Search found 38 matches
- Sun Jan 27, 2019 8:33 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Le Chatelier's Principle question
- Replies: 4
- Views: 460
Re: Le Chatelier's Principle question
Expansion will result in an increase in volume and therefore a decrease in pressure. The reaction will likely then favor the side of the reaction that has been expanded since its pressure is lower. Compression will result in a decrease in volume and an increase in pressure. Therefore, the reaction w...
- Sun Jan 27, 2019 8:30 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: pH
- Replies: 9
- Views: 1016
Re: pH
pH is a description of the acidity or alkalinity of a solution. pH<7 is acidic, pH=7 is neutral, and pH>7 is basic. to find pH, use the equation pH=-log(H3O+)
- Sun Jan 27, 2019 8:28 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: endothermic vs exothermic
- Replies: 6
- Views: 801
Re: endothermic vs exothermic
Exothermic reactions are reactions in which heat is released as a result of the reaction (heat is a product). In endothermic reactions, heat is an input (reactant) of the reaction.
- Sun Jan 27, 2019 8:27 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Changing Pressure
- Replies: 6
- Views: 686
Re: Changing Pressure
Changing the volume results in a change in pressure. If the volume is decreased on one side of the reaction, the reaction will likely favor the other side if the pressure is lower. The reaction will favor the side with lower pressure in this case.
- Sun Jan 27, 2019 8:26 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Increase in Volume Effect on Equilibrium
- Replies: 6
- Views: 1495
Re: Increase in Volume Effect on Equilibrium
When volume is increased, pressure is decreased. So when volume is decreased on one side of the reaction, the other side of the reaction will be favored due to its lower pressure.
- Sun Jan 27, 2019 8:24 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: ICE
- Replies: 19
- Views: 1429
Re: ICE
In the ICE box, I stands for initial (so initial concentrations), C stands for Change, and E stands for Equilibrium.
- Sun Jan 13, 2019 5:14 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Heterogeneous and homogeneous equilibria [ENDORSED]
- Replies: 8
- Views: 716
Re: Heterogeneous and homogeneous equilibria [ENDORSED]
In heterogenous equilibria, some of the components are in different phases (solids, gases, etc.) while in homogenous equilibria the components are all in the same phase.
- Sun Jan 13, 2019 5:12 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: converting from pressure to concentration
- Replies: 4
- Views: 420
Re: converting from pressure to concentration
It is a constant that will probably be included in the equations list for tests.
- Sun Jan 13, 2019 5:11 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: solids in calculating equilibrium constant? [ENDORSED]
- Replies: 8
- Views: 812
Re: solids in calculating equilibrium constant? [ENDORSED]
No, only aqueous solutions and gases are included in calculating the equilibrium constant.
- Sun Dec 09, 2018 11:26 pm
- Forum: Empirical & Molecular Formulas
- Topic: Going from empirical to Molecular formula
- Replies: 14
- Views: 2104
Re: Going from empirical to Molecular formula
The number should be a whole number; if you get a fraction and have checked your work, multiply all by a number to give you whole numbers.
- Sun Dec 09, 2018 11:25 pm
- Forum: Empirical & Molecular Formulas
- Topic: Empirical Formula [ENDORSED]
- Replies: 6
- Views: 902
Re: Empirical Formula [ENDORSED]
Using percentages, you can calculate as though the sample were 100 g. Example: 60% O, 30% H, 10% N. Use 60 g O, 30 g H, and 10 g N.
- Sun Dec 09, 2018 11:24 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge
- Replies: 12
- Views: 1220
Re: Formal Charge
It is always better to show work just in case, but generally for formal charge I do not think it is necessary
- Sun Dec 09, 2018 11:23 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Stable Vs. Formal
- Replies: 4
- Views: 1053
Re: Stable Vs. Formal
Formal charge is the overall charge of an atom or molecule; the most stable charge for a molecule is generally the formal charge closest to 0.
- Sun Dec 09, 2018 11:21 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge vs Partial charge
- Replies: 4
- Views: 2250
Re: Formal Charge vs Partial charge
Formal charge shows the overall charge of an atom or molecule; partial charges can be used to indicate polarity of a molecule. For example, in H2O, the H atoms have a partial positive charge while the O atom has a partial negative charge.
- Sun Dec 09, 2018 10:41 am
- Forum: Naming
- Topic: order of ligand name
- Replies: 5
- Views: 695
Re: order of ligand name
For the ligand names, just put them in alphabetical order ignoring any prefixes. Place the transition metal at the end.
- Sun Dec 09, 2018 10:40 am
- Forum: Naming
- Topic: Order of ligands
- Replies: 6
- Views: 804
Re: Order of ligands
When writing the formula, arrange ligands in alphabetical order, ignoring any prefixes.
- Sun Dec 09, 2018 10:38 am
- Forum: Biological Examples
- Topic: What should we know for the final?
- Replies: 9
- Views: 982
Re: What should we know for the final?
I think it is important to know about cisplatin, myoglobin, and hemoglobin for the final.
- Sun Dec 09, 2018 10:35 am
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal charge on central atom
- Replies: 5
- Views: 1060
Re: Formal charge on central atom
A formal charge closer to zero is more stable than other higher charges.
- Sun Dec 09, 2018 10:33 am
- Forum: Lewis Structures
- Topic: Elements that break the octet rule
- Replies: 6
- Views: 829
Re: Elements that break the octet rule
Elements with a d-orbital may have an expanded octet. This is generally elements in row 3 or lower.
