Search found 44 matches

by Brian Kwak 4H
Sun Feb 17, 2019 1:09 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Heat and Entropy
Replies: 3
Views: 21

Re: Heat and Entropy

It is a multi-step process where first you use q=nCΔt and rearrange the equation to solve for the specific heat because the specific heat is needed to solve for ΔS=nCln(T2/T1).
by Brian Kwak 4H
Sun Feb 17, 2019 1:05 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: adding entropy
Replies: 5
Views: 22

Re: adding entropy

If you are referring to the changes in entropy due to changes in temperature and volume then yes. Since entropy is a state function. You can add the entropy values due to changes in volume and temperature.
by Brian Kwak 4H
Sun Feb 17, 2019 12:54 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Adding reaction entropies
Replies: 8
Views: 19

Re: Adding reaction entropies

Entropy is a STATE FUNCTION. So therefore entropy is path independant meaning that you only need the final and initial values to calculate the entropy.
by Brian Kwak 4H
Mon Feb 11, 2019 2:50 pm
Forum: Administrative Questions and Class Announcements
Topic: Thermochemistry Review Packet
Replies: 4
Views: 67

Re: Thermochemistry Review Packet

Thank you for the review session! I also thank you for posting these notes to help supplement my own notes and conceptual understanding of the material!
by Brian Kwak 4H
Fri Feb 08, 2019 4:56 pm
Forum: Ideal Gases
Topic: atm vs. bar?
Replies: 17
Views: 109

Re: atm vs. bar?

I think the most important part for atm and bar is to be consistent with the units throughout the calculations so you don’t get points deducted. I would really pay attention to the wording of the problem if they give you atm then just use atm throughout your calculations. Consistency is important, t...
by Brian Kwak 4H
Fri Feb 08, 2019 4:50 pm
Forum: Ideal Gases
Topic: Lyndon's review session
Replies: 7
Views: 118

Re: Lyndon's review session

Lyndon is a very busy man... he hasn’t made the worksheets yet but he will over the weekend from what he told me. I believe it will be named hotdog because Dr.lavelle made a joke about naming it that and ... maybe just maybe it will be named HOTDOG! But don’t quote me on that. Also the time is at 7p...
by Brian Kwak 4H
Fri Feb 08, 2019 4:45 pm
Forum: Ideal Gases
Topic: Reading the textbook [ENDORSED]
Replies: 74
Views: 25295

Re: Reading the textbook [ENDORSED]

I read the textbook but in a very organized way. Since there is a lot of information in the textbook which can sometimes make it confusing and hinders your comprehension. I use the outlines for each section and cater my reading to focus on the things that were on the outline. For example I would rea...
by Brian Kwak 4H
Fri Feb 08, 2019 4:26 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Useful Summary of Thermodynamic Definitions
Replies: 21
Views: 13037

Re: Useful Summary of Thermodynamic Definitions

Just asking for clarification but for an Adiabatic isolated system as dr.lavelle stated that there can be exchange or more specificly loss of internal energy as work correct? So compared to an isolated system where there is no exchange of matter or energy because there is no surroundings therefore m...
by Brian Kwak 4H
Fri Feb 08, 2019 4:17 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Adiabatic isolated system vs isolated system.
Replies: 1
Views: 17

Adiabatic isolated system vs isolated system.

Could anyone help me with these two terms. I know that a adiabatic isolated system is one with adiabatic boundaries where energy can leave as work and there is no exchange in matter or energy. An isolated system is one where there is no exchange of energy and matter. I am having difficulty understan...
by Brian Kwak 4H
Wed Jan 30, 2019 4:32 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Best Method
Replies: 7
Views: 49

Re: Best Method

Methods one and three are more accurate than method 2. The reason is because for the bond enthalpy chart, it has the average values of the bond enthalpies and doesn’t take into consideration the reaction. Methods 1 and 3 should yield similar results that are more accurate than method 2. It really de...
by Brian Kwak 4H
Wed Jan 30, 2019 4:19 pm
Forum: Phase Changes & Related Calculations
Topic: Standard State
Replies: 6
Views: 26

