Search found 31 matches
- Sat Dec 08, 2018 2:17 pm
- Forum: Empirical & Molecular Formulas
- Topic: Midterm Solutions Fall 2018-2019 year
- Replies: 2
- Views: 623
Re: Midterm Solutions Fall 2018-2019 year
Is this the problem about the empirical/molecular formulas of gallic acid? After calculating the number of g of H produced through combustion using the molar mass of H2O and the molar ratio of H and H2O, you divide by H's molar mass (1.007) to find the number of moles!
- Sat Dec 08, 2018 1:20 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Polydentate
- Replies: 11
- Views: 1194
Re: Polydentate
I believe carbonato is bidentate!
- Sat Dec 08, 2018 1:15 pm
- Forum: Naming
- Topic: memorizing complexes?
- Replies: 2
- Views: 274
Re: memorizing complexes?
I would memorize them just to be safe!
- Sat Dec 08, 2018 1:08 pm
- Forum: Administrative Questions and Class Announcements
- Topic: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]
- Replies: 118
- Views: 22022
Re: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]
Thank you for posting these!
- Sun Dec 02, 2018 11:49 pm
- Forum: Administrative Questions and Class Announcements
- Topic: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]
- Replies: 118
- Views: 22022
Re: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]
Thank you so much for these problems!
- Sun Dec 02, 2018 11:48 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final Grades
- Replies: 10
- Views: 1102
Re: Final Grades
If you get at least 250 points, you're guaranteed a C-. I believe Dr. Lavelle said he would work out the specific letter grade/point distributions after the final?
- Sun Dec 02, 2018 11:44 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Seesaw
- Replies: 13
- Views: 2112
Re: Seesaw
The bond angles for a seesaw shape will be a little bit less than 90 and 120 degrees due to the lone pairs' repulsion pushing the bonds slightly.
- Sat Nov 24, 2018 11:08 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: double and triple bonds
- Replies: 10
- Views: 1140
Re: double and triple bonds
Single, double, and triple bonds all count as one region of electron density, so the bond type doesn't affect naming using VSEPR.
- Sat Nov 24, 2018 11:05 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Naming the Shape
- Replies: 16
- Views: 1289
Re: Naming the Shape
I think it's helpful but not 100% necessary to memorize the bond angles, since you can usually determine them by visualizing the shape.
- Sat Nov 24, 2018 11:01 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Sigma and Pi bonds
- Replies: 6
- Views: 688
Re: Sigma and Pi bonds
Adding on, because sigma bonds overlap end-to-end, they allow bound atoms to rotate, while pi bonds, which overlap side-to-side, do not allow bound atoms to rotate. Sigma bonds are also formed between atoms, while pi bonds are formed above/under/beside sigma bonds.
- Sun Nov 18, 2018 8:38 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
- Replies: 135
- Views: 39801
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
Thank you again for posting these worksheets!
- Sun Nov 18, 2018 8:36 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shape vs. Electron Geometry
- Replies: 4
- Views: 452
Re: Molecular Shape vs. Electron Geometry
Electron geometry refers to how electron groups are arranged, while molecular shape how all the atoms in a molecule are arranged. Lone and bonding electron pairs are considered in electron geometry, while molecular shape only considers bonding electron pairs. For example, using electron geometry, a ...
- Sun Nov 18, 2018 8:28 pm
- Forum: Student Social/Study Group
- Topic: Turning in Homework (Thanksgiving Break)
- Replies: 8
- Views: 867
Re: Turning in Homework (Thanksgiving Break)
We just need to submit 14 problems (for both week 8 and week 9) the week after we get back from break!
- Sat Nov 10, 2018 5:25 pm
- Forum: Lewis Structures
- Topic: Atoms with 8+ valence e-
- Replies: 6
- Views: 1028
Re: Atoms with 8+ valence e-
The energy between the 3d and 4s orbitals is not very big, so the d-orbitals can take in additional e- to give an expanded octet. In the first and second periods of the periodic table, no d-orbital exists, but starting with the third period, the d-orbital is present and can accomodate additional e-.
- Sat Nov 10, 2018 5:15 pm
- Forum: Limiting Reactant Calculations
- Topic: Actual Yield
- Replies: 7
- Views: 1238
Re: Actual Yield
Actual yield is calculated based off of the results of an experiment while theoretical yield is calculated based off of the complete reaction of the limiting reactant. Actual yield should be given to us in any problem that requires it since it's impossible to determine without conducting the experim...
- Sat Nov 03, 2018 1:44 am
- Forum: Limiting Reactant Calculations
- Topic: Midterm Review Q2
- Replies: 8
- Views: 4390
Re: Midterm Review Q2
First, calculate the molar mass of KMnO4 (158.09g/mol). Next, concert 5g KMnO4 to moles and 150mL to L and use the formula M=mol/L to calculate the molarity of the first solution. Lastly, use the equation M1V1=M2V2 equation to calculate the concentration of the second flask by using the value you pr...
- Fri Nov 02, 2018 12:59 am
- Forum: Ionic & Covalent Bonds
- Topic: Ionic vs Covalent Bonds
- Replies: 18
- Views: 1831
Re: Ionic vs Covalent Bonds
Ionic bonds are usually formed between a metal and a nonmetal; the metal loses electrons are transferred to the nonmetal so that both atoms can have the same electron configuration as the preceding/following noble gas. Covalent bonds, on the other hand, involve electrons being shared between atoms t...
- Fri Nov 02, 2018 12:56 am
- Forum: Ionic & Covalent Bonds
- Topic: Group Me
- Replies: 2
- Views: 403
Re: Group Me
There's also a Facebook Messenger chat that's fairly active!
