Search found 71 matches
- Sat Dec 07, 2019 2:43 pm
- Forum: Conjugate Acids & Bases
- Topic: How was this equation derived?? Marshmallow #34
- Replies: 1
- Views: 361
How was this equation derived?? Marshmallow #34
Lyndon sees his crush and panics, accidentally dropping 382.7 mg of HCl and 147.1 mg CaO into a 1L flask. After filling that flask with water up to the 1L mark, what is the pH of the resulting solution? How do you go about deriving the equation HCl + Cao --> CaCl2 + H2O from this starting to point? ...
- Thu Dec 05, 2019 11:20 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: what is an oxidation number?
- Replies: 1
- Views: 226
Re: what is an oxidation number?
The oxidation number is the charge of a particular atom or molecule.
The coordination number is the number of separate points at which ligands attach to a central atom
The coordination number is the number of separate points at which ligands attach to a central atom
- Thu Dec 05, 2019 11:10 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: bond strength v electronegativity
- Replies: 2
- Views: 294
Re: bond strength v electronegativity
Refer to table 6C.7 in the book to clear up this confusion on how to determine acid strengths, I have it attached here: https://i.imgur.com/IFnknpN.png
- Thu Dec 05, 2019 11:03 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: H2CO3 vs H2GeO3 [ENDORSED]
- Replies: 3
- Views: 1040
Re: H2CO3 vs H2GeO3 [ENDORSED]
Both of these are oxoacids, both oxoacids have the same number of Oxygen atoms, so you take a look at the electronegativity of the attached group. H2C is more electronegative than HGe (C is more electronegative than Ge), therefore it is the stronger acid.
- Thu Dec 05, 2019 5:19 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: -ate
- Replies: 11
- Views: 747
Re: -ate
You use -ate with negatively charged atoms.
Re: 9C.1 a
Both 'cyano' and 'cyanido' refer to CN- and both are accepted for this class. Please refer to the following document that Dr. Lavelle emailed us: https://lavelle.chem.ucla.edu/wp-content/supporting-files/Chem14A/NamingCoordinationCompounds.pdf I would personally stick to the traditional naming schem...
- Thu Dec 05, 2019 5:04 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Determining Coordination Number
- Replies: 2
- Views: 238
Re: Determining Coordination Number
You would count a double bond as a single point, except in the case of molecules with polydentate qualities, that are able to bind to the central metal in more than one place. These molecules could contribute more attachments to the bonding number.
- Thu Dec 05, 2019 4:59 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: 6C.21 B)
- Replies: 1
- Views: 167
Re: 6C.21 B)
It is important to first note that both CH3COOH and HCOOH are Carboxylic Acids, meaning that they both contain the COOH group, and as such we can use the information summarized in Table 6C.7 of the textbook in order to understand how to derive which of the two is the stronger acid. For carboxylic ac...
- Wed Dec 04, 2019 4:39 pm
- Forum: Hybridization
- Topic: 2.45 Hybridization
- Replies: 3
- Views: 341
2.45 Hybridization
Can someone explain how the hybridization of the lone pairs in part b of this question are derived? I have never seen a question like this before and I'm not even sure that we have went over it.
- Fri Nov 29, 2019 2:43 pm
- Forum: Hybridization
- Topic: Sigma and Pi bonds
- Replies: 7
- Views: 523
Re: Sigma and Pi bonds
A single bond is a sigma bond.
A double bond consists of one sigma bond, one pi bond
A triple bond consists of one sigma bond, two pi bonds.
A double bond consists of one sigma bond, one pi bond
A triple bond consists of one sigma bond, two pi bonds.
- Fri Nov 29, 2019 2:34 pm
- Forum: Hybridization
- Topic: Reason for 1 sigma and multiple pi bonds
- Replies: 3
- Views: 283
Re: Reason for 1 sigma and multiple pi bonds
There must be a side by side overlap between orbitals in order for them to form double or triple bonds, this specific arrangement, wherein orbitals are bonded side by side as opposed to end to end, is referred to as pi bonding.
- Fri Nov 29, 2019 2:32 pm
- Forum: Bronsted Acids & Bases
- Topic: Acid vs Base
- Replies: 4
- Views: 345
Re: Acid vs Base
Bronsted acids usually start with a Hydrogen "H" atom, while Bronsted bases usually end in an Oxygen and Hydrogen "OH"
- Fri Nov 29, 2019 2:30 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: cis platinum
- Replies: 6
- Views: 432
Re: cis platinum
Cisplatin helps in mitigating cancerous cell mutation, it is an important example to know the structure and significance of for this course.
