## Search found 60 matches

Sun Jan 17, 2021 1:51 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6E.3 Question
Replies: 2
Views: 6

### Re: 6E.3 Question

The 2nd deprotonation is when the acid loses another H after the first reaction.
For example, when H2SO4 reacts with water, the 2nd deprotonation will be when HSO4- turns into SO4 2-
Sometimes we are able to ignore the 2nd ka because the change to the pH is so small.
Sun Jan 17, 2021 1:38 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Diprotic Acids
Replies: 2
Views: 14

### Re: Diprotic Acids

To add on, I think you have to consider the 2nd ka value when doing strong acids like Sulfuric acid H2SO4.
Sun Jan 17, 2021 1:24 pm
Forum: Ideal Gases
Topic: Inverse Kc
Replies: 28
Views: 60

### Re: Inverse Kc

You will typically use the inverse Kc when solving for the reverse equation.
For example in the reaction 2SO3 = 2SO2 +O2.
kc will equal ([SO2]^2[02])/[SO3]^2
The inverse kc will equal [SO3]^2/([SO2]^2[02])
Sun Jan 17, 2021 1:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: sapling week 1/2 #2
Replies: 3
Views: 21

### Re: sapling week 1/2 #2

A couple of places you should check:
- whether you changed moles to molar concentration
- whether your kc formula is correct = (SO2)^2*(O2)/SO3^2
- whether the concentrations of the final values are correct
- remember that the change for the ice table will be -2x = 2x x
Sat Jan 16, 2021 9:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook Question 6E.1
Replies: 2
Views: 9

### Re: Textbook Question 6E.1

Since H2SO4 can deprotonate 2 times you will have to make an ice table for the weak acid HSO4-. The ice table should start with .15M of HSO4- and .15M of H3O+.
Sun Jan 10, 2021 2:56 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: What are the small elements over the equilibrium symbols?
Replies: 5
Views: 25

### Re: What are the small elements over the equilibrium symbols?

Yes, I would also assume that the elements above are catalysts of the reaction. They likely affect the reactants in a way that allows the chemical reaction to occur while not being consumed by the reaction.
Sun Jan 10, 2021 2:47 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Are there reactions that just do not/ can not ever reach equilibrium?
Replies: 18
Views: 54

### Re: Are there reactions that just do not/ can not ever reach equilibrium?

Every chemical reaction should have the potential to reach equilibrium given that it has the right conditions to reach the reaction's equilibrium constant. This could depend on things like time, since reactions need time to occur and reach that equilibrium constant. I think that there are reactions...
Sun Jan 10, 2021 1:50 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: I in ICE Chart
Replies: 11
Views: 34

### Re: I in ICE Chart

The question will likely tell you when the product is not zero. The examples provided above will also imply that the product isn't zero.
Sun Jan 10, 2021 1:47 pm
Forum: Ideal Gases
Topic: inert gas and pressure changes
Replies: 9
Views: 33

### Re: inert gas and pressure changes

It might be good to consider these inert gases like the solvents in the normal solution. Since the inert gases don't react to anything, when solving for the K constant, we put the inert gas both on the reaction and product part of the equation, thus causing them to cancel each other out.
Sun Jan 10, 2021 1:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating Equilibrium Concentrations
Replies: 10
Views: 40

### Re: Calculating Equilibrium Concentrations

You should be careful with the liquids. While solvents aren't taken into account for the K value, liquids that are reacted together can be involved in the K concentration.
Fri Dec 11, 2020 10:16 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Example Problem
Replies: 2
Views: 18

### Re: Example Problem

You could also use -log (3.50 x 10-3 M) to find the pOH and subtract the result from 14 (because pH+pOH = 14). You should get 11.54 pH
Fri Dec 11, 2020 10:11 pm
Forum: Lewis Acids & Bases
Topic: Aluminum Chloride naming in today's review
Replies: 4
Views: 37

### Re: Aluminum Chloride naming in today's review

Since it is an ionic compound, we don't use the prefixes because we can find out the number by checking their respective charges. We use prefixes in covalent bonds because the number of atoms in the molecule is more ambiguous.
Fri Dec 11, 2020 9:18 pm
Forum: Calculating the pH of Salt Solutions
Topic: Na and Cl's influence on pH
Replies: 4
Views: 43

