Search found 31 matches
- Wed Jun 13, 2018 7:31 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: french toast #15
- Replies: 3
- Views: 608
french toast #15
15. Determine the molecule's shape and polarity: AX2E2 The answer is bent but it has 2 lone pairs so i'm confused why the molecule would be bent since bent molecules only have 1 lone pair and 2 bonding electron pairs. Why wouldn't the answer be angular since angular molecules have 2 lone pairs and 2...
- Sun Jun 10, 2018 9:17 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Question about HF (aq)
- Replies: 1
- Views: 548
Question about HF (aq)
Why is HI(aq) a stronger acid than HF(aq)? I thought that since Fluorine wants to fill its octet and Hydrogen wants to share its one electron that would mean HF would be stronger since they would hold on tighter to eachother based on a larger difference in electronegativity, but HI is a stronger aci...
- Sun Jun 10, 2018 9:13 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Strength of an acid
- Replies: 14
- Views: 1697
Re: Strength of an acid
Strong acids and bases completely dissociate in solution. Therefore, they must have a small change in electronegativity between atoms in order for the molecule to completely dissociate in solution. On the other hand, weak acids and bases may partially dissociate in solution, but they do not complete...
- Sun Jun 10, 2018 9:07 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizability for covalent bonds?
- Replies: 3
- Views: 789
Re: Polarizability for covalent bonds?
I'm not sure I understand your question, but covalent bonds can have polar characeristics. Polarizability of molecules bound by covalent bonds is determined by both the size and charge of the atoms.
- Sun Jun 10, 2018 8:55 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3642796
Re: Post All Chemistry Jokes Here
My favorite meme
- Sun Jun 10, 2018 8:43 pm
- Forum: Bronsted Acids & Bases
- Topic: Bronsted vs Lewis Acids and Bases
- Replies: 5
- Views: 1353
Re: Bronsted vs Lewis Acids and Bases
Brønsted acids are H+ donors while Brønsted bases are H+ acceptors.
Lewis acids accept an e- pair, Lewis bases donate an e- pair.
Lewis acids accept an e- pair, Lewis bases donate an e- pair.
- Tue Jun 05, 2018 10:36 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shapes On the Final
- Replies: 3
- Views: 425
Molecular Shapes On the Final
Which molecular shapes will we be responsible for knowing for the final? Will we need to know their hybridization and polarity as well?
- Tue Jun 05, 2018 10:34 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Hybridization
- Replies: 7
- Views: 858
Re: Hybridization
by having the shapes memorized, you should be able to figure out the hydridization based on how many regions of electron density there are around the central atom.
- Tue Jun 05, 2018 10:33 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 4.27
- Replies: 2
- Views: 384
Re: 4.27
You can determine whether the molecule is polar or nonpolar by first looking at the molecules shape (draw the lewis structure). For elements across from eachother, if their difference in electronegativity is significant enough, then the molecule is polar. Typically, bonds with an electronegativity d...
- Thu May 24, 2018 9:01 pm
- Forum: Lewis Structures
- Topic: 3.45
- Replies: 3
- Views: 544
3.45
In problem 3.45, we are asked to draw the lewis structures that contribute to the resonance hybrid for ClNO2. In the answer, there are only two structures. I was able to make a lot more than 2, does that mean that the other ones I made are not "resonance contributors"? How can I determine ...
- Sun May 20, 2018 2:05 am
- Forum: Quantum Numbers and The H-Atom
- Topic: ms quantum number
- Replies: 1
- Views: 448
ms quantum number
Why is it that an H atom can only have +1/2 and -1/2 spin? What exactly does the value of 1/2 mean?
- Sun May 20, 2018 1:57 am
- Forum: Limiting Reactant Calculations
- Topic: Knowing if it's Limiting Reactions
- Replies: 6
- Views: 742
Re: Knowing if it's Limiting Reactions
Anytime you are given certain amounts of reactants and are asked to find the product, this will be a limiting reactant problem. While it may not say so specifically in the problem, you can know it'a a limiting reactant problem because you can only make as much product as your reactants allow. For ex...
- Sun May 20, 2018 1:49 am
- Forum: Lewis Structures
- Topic: Dots vs lines to represent electrons
- Replies: 8
- Views: 1974
Re: Dots vs lines to represent electrons
When you want to draw a lone pair, you should use two dots to represent that. The line is just used for bonds between atoms, also representing 2 electrons. The line representing a bond between two atoms shows the sharing of two electrons between the atoms.
- Fri May 18, 2018 4:56 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Does being more polarizable= Being stronger?
- Replies: 5
- Views: 3243
Re: Does being more polarizable= Being stronger?
High polarizability means that the electron cloud can easily be distorted or electrons are more easily pulled away from the central atom. They form bonds with greater covalent character because the electron is pulled further between the two bonding molecules. As polarizability increases, the dispers...
- Fri May 18, 2018 4:50 pm
- Forum: Lewis Structures
- Topic: Exceptions to the Octet
- Replies: 5
- Views: 634
Re: Exceptions to the Octet
I agree with @Nienjou Claire. They can have up to ten electrons because that's how many e- are needed to fill the d block.
- Fri May 18, 2018 4:47 pm
- Forum: Lewis Structures
- Topic: Creating a Lewis Stucture
- Replies: 8
- Views: 1002
Re: Creating a Lewis Stucture
I don't think it matters where you put the rest of the elements around the center as long as you satisfy the proper formal charge and octets(or duets).
- Tue May 08, 2018 1:25 am
- Forum: Resonance Structures
- Topic: Understanding Resonance Structures
- Replies: 6
- Views: 978
Re: Understanding Resonance Structures
When a molecule has multiple resonance structures, it just means that the representation of the actual structure of the molecule is a blend of all the resonance structures, each bond that could be displayed as a double bond has a partial double bond character. This blending of characters is what mak...