- Fri Nov 29, 2019 2:15 pm
- Forum: Conjugate Acids & Bases
- Topic: Definition of conjugate base
- Replies: 6
- Views: 673
Re: Definition of conjugate base
When in an acid loses a hydrogen atom in a chemical reaction, the formed compound is called the conjugate base.
- Fri Nov 29, 2019 2:14 pm
- Forum: Bronsted Acids & Bases
- Topic: Weak Acid Strength
- Replies: 3
- Views: 258
Re: Weak Acid Strength
The more electronegative an atom, the weaker the acids it will form.
- Mon Nov 25, 2019 11:24 am
- Forum: Resonance Structures
- Topic: Resonance
- Replies: 5
- Views: 462
Re: Resonance
2 charges of 1 or -1 is usually preferable.
- Mon Nov 25, 2019 11:17 am
- Forum: Electronegativity
- Topic: Electronegativity
- Replies: 16
- Views: 1087
Re: Electronegativity
Electronegativity is correlated with shorter bond lengths, which are also stronger bonds by virtue of their compactness
Re: Naming
Yes, we have to understand the naming algorithm for coordination compounds.
- Mon Nov 25, 2019 11:11 am
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: bond order
- Replies: 4
- Views: 389
Re: bond order
Bond order is defined as the difference between the # of bonds and the # of antibonds
- Mon Nov 25, 2019 11:11 am
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: bond order
- Replies: 4
- Views: 389
Re: bond order
Bond order is defined as the difference between the # of bonds and the # of antibonds
- Mon Nov 25, 2019 11:09 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent vs linear
- Replies: 56
- Views: 4371
Re: Bent vs linear
Bent molecules have a lone pair.
- Mon Nov 25, 2019 11:07 am
- Forum: Sigma & Pi Bonds
- Topic: Pi Bonding
- Replies: 6
- Views: 405
Re: Pi Bonding
Pi bonds exist in all double and triple bonds
- Thu Nov 21, 2019 5:52 pm
- Forum: Ionic & Covalent Bonds
- Topic: Bond Strengths
- Replies: 2
- Views: 245
Re: Bond Strengths
Strongest to weakest:
1. Ion-Ion
2. Ion-Dipole
3. Hydrogen Bond
4. Dipole-Dipole
5. London Dispersion
1. Ion-Ion
2. Ion-Dipole
3. Hydrogen Bond
4. Dipole-Dipole
5. London Dispersion
- Mon Nov 18, 2019 1:37 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bonds in VSEPR
- Replies: 11
- Views: 661
Re: Bonds in VSEPR
We consider unbonded electron pairs as well as single, double, and triple bonds to just be individual "regions of electron density" for the sake of VSEPR models
- Sun Nov 17, 2019 7:56 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: types of bonds
- Replies: 14
- Views: 1240
Re: types of bonds
Yes, a triple bond has 1 sigma bond and 2 pi bonds.
- Sun Nov 17, 2019 7:52 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR
- Replies: 5
- Views: 307
Re: VSEPR
The number of bonding pairs and lone pairs attached to a central atom determines its shape, I would recommend looking up a VSEPR chart as it shows how intuitive it is.
- Sun Nov 17, 2019 7:48 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: Relation of the Shape of a Molecule with strength of interactions
- Replies: 2
- Views: 149
Re: Relation of the Shape of a Molecule with strength of interactions
The shape and as such the bond angles do influence the strength of interactions and is one of the reasons molecular shape is valuable.
- Sun Nov 17, 2019 7:46 pm
- Forum: Ionic & Covalent Bonds
- Topic: Hydrogen Bonds
- Replies: 6
- Views: 414
Re: Hydrogen Bonds
Hydrogen atom covalently bonded to Nitrogen, Oxygen, or Fluorine.
- Sun Nov 17, 2019 7:46 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Test 2
- Replies: 19
- Views: 904
Re: Test 2
Draw the most stable structure (formal charges in mind) in order to accurately predict the shape
- Sun Nov 17, 2019 7:45 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: dipole moments
- Replies: 7
- Views: 439
Re: dipole moments
Yes, any discrepancy in electronegativity causes dipole moments
- Sun Nov 10, 2019 4:19 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizability
- Replies: 4
- Views: 331
Re: Polarizability
Polarizability increases toward down and to the left on the periodic table, while polarizing power increases up and to the right on the periodic table.