- Sun Dec 09, 2018 10:30 am
- Forum: Trends in The Periodic Table
- Topic: electronegativity
- Replies: 10
- Views: 3269
Re: electronegativity
Electronegativity is related to the electron-pulling ability of an atom. Elements at the top right corner of the periodic table have the highest electronegativity, meaning that electronegativity increases as you move right across the table and decreases as you move down.
- Sun Dec 09, 2018 10:29 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Momentum Uncertainty
- Replies: 3
- Views: 676
Re: Momentum Uncertainty
According to the equation λ = h/p, momentum and wavelength have an inverse relationship. Therefore, as uncertainty in wavelength increases, uncertainty in momentum decreases and vice versa.
- Sun Dec 09, 2018 10:27 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Heisenberg and Wavelength
- Replies: 11
- Views: 1688
Re: Heisenberg and Wavelength
Because wavelength=planck's constant/momentum, they have an inverse relationship. As momentum increases, wavelength decreases.
- Sun Dec 09, 2018 10:24 am
- Forum: DeBroglie Equation
- Topic: wavelike properties
- Replies: 4
- Views: 620
Re: wavelike properties
A wavelength smaller than 1*10^-18 cannot be detected; however, it can still be calculated.
- Sun Dec 09, 2018 10:22 am
- Forum: Molarity, Solutions, Dilutions
- Topic: Actual/Theoretical Yield
- Replies: 8
- Views: 4228
Re: Actual/Theoretical Yield
Actual yield should generally be lower than theoretical yield; this is due to human error, etc. However, in a laboratory setting if you obtain results in which actual yield>theoretical yield, then it is likely that your sample is contaminated.
- Sun Dec 09, 2018 10:19 am
- Forum: Empirical & Molecular Formulas
- Topic: Order of Molecules
- Replies: 4
- Views: 981
Re: Order of Molecules
Generally, the order of atoms should be in alphabetical order.
- Sun Dec 09, 2018 10:18 am
- Forum: Empirical & Molecular Formulas
- Topic: Mass Percent Composition
- Replies: 7
- Views: 1090
Re: Mass Percent Composition
Mass percent should always add up to 100%. If you are given non-Oxygen elements and they do not add up to 100, then Oxygen is likely the remaining element and can be used to fill the deficit.
- Sun Dec 09, 2018 10:16 am
- Forum: Empirical & Molecular Formulas
- Topic: Determining Empirical formula
- Replies: 4
- Views: 685
Re: Determining Empirical formula
First, you must convert the molecules to moles. Using molar ratios, you can find grams of each of the individual elements. Then convert the masses of the individual elements to moles, and proceed to divide by the smallest number of moles (ex: if H=2, O=4, and H=6 divide all by 2) to find Empirical f...
- Sun Dec 09, 2018 10:13 am
- Forum: Empirical & Molecular Formulas
- Topic: combustion analysis?
- Replies: 2
- Views: 529
Re: combustion analysis?
For a combustion analysis: 1) Convert the given masses of CO2 and H2O to moles 2) Use the molar ratios to find the masses of Carbon and Hydrogen in the original sample 3) Subtract C and H from the mass of the original sample given to find the mass of Oxygen 4) Proceed to find empirical and molecular...
- Sun Dec 09, 2018 10:09 am
- Forum: Naming
- Topic: Regarding the test... [ENDORSED]
- Replies: 12
- Views: 5695
Re: Regarding the test... [ENDORSED]
I believe that they will be on the test since they were covered in class and are included under the lecture outlines on Dr. Lavelle's website.
- Sun Dec 02, 2018 9:31 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Square Planar
- Replies: 12
- Views: 1941
Re: Square Planar
Because the lone pairs are on exactly opposite sides of the molecule, the repulsion from the lone pairs has a net strength of zero (they "cancel out") and so the bond angles will be 90 degrees.
- Sun Dec 02, 2018 9:26 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone pairs
- Replies: 4
- Views: 537
Re: Lone pairs
Because repulsions between lone pairs and atoms are significantly stronger than those just between atoms, the repulsion from the lone pairs pushes the atoms closer together, creating smaller bond angles in the molecule.
- Sun Dec 02, 2018 9:18 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Seesaw
- Replies: 13
- Views: 2007
Re: Seesaw
The bond angles would be slightly less than 90 and slightly less than 120; this is due to the fact that repulsion from the lone pairs causes the angles of the bonds to be slightly smaller since they are being pushed together.
- Sun Nov 25, 2018 7:27 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Homework for week 9
- Replies: 11
- Views: 1124
Re: Homework for week 9
Yes I think the most important thing is just having all 14 problems done!
- Sun Nov 25, 2018 7:26 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 3 material
- Replies: 6
- Views: 700
Re: Test 3 material
Yes I heard that it is all of the material from the midterm up until now.
- Sun Nov 25, 2018 7:25 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
- Replies: 135
- Views: 38507
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
Thank you so much--this is so helpful!
- Sun Nov 18, 2018 10:52 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Multiple different bond angles
- Replies: 6
- Views: 887
Re: Multiple different bond angles
Yes, having different molecular geometry results in the angles between different atoms being different sizes. Lone pairs can play a role in this geometry.
- Sun Nov 18, 2018 10:49 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles for H2O
- Replies: 8
- Views: 8868
Re: Bond Angles for H2O
The lone pairs result in a decrease in the size of the angle .
- Sun Nov 18, 2018 10:46 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Peer Learning Sessions [ENDORSED]
- Replies: 10
- Views: 7789
Re: Peer Learning Sessions [ENDORSED]
Will peer learning sessions still be at the regular times this week (with the exception of Thursday and Friday) since it is Thanksgiving week?