## Search found 106 matches

Sun Mar 14, 2021 11:41 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Sponetanity
Replies: 2
Views: 16

### Re: Sponetanity

When deltaG (Gibbs) is negative, it's spontaneous. You can use the equation deltaG=deltaH - TdeltaS. and see when delta H and delta S make delta G negative. Also when deltaS is positive then the reaction is spontaneous. When deltaH is negative then the reaction is spontaneous. But again plug in the ...
Sun Mar 14, 2021 11:37 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: strong vs weak acid pH level
Replies: 2
Views: 18

### Re: strong vs weak acid pH level

Strong acids are going to fully dissociate into H+/H3O+ ions with their respective conjugate base. The concentration of H+ ions of a strong acid is gonna be greater than a weak acid's, so that leads to strong acids having lower pHs than a weak acid.
Sun Mar 14, 2021 8:05 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: EA
Replies: 11
Views: 76

### Re: EA

Didn't see much use of EA, so I'm gonna assume they both mean activation energy? I'd rather use Ea because the capital and subscript make it more obvious that it's an energy.
Sun Mar 14, 2021 8:01 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Which form of equation
Replies: 7
Views: 49

### Re: Which form of equation

Depends on what I'm solving for. If I'm solving for Ea or T, then I'd use the ln(k)=-Ea/RT + ln(A) because it doesn't need to be modified by a power/exponent or natural log. Rather if I'm solving for k or A, then k=Ae^(-Ea/RT) would be better imo.
Sun Mar 14, 2021 7:59 pm
Forum: Zero Order Reactions
Topic: zero order
Replies: 30
Views: 84

### Re: zero order

Zero Order means the reaction isn't affected by the concentration. The equations that come with it are [A]=-kt+[A0], d[A]=-kdt, t(1/2)= [A0]/ (2k).
Sat Mar 13, 2021 9:02 pm
Forum: Zero Order Reactions
Topic: Half Life
Replies: 6
Views: 62

### Re: Half Life

1st order reaction half life: t1/2 = 0.693/k. 2nd Order is: t1/2 = 1/(k[A]o). Zero order: t1/2 = ([A]o)/(2k). The little o's mean "naught."
Sat Mar 13, 2021 8:57 pm
Forum: Zero Order Reactions
Topic: Le Chatelier's principle
Replies: 3
Views: 32

### Re: Le Chatelier's principle

Le Chatelier's principle says that if equilibrium is altered by changing the conditions of pressure or volume or temperature or concentration, the position of equilibrium shifts to counteract the change to re-establish an equilibrium. Generally, ur gonna see problems where it's like if u increase th...
Sun Mar 07, 2021 7:42 pm
Forum: Zero Order Reactions
Topic: Catalysts
Replies: 6
Views: 51

### Catalysts

Catalysts were only mentioned within zero order reactions? Can catalysts or enzymes be used in any order reaction or is it only exclusive to zero-order reactions. If so why is it only exclusive to them?
Sun Mar 07, 2021 7:37 pm
Forum: General Rate Laws
Topic: Multiple Reactants
Replies: 7
Views: 45

### Multiple Reactants

So far in lecture I have only seen one reactant, while there can be many products. Is there anything special or different when there are multiple reactants?
Sun Mar 07, 2021 7:22 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic Cells
Replies: 4
Views: 26

### Re: Galvanic Cells

I think when the reaction is spontaneous, then the E(naught) is +, but it will not always be positive.
Sun Mar 07, 2021 7:17 pm
Forum: Zero Order Reactions
Topic: Order Definition
Replies: 4
Views: 32

### Order Definition

Order is in the context of the reactant and it is the given in the form of n and can be 0,1, or 2. What exactly is an order? Is it like a magnitude?
Sun Mar 07, 2021 7:13 pm
Forum: First Order Reactions
Topic: C is [A]nought
Replies: 6
Views: 43

### C is [A]nought

When finishing up each integral, why did we say that the constant of the indefinite integral is a variation of [A]nought? Ex. ln( [A]nought ) or 1/ [A]nought, etc.
Sun Feb 28, 2021 11:18 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernest equation log Q
Replies: 2
Views: 11

### Re: Nernest equation log Q

You are able to use it given certain variables. The log equation is originally derived from the ln equation. For the log equation we have V vs. the ln equation that has T. Just depends on what you have.
Sun Feb 28, 2021 11:14 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Sapling 10
Replies: 9
Views: 27

