Search found 60 matches

by Lauren Huang 1H
Tue Mar 12, 2019 3:26 pm
Forum: Student Social/Study Group
Topic: Studying for the Final
Replies: 25
Views: 518

Re: Studying for the Final

It's also helpful to do the modules and go to office hours!
by Lauren Huang 1H
Tue Mar 12, 2019 3:22 pm
Forum: Zero Order Reactions
Topic: zero order in rate law
Replies: 7
Views: 140

Re: zero order in rate law

You don't need to include it since anything to the zeroth power is equal to one.
by Lauren Huang 1H
Tue Mar 12, 2019 3:19 pm
Forum: Ideal Gases
Topic: units
Replies: 15
Views: 240

Re: units

Although the products and reactants involved in Kp and Kc use units such as molarity and bar, the units cancel out in the end so K is unitless.
by Lauren Huang 1H
Fri Mar 08, 2019 12:33 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: oxidizing power vs reducing power
Replies: 3
Views: 95

Re: oxidizing power vs reducing power

So the reducing agent will have a high oxidizing power, and the oxidizing agent will have a high reducing power.
by Lauren Huang 1H
Fri Mar 08, 2019 12:30 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Test 2
Replies: 12
Views: 187

Test 2

Can someone please explain why Gibbs free energy for the combustion of a gas used to heat a BBQ at a pool party is negative? Wouldn't it require be a non-spontaneous process for the combustion to occur?
by Lauren Huang 1H
Fri Mar 08, 2019 12:22 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Test 2
Replies: 4
Views: 117

Re: Test 2

I think they meant the Van't Hoff equation; it was provided to us on the equation sheet.
by Lauren Huang 1H
Tue Feb 26, 2019 11:19 pm
Forum: Ideal Gases
Topic: atm vs. bar?
Replies: 23
Views: 416

Re: atm vs. bar?

The units can be atm or bar depending on the problem. Note that this will change the value of R.
by Lauren Huang 1H
Tue Feb 26, 2019 11:17 pm
Forum: Ideal Gases
Topic: Q and K
Replies: 13
Views: 173

Re: Q and K

Q is when the reaction is not at equilibrium. K is when the reaction is at equilibrium. Q is compared to K to determine whether the reaction will shift to the left or right due to the Le Chatalier's Principle.
by Lauren Huang 1H
Tue Feb 26, 2019 11:06 pm
Forum: Balancing Redox Reactions
Topic: basic/acidic solutions
Replies: 5
Views: 70

basic/acidic solutions

How do we know if a redox reaction is acidic or basic if no H+ or OH- is given?
by Lauren Huang 1H
Mon Feb 18, 2019 9:47 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q VS. K
Replies: 13
Views: 211

Re: Q VS. K

Both can be calculated the same way. The only difference is that Q is when the reaction is not at equilibrium and K is when the reaction is at equilibrium.
by Lauren Huang 1H
Mon Feb 18, 2019 9:44 pm
Forum: Student Social/Study Group
Topic: Midterms
Replies: 5
Views: 89

Re: Midterms

You should be able to ask for regrading. Just let your TA know and he/she should be able to help with that.
by Lauren Huang 1H
Mon Feb 18, 2019 9:34 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Final exam
Replies: 8
Views: 165

Re: Final exam

The final exam should be on Sunday, March 17 at 11:30am-2:30pm
by Lauren Huang 1H
Fri Feb 15, 2019 2:49 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Liquid and moles
Replies: 8
Views: 181

Re: Liquid and moles

H20 (l) is not included in the equation because water is in a much larger quantity in comparison to the rest of the reactants so the change in its concentration during a reaction is negligible.
by Lauren Huang 1H
Fri Feb 15, 2019 2:47 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs free energy
Replies: 5
Views: 82

Re: Gibbs free energy

Also, Dr. Lavelle said in lecture that Gibbs free energy only refers to situations where the system is not at equilibrium, since delta G when the system is at equilibrium is zero.
by Lauren Huang 1H
Fri Feb 15, 2019 2:46 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Q. 9.47
Replies: 1
Views: 59

Q. 9.47

Question 9.47 in the sixth edition says: Initially a sample of ideal gas at 323 K occupies 1.67 L at 4.95 atm. The gas is allowed to expand to 7.33 L by two pathways: (a) isothermal, reversible expansion; (b) isothermal, irreversible free expansion. Calculate deltaS(tot), deltaS(sys), and deltaS(sur...
by Lauren Huang 1H
Wed Feb 06, 2019 5:01 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Q. 8.27
Replies: 1
Views: 52

Q. 8.27

Question 8.27 from the 6th edition says: Calculate the work for each of the following processes beginning with a gas sample in a piston assembly with T = 305 K, P = 1.79 atm, and V = 4.29 L: (a) irreversible expansion against a constant external pressure of 1.00 atm to a final volume of 6.52 L; (b) ...
by Lauren Huang 1H
Wed Feb 06, 2019 4:50 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Unit for Heat Capacity
Replies: 2
Views: 72

Unit for Heat Capacity

Question 8.43 for the 6th edition give the heat capacities of the different states in units of J/mol. Why is this? I thought the definition of heat capacity is the heat required to raise the temperature of an object by one degree. Wouldn't the units have to include degrees celsius or Kelvin?
by Lauren Huang 1H
Wed Feb 06, 2019 4:30 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: What is q equal to in the second law of thermodynamics?
Replies: 5
Views: 163

Re: What is q equal to in the second law of thermodynamics?