- Sun Nov 10, 2019 4:17 pm
- Forum: Lewis Structures
- Topic: Electronegative
- Replies: 14
- Views: 865
Re: Electronegative
Yes, elements with higher electronegativity are more likely to get electrons as they are closer to reaching a stable configuration.
- Sun Nov 10, 2019 4:15 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Magnetic Quantum numbers
- Replies: 13
- Views: 831
Re: Magnetic Quantum numbers
The magnetic quantum number ranges from the values -l to +l
- Sun Nov 10, 2019 4:14 pm
- Forum: Lewis Structures
- Topic: Xenon
- Replies: 4
- Views: 783
Re: Xenon
All elements with access to the d orbital follow the same exception as Xenon as they can hold more electrons because of their access to the orbital.
- Sun Nov 10, 2019 4:14 pm
- Forum: Lewis Structures
- Topic: Exceptions like Xenon
- Replies: 3
- Views: 235
Re: Exceptions like Xenon
All elements with access to the d orbital follow the same exception as Xenon.
- Sun Nov 10, 2019 4:13 pm
- Forum: Dipole Moments
- Topic: Van der Waals
- Replies: 2
- Views: 176
Re: Van der Waals
For the purposes of the course so far, we don't need to distinguish between them, though it is very good to know this for future courses
- Sun Nov 10, 2019 4:12 pm
- Forum: Bond Lengths & Energies
- Topic: Strongest Bond
- Replies: 15
- Views: 7326
Re: Strongest Bond
In increasing strength:
Single bonds < Double bonds < Triple bonds.
Single bonds < Double bonds < Triple bonds.
- Sun Nov 10, 2019 4:11 pm
- Forum: General Science Questions
- Topic: Extra Credit
- Replies: 19
- Views: 852
Re: Extra Credit
There's unfortunately no extra credit opportunities for 14A :(
- Sun Nov 10, 2019 4:11 pm
- Forum: General Science Questions
- Topic: Test 2
- Replies: 20
- Views: 867
Re: Test 2
The second test will cover content from only after the midterm, check the syllabus for more info.
- Sun Nov 03, 2019 10:57 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: How to know where a double bond should go?
- Replies: 10
- Views: 1229
Re: How to know where a double bond should go?
Just sorted it out by doing the formal charges for the atoms in both possible structures, unfortunately had to the formal charges for all the oxygen atoms to get a clear answer but its definitely obvious now. Thanks everyone!
- Sun Nov 03, 2019 10:37 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: How to know where a double bond should go?
- Replies: 10
- Views: 1229
How to know where a double bond should go?
As in part (c) of question 2C.5, the double bond is drawn between the O and N atoms, why is this the case? Why isn't it drawn between the Cl and O atoms?
- Sun Nov 03, 2019 10:34 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Uncertainty in position
- Replies: 1
- Views: 109
Re: Uncertainty in position
Use the equation ΔpΔx ≥ h/4π
wherein
Δp = momentum, also equal to m*v (mass times velocity)
Δx = position
h = planck's constant
wherein
Δp = momentum, also equal to m*v (mass times velocity)
Δx = position
h = planck's constant
- Sun Nov 03, 2019 10:30 pm
- Forum: Octet Exceptions
- Topic: Expanded Valence Shells
- Replies: 6
- Views: 226
Re: Expanded Valence Shells
Elements with d orbitals (period 3 and beyond), can have expanded valence shells.
- Sun Nov 03, 2019 10:28 pm
- Forum: Lewis Structures
- Topic: Resonance
- Replies: 5
- Views: 252
Re: Resonance
Resonance describes any lewis structure with more than one way of being drawn without altering the structure of the drawn molecule.
- Sun Nov 03, 2019 10:27 pm
- Forum: Electronegativity
- Topic: definitions
- Replies: 8
- Views: 506
Re: definitions
The ionization energy is the amount of energy that is required to remove an electron from an atom, while an atom's electron affinity is the amount of energy released or spent when an electron is added to an atom.
- Sun Nov 03, 2019 10:24 pm
- Forum: Electronegativity
- Topic: electronegativity trend
- Replies: 9
- Views: 718
Re: electronegativity trend
It decreases a the distance between the electrons increases further away from the nucleus, as such decreasing their attraction.
- Mon Oct 28, 2019 10:03 pm
- Forum: Properties of Light
- Topic: Midterm formulas
- Replies: 6
- Views: 497
Re: Midterm formulas
The formula sheet is available to print out on Lavelle's site.