### Sapling 10

Arrange these species by their ability to act as an oxidizing agent given Au3+, Na+, Cr3+, Cu+. Without looking up standard reduction potentials and the tables, could we intuitively know how to figure out how good of an oxidizing agent is?
Sun Feb 28, 2021 11:06 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst Equations
Replies: 7
Views: 50

### Re: Nernst Equations

K is used when the reaction is at equilibrium hence, the E is 0 and thus E(nought) = RT/nFlnK. They are the same equation but at a very specific moment. You could still use the second equation and still have Q. Just know that Q = K at equilibrium.
Sun Feb 28, 2021 11:03 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Sapling #7
Replies: 4
Views: 38

### Sapling #7

Complete the half‑reactions for the cell shown, and show the shorthand notation for the cell. The electrode on the left is the anode, and the one on the right is the cathode. We were given PbCl2, AgCl2, etc that problem. For the shorthand notation, I had the right components on both sides but after ...
Sun Feb 28, 2021 10:48 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Sapling 17
Replies: 3
Views: 45

### Sapling 17

What would the potential of a standard hydrogen electrode (S.H.E.) be under the given conditions?
[H+]=0.69 M PH2=1.1 atm T=298 K

Why/how can we divide the two concentrations if they are different units?
Sun Feb 28, 2021 10:09 pm
Forum: Balancing Redox Reactions
Topic: Sapling #3
Replies: 2
Views: 16

### Sapling #3

For a particular redox reaction, MnO2 is oxidized to MnO−4 and Cu2+ is reduced to Cu+ . Complete and balance the equation for this reaction in basic solution. The phases are optional. I got the answer right, but after using hints and feedback. Why do we use OH or H2O? Maybe I wasn't paying attention...
Sun Feb 21, 2021 10:29 pm
Forum: Calculating the pH of Salt Solutions
Topic: Acids & Bases: Calculating the pH
Replies: 2
Views: 27

### Re: Acids & Bases: Calculating the pH

Ka x Kb = Kw. Kw is 1.0x10^-14. You're thinking of pKa and pKb, thats where you subtract 14. to find either value.
Sun Feb 21, 2021 7:17 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Porous vs Salt
Replies: 2
Views: 26

### Porous vs Salt

What are the benefits of using a salt bridge vs a porous disk? What are the key differences and why should one be used in a certain circumstance over the other?
Sun Feb 21, 2021 7:14 pm
Forum: Administrative Questions and Class Announcements
Topic: Chem community points
Replies: 10
Views: 50

### Re: Chem community points

We should have 35 posts total up to this week. But be careful, because you may have done a ton of posts last quarter and it may give you a large number. But you still have to do posts lol. Myucla should get updated and then we'll see our participation.
Sun Feb 21, 2021 7:11 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: E Cell Equation
Replies: 2
Views: 25

### E Cell Equation

How come the $\Delta \Phi$n is always positive, when the right side is gaining electrons? Wouldn't the right side get more negative and therefore there would be even more negativity. Super confused.
Sun Feb 21, 2021 7:07 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Solving for changes in entropy
Replies: 1
Views: 29

### Re: Solving for changes in entropy

I don't know the answer but here is my thought process. I think you would use deltaS= nR ln(V2/V1). We know moles and R. While we don't know the exact values of the V's, we know that V2 is equal to 2 times V1, bc it stated the two equal sections/two equal volumes. So 2 times V1 divided by V1 =2. the...
Sun Feb 14, 2021 8:54 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Sapling #19
Replies: 4
Views: 35

### Re: Sapling #19

To solve K, it gives you all the partial pressures for your reactants and products. We can get K or rather Q just by doing what we have been doing in equilibrium! Q=(CH4)^2/(C2H6)(H2) Maybe I'm thinking of a different number 19?
Sun Feb 14, 2021 8:47 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Sapling Week 5/6 HW #7
Replies: 7
Views: 61

### Re: Sapling Week 5/6 HW #7

You first need to find Hvap. The power is in watts and 1 W=1 J⋅s−1. Notice the unit seconds at the bottom? It means it's a rate. The sample is heated for 3.50 min. (3.50 min)×(60 s/1 min)×(525.0 J/1 s)=1.10×105 J. This is your power and now you need to divide it by the molar difference between the f...
Sun Feb 14, 2021 8:41 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Equations for Thermodynamics and Thermochemisty
Replies: 2
Views: 30

### Re: Equations for Thermodynamics and Thermochemisty

Equations that include Gibbs Free Energy:
G=H-TS
G= (-RT)ln(K)
deltaG= G+RT(ln(K)
G(total)=SumOfG(products)-SumOfG(reactants)
Sun Feb 14, 2021 8:36 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Sapling Week 5/6 #15
Replies: 5
Views: 28

### Re: Sapling Week 5/6 #15

What I did was calculate the total deltaH and deltaS so that it would clean in the end. Beware that you have to flip signs and adjust the values if you need to scale either equation. But after you get your total values, plug them into G= H-TS. Should give you what you are looking for! But all of the...
Sun Feb 14, 2021 5:25 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Sapling HW17
Replies: 1
Views: 25

### Sapling HW17

The final step in the industrial production of nitric acid.