The second law of thermodynamics states that delta S=q/T=nRln(V2/V1). So q=nRTln(V2/V1) if you multiply both sides by temperature. I believe the unit for q is Joules.
by Lauren Huang 1H
Mon Jan 28, 2019 8:52 pm
Forum: Phase Changes & Related Calculations
Topic: Week 4 Homework
Replies: 12
Views: 184

Re: Week 4 Homework

I believe Week 4 HW should be on the questions in the Thermodynamics section.
by Lauren Huang 1H
Mon Jan 28, 2019 8:50 pm
Forum: Ideal Gases
Topic: pH and pOH
Replies: 18
Views: 308

Re: pH and pOH

Also, when your chemical reaction includes H30+, you are finding the pH, and when it includes OH-, you are finding the pOH. Make sure to use the equation pH+pOH=14 if you are trying to convert between the two.
by Lauren Huang 1H
Mon Jan 28, 2019 8:42 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Extensive
Replies: 4
Views: 75

Re: Extensive

State property is a quantity that is determined by its current state but is not dependent on the path taken to obtain that state (ex: altitude, volume). Extensive property is a property of matter that depends on the amount of substance (ex: heat capacity).
by Lauren Huang 1H
Mon Jan 21, 2019 9:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Table 11.2
Replies: 1
Views: 47

Table 11.2

Table 11.2 has two columns of equilibrium constants denoted K and Kc. While the values are similar for the first few equations, it differs in the latter half. Does anyone know the difference between the two?
by Lauren Huang 1H
Mon Jan 21, 2019 8:02 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: calculating x cubically
Replies: 2
Views: 41

Re: calculating x cubically

I don't think we will have to know how to do that for this class. Here's the link that Dr. Lavelle sent out in an email on solving cubics: viewtopic.php?f=49&t=40016
by Lauren Huang 1H
Mon Jan 21, 2019 7:50 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pka and ka
Replies: 1
Views: 33

Re: Pka and ka

The lower the pKa, the higher the corresponding Ka is, which relates to increasing acid strength (stronger acids).
by Lauren Huang 1H
Mon Jan 14, 2019 12:20 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Converting Kc to Kp
Replies: 3
Views: 130

Converting Kc to Kp

Do we convert Kc to Kp or vice versa the same way we do for converting individual concentrations/partial pressures using P=(n/V)*(RT)?
by Lauren Huang 1H
Mon Jan 14, 2019 12:15 am
Forum: Student Social/Study Group
Topic: New to Lavelle
Replies: 32
Views: 614

Re: New to Lavelle

I personally think going to office hours is also really helpful since it is a good way to get some answers to the questions you might have after doing the homework problems.
by Lauren Huang 1H
Mon Jan 14, 2019 12:12 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Chemical Equilibrium Pt. 4 Module Q. 14
Replies: 1
Views: 58

Chemical Equilibrium Pt. 4 Module Q. 14

14. The two air pollutants SO2 and NO2 can react in the atmosphere as follows: SO2 (g) + NO2 (g) ⇌ SO3 (g) + NO (g) Predict the effect of the following changes to the amount of NO when the reaction above has come to equilibrium in a stainless steel bulb equipped with entrants for chemicals. i. The a...
by Lauren Huang 1H
Sat Jan 12, 2019 5:22 pm
Forum: General Science Questions
Topic: Week 1 Homework
Replies: 5
Views: 108

Re: Week 1 Homework

I think we were also allowed to turn in our homework during discussion for Week 1. It should be fine as long as you turned it in by the Friday lecture.
by Lauren Huang 1H
Sat Jan 12, 2019 5:15 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: partial pressures vs concentrations
Replies: 4
Views: 49

Re: partial pressures vs concentrations

If the reactants or products are gases, then you can usually use either Kp or Kc. However, you can only use Kc for reactions involving aqueous solutions.
by Lauren Huang 1H
Sat Jan 12, 2019 5:13 pm
Forum: Ideal Gases
Topic: Pv=nRT [ENDORSED]
Replies: 12
Views: 177

Re: Pv=nRT [ENDORSED]