### Re: Na and Cl's influence on pH

Rather than not interacting, Na+ isn't strong enough to make the water molecules lose a hydrogen like Fe, Cr, Al, Cu, and Ni. A general rule to follow is that the cations in groups 1 and 2 aren't strong enough to affect the pH. For anions, the really strong anions create a more basic solution becaus...
Fri Dec 11, 2020 9:03 pm
Forum: Amphoteric Compounds
Topic: memorizing amphoteric oxides
Replies: 3
Views: 50

### Re: memorizing amphoteric oxides

Here is a picture of the amphoteric oxides for convenience.
Fri Dec 11, 2020 8:26 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Textbook 6D.11
Replies: 3
Views: 51

### Re: Textbook 6D.11

How do we know that Al 3+ forms a complex with water and that it'll react with more water to form hydronium ions? In one of his classes (I think it's the 12/7 one), our professor went over the small cations that acted as lewis acids when alone in an aqueous solution. (this is why the problem is Ph<...
Sun Dec 06, 2020 2:46 pm
Forum: Bronsted Acids & Bases
Topic: Strong acids
Replies: 7
Views: 69

### Re: Strong acids

I actually think the atom with the larger radius is the "stronger" acid because the bonds are more easily broken (longer bonds = weaker bonds). This is why HF is considered a weaker acid than HI. If we look at the group 17 acids, HF<HCl<HBr<HI in terms of acidity. Remember that the weak/st...
Sun Dec 06, 2020 2:11 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Memorizing shapes based on general formula?
Replies: 5
Views: 39

### Re: Memorizing shapes based on general formula?

My TA gave us this resource to memorize the vespr model. It was a very helpful resource and wanted to share.
http://chem.illinois.edu/chemdoodleweb/table.html
Sun Dec 06, 2020 2:00 pm
Forum: Lewis Acids & Bases
Topic: Equilibrium
Replies: 3
Views: 40

### Re: Equilibrium

^ Adding onto this, the equation that he has in his lecture Ka = [A-][H+]/[AH] is just the concentrations of the products divided by the concentration of the reactants, but I am not 100% sure if we would have to know this/calculate the equilibrium of the weak acid so if someone could answer that'd ...
Sun Dec 06, 2020 1:53 pm
Forum: Lewis Acids & Bases
Topic: Example Problem
Replies: 5
Views: 59

### Re: Example Problem

For future reference, I think it is also good to memorize the specific charge for the ligands so you can easily find the charge (or oxidation) of the transition metal.
Sun Dec 06, 2020 1:44 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: pH and pOH
Replies: 6
Views: 45

### Re: pH and pOH

The difference between pH and pOH is that they both measure different things. pH measures the concentration of H3O+ while pOH measures the concentration of OH-. They both add up to 14 so if they give you one of them, you can find the other one easily. However, we usually use pH so be careful not to ...
Fri Nov 27, 2020 4:33 pm
Forum: Sigma & Pi Bonds
Topic: Carbon bonds
Replies: 4
Views: 55

### Re: Carbon bonds

The carbon usually forms 4 bonds because it wants to fill up it's 4 orbitals (2sp3) to be stable. There are many reasons why carbon can be called "special" - it can form huge chains of carbon that can form macromolecules which are big enough for larger organism to use. - it is very stable ...
Fri Nov 27, 2020 4:14 pm
Forum: Sigma & Pi Bonds
Topic: Delocalized Pi Bonds
Replies: 4
Views: 56

### Re: Delocalized Pi Bonds

I think you can spot delocalized bonds by assessing their resonance structures. For example, in benzene since the combination of the resonance structures will result in single/double bond characteristics in all the bonds. With this, we can tell that there is one sigma bond between each of them and a...
Fri Nov 27, 2020 3:52 pm
Forum: Sigma & Pi Bonds
Topic: Delocalized Pi Bond
Replies: 5
Views: 58

### Re: Delocalized Pi Bond

Hello. I think this image does a good job describing how a delocalized pi bond is formed in benzene. It is because the resonance structures all combine to form a molecule with bonds with both double and single bond characteristics. During this process, the pi bonds forms a large e- cloud (which is w...
Fri Nov 27, 2020 3:40 pm
Forum: Sigma & Pi Bonds
Topic: Main Difference between Sigma & Pi Bonds Q
Replies: 4
Views: 42