3NO2(g)+H2O(l)↽−−⇀2HNO3(aq)+NO(g).

The goal is to find K. Why do we include H2O in our Gibbs when we do not include liquids or solids in our K concentration ratio equation?
Sun Feb 14, 2021 2:15 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Sapling HW7
Replies: 1
Views: 17

### Sapling HW7

"You have reversed the order of the compounds. A larger molar entropy of vaporization, which correlates to a greater increase in disorder, indicates a more ordered arrangement of the molecules in the liquid state." Why does greater disorder from a large deltaS value indicated a more ordere...
Sun Feb 07, 2021 11:07 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Does phase matter in Hess's Law?
Replies: 21
Views: 106

### Re: Does phase matter in Hess's Law?

I think the way that each deltaH value is given is based on the standard enthalpy formation method, meaning each compound and its different phases have their own value. So we just manipulate the equations in a way that we can find the overall equation we want even if we don't know the specific numbe...
Sun Feb 07, 2021 10:58 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Does phase matter in Hess's Law?
Replies: 21
Views: 106

### Re: Does phase matter in Hess's Law?

You can't cancel if the phases of the same compound are different. They have to be the exact same phase and compound in order to be able to cancel if they are on opposite sides of different equations.
Sun Feb 07, 2021 10:55 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: How can we change the energy in an isolated system?
Replies: 4
Views: 27

### Re: How can we change the energy in an isolated system?

You can't increase or decrease the energy in an isolated system and can't exchange heat with its surroundings, so this makes its internal energy equal to zero. Not sure if that's what you meant by change. If not I would not know how to convert one form of E into another.
Sun Feb 07, 2021 10:45 pm
Forum: Student Social/Study Group
Topic: Bonus Points
Replies: 2
Views: 16

### Re: Bonus Points

Would be nice, but I wouldn't count on it. Hopefully it happens but guess it just means we gotta grind even harder haha. I just gotta find better ways to study and apply concepts.
Sun Feb 07, 2021 10:43 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Sapling HW18
Replies: 1
Views: 35

### Sapling HW18

A 0.305 mol sample of SO2(g), initially at 298 K and 1.00 atm, is held at constant pressure while enough heat is applied to raise the temperature of the gas by 10.9 K. Calculate the amount of heat q required to bring about this temperature change, and find the corresponding total change in the inter...
Sun Feb 07, 2021 9:52 pm
Forum: Calculating Work of Expansion
Topic: sapling HW13
Replies: 2
Views: 12

### sapling HW13

A(s)+B(s)⟶C(g). Why does this system do work on the surrounding? Is it because we don't include moles of solids, so the reactants count as 0?
Sun Feb 07, 2021 8:18 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Photo in Lecture
Replies: 1
Views: 11

### Photo in Lecture

Can someone explain this photo? Confused about the arrows and what the different color means. Thanks
Sun Jan 31, 2021 10:07 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Work-/+
Replies: 9
Views: 70

### Work-/+

We are given in multiple equations that work is negative. Can work be positive, would it have to be in a different direction or the volume had to be increased right?
Sun Jan 31, 2021 9:54 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: System and Surrounding
Replies: 4
Views: 26

### System and Surrounding

I remember seeing in lecture that System + surroundings = 0, but then system + surroundings = universe. What is the context of these two? By "perfect system" do they just mean that there is an equal and opposite force or reaction? But then it's said that the surroundings are on a totally l...
Sun Jan 31, 2021 9:09 pm
Forum: Student Social/Study Group
Topic: Students Who Have a Job
Replies: 80
Views: 471

### Re: Students Who Have a Job

Yeah, I work less than 10 hours a week so I have a bit of flexibility. I set myself on a schedule and have a calendar planned what needs to be done. I try to watch lectures as they come out rather than waiting or looking at them on the weekend. I try to do as much work as I can in my given free time...
Sun Jan 31, 2021 7:18 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: "Bomb Calorimetry"
Replies: 4
Views: 27