- Mon Oct 28, 2019 9:56 pm
- Forum: Trends in The Periodic Table
- Topic: electronegativity table
- Replies: 5
- Views: 375
Re: electronegativity table
If we need to work with any actual numerical values, then yes, they will be given.
- Mon Oct 28, 2019 9:50 pm
- Forum: Electronegativity
- Topic: Calculating Electronegativity
- Replies: 3
- Views: 140
Re: Calculating Electronegativity
We would only have to calculate the differences in electronegativity between already given values, as in we should be provided with either an electronegativity table or the relevant exact figures for a given problem.
- Mon Oct 28, 2019 9:21 pm
- Forum: Octet Exceptions
- Topic: aufbau principle
- Replies: 8
- Views: 360
Re: aufbau principle
Base it purely off the number order,
3d is n = 3
4s is n = 4
4 > 3
3 is at a lower energy level
3d is n = 3
4s is n = 4
4 > 3
3 is at a lower energy level
- Mon Oct 28, 2019 1:52 pm
- Forum: Ionic & Covalent Bonds
- Topic: Delocalized Bond
- Replies: 4
- Views: 138
Re: Delocalized Bond
Delocalized bonds are not tied down to a single nucleus in the same way localized bonds are. Delocalized bonds occur in every example of resonance bonding, as they contain electrons that are free to move about in the structure and thus allowing different lewis structures to be draw representing the ...
- Mon Oct 28, 2019 1:47 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 1E #13
- Replies: 3
- Views: 331
Re: 1E #13
This is an "exception to the exception" that is the Aufbau Principle and I don't think we're quite required to know. There is a more concise explanation on this link: https://socratic.org/questions/57b1630911ef6b4fbd986ed8
- Mon Oct 28, 2019 1:40 pm
- Forum: Bond Lengths & Energies
- Topic: Electron-Electron Repulsion
- Replies: 2
- Views: 185
Re: Electron-Electron Repulsion
One proton has a greater affect on radius than one electron, hence why as you go from left to right across a period, atomic radius tends to decrease.
- Mon Oct 28, 2019 1:37 pm
- Forum: General Science Questions
- Topic: homework
- Replies: 5
- Views: 220
Re: homework
Any 5 problems off the Chemical Bonds section on the syllabus are fair game
- Mon Oct 28, 2019 1:34 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ground-State electron configuration
- Replies: 3
- Views: 177
Re: Ground-State electron configuration
The ground state describes an atom at its lowest possible energy level. An atom is at an excited state when the energy level of its electron is at a higher energy level than its ground state. You can tell them apart by looking at the electron configuration, as any electron configuration in which the...
- Sun Oct 20, 2019 12:17 am
- Forum: Properties of Electrons
- Topic: Constants given on tests?
- Replies: 2
- Views: 228
Re: Constants given on tests?
Yes, we'll receive the values and units for all the constants we'd need as we did on the front page of Test #1.
- Sun Oct 20, 2019 12:11 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Spin up and spin down
- Replies: 13
- Views: 1200
Re: Spin up and spin down
For the purposes of this class we don't need to know much beyond what he went over in lecture about what an electron's spin is. However, you could liken the spin of an electron to a the spinning of our earth, as it goes in a single direction, spins on an axis, and it is a property that describes its...
- Sun Oct 20, 2019 12:06 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Electron States
- Replies: 3
- Views: 146
Re: Electron States
Orbitals are not a real part of an atom, it is essentially a mathematical way of computing an atom an electron's wave-like and complex pattern of behavior.
- Sun Oct 20, 2019 12:03 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Which Element to Use in Electron Configurations
- Replies: 5
- Views: 258
Re: Which Element to Use in Electron Configurations
As far as this class is concerned, always use the noble gas configuration when applicable unless otherwise indicated. It saves a lot of time and is definitely the "proper" way of doing it.
- Sun Oct 20, 2019 12:02 am
- Forum: Properties of Electrons
- Topic: d vs s orbitals
- Replies: 6
- Views: 239
Re: d vs s orbitals
For elements that are considered exceptions, you write 4s --> 3d because 4s has less energy, but most of the time it you would just do 3d --> 4s
- Sat Oct 12, 2019 2:54 pm
- Forum: DeBroglie Equation
- Topic: De Broglie equation
- Replies: 5
- Views: 187
Re: De Broglie equation
h (plack's constant) is usually given in J*s, which means mass is most simply computed in kilograms, and length in meters as J=kg×m^2
- Sat Oct 12, 2019 2:46 pm
- Forum: Properties of Light
- Topic: Equations
- Replies: 4
- Views: 165
Re: Equations
De Broglie does not apply to electromagnetic radiation as it is focused on objects with mass and momentum. All others (that we have learned at least) are EM equations
- Sat Oct 12, 2019 2:44 pm
- Forum: Significant Figures
- Topic: Significant Figures and Molar Masses
- Replies: 5
- Views: 436
Re: Significant Figures and Molar Masses
No, do not use molar masses as part of figuring out how many significant figures should be used. Only use given usable values in the equation.