### Re: Main Difference between Sigma & Pi Bonds Q

As Tamara said above, the major difference that you should look out for is that sigma bonds can rotate and the pi bonds are rigid. I also wanted to add a visual to help. https://cdn.shortpixel.ai/client/q_glossy,ret_img,w_596/https://vivadifferences.com/wp-content/uploads/2019/06/Sigma-Vs-Pi-Bond.png
Fri Nov 27, 2020 3:33 pm
Forum: Properties of Electrons
Topic: Difference between electrons and light properties
Replies: 5
Views: 62

### Re: Difference between electrons and light properties

Although they can be considered to have both particle and waves like motions, I think that you shouldn't see them as very similar. The negativity of the electron and the mass-less light greatly differentiate them from each other and have very different implications in chemical reactions.
Sun Nov 22, 2020 12:50 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Boiling Point/vapor pressure
Replies: 5
Views: 67

### Re: Boiling Point/vapor pressure

I don't know if this will help but an easy way to think of vapor pressure is to think of it as the urge to become a vapor. So the higher the vapor pressure, the higher the urge to become a vapor. In terms of boiling point, the lower the vapor pressure, the higher the boiling temperature.
Sun Nov 22, 2020 12:37 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Expanded Octets
Replies: 9
Views: 85

### Re: Expanded Octets

Like those above, the atoms after period 3 can all have expanded octets. The periodic table is always expanding as we find more atoms, so there is likely an 8d that just hasn't been discovered yet. I think for this course we will only need to know that the atoms after neon can have octets because n=3.
Sun Nov 22, 2020 12:24 pm
Forum: Dipole Moments
Topic: Dipole Moments Cancelling out
Replies: 10
Views: 90

### Re: Dipole Moments Cancelling out

I think looking at the forces in terms of vectors may help. Note that the example below works because the atoms surrounding the dipole moments are exactly the same, thus having the same forces acted upon it (just in a different direction). https://www.andrew.cmu.edu/course/09-105/GIFs/DIPOLE.08.GIF
Sun Nov 22, 2020 12:16 pm
Forum: Dipole Moments
Topic: Dipole Moments on cis-dichloroethene
Replies: 3
Views: 33

### Re: Dipole Moments on cis-dichloroethene

To add on, I think that looking at the general direction of the forces will be helpful in determining whether they are polar or not. The trans-dicholorethene are nonpolar because they point the opposite way while cisdichloroethene is polar because they point towards a general direction. https://www....
Sat Nov 21, 2020 8:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR
Replies: 4
Views: 96

### Re: VSEPR

I also don't think we need to know it but I think this website is quite informative for learning electrostatic potential maps. link: https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Chemical_Bonding/Fun...
Sat Nov 14, 2020 7:21 pm
Forum: Bond Lengths & Energies
Topic: Energy released
Replies: 3
Views: 32

### Re: Energy released

In general intramolecular interactions will require more energy to break than intermolecular interaction since intramolecular bonds are usually a lot stronger.
Sat Nov 14, 2020 6:59 pm
Forum: Sigma & Pi Bonds
Topic: Triple bond?
Replies: 21
Views: 165

### Re: Triple bond?

Catherine Bubser 2C wrote:What is an example of a molecule that exhibits a delta bond?

I don't think we need to know this but apparently Re2Cl8 2- ion has a delta bond .
Sat Nov 14, 2020 6:51 pm
Forum: Ionic & Covalent Bonds
Topic: Cation vs Anion
Replies: 5
Views: 66

### Re: Cation vs Anion

Hello. Like Emily said, I think you should follow the trends of the periodic table. Think about how many electrons they need or don't need to become stable. As a general trend the atoms on the left side are usually cations while the atoms on the right side are anions. If you need additional help you...
Sat Nov 14, 2020 6:41 pm
Forum: Dipole Moments
Topic: Interaction potential energy
Replies: 2
Views: 22

### Re: Interaction potential energy

The negative sign represents that the energy is being released outside the system.
Sat Nov 14, 2020 5:10 pm
Forum: Resonance Structures
Topic: Finding The Most Plausible Resonance Structure
Replies: 3
Views: 41

### Re: Finding The Most Plausible Resonance Structure

To add on to what Edward said, the formal charge exaggerates the covalent character of the bond by assuming that all the bonds are equally shared while the oxidation number exaggerates the ionic character by assuming that the more electronegative gets the e-. So in the scope of this question, since ...
Sat Nov 07, 2020 4:31 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron configurations of f state
Replies: 4
Views: 46