### "Bomb Calorimetry"

How does the bomb calorimetry work? Got confused by what the different parts do and how they function as a whole.
Sun Jan 31, 2021 7:08 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Cp & Cv
Replies: 7
Views: 62

### Cp & Cv

Hey, I'm sort of confused about the difference between Cp and Cv. I thought that volume and pressure were related and there wouldn't be a difference in what Cv and Cp are. How can you have constant pressure if a piston is making the volume smaller, which will increase the pressure? Pretty confused a...
Sun Jan 24, 2021 5:56 pm
Forum: Phase Changes & Related Calculations
Topic: Heat vs Temp
Replies: 3
Views: 35

### Heat vs Temp

Why is Temperature is a state property but heat isn't? What is heat then in this context?
Sun Jan 24, 2021 5:51 pm
Forum: Phase Changes & Related Calculations
Topic: Work on vs by
Replies: 4
Views: 44

### Work on vs by

Why is the work done on a system a negative value?
Sun Jan 24, 2021 5:45 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D.19
Replies: 2
Views: 30

### Re: 4D.19

You have to use Hess' Method. You are going to have to add and subtract certain compounds in order to make the final equation they want. The trickiest part is most likely manipulating or reversing the equation to get the reactants or products on a certain side. If you do reverse an equation make sur...
Sun Jan 24, 2021 5:38 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Calculating Standard Enthalpy
Replies: 2
Views: 21

### Re: Calculating Standard Enthalpy

To get standard state water then yes I think you have to find the enthalpy condensation if you are going from gas to liquid. But there is already an enthalpy for H2O in gas form but again that isn't in standard enthalpy of formation.
Sun Jan 24, 2021 5:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: percent ionization
Replies: 4
Views: 40

### Re: percent ionization

Percent ionization is [conjugate base/acid]/[inital acid/base] then multiply by 100 to get a percentage. They have similar equations but differ based on the product, reactant, and if each is getting ionized/protonated, etc.
Sun Jan 17, 2021 7:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Homework #5
Replies: 9
Views: 67

### Re: Sapling Homework #5

Look for all the compounds that are in the final equation that it wants. You then have to pick and choose equations to see like 'oh this has NH3 and oh this other one has I 2 .' You might have to look at the reverse reaction of each of them or maybe multiply a reaction by a factor to get the correct...
Sun Jan 17, 2021 7:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ice tables
Replies: 7
Views: 57

### Re: ice tables

Could they be like careless errors? Maybe you didn't set the right coeffienct for x? The Ice Box itself makes sense logically and you seem to understand, but I would then think it's just the algebra portion that you got to stay aware of. Check units and see what info you have to make sure the number...
Sun Jan 17, 2021 7:30 pm
Forum: Student Social/Study Group
Topic: Study Strategies
Replies: 31
Views: 95

### Re: Study Strategies

I've tried doing the textbook work, but not doing it all in one night. Do some problems every night so that every day you are approaching the same concepts, rather than doing all of them on a given night or right before the midterm/final. I think consistency is a good way a learn more in this class ...
Sun Jan 17, 2021 7:27 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE Box
Replies: 3
Views: 50

### Re: ICE Box

How do we find the difference in molar concentration using molar ratio? I know he did something with it in the third module, but is there a rule that explains how to convert the molar ratios in the empirical formula to find the difference? Whatever molar ratio or constant is given for the formula, ...
Sun Jan 17, 2021 4:21 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Questions About Acids and Bases from Friday Lecture
Replies: 1
Views: 29

### Re: Questions About Acids and Bases from Friday Lecture

Autoprotolysis, when water acts as both an acid and base to either receive or give a H+ atom, generates 10^-7 mol/L H3O+. When the concentration of H3O is less than 10^-7 the change is so small and it's pretty much negligible. Therefore with no intense change, the pH is still neutral.
Sun Jan 10, 2021 5:35 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Stable Reactants and Products
Replies: 7
Views: 43

### Re: Stable Reactants and Products

I think stability implies or means that a certain side is favored or not. If we have a large K this means that the equilibrium concentration of products is greater than that of reactants, which also means the formation of products (the forward reaction) is considered more stable than the reverse rea...
Sun Jan 10, 2021 5:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K=1
Replies: 8
Views: 76

### K=1

I remember in the lecture that Dr. Lavelle said K=1 was rare. Why is it rare? I get that it means that neither R or P is favored since it is in the range of 10^-3 and 10^3. But why is that specific value rare? Might not be important but I'm curious
Sun Jan 10, 2021 5:17 pm
Forum: Ideal Gases
Topic: partial pressures
Replies: 14
Views: 105

