Search found 38 matches

by uhedlund
Sun Jan 27, 2019 8:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Le Chatelier's Principle question
Replies: 4
Views: 29

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...
by uhedlund
Sun Jan 27, 2019 8:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pH
Replies: 9
Views: 40

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+)
by uhedlund
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: 32

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.
by uhedlund
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: 44

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.
by uhedlund
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: 40

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.
by uhedlund
Sun Jan 27, 2019 8:24 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: ICE
Replies: 14
Views: 40

Re: ICE

In the ICE box, I stands for initial (so initial concentrations), C stands for Change, and E stands for Equilibrium.
by uhedlund
Sun Jan 13, 2019 5:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Heterogeneous and homogeneous equilibria [ENDORSED]
Replies: 8
Views: 36

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.
by uhedlund
Sun Jan 13, 2019 5:12 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: converting from pressure to concentration
Replies: 4
Views: 30

Re: converting from pressure to concentration

It is a constant that will probably be included in the equations list for tests.
by uhedlund
Sun Jan 13, 2019 5:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: solids in calculating equilibrium constant? [ENDORSED]
Replies: 8
Views: 35

Re: solids in calculating equilibrium constant? [ENDORSED]

No, only aqueous solutions and gases are included in calculating the equilibrium constant.
by uhedlund
Sun Dec 09, 2018 11:26 pm
Forum: Empirical & Molecular Formulas
Topic: Going from empirical to Molecular formula
Replies: 14
Views: 252

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.
by uhedlund
Sun Dec 09, 2018 11:25 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical Formula
Replies: 1
Views: 20

Re: Empirical Formula

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.
by uhedlund
Sun Dec 09, 2018 11:24 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 9
Views: 108

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
by uhedlund
Sun Dec 09, 2018 11:23 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Stable Vs. Formal
Replies: 4
Views: 68

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.
by uhedlund
Sun Dec 09, 2018 11:21 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge vs Partial charge
Replies: 4
Views: 42

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.
by uhedlund
Sun Dec 09, 2018 10:41 am
Forum: Naming
Topic: order of ligand name
Replies: 5
Views: 45

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.
by uhedlund
Sun Dec 09, 2018 10:40 am
Forum: Naming
Topic: Order of ligands
Replies: 6
Views: 46

Re: Order of ligands

When writing the formula, arrange ligands in alphabetical order, ignoring any prefixes.
by uhedlund
Sun Dec 09, 2018 10:38 am
Forum: Biological Examples
Topic: What should we know for the final?
Replies: 6
Views: 93

Re: What should we know for the final?

I think it is important to know about cisplatin, myoglobin, and hemoglobin for the final.
by uhedlund
Sun Dec 09, 2018 10:35 am
Forum: Formal Charge and Oxidation Numbers
Topic: Formal charge on central atom
Replies: 5
Views: 54

Re: Formal charge on central atom

A formal charge closer to zero is more stable than other higher charges.
by uhedlund
Sun Dec 09, 2018 10:33 am
Forum: Lewis Structures
Topic: Elements that break the octet rule
Replies: 6
Views: 52

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.
by uhedlund
Sun Dec 09, 2018 10:30 am
Forum: Trends in The Periodic Table
Topic: electronegativity
Replies: 2
Views: 27

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.
by uhedlund
Sun Dec 09, 2018 10:29 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Momentum Uncertainty
Replies: 3
Views: 44

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.
by uhedlund
Sun Dec 09, 2018 10:27 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg and Wavelength
Replies: 11
Views: 137

Re: Heisenberg and Wavelength

Because wavelength=planck's constant/momentum, they have an inverse relationship. As momentum increases, wavelength decreases.
by uhedlund
Sun Dec 09, 2018 10:24 am
Forum: DeBroglie Equation
Topic: wavelike properties
Replies: 4
Views: 92

Re: wavelike properties

A wavelength smaller than 1*10^-18 cannot be detected; however, it can still be calculated.
by uhedlund
Sun Dec 09, 2018 10:22 am
Forum: Molarity, Solutions, Dilutions
Topic: Actual/Theoretical Yield
Replies: 7
Views: 196

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.
by uhedlund
Sun Dec 09, 2018 10:19 am
Forum: Empirical & Molecular Formulas
Topic: Order of Molecules
Replies: 4
Views: 101

Re: Order of Molecules

Generally, the order of atoms should be in alphabetical order.
by uhedlund
Sun Dec 09, 2018 10:18 am
Forum: Empirical & Molecular Formulas
Topic: Mass Percent Composition
Replies: 7
Views: 147

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.
by uhedlund
Sun Dec 09, 2018 10:16 am
Forum: Empirical & Molecular Formulas
Topic: Determining Empirical formula
Replies: 4
Views: 65

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...
by uhedlund
Sun Dec 09, 2018 10:13 am
Forum: Empirical & Molecular Formulas
Topic: combustion analysis?
Replies: 2
Views: 33

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...
by uhedlund
Sun Dec 09, 2018 10:09 am
Forum: Naming
Topic: Regarding the test... [ENDORSED]
Replies: 11
Views: 1260

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.
by uhedlund
Sun Dec 02, 2018 9:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Square Planar
Replies: 12
Views: 82

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.
by uhedlund
Sun Dec 02, 2018 9:26 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone pairs
Replies: 4
Views: 35

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.
by uhedlund
Sun Dec 02, 2018 9:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw
Replies: 13
Views: 112

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.
by uhedlund
Sun Nov 25, 2018 7:27 pm
Forum: Administrative Questions and Class Announcements
Topic: Homework for week 9
Replies: 11
Views: 97

Re: Homework for week 9

Yes I think the most important thing is just having all 14 problems done!
by uhedlund
Sun Nov 25, 2018 7:26 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 3 material
Replies: 6
Views: 48

Re: Test 3 material

Yes I heard that it is all of the material from the midterm up until now.
by uhedlund
Sun Nov 18, 2018 10:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Multiple different bond angles
Replies: 6
Views: 33

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.
by uhedlund
Sun Nov 18, 2018 10:49 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles for H2O
Replies: 8
Views: 40

Re: Bond Angles for H2O

The lone pairs result in a decrease in the size of the angle .
by uhedlund
Sun Nov 18, 2018 10:46 pm
Forum: Administrative Questions and Class Announcements
Topic: Peer Learning Sessions [ENDORSED]
Replies: 10
Views: 6297

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?

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