### Re: Electron configurations of f state

If I remember correctly, in one of the lectures the professor said that we will be focusing on s, p, and d blocks so I don't think the f block is necessary. However, if you want to learn it just incase I recommend watching this video: https://youtu.be/KJLgnAUVALc
Sat Nov 07, 2020 4:18 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Inner Core
Replies: 4
Views: 71

### Re: Inner Core

The inner core would be the electrons that are already filled in. I like to think of it as the electrons that aren't touched in a reaction so this will usually be the closest noble gas.
Sat Nov 07, 2020 4:06 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: S vs P electrons
Replies: 5
Views: 59

### Re: S vs P electrons

The s-electrons have lower energies because they are closer to the nucleus than the p-electrons. This protects the p-electrons from the nucleus's charge (aka shielding). You can probably get a better explanation here: https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textboo...
Sat Nov 07, 2020 2:42 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Isoelectric atoms
Replies: 9
Views: 38

### Re: Isoelectric atoms

To add on to those above me, you should focus on how many protons they have to determine their electronegativities and ionization.
Sat Nov 07, 2020 2:28 pm
Forum: Trends in The Periodic Table
Topic: Easy Way to Remember Trends
Replies: 5
Views: 99

### Re: Easy Way to Remember Trends

Hello,
I don't have an acronym to remember the trends but I found this website very helpful in doing so.
Website: https://chem.libretexts.org/Bookshelves ... _Chemistry)/Descriptive_Chemistry/Periodic_Trends_of_Elemental_Properties/Periodic_Trends
Sat Oct 31, 2020 9:33 pm
Forum: Ionic & Covalent Bonds
Topic: Non Metals
Replies: 10
Views: 92

### Re: Non Metals

To add on to those above me, the high ionization energy of these materials are also the reason why they are bad conductors of electricity.
Sat Oct 31, 2020 9:15 pm
Forum: Octet Exceptions
Topic: Octet Exceptions
Replies: 10
Views: 48

### Re: Octet Exceptions

To add on to those above me, I think there is a correlation between the charge of the electrons and the nucleus. I don't think the charges of the nucleus of these atoms (+1 H, +2 H, +3 Li, +4 B) are strong enough to hold all 8 electrons together.
Sat Oct 31, 2020 9:02 pm
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 7
Views: 201

### Re: Lewis Structures

You will need to find the atom with the lowest electromagnetic and then surround it based on how many valence electrons it needs. For more complex molecules, there are isomers (molecules with same number of molecules but different structures) so we may have to build our structures based on the infor...
Sat Oct 31, 2020 8:53 pm
Forum: Ionic & Covalent Bonds
Topic: Homework due date
Replies: 49
Views: 336

### Re: Homework due date

You should finish it by 11:59pm on Sunday but I assume that you can still do the problems past the time since he didn't seem to set an "available from date" on the website itself.
Sat Oct 31, 2020 8:40 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic Vs. Covalent
Replies: 7
Views: 63

### Re: Ionic Vs. Covalent

To add on, ionic bonds are held together by the charges of the whole atom while covalent bonds are held together by their shared electron.
Sun Oct 25, 2020 6:43 pm
Forum: Limiting Reactant Calculations
Topic: M.7
Replies: 6
Views: 78

### Re: M.7

The LR for this problem would be Mg because the weight of 3 Mg's are greater than the weight of B2O3. The book seems to also use Mg as the LR so you may have done your calculations wrong.
Sun Oct 25, 2020 5:58 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Replies: 92
Views: 2069

To add onto those ahead of me, if you are having problems with a specific topic, I recommend that you watch The Organic Chemistry Tutor on youtube. I find him really helpful because he goes over each problem step by step.
Sun Oct 25, 2020 5:10 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Rearranging uncertainty in velocity
Replies: 5
Views: 38

### Re: Rearranging uncertainty in velocity

In order to solve for the delta V, we have to divide each side by M (Delta V= delta P/M). I think it will help if you think of the deltas (delta V and Delta P in this case)as a variable that cannot be split.
Sun Oct 25, 2020 4:33 pm
Forum: Properties of Light
Topic: J/mol or J/photon
Replies: 2
Views: 33