### Re: partial pressures

Partial pressure is like the force exerted by a gas if it was just by itself in some volume. In PV=nRT, we can manipulate it to be: P/RT = n/v. n/V is concentration, and we can see that Pressure is proportional to concentration. 1/RT is our proportionality constant.
Sun Jan 10, 2021 5:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling week 1 #2
Replies: 3
Views: 24

### Re: Sapling week 1 #2

The best way to start this is to make a table showing the initial concentration, change in concentration, and equilibrium concentration. Know that initially, you're given that SO3 is some amount of moles in a container. You can convert into molarity now or later but you have to be consistent with th...
Sun Jan 10, 2021 5:06 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Module Question 13
Replies: 2
Views: 21

### Re: Module Question 13

12. Consider the following reaction at 1200 K, for which you know Kc = 1.7 x 10-3. Br2 (g) ⇌ 2 Br (g) Your experimental setup is able to measure the equilibrium concentration of Br2 based on its color, but you are unable to measure the concentration of Br directly. If you measure at equilibrium [Br...
Wed Dec 16, 2020 11:25 pm
Forum: General Science Questions
Topic: Study Habits
Replies: 16
Views: 152

### Study Habits

What were some of the ways you guys studied for the final? Office hours, review, textbook,etc? How did you understand the material? If you didn't at first but then did how did you learn? I know I definitely should've spread my time out more in order to prepare for the final and should have done all ...
Sat Dec 12, 2020 8:46 pm
Forum: SI Units, Unit Conversions
Replies: 12
Views: 210

We use Avogadro's number when converting from moles to atoms/molecules or vice versa. Depending on how you do your dimensional analysis, you can either divide or multiply by Avogadros number which has a unit of atoms/molecules.
Sat Dec 12, 2020 4:29 pm
Forum: Polyprotic Acids & Bases
Topic: Amphiprotic
Replies: 2
Views: 33

### Re: Amphiprotic

Amphoteric or Amphiprotic means the compound has both acidic and basic characteristics. You can identify this by looking to see if an atom has both a lone pair and H atom attached it. Thus, you could see that it could act as both a Lewis Base (donates electrons) and Lewis acid (accepts electrons.)
Thu Dec 10, 2020 9:45 pm
Forum: Amphoteric Compounds
Topic: Sapling 6.21
Replies: 2
Views: 50

### Sapling 6.21

The two strands of the nucleic acid DNA are held together by hydrogen bonding between four organic bases. The structure of one of these bases, thymine, is shown below. (a) How many protons can this base accept? (b) Draw the structure of each conjugate acid that can be formed. (c) Mark with an asteri...
Thu Dec 10, 2020 8:21 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Sapling 6C.17
Replies: 2
Views: 43

### Sapling 6C.17

Which is the stronger base, the hypobromite ion, BrO−, or morphine, C17H19O3N? Justify your answer. I said that BrO- was stronger because I guessed that morphine had a nitrogen with a lone pair meaning it's a weak base. Obviously I don't want to guess next time. Would I have to make the lewis struct...
Thu Dec 10, 2020 5:37 pm
Forum: Naming
Topic: Prefixes Used for Naming Compounds
Replies: 3
Views: 56

### Re: Prefixes Used for Naming Compounds

I mean I guess we could learn all of them. But the most common ones I've seen in the textbook or in problems are mono-, di-, tri-, tetra-, penta-, hexa-. I haven't seen anything more than 6 in our lectures. They are just prefixes though so I don't think it's gonna be complicated.
Thu Dec 10, 2020 5:35 pm
Forum: *Titrations & Titration Calculations
Topic: Final Exam
Replies: 3
Views: 41

### Re: Final Exam

The concepts we have taken more time to learn will be more prevalent in the final. For example, we spent a long time on quantum so we should expect more questions to be on the final rather than biological significance. Acids and bases is a huge topic that took a while to get through as well.
Thu Dec 10, 2020 5:33 pm
Forum: Identifying Acidic & Basic Salts
Topic: Classifying salts as acidic, basic, or neutral
Replies: 3
Views: 37

### Re: Classifying salts as acidic, basic, or neutral

What I do and have learned from TA sessions is to separate the salt into their conjugate bases or acids. Take LiBr for example. We separate them to Li+ (conjugate acid) and Br-(conjugate base.) Looking at the charges we look at which of them likes a positive H ion or a negative OH ion. From there we...
Mon Dec 07, 2020 10:33 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Identifying Bases
Replies: 7
Views: 74