Re: Standard State

Two elements are liquid in their standard state: mercury and bromine. Eleven elements are gas in their standard state. All of the noble gases (He, Ne, Ar, Kr, Xe, Rn) as well the halogens flourine and chlorine. Hydrogen, oxygen and nitrogen are the others. All other elements are solid in their stand...
by Brian Kwak 4H
Wed Jan 30, 2019 4:15 pm
Forum: Phase Changes & Related Calculations
Topic: Standard entalpy of formation
Replies: 6
Views: 20

Re: Standard entalpy of formation

Molecules in their standard state (most stable) have an standard enthalpy formation of zero. It is important to note “Standard” which refers to a specific pressure which is 1 atm and a specific heat which is 25 degrees celcius. If a molecule is in its most stable state at 1 atm and 25 degrees celciu...
by Brian Kwak 4H
Thu Jan 17, 2019 10:59 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Acid and Base Equilibria
Replies: 7
Views: 31

Re: Acid and Base Equilibria

I also wanted to input that pH is also related to the concentration of Hydronium ions (H3O+). For example if you have a pH of 1 to convert that into concentration you would take the antilog of -1 (The reason you take the antilog is because pH=-log[H3O+] and we know that the ph is 1 so we solve for t...
by Brian Kwak 4H
Thu Jan 17, 2019 10:27 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: sig figs
Replies: 4
Views: 39

Re: sig figs

I posted a photo further specifying significant figures for logs. But as it states on dr Lavelles PDF of “More on Significant figures” how ever many significant figures in the number your calculating is how ever many significant figures you have after the calculation.
by Brian Kwak 4H
Thu Jan 17, 2019 10:19 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6A.23
Replies: 2
Views: 19

Re: 6A.23

Sorry could you specify what question it is? Also there is a solution manual errors pdf on Dr.Lavelles website (Chemistry Community). All solution manual errors would be on that pdf. If its not on there then you could always back track to see if there were any errors calculating.
by Brian Kwak 4H
Fri Jan 11, 2019 2:47 pm
Forum: Ideal Gases
Topic: Use of the Ideal Gas law vs Combined Gas Law
Replies: 2
Views: 15

Re: Use of the Ideal Gas law vs Combined Gas Law

Thank You for the clarification! So, can I assume that if Professor Lavelle asks a question pertaining to finding Pressure, Temperature, Moles, or Volume to use the Ideal gas constant to calculate it, if I am given the other variables?
by Brian Kwak 4H
Fri Jan 11, 2019 10:45 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework 11.39 Edition 6
Replies: 4
Views: 49

Re: Homework 11.39 Edition 6

We multiple it because we want to find the K(constant) for the given equation: 2BrCl(g) + H2(g) =(this is suppose to be the forward and reverse reaction) Br2(g) + 2 HCl(g). If you derive the Equilibrium constant for this equation it gives you: ([HCl]^2 [Br]^2)\([Brcl]^2 [H2]) If you add the equation...
by Brian Kwak 4H
Fri Jan 11, 2019 10:33 am
Forum: Ideal Gases
Topic: Use of the Ideal Gas law vs Combined Gas Law
Replies: 2
Views: 15

Use of the Ideal Gas law vs Combined Gas Law

I am confused of when to use the Combined Gas Law. I know that if I am give moles and other information that I can calculate for Pressure, Temperature, or Volume, but when would I have to use the Combined Gas Law? If they change the variable and ask a question where the volume and temperature change...
by Brian Kwak 4H
Thu Jan 10, 2019 10:49 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework 11.39 Edition 6
Replies: 4
Views: 49

Re: Homework 11.39 Edition 6

If I am not mistaken it is because when you multiple K1 and K2 (the equilibrium constant equation for both of the given chemical reactions) you the equilibrium constant for the given equation after you do the algebra and cancel out the Cl2. It makes more sense when you write out the Equilibrium cons...
by Brian Kwak 4H
Fri Dec 07, 2018 12:54 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Calculate the strength of an acid?
Replies: 3
Views: 29

Re: Calculate the strength of an acid?