Since there are multiple values of R, make sure the units of the R you are using cancel out/correspond with the other units in the equation.
by Lauren Huang 1H
Mon Dec 03, 2018 6:00 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: AXE formula
Replies: 19
Views: 882

Re: AXE formula

Yes, the AXE formula can help you draw the shape of the structure, but it will not tell you the elements involved.
by Lauren Huang 1H
Mon Dec 03, 2018 5:54 pm
Forum: Hybridization
Topic: s character
Replies: 3
Views: 61

Re: s character

It's essentially saying that the trend for s-character is the inverse of the trend for p-character.
by Lauren Huang 1H
Mon Dec 03, 2018 5:44 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 3
Replies: 4
Views: 139

Test 3

Will be get our test 3 back during discussion this week?
by Lauren Huang 1H
Wed Nov 28, 2018 11:44 am
Forum: Lewis Structures
Topic: lewis structure
Replies: 2
Views: 65

Re: lewis structure

The triple bond to nitrogen and single bond to chlorine would also be preferable since it satisfies the octet rule for carbon.
by Lauren Huang 1H
Wed Nov 28, 2018 11:41 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles Preference
Replies: 2
Views: 62

Bond Angles Preference

Would it be ok if I wrote the bond angles for 3 bonds pairs and 1 lone pair to be 107.5, and the bond angles for 2 bond pairs and 2 lone pairs to be 104.5? Or would writing "less than 109.5 degree" be preferred?
by Lauren Huang 1H
Wed Nov 28, 2018 11:38 am
Forum: Hybridization
Topic: pi vs sigma
Replies: 12
Views: 219

Re: pi vs sigma

The head of the sigma bonds overlap directly while the pi bonds overlap laterally since they are parallel to each other, so it is easier to break the pi bonds.
by Lauren Huang 1H
Sat Nov 24, 2018 7:08 pm
Forum: Bond Lengths & Energies
Topic: Single, Double, Triple Bond Lengths
Replies: 5
Views: 111

Re: Single, Double, Triple Bond Lengths

This is because the additional bonding of electrons attracts the nuclei of the bonded atoms closer to each other.
by Lauren Huang 1H
Sat Nov 24, 2018 7:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lewis Structure N2O
Replies: 4
Views: 85

Re: Lewis Structure N2O

This rule usually applies to most structures, where the central atom is the element with the lowest ionization energy and least electronegativity.
by Lauren Huang 1H
Sat Nov 24, 2018 7:00 pm
Forum: Sigma & Pi Bonds
Topic: Sigma and Pi bonds
Replies: 5
Views: 137

Re: Sigma and Pi bonds

They might also ask us about the differences between the two types of bonds.
by Lauren Huang 1H
Sat Nov 17, 2018 10:53 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Structure
Replies: 1
Views: 51

Molecular Structure

If the two lone pairs of Xe in XeF4 are placed opposite each other due to electron repulsion, why is it that the two lone pairs in H20 are placed next to each other?
by Lauren Huang 1H
Sat Nov 17, 2018 10:51 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Test 3
Replies: 19
Views: 286

Re: Test 3

Memorizing them would definitely help you do the problems faster and focus on other parts of the problem.
by Lauren Huang 1H
Sat Nov 17, 2018 9:40 pm
Forum: Hybridization
Topic: Hybridization Notation
Replies: 2
Views: 72

Hybridization Notation

Are the notations that we are learning for hybridization only sp,sp2,and sp3?
by Lauren Huang 1H
Sat Nov 10, 2018 10:33 am
Forum: Student Social/Study Group
Topic: Sig Figs on Midterm
Replies: 13
Views: 471

Re: Sig Figs on Midterm

I would stick to the sig figs rules just to be safe.
by Lauren Huang 1H
Sat Nov 10, 2018 10:31 am
Forum: Balancing Chemical Reactions
Topic: Combustion Equation
Replies: 18
Views: 668

Re: Combustion Equation

Sometimes nitrogen can be an added reactant and product of the equation.
by Lauren Huang 1H
Sat Nov 10, 2018 10:25 am
Forum: Determining Molecular Shape (VSEPR)
Topic: HW for discussion
Replies: 9
Views: 214

Re: HW for discussion

I did the problems after 3.11 since I believe professor Lavelle said we only needed to know the questions up to 3.11 for the midterm test
by Lauren Huang 1H
Wed Oct 31, 2018 12:44 am
Forum: Lewis Structures
Topic: Exception to Octet Rule [ENDORSED]
Replies: 3
Views: 75

Re: Exception to Octet Rule [ENDORSED]

Some common elements that have expanded octets are sulfur, phosphorus, silicon, and chlorine.
by Lauren Huang 1H
Wed Oct 31, 2018 12:29 am
Forum: Ionic & Covalent Bonds
Topic: 6th Edition, Question 3.5
Replies: 3
Views: 74