### Re: Identifying Bases

Bases in water produce hydroxide ions (OH - ), but don't necessarily need to have OH in its formula to be called a base. For example KOH, Ca(OH) 2 , NaOH, Mg(OH) 2 all have OH and are bases. There are some bases that don't have OH but look like CaO, Li 2 O, CH 3 NH 2 that are all bases. As long as t...
Mon Dec 07, 2020 9:36 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelates
Replies: 2
Views: 57

### Re: Chelates

Chelates are any sort of coordination compound that has a central metal atom attached to a ligand in a ring-like structure. I'm gonna attach a photo to give an example of the shape. download.png Ligands that bond to the same metal ion at 2+ amount of pairs are polydentate ligands. Chelates are a typ...
Sun Dec 06, 2020 5:31 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: concept acid and bases
Replies: 3
Views: 39

### Re: concept acid and bases

Is it the entirety of the unit or a specific concept or example? I'd love to help. Khan academy and organic chemistry tutor are saviors. They break down everything very easily as well as examples for most topics.
Sun Dec 06, 2020 4:53 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Negative pH of acid
Replies: 16
Views: 92

### Re: Negative pH of acid

According to Dr. Lavelle, the range of molarity when calculating pH is 1.0M to 10 -14 M. If you plug those both into the pH equation. We get a pH range of 0-14. If our molarity was allowed to more than 1 I guess a negative pH does exist. I just don't know how you would verify with like litmus paper ...
Sun Dec 06, 2020 4:47 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Sapling #3
Replies: 7
Views: 48

### Re: Sapling #3

The Sapling question was a bit strange. It does ask you for the common complexes with a coordination number of 6. The more common one that we have generally talked about is octahedral. Square pyramid which is 5 outer atoms and 1 lone pair and Square planar which is 4 outer atoms and 2 lone pairs sti...
Sun Dec 06, 2020 4:34 pm
Forum: Naming
Topic: Naming on the Final
Replies: 4
Views: 42

### Re: Naming on the Final

My TA said that the final's questions will probably have more questions over the stuff we took more time to learn. For example, we took so much time on quantum so I would expect a huge portion of questions to be on that. We spent less than a week on Naming. However, it is still part of the final and...
Sun Dec 06, 2020 4:29 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Relative Acidity
Replies: 3
Views: 11

### Relative Acidity

Dr. Lavelle gave the example that in hypochlorous acid Cl-O-H that the electron-withdrawing atoms delocalize the negative charges, which make the resulting anion more stable. The Hypochlorous acid then turns to Cl-O and H3O+. In each of these examples, which are delta + and delta- dipoles? I'm confu...
Sun Dec 06, 2020 4:11 pm
Forum: Naming
Topic: Potassium
Replies: 8
Views: 111

### Re: Potassium

In cases of naming, it can be both. It just depends on if it's within the coordination sphere/ in the brackets or not. Usually, the ligand would have like a di-, tri-, tetra- prefix to indicate the number of ligands. But for example, K3[CoF6] is potassium-hexa-fluoro-cobaltate(III). The three potass...
Sun Dec 06, 2020 3:59 pm
Forum: Administrative Questions and Class Announcements
Replies: 13
Views: 141

The same thing was happening to me. I thought it was my internet, but my TA just said that UCLA and CCLE have been funky, so the connection has been very iffy. I couldn't get to the last five minutes of when he was talking about the trichloroacetic acid being used to remove tattoos. So not just you....
Wed Dec 02, 2020 5:34 pm
Forum: Biological Examples
Topic: Co - VitB12
Replies: 7
Views: 79

### Co - VitB12

What is the effect that Co has on Vit B12? Is it within that vitamin or does it interact with it?
Wed Dec 02, 2020 5:32 pm
Forum: Biological Examples
Topic: Cr - insulin Example
Replies: 2
Views: 92

### Cr - insulin Example

Dr. Lavelle stated that Chromium assists insulin in the control of blood sugar. Is Chromium regulated in the same way that Insulin is in the negative feedback cycle? When blood sugar goes down and the insulin is no longer needed where does the Chromium go?
Wed Dec 02, 2020 5:22 pm
Forum: Naming
Topic: Roman Numeral
Replies: 3
Views: 9

### Roman Numeral

For the Roman Numerals used to tell the oxidation number, do we calculate that based on the entire compound or just what is in the brackets (coordination sphere)?
Wed Dec 02, 2020 5:19 pm
Forum: Naming
Topic: Bis-, Tris-, Tetrakis- Ex
Replies: 1
Views: 27