I don’t think we have to since it wasn’t really covered in lecture from what i remember, but i would remember the how to calculate pH and pOh which is -log[H] and -log[OH].
by Brian Kwak 4H
Fri Dec 07, 2018 12:52 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Final Exam
Replies: 3
Views: 41

Final Exam

What exactly do we need to know from this section for the final exam?
by Brian Kwak 4H
Fri Dec 07, 2018 12:45 pm
Forum: Trends in The Periodic Table
Topic: Ionization Energy and Electron Affinity Trend Exceptions
Replies: 2
Views: 56

Re: Ionization Energy and Electron Affinity Trend Exceptions

Also wanted to stated that the trend also applies to electronegativity as well.
Decreases down a column and increases acreage the row.
by Brian Kwak 4H
Sun Nov 25, 2018 9:32 am
Forum: Determining Molecular Shape (VSEPR)
Topic: How to state bond angles.
Replies: 7
Views: 51

Re: How to state bond angles.

Answering with slightly less than 109.5 is what Lavelle probably expects. From speaking with friends that took this course previously that would suffice for an answer.
by Brian Kwak 4H
Sun Nov 25, 2018 9:06 am
Forum: Bond Lengths & Energies
Topic: Single, Double, Triple Bond Lengths
Replies: 5
Views: 56

Re: Single, Double, Triple Bond Lengths

Single > double > triple bonds. My thought process is that since double and triple bonds have pi bonds, which are overlap/side-to-side orbital interactions the bonds have to be closer than a single.
by Brian Kwak 4H
Sun Nov 25, 2018 8:54 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Linear structure with lone pairs
Replies: 6
Views: 46

Re: Linear structure with lone pairs

AX2, AXE, AXE2, and AX2E3 are the only linear structures.
by Brian Kwak 4H
Sat Nov 03, 2018 9:25 pm
Forum: Trends in The Periodic Table
Topic: Periodic trends
Replies: 4
Views: 27

Re: Periodic trends

Thank you guys for posting this. Missed some lectures due to a concussion and you guys just saved my life.
by Brian Kwak 4H
Sat Nov 03, 2018 9:17 pm
Forum: *Particle in a Box
Topic: Midterm
Replies: 14
Views: 390

Re: Midterm

Sorry I cant find the midterms from last year would the person that found it be so kind enough to elaborate so use laymen can find it to practice?
by Brian Kwak 4H
Sat Nov 03, 2018 9:10 pm
Forum: Administrative Questions and Class Announcements
Topic: Cheat sheet or open notes? [ENDORSED]
Replies: 2
Views: 67

Re: Cheat sheet or open notes? [ENDORSED]

No cheat sheets sorry. I asked people that previously took this course and nope there will not be any cheet sheets or open notes allowed. The periodic table and list of constants and equations will be given unless things have changed like the last 2-3 quarters.
by Brian Kwak 4H
Sat Nov 03, 2018 9:06 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Layout
Replies: 3
Views: 69

Re: Midterm Layout

Its completely free response.
by Brian Kwak 4H
Sat Nov 03, 2018 8:52 pm
Forum: DeBroglie Equation
Topic: Momentum
Replies: 10
Views: 152

Re: Momentum

I would recommend using a systematic approach to these kinds of problems. Just write the equation that you need to use to find the answer and if you don’t have all relevant information for that equation them most likely you would have to use another equation like de Broglie to get that information a...
by Brian Kwak 4H
Sat Nov 03, 2018 8:28 pm
Forum: Coordinate Covalent Bonds
Topic: Coordinate Covalent Bond Definition
Replies: 14
Views: 297

Re: Coordinate Covalent Bond Definition

Thanks for clarifying!
by Brian Kwak 4H
Sat Nov 03, 2018 8:26 pm
Forum: Resonance Structures
Topic: Determine Number of Resonance Structures
Replies: 2
Views: 48