- Fri Nov 02, 2018 12:54 am
- Forum: Administrative Questions and Class Announcements
- Topic: MIDTERM PRACTICE - Garlic Bread Review Session [ENDORSED]
- Replies: 121
- Views: 24480
Re: MIDTERM PRACTICE - Garlic Bread Review Session [ENDORSED]
Thanks for the practice midterm problems!
- Sun Oct 28, 2018 8:39 pm
- Forum: Ionic & Covalent Bonds
- Topic: 2A.21 7th Edition Question
- Replies: 2
- Views: 291
Re: 2A.21 7th Edition Question
The normal ground state configuration for Ag is [Kr]4d^10 5s^1. Based off of the Aufbau principle, silver's expected configuration would be [Kr]4d^9 5s^2, but since a full or half-full subshell is more stable than a partially-filled one, the s electron is transferred to the d orbital since having th...
- Sun Oct 28, 2018 5:57 pm
- Forum: Ionic & Covalent Bonds
- Topic: Friday 10/26/18 lecture
- Replies: 4
- Views: 563
Re: Friday 10/26/18 lecture
He focused mainly on the differences between ionic and covalent bonds and how they each achieved the octet rule, and also demonstrated how to draw several different Lewis structures.
- Sun Oct 28, 2018 5:52 pm
- Forum: Ionic & Covalent Bonds
- Topic: Trend of Ionic Radii
- Replies: 5
- Views: 523
Re: Trend of Ionic Radii
Ionic radii increase in size down a group (column) since more shells means that valence electrons are further away from the nucleus and decrease across a period (row) since atoms' increased nuclear charge means that they will pull their electrons in more closely (shell contraction).
- Sat Oct 20, 2018 11:39 pm
- Forum: DeBroglie Equation
- Topic: DeBroglie Equation Post Assessment
- Replies: 4
- Views: 586
Re: DeBroglie Equation Post Assessment
That should be correct, although when you're plugging numbers into your calculator, make sure to put parentheses around (m*wavelength). It is not reasonable for an electron to be faster than the speed of light, but if the electron is below 10^5m/s, this may also be too slow to be reasonable.
- Sat Oct 20, 2018 11:16 pm
- Forum: Properties of Light
- Topic: Calculating the wavelength of light
- Replies: 7
- Views: 1238
Re: Calculating the wavelength of light
Both are okay to use but 2.998*10^8 m/s will give you a more accurate answer!
- Thu Oct 18, 2018 9:12 am
- Forum: Einstein Equation
- Topic: Question 1.65 (Sixth Edition)
- Replies: 1
- Views: 257
Re: Question 1.65 (Sixth Edition)
Starting with 348kJ/mol, you would multiply by 348kJ/mol C-C bonds * 1mol C-C bonds/6.022*10^23 C-C bonds *1000J/kJ to ultimately end up 5.78*10^(-19)J as ΔE. You can then use the equation λ=hc/ΔE and plug in Planck's constant, the speed of light, and ΔE to get 3.44*10^-7m (or 344nm). This falls und...
- Sun Oct 14, 2018 4:38 pm
- Forum: Significant Figures
- Topic: When to round the answers to significant figures
- Replies: 11
- Views: 2731
Re: When to round the answers to significant figures
I would try to round at the very end whenever possible! Keeping more sig figs in your calculations allows you to end up with a more accurate final result.
- Thu Oct 11, 2018 11:56 pm
- Forum: Balancing Chemical Reactions
- Topic: L.5 Part B Sixth Edition [ENDORSED]
- Replies: 5
- Views: 649
Re: L.5 Part B Sixth Edition [ENDORSED]
Your steps look right; maybe double check that you're using the right molar masses and inputting the correct numbers into your calculator?
- Thu Oct 11, 2018 10:47 am
- Forum: Balancing Chemical Reactions
- Topic: Chemical compounds
- Replies: 3
- Views: 452
Re: Chemical compounds
I would go with whatever your TA says to your discussion section; our TA specified that we would be given formulas for any chemical compounds!
- Fri Oct 05, 2018 12:03 am
- Forum: Limiting Reactant Calculations
- Topic: Comparing Calculated Moles step M7(b)
- Replies: 2
- Views: 1494
Re: Comparing Calculated Moles step M7(b)
If you go ahead and balance the chemical equation first, you get B2O3 + 3Mg(s) -> 3MgO(s) + 2B(s). You then need to calculate the mass of boron that is produced from both Mg and B2O3. First, convert the masses of both from kg to g, divide by the molar mass of the compound, multiply by the ratio of B...
- Thu Oct 04, 2018 11:55 pm
- Forum: Balancing Chemical Reactions
- Topic: Mole Coefficients in Chemical Equations
- Replies: 6
- Views: 747
Re: Mole Coefficients in Chemical Equations
The coefficients are used to represent the number of atoms/molecules on each side! With coefficients of 2, 2, 2, and 1, both sides of the reaction end up with 2 atoms of Na, 4 atoms of H, and 2 atoms of O.
- Thu Oct 04, 2018 11:46 pm
- Forum: Significant Figures
- Topic: sig figs urgent question!
- Replies: 12
- Views: 2226
Re: sig figs urgent question!
1.001 has 4 significant figures! A trick I use to remember which numbers to count as sig figs is the the Atlantic/Pacific analogy. If there's a decimal point present, start from the left (since the Pacific ocean is on the left/west coast of the US) and count starting from the first non-zero number. ...