Topic: Module: limiting chemical reactions
- Replies: 3
- Views: 151
Re: Module: limiting chemical reactions
Hi Rosa, We are given that in a neutralization reaction, CaCO3(s) + H2SO4(aq) ---> CaSO4(s) + CO2(g) + H2O(l), 1kg of CaCO3(s) produces 'x' moles of CO2(g). To solve for moles of CO2(g), first convert 1kg CaCO3 into grams, and then convert it to moles using molar mass, so that through stoichiometric...
- Wed Oct 02, 2019 10:37 pm
- Forum: Limiting Reactant Calculations
- Topic: limiting reactant
- Replies: 5
- Views: 357
Re: limiting reactant
Chemical Reaction: CaCO3(s) --> CaO(s) + CO2(g). Hi Jessica! Like what Sophia said, as CaCO3 is the only reactant in this reaction, we can assume this to be the limiting reactant, but I don't think that information is necessary to solve for the percentage yield. The problem tells us that the thermal...