- Sat Oct 12, 2019 2:42 pm
- Forum: DeBroglie Equation
- Topic: De Broglie's Equation
- Replies: 13
- Views: 581
Re: De Broglie's Equation
The De Broglie equation is used to describe the wave properties of matter, and as such the equation is reserved for things that have mass, such as electrons. In practice, De Broglie is used when we are solving for an object's wavelength, and it has mass. This is in contrast to what you would use whe...
- Sat Oct 12, 2019 2:39 pm
- Forum: Limiting Reactant Calculations
- Topic: Wrong calculation-can' find the Lim. Reactant
- Replies: 2
- Views: 266
Re: Wrong calculation-can' find the Lim. Reactant
Since you have 1.26 moles of NH3 and 1.33 mol of O2, then you can already deduce that NH3 is the limiting reactant. You can now use the mole ratio of 4 NH3 for every 4 NO molecules to deduce how many grams of NO are produced, and then use the same process to figure out how many grams of H2O, by usin...
- Wed Oct 02, 2019 3:16 pm
- Forum: Significant Figures
- Topic: Sig Fig Decimal
- Replies: 10
- Views: 501
Re: Sig Fig Decimal
114 and 114. have the same number of sig figs.
114 and 114.0 do not have the same number of sig figs.
114 has 3 significant figures.
114.0 has 4 significant figures.
114 and 114.0 do not have the same number of sig figs.
114 has 3 significant figures.
114.0 has 4 significant figures.
- Wed Oct 02, 2019 2:01 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Please clarify what M means
- Replies: 5
- Views: 353
Re: Please clarify what M means
Capital M denotes molarity, which is moles of solute per liter of solution.
- Wed Oct 02, 2019 1:52 pm
- Forum: Empirical & Molecular Formulas
- Topic: Homework problem E1
- Replies: 9
- Views: 401
Re: Homework problem E1
E1. Step 1: 1 mol Ag * (6.022*10^23 Ag atoms / 1 mol Ag) = 6.022*10^23 atoms of Ag Step 2: Multiply 144 by 2 to get 288 (convert radius to diameter), and then multiply by the number of atoms of Ag. --> 288 * 6.022*10^23 = 1.73*10^26pm Step 3: Convert our answer from picometers (pm) to meters (m). --...
- Wed Oct 02, 2019 1:47 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: How do I do problem E.3 on page F45 of the textbook?
- Replies: 4
- Views: 365
Re: How do I do problem E.3 on page F45 of the textbook?
The question is written confusingly but has a rather straight forward answer, it is more logic-based than it is chemistry. You have 9 atoms of Gallium at 70g/mol (total of 9 * 70 = 630). You want to figure out how many atoms of Astatine, which is given as 210 g/mol, would be equal to this. Therefore...
- Tue Oct 01, 2019 6:26 pm
- Forum: Empirical & Molecular Formulas
- Topic: E.25 Parts (b) & (c)
- Replies: 2
- Views: 146
E.25 Parts (b) & (c)
For some reason I can't seem to get the same answers as the textbook, anyone care to do a step by step? E.25 (a) Determine the number of KNO 3 formula units in 0.750 mol KNO 3. (b) What is the mass (in milligrams) of 2.39 ? 10 20 formula units of Ag2SO4? (c) Estimate the number of NaHCO 2 formula un...
- Tue Oct 01, 2019 3:25 pm
- Forum: Limiting Reactant Calculations
- Topic: Question on E9
- Replies: 4
- Views: 264
Re: Question on E9
In order to find out how many atoms of oxygen are in 5.15 g of Epsom salts we have to find out how many moles of magnesium sulfare heptahydrate (246.48 g/mol) are present in the sample. O = (5.15 g / 246.48 g/mol) * (11 mol O-atoms/1 mol MgSO4·7H2O) * (6.022x10^23 atoms/mol) = 1.38 x 10^23 atoms of ...