Re: 6th Edition, Question 3.5

Chromium and copper are the two main exceptions to electron configuration. For both elements, an electron from 4s subshell is moved to 3d subshell to make a half full 3d (3d^5) for chromium and a full 3d (3d^10) for Copper, since doing so makes the atom more stable. So for this problem, Cu at ground...
by Lauren Huang 1H
Tue Oct 30, 2018 10:41 pm
Forum: Hybridization
Topic: Question 2.43
Replies: 4
Views: 134

Question 2.43

When writing out the electron configuration for silver and antimony, why is 4d^10 before 5s when 4d^10 is after 5s in the periodic table?
by Lauren Huang 1H
Fri Oct 26, 2018 4:38 pm
Forum: Properties of Light
Topic: Speed of Light
Replies: 12
Views: 260

Speed of Light

Can nothing be faster than the speed of light?
by Lauren Huang 1H
Fri Oct 26, 2018 4:35 pm
Forum: Quantum Numbers and The H-Atom
Topic: Principal Quantum Number - Periodic Table
Replies: 2
Views: 80

Principal Quantum Number - Periodic Table

Why is it that 3d is not on the same level as 3s and 3p on the periodic table?
by Lauren Huang 1H
Wed Oct 24, 2018 12:43 am
Forum: Trends in The Periodic Table
Topic: Test 2
Replies: 3
Views: 99

Test 2

Will Test 2 covers all the questions from Ch. 2 since the questions cover electron affinity, atomic radius, ionic radius, ionization energy and the periodic trends? And if not, up to which questions would you say the test covers?
by Lauren Huang 1H
Tue Oct 16, 2018 11:12 pm
Forum: Quantum Numbers and The H-Atom
Topic: Atomic Spectra Module Question 44
Replies: 1
Views: 55

Atomic Spectra Module Question 44

Can someone help me explain how to do this question? 44. In the hydrogen atomic spectrum, what is the wavelength of light associated with the n = 4 to n = 1 electron transition? What part of the electromagnetic spectrum is this wavelength? Also will we be required to know the electromagnetic spectru...
by Lauren Huang 1H
Tue Oct 16, 2018 10:57 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Wavelengths
Replies: 5
Views: 116

Wavelengths

Can wavelengths have negative values?
by Lauren Huang 1H
Tue Oct 16, 2018 10:55 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Negative Signs
Replies: 2
Views: 65

Negative Signs

What does it mean when the answer from using the equation (E=-hR/n^2+hR/n^2) to find the energy difference between two energy levels in a H-atom comes out to be negative?
by Lauren Huang 1H
Tue Oct 09, 2018 3:49 pm
Forum: Properties of Light
Topic: Exam
Replies: 7
Views: 141

Re: Exam

You can also go to the TAs office hours or UA peer learning sessions.
by Lauren Huang 1H
Tue Oct 09, 2018 3:46 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 1 Study Plan
Replies: 6
Views: 171

Re: Test 1 Study Plan

You still need a new set of 7 problems (from Fundamentals or The Quantum World) by your discussion though, so make sure to finish those before then.
by Lauren Huang 1H
Tue Oct 09, 2018 2:21 pm
Forum: Molarity, Solutions, Dilutions
Topic: Question G13 (Sixth Edition)
Replies: 3
Views: 166

Question G13 (Sixth Edition)

Can someone please explain how to do G13? It says: "To prepare a fertilizer solution, a florist dilutes 1.0 L of 0.20 m NH4NO3(aq) by adding 3.0 L of water. The florist then adds 100. mL of the diluted solution to each plant. How many moles of nitrogen atoms will each plant receive? Solve this ...
by Lauren Huang 1H
Fri Oct 05, 2018 1:35 am
Forum: Limiting Reactant Calculations
Topic: multiple limiting reactants
Replies: 9
Views: 161

Re: multiple limiting reactants

Yea, when I took the online module that had this question, the correct answer was no (there cannot be more than one limiting reactant). This makes sense because if there were two reactants with the same mole ratio, then neither one would limit the other since they were both consumed completely in th...
by Lauren Huang 1H
Fri Oct 05, 2018 1:29 am
Forum: Balancing Chemical Reactions
Topic: Balancing reactions tips
Replies: 29
Views: 759

Re: Balancing reactions tips

Make sure to double check your answer before you move on! Sometimes I make a couple of arithmetic mistakes without knowing, so make sure you check that both sides have the same number of elements.
by Lauren Huang 1H
Fri Oct 05, 2018 1:24 am
Forum: Empirical & Molecular Formulas
Topic: Empirical formula from MPC
Replies: 3
Views: 72

Re: Empirical formula from MPC

There are no decimals used in empirical formulas so you would have to divide the moles by the smallest number of moles calculated and round to the nearest whole number. So in this problem, you would use the molar ratio 3 : 4 : 3

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