### Bis-, Tris-, Tetrakis- Ex

I saw that Bis-, Tris-, Tetrakis-, etc was used to convey part of a name. What did these prefixes mean, and when would we use them? What are some examples of these... they seem more used in large compounds but idk? :) Thanks
Mon Nov 30, 2020 12:10 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Oxidation State
Replies: 3
Views: 48

### Re: Oxidation State

They are the same. The oxidation state can tell you the number of electrons that have been added or removed from an element to get to its present state. If it's positive then it means electrons were removed and if it is negative then electrons were added to the element. You can see why the oxidation...
Sun Nov 29, 2020 11:56 pm
Forum: Biological Examples
Topic: Cisplatin Bonding
Replies: 4
Views: 30

### Re: Cisplatin Bonding

As long as the 2 nitrogen have lone pairs in 2 base pairs, then the cisplatin can bond and get rid of the Cl. It may be that 2 guanines are needed because if it were only 1 guanine it would be weak and enzyme reading the base pairs would just overpower the Cisplatin.
Fri Nov 27, 2020 6:01 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: "En" Ligand Chelate Example
Replies: 1
Views: 9

### "En" Ligand Chelate Example

What did the "en" mean? Is that just to symbolize that there is a ring shape formed by chelating ligands? Is it not important to identify the groups of CH2?
Fri Nov 27, 2020 3:27 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: TM "Octet"
Replies: 4
Views: 53

### TM "Octet"

Do transition metals follow the Octet Rule? I know that they would use their d orbital which is 10 valence electrons rather than the p-orbital's six. Would this mean that they become stable with 12 valence electrons when accounting the s-block too?
Wed Nov 25, 2020 2:28 pm
Forum: Sigma & Pi Bonds
Topic: Rules of Sigma and Pi Bonds
Replies: 1
Views: 20

### Rules of Sigma and Pi Bonds

I noticed for single bonds will always be sigma bonds and double bonds will have 1 sigma and 1 pi bond. Will triple bonds always have 1 sigma and 2 pi bonds. Why can't it be 2 sigma bonds and 1 pi bond? Trying to understand why it works rather than just knowing it exists.
Wed Nov 25, 2020 2:25 pm
Forum: Hybridization
Topic: Hybridization Process
Replies: 2
Views: 16

### Hybridization Process

While doing Hybridization, I noticed that Dr. Lavelle would look at the electron density of just one carbon atom rather than the whole molecule. For example for ethylene, it seemed like he split C2H4 into 2 groups of CH2 with a double bond. Is it best to think singularly for each C atom or think of ...
Wed Nov 25, 2020 2:23 pm
Forum: Hybridization
Topic: Ethylene Example
Replies: 1
Views: 34

### Ethylene Example

Was confused about some examples when going over lectures. For hybridization for C2H4, why can't the lone electron go to the 2sp^2 orbital similar to NH3's example? Is this because the regions of e density are different?
Tue Nov 17, 2020 12:04 pm
Forum: Administrative Questions and Class Announcements
Topic: 14B and 14BL
Replies: 13
Views: 219

### 14B and 14BL

Is it best to do 14BL with 14B in winter quarter? Or is it better to just do 14BL in spring? What are your guys' schedules looking like?
Sun Nov 15, 2020 10:19 pm
Forum: Electronegativity
Topic: Zeff and Shielding
Replies: 3
Views: 17

### Re: Zeff and Shielding

Shielding refers to blocking electron attraction of the valence electrons. Lower levels shield higher levels, so when an element has a lot of electrons (has a lot of volume), there is less density. I didn't know what Zeff was until you posted it. The internet says that Zeff is effective nuclear char...
Sun Nov 15, 2020 10:10 pm
Forum: Bond Lengths & Energies
Topic: Hydrogen Bond Length
Replies: 3
Views: 15

### Re: Hydrogen Bond Length

Pretty sure the actual value or number of the bond length is not as important. A lot of different bonds we've seen in lectures or in our HW have been given to us. Lots of them are different. I think we just have to know the general idea that long bonds are weaker than shorter bonds.
Sun Nov 15, 2020 10:05 pm
Forum: Bond Lengths & Energies
Topic: Valence electrons of nitrogen
Replies: 10
Views: 64

### Re: Valence electrons of nitrogen

I think he was referring to the Nitrogen having a complete octet (8 valence electrons.) Nitrogen itself does have 5 valence electrons.
Sun Nov 15, 2020 9:59 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: Hydrogen Bonding Sites
Replies: 4
Views: 22