- Tue May 08, 2018 1:17 am
- Forum: Significant Figures
- Topic: Zeros in Sig Figs
- Replies: 3
- Views: 1296
Re: Zeros in Sig Figs
Leading zeroes are never significant. Example: both 0.0009 and .9 have 1 significant figure Trailing zeroes are only significant if they are after a decimal, or are followed by a decimal. Example: 0.900 has 3 sig figs. 900 only has 1 sig fig. however, 900. (notice the decimal at the end) has 3 sig f...
- Tue May 08, 2018 1:12 am
- Forum: Significant Figures
- Topic: diference in sig figs
- Replies: 5
- Views: 566
Re: diference in sig figs
Does that essentially mean that for multiplication and division we are basing the answer on the least number of sig figs present whereas for addition and subtraction we are basing it on the the least number of decimal places present? Yes, for multiplication and division, your answer will have the s...
- Tue May 08, 2018 1:06 am
- Forum: Lewis Structures
- Topic: Best way to start Lewis Structures
- Replies: 12
- Views: 1282
Re: Best way to start Lewis Structures
First, find out how many total valence electrons youll need, find the central atom (the atom with the lowest ionization energy), then, fill out the atoms with lone pairs according to the octet rule. Count all the valence electrons, if there are too many, add double bonds as needed and remove the ext...
- Tue May 08, 2018 1:04 am
- Forum: Lewis Structures
- Topic: Order of Dots
- Replies: 11
- Views: 1273
Re: Order of Dots
I'm not sure I understand your question, but to start, count the valence electrons for each atom in the compound. Next, choose the atom with the lowest ionization energy and this will be the element in the center of the lewis structure. From there, arrange the remaining atoms symmetrically around th...
- Thu Apr 26, 2018 4:57 pm
- Forum: DeBroglie Equation
- Topic: 1.33 [ENDORSED]
- Replies: 2
- Views: 438
1.33 [ENDORSED]
The velocity of an electron that is emitted from a metallic surface by a photon is 3.6 x 10^3 km x s^-1. a) what is the wavelength of the ejected electron? In the solutions, they use lambda= h/mv. I just don't understand how the units for mass (kg) cancel out? There's not other mass units in the equ...
- Mon Apr 23, 2018 11:32 am
- Forum: Administrative Questions and Class Announcements
- Topic: Test Time
- Replies: 6
- Views: 956
Re: Test Time
It was kinda short but if you practice all the problems and know how to do them without thinking too hard about what the question, it should be a good amount of time. After finishing all the homework problems (not just 7) I was able to finish the test with 5 minutes left to check my answers.
- Mon Apr 23, 2018 11:30 am
- Forum: Properties of Light
- Topic: Memorizing formulas test 2
- Replies: 16
- Views: 1761
Re: Memorizing formulas test 2
Do all of the problems and you should naturally memorize them. Although all equations and constants will be given on the test, it's helpful to memorize them so that you can save time from looking for the formula on the exam.
- Mon Apr 23, 2018 11:28 am
- Forum: DeBroglie Equation
- Topic: DeBroglie
- Replies: 5
- Views: 747
Re: DeBroglie
It's used to calculate the wavelength using the Planck's constant(h) and the mass of the particle (m).
- Sun Apr 15, 2018 11:14 pm
- Forum: Limiting Reactant Calculations
- Topic: Limiting Reactants
- Replies: 5
- Views: 584
Re: Limiting Reactants
I'm not sure I understand your question, but to determine limiting reactant you can convert the grams of both reactants to moles of the same product, the reactant that results in the lesser moles of product will determine how much product is made and is therefore your limiting reactant.
- Sun Apr 15, 2018 11:06 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Units - L or mL? [ENDORSED]
- Replies: 15
- Views: 4760
Re: Units - L or mL? [ENDORSED]
As long as your answer is correct and you specify which units your answer is in (mL or L) I don't think it matters what you put your answer in unless they specify that they want your answer in specific units.
- Sun Apr 15, 2018 11:04 pm
- Forum: Balancing Chemical Reactions
- Topic: Trick to balance?
- Replies: 5
- Views: 812
Re: Trick to balance?
I usually make a table on each side of my reaction listing all the elements and how many of each there are for both reactants and products, from there you can see what you need to balance and you can balance the elements that occur only once first and balance elements that are in more than one molec...
- Sun Apr 15, 2018 7:12 pm
- Forum: Balancing Chemical Reactions
- Topic: Balancing Chemical Equations and Combustion
- Replies: 7
- Views: 1020
Re: Balancing Chemical Equations and Combustion
If they give you the reactants and not the products and you're told that its undergoing combustion, you can assume that the reactants are oxygen (O2) as well as the other reactant given. The products of combustion are always H2O and CO2, but sometimes other products will be given. From there, you st...
- Sun Apr 15, 2018 7:07 pm
- Forum: Empirical & Molecular Formulas
- Topic: Determining Formulas Based on Molecule
- Replies: 4
- Views: 651
Re: Determining Formulas Based on Molecule
For the molecular formula, you count the number of each element, for example 12 Hydrogen, 6 Carbon, and 6 Oxygen. so that would give a molecular formula of C6H12O6, then to find empirical you divide by the lowest common factor, in this case it's 6. so the empirical formula would be CH2O.
- Sun Apr 15, 2018 7:00 pm
- Forum: Significant Figures
- Topic: Rounding: when and where?
- Replies: 10
- Views: 889
Re: Rounding: when and where?
It wouldn't be marked as wrong because rounding rules still apply with sig figs. As long as you didn't round earlier in the problem, it's okay to round your final answer while still following the sig fig rules.