Re: Determine Number of Resonance Structures

I don’t think knowing the possible resonance structures would be important. Working through some of the practice exams I got didn’t see any questions where they asked to draw all resonance structures or asking how many possible ones there are. So far I have been drawing the most stable Lewis structu...
by Brian Kwak 4H
Sat Nov 03, 2018 7:53 pm
Forum: Photoelectric Effect
Topic: Question on kinetic energy
Replies: 5
Views: 61

Re: Question on kinetic energy

Thank you for the clarification.
by Brian Kwak 4H
Sat Nov 03, 2018 7:51 pm
Forum: Quantum Numbers and The H-Atom
Topic: Exceptions to the Octet Rule
Replies: 2
Views: 44

Re: Exceptions to the Octet Rule

Thank you for these explanations. Y’all are my heroes.
by Brian Kwak 4H
Sat Nov 03, 2018 7:45 pm
Forum: Trends in The Periodic Table
Topic: Ionic Radius
Replies: 2
Views: 30

Re: Ionic Radius

From my limited understanding Protons are what you should be mainly concerned about because the protons are what gives a positive charge for the electrons to be attracted to. Therefor the more protons the higher the positive charge and therefor electrons will be closer to the nucleus.
by Brian Kwak 4H
Sat Nov 03, 2018 7:37 pm
Forum: Photoelectric Effect
Topic: Kinetic energy
Replies: 8
Views: 92

Re: Kinetic energy

As stated before the Formula is used only to find the Kinetic energy but if you don’t have all the requested information I’m pretty sure you can also use de Broglie equation to help you find that portion. Since the equation is KE= 1/2 MV^2 and you don’t have velocity you can use de Broglie’s equatio...
by Brian Kwak 4H
Sat Nov 03, 2018 7:31 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic vs Covalent Bonds
Replies: 18
Views: 151

Re: Ionic vs Covalent Bonds

I just had a question. For Ionic and Covalent bonds would it be specifically one or would it be more accurate to say its one a spectrum? For example a Bond would have more ionic properties than covalent?
by Brian Kwak 4H
Sat Nov 03, 2018 7:27 pm
Forum: Lewis Structures
Topic: Memorizing chemical formulas from their names?
Replies: 3
Views: 35

Re: Memorizing chemical formulas from their names?

From what my TA said there will be a few common ions that we will have to remember. Didn’t really specify which ones so I understand your pain. Just to be safe though I am remembering all the common ions that Lavelle posted on his site. But I think as long as you know the suffix and prefixes for ion...
by Brian Kwak 4H
Fri Oct 12, 2018 9:04 am
Forum: General Science Questions
Topic: Exams.
Replies: 2
Views: 107

Exams.

Will the formulas and constants always be given on the exams? I’m asking because for test 1 will we always be given them? Or will we have to memorize them as we go like for the midterms and finals?
by Brian Kwak 4H
Fri Oct 12, 2018 8:59 am
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student [ENDORSED]
Replies: 86
Views: 25124

Re: Advice from a Medical Student [ENDORSED]

Thank you for the advice its very helpful since I will be taking the mcat sometime next year.
by Brian Kwak 4H
Fri Oct 12, 2018 8:51 am
Forum: Administrative Questions and Class Announcements
Topic: Audio-Visual Assignments
Replies: 4
Views: 46

Re: Audio-Visual Assignments

No its not part of our grade. Looking at the syllabus it says nothing about the audio visual assignments. I believe its there to help the students that are rusty with chem topics before taking this like such as myself ...
by Brian Kwak 4H
Fri Oct 12, 2018 8:46 am
Forum: Student Social/Study Group
Topic: Step-up program
Replies: 1
Views: 81

Step-up program

Does anyone know if the step up program covers material that the professor covere that week or if they also help with previous weeks materials if we are still struggling even after the practice questions/homework??
by Brian Kwak 4H
Fri Oct 12, 2018 8:39 am
Forum: Empirical & Molecular Formulas
Topic: Empirical & Molecular Formulas
Replies: 11
Views: 327

Re: Empirical & Molecular Formulas

Yes the molecular and empirical formulas can be the same. Just remember to calculate the molar mass of said compound. Since the empirical formula is the ratio of atoms in relation to the element with the lowest moles.

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