### Re: Hydrogen Bonding Sites

Count F, O, N sites that have a lone pair. Not C because it isn't electronegative enough I believe. Also don't forget that if there are H atoms, they count as sites to connect to other F, O, N.
Sun Nov 15, 2020 9:56 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: lodon dispersion forces
Replies: 8
Views: 17

### Re: lodon dispersion forces

All molecules have London dispersion forces. It is weak because it is a temporary dipole when electrons randomly shift. These shifts can induce other dipoles, but the London dispersion is temporary.
Thu Nov 12, 2020 4:59 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Denature of Enzyme & Polarity
Replies: 2
Views: 31

### Denature of Enzyme & Polarity

I remember in Monday's Lecture that enzymes and their active site can be denatured if they lose their shape. There are multiple ways to denature or destroy a protein, but I remember that if surrounded by a very acidic or basic solution, the acidity/basicity would destroy the tertiary structure of a ...
Fri Nov 06, 2020 10:22 pm
Forum: Lewis Structures
Topic: Lewis Bases and Lone Pair Electrons
Replies: 3
Views: 35

### Re: Lewis Bases and Lone Pair Electrons

Do Lewis bases tend to have lone pair electrons on their central atoms or lone pair electrons on any of the atoms? I think as long as you satisfy the octet rule, you should be fine. A lot of central atoms are bonded with multiple other atoms but as long as they all have 8 valence electrons, and are...
Fri Nov 06, 2020 10:15 pm
Forum: Electronegativity
Topic: lecture ex regarding bond length
Replies: 3
Views: 30

### Re: lecture ex regarding bond length

In the example Ag is paired with different electronegative atoms. F- has the least electronegativity and I- has the highest. It is mentioned how the I- forms a weaker bond. But earlier in the lecture isn't it mentioned how higher electronegativity forms a more covalent bond? Wouldn't the I- bond be...
Fri Nov 06, 2020 5:25 pm
Forum: Ionic & Covalent Bonds
Topic: Electron Affinity vs. Electronegativity
Replies: 12
Views: 72

### Electron Affinity vs. Electronegativity

Are electron affinity and electronegativity the same thing? If not, what makes them different?
Fri Nov 06, 2020 3:22 pm
Forum: Octet Exceptions
Topic: Boron Trifluoride Example
Replies: 2
Views: 43

### Boron Trifluoride Example

Dr. Lavelle did say that his BF3 was correct because Boron is an exception to the octet. However what is the benefit of making it into BF4-1 rather than double bonding two BF3together?
Fri Nov 06, 2020 3:14 pm
Forum: Octet Exceptions
Topic: Phosphorus and d-Orbital
Replies: 7
Views: 67

### Phosphorus and d-Orbital

I'm super confused with the quantum numbers/spdf and how they relate to Phosphorus in the example PCL5. Why does phosphorus use a d orbital rather than the 4s? Thanks.
Fri Oct 23, 2020 8:25 pm
Forum: Properties of Light
Topic: Emission/Absorption
Replies: 6
Views: 86

### Re: Emission/Absorption

I would rather think of n1 and n2 as N Final and E initial . We can differentiate the difference between the two so that you know what to place as both your n's. If an electron wants to go towards the nucleus, it has to emit energy. When a particle gets a little too excited and wants to calm down, i...
Thu Oct 22, 2020 10:07 pm
Forum: Molarity, Solutions, Dilutions
Topic: Solute vs Solvent
Replies: 6
Views: 152

### Solute vs Solvent

Hi!

What makes something a solvent or a solute? How can we just know? I know that solutes are dissolved in solvents to create a solution such as salt and water, respectively. However, if given two items, how would I know? What makes something soluble I guess?
Thu Oct 22, 2020 9:56 pm
Forum: Limiting Reactant Calculations
Topic: Fundamental M11A
Replies: 2
Views: 56

### Re: Fundamental M11A

You can figure out which is the limiting reactant by finding whether each is an excess or not. If you get the moles and multiply by the correct ratio of moles given in the chemical reaction, you can tell based on the differences if one is an excess or not. You don't have to choose a specific reactan...
Thu Oct 22, 2020 9:50 pm
Forum: Balancing Chemical Reactions
Topic: Chemical Compounds
Replies: 4
Views: 61

### Re: Chemical Compounds

We do not have to know the nomenclature of compounds, and he doesn't want to make it complicated. According to others, he said that he expects easier/more common ones like H20, CO2, etc. I wouldn't worry about naming and knowing every single compound. :)