Search found 31 matches

by 204917020
Wed Jun 13, 2018 7:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: french toast #15
Replies: 3
Views: 136

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...
by 204917020
Sun Jun 10, 2018 9:17 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Question about HF (aq)
Replies: 1
Views: 167

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...
by 204917020
Sun Jun 10, 2018 9:13 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Strength of an acid
Replies: 14
Views: 434

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...
by 204917020
Sun Jun 10, 2018 9:07 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability for covalent bonds?
Replies: 3
Views: 220

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.
by 204917020
Sun Jun 10, 2018 8:55 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7337
Views: 785949

Re: Post All Chemistry Jokes Here

My favorite meme
by 204917020
Sun Jun 10, 2018 8:43 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted vs Lewis Acids and Bases
Replies: 5
Views: 246

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.
by 204917020
Tue Jun 05, 2018 10:36 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shapes On the Final
Replies: 3
Views: 82

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?
by 204917020
Tue Jun 05, 2018 10:34 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Hybridization
Replies: 7
Views: 171

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.
by 204917020
Tue Jun 05, 2018 10:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 4.27
Replies: 2
Views: 67

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...
by 204917020
Thu May 24, 2018 9:01 pm
Forum: Lewis Structures
Topic: 3.45
Replies: 3
Views: 109

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 ...
by 204917020
Sun May 20, 2018 2:05 am
Forum: Quantum Numbers and The H-Atom
Topic: ms quantum number
Replies: 1
Views: 131

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?
by 204917020
Sun May 20, 2018 1:57 am
Forum: Limiting Reactant Calculations
Topic: Knowing if it's Limiting Reactions
Replies: 6
Views: 247

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...
by 204917020
Sun May 20, 2018 1:49 am
Forum: Lewis Structures
Topic: Dots vs lines to represent electrons
Replies: 8
Views: 184

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.
by 204917020
Fri May 18, 2018 4:56 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Does being more polarizable= Being stronger?
Replies: 2
Views: 180

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...
by 204917020
Fri May 18, 2018 4:50 pm
Forum: Lewis Structures
Topic: Exceptions to the Octet
Replies: 5
Views: 114

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.
by 204917020
Fri May 18, 2018 4:47 pm
Forum: Lewis Structures
Topic: Creating a Lewis Stucture
Replies: 8
Views: 160

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).
by 204917020
Tue May 08, 2018 1:25 am
Forum: Resonance Structures
Topic: Understanding Resonance Structures
Replies: 6
Views: 300

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...
by 204917020
Tue May 08, 2018 1:17 am
Forum: Significant Figures
Topic: Zeros in Sig Figs
Replies: 3
Views: 199

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...
by 204917020
Tue May 08, 2018 1:12 am
Forum: Significant Figures
Topic: diference in sig figs
Replies: 5
Views: 172

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...
by 204917020
Tue May 08, 2018 1:06 am
Forum: Lewis Structures
Topic: Best way to start Lewis Structures
Replies: 12
Views: 422

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...
by 204917020
Tue May 08, 2018 1:04 am
Forum: Lewis Structures
Topic: Order of Dots
Replies: 11
Views: 290

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...
by 204917020
Thu Apr 26, 2018 4:57 pm
Forum: DeBroglie Equation
Topic: 1.33 [ENDORSED]
Replies: 2
Views: 129

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...
by 204917020
Mon Apr 23, 2018 11:32 am
Forum: Administrative Questions and Class Announcements
Topic: Test Time
Replies: 6
Views: 240

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.
by 204917020
Mon Apr 23, 2018 11:30 am
Forum: Properties of Light
Topic: Memorizing formulas test 2
Replies: 16
Views: 471

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.
by 204917020
Mon Apr 23, 2018 11:28 am
Forum: DeBroglie Equation
Topic: DeBroglie
Replies: 5
Views: 199

Re: DeBroglie

It's used to calculate the wavelength using the Planck's constant(h) and the mass of the particle (m).
by 204917020
Sun Apr 15, 2018 11:14 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactants
Replies: 5
Views: 206

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.
by 204917020
Sun Apr 15, 2018 11:06 pm
Forum: Molarity, Solutions, Dilutions
Topic: Units - L or mL? [ENDORSED]
Replies: 15
Views: 444

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.
by 204917020
Sun Apr 15, 2018 11:04 pm
Forum: Balancing Chemical Reactions
Topic: Trick to balance?
Replies: 5
Views: 243

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...
by 204917020
Sun Apr 15, 2018 7:12 pm
Forum: Balancing Chemical Reactions
Topic: Balancing Chemical Equations and Combustion
Replies: 7
Views: 246

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...
by 204917020
Sun Apr 15, 2018 7:07 pm
Forum: Empirical & Molecular Formulas
Topic: Determining Formulas Based on Molecule
Replies: 4
Views: 134

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.
by 204917020
Sun Apr 15, 2018 7:00 pm
Forum: Significant Figures
Topic: Rounding: when and where?
Replies: 10
Views: 419

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.

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