### Re: J/mol or J/photon

The problems will typically be in J/photons unless they tell you to convert to moles. In this problem, instead of changing it to moles, you had to divide 36.14 J by the joules of the photon with the wavelength of 6.18×10−4 cm.
Sun Oct 25, 2020 2:57 pm
Forum: Properties of Light
Topic: Midterm
Replies: 42
Views: 390

### Re: Midterm

So we're going to be in a zoom call with our whole discussion group? Doesn't that mean that we'll be able to see each other's work? Yes, I'm pretty sure we will be in a zoom call with our group, however I think it will be quite hard to cheat off of each other since the TA will be watching your scre...
Sat Oct 17, 2020 1:59 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Module Question 14
Replies: 2
Views: 34

### Re: Module Question 14

Yes, you are correct. Although every object has a wave-like property, for classical objects like baseballs we often consider them as particle-like objects since the lambda is too small to be noticed or have substantial effects.
Sat Oct 17, 2020 1:49 pm
Forum: DeBroglie Equation
Topic: Wavelike Properties
Replies: 4
Views: 62

### Re: Wavelike Properties

To add to the post above, while all objects have wave-like properties, we consider classical objects like baseballs to have particle-like properties since the lambda is too small to consider.
Sat Oct 17, 2020 1:36 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: IB27
Replies: 2
Views: 34

### Re: IB27

Hi. It is 10m/s because you have to consider both the negative and positive uncertainty of the equation. For example, if a ball had a velocity of 7.00 ± 3.0 m/s. The uncertainty will be 6.
Sat Oct 17, 2020 12:49 pm
Replies: 6
Views: 93

The black body radiation is a item that can absorb all frequencies of light and is purely theoretical. Scientist still haven't found any material able to do so. But the reason why black gets hotter than the other colors is because it can absorb more light frequencies than them.
Sat Oct 17, 2020 12:29 pm
Forum: Student Social/Study Group
Topic: How are you studying?
Replies: 203
Views: 1289

### Re: How are you studying?

To add onto the posts above, I personally think the Audio-Visual Focus-Topics really straightened-out a lot of topics for me. If you are struggling with some of the topics there, you can re-watch and redo the post-assessment. I plan on redoing the post-assessment test and re-watching the video befor...
Fri Oct 09, 2020 4:04 pm
Forum: Limiting Reactant Calculations
Topic: Determining Limiting Reactant
Replies: 4
Views: 34

### Re: Determining Limiting Reactant

You can do either, but I think it is safer to find the moles of the product since it will always consider the moles ratios between the product and reactant unlike the first option.
Fri Oct 09, 2020 3:46 pm
Forum: Limiting Reactant Calculations
Topic: Determining the Limiting Reactant
Replies: 4
Views: 43

### Re: Determining the Limiting Reactant

Yes, you are correct C14H18N205 is the limiting reactant in this case since it has less moles, meaning the reaction runs less. If you are unsure, you can always check your answer by just converting it to the moles of the product. Hope this helps!
Fri Oct 09, 2020 3:29 pm
Forum: Molarity, Solutions, Dilutions
Topic: Week 1 HW Q#10
Replies: 5
Views: 59

### Re: Week 1 HW Q#10

No, you don't need to know what 2-butanone or 1-bromopropane are. You can determine their elemental composition by counting the provided Lewis structures. The Hydrogens aren't usually shown in Lewis structures so you will have to add hydrogens based on how many electrons each element needs for a sta...
Thu Oct 08, 2020 9:24 pm
Forum: Balancing Chemical Reactions
Topic: Textbook Problem L35.
Replies: 8
Views: 93

### Re: Textbook Problem L35.

After changing the 2.5 t into moles of NaBr, you need to convert the moles of NaBr to Fe3Br8 (1mole of Fe3Br8/8 moles of NaBr); then, convert moles of Fe3Br8 to moles of FeBr2 (3 moles of FeBr2/1 mole Fe3Br8); then, FeBr2 to Fe (1 mole of Fe/1 mole of FeBr2). As you're doing this, you should find th...
Thu Oct 08, 2020 6:30 pm
Forum: Balancing Chemical Reactions
Topic: Question H 7d
Replies: 3
Views: 36

### Question H 7d

The question: "the reaction of ammonia gas with oxygen gas at high temperatures in the presence of a copper metal catalyst produces the gases water and nitrogen dioxide." If the copper metal is a catalyst of the formula, is the copper metal included in the chemical equation? If not, how do...