Search found 51 matches

by Brandon Fujii 1K
Thu Mar 15, 2018 5:03 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 8.49
Replies: 2
Views: 96

Re: 8.49

I think that we assume that this is an ideal gas because we assume that it only interacts with the water vapor and is not affected by other external forces.
by Brandon Fujii 1K
Thu Mar 15, 2018 4:58 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Collision theory for Reaction Mechanisms
Replies: 2
Views: 98

Re: Collision theory for Reaction Mechanisms

Hi if I recall correctly, Dr. Lavelle gave the example of the throwing tennis balls in the air. The probability of throwing three balls in the air and having them collide at the exact same time is lower than the probability of throwing two balls in the air and having them collide at the exact same t...
by Brandon Fujii 1K
Thu Mar 15, 2018 4:38 pm
Forum: *Amines
Topic: Memorization
Replies: 2
Views: 201

Re: Memorization

Here are the connections that I made for each functional group Alcohol --> Ether (The H in OH becomes an R group) Alcohol --> Aldehyde (Dehydrogenation OH becomes H + O) Aldehyde --> Ketone (H becomes R group = reason why Ketone is in the middle of the carbon chain unlike Aldehydes which are found a...
by Brandon Fujii 1K
Sat Mar 10, 2018 5:45 pm
Forum: Second Order Reactions
Topic: 15.35
Replies: 6
Views: 324

Re: 15.35

We cannot simply multiply the half life by a factor of 4 because the half life of a second order reaction is reliant on the initial concentration of the reactant (while the first order half life reaction only relies on the equilibrium constant.) Second order half life equation: 1/k[A] o First order ...
by Brandon Fujii 1K
Sat Mar 10, 2018 5:38 pm
Forum: Experimental Details
Topic: Homework Problem 15.3 Part C
Replies: 5
Views: 228

Re: Homework Problem 15.3 Part C

Note that the unique rate is the rate of formation, and the rate of formation for reactants is negative (because reactants are consumed in the reaction). Therefore, we must put a negative sign in front of the reactant's rate of formation to give it a positive value that equals the positive rate of f...
by Brandon Fujii 1K
Sat Mar 10, 2018 5:33 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Negative Order
Replies: 7
Views: 321

Re: Negative Order

A negative first order would occur if a the rate is halved when the concentration of a reactant is doubled.
by Brandon Fujii 1K
Sat Mar 03, 2018 9:27 pm
Forum: General Rate Laws
Topic: half-life
Replies: 8
Views: 181

Re: half-life

Half life can also tell you how fast a substance decays.

ie. A substance that has a half life of 10 seconds has a faster rate of decay in comparison to a substance that has a half life of 10 days.
by Brandon Fujii 1K
Sat Mar 03, 2018 9:22 pm
Forum: General Rate Laws
Topic: Test 3 - Derivations
Replies: 4
Views: 143

Re: Test 3 - Derivations

Although the formulas for Rate Laws and Integrated Rate Laws are given, it is helpful to know how to derive the integrated rate law to have a better understanding of the concepts.
by Brandon Fujii 1K
Sat Mar 03, 2018 2:46 pm
Forum: First Order Reactions
Topic: Naming Orders
Replies: 3
Views: 121

Naming Orders

I know that the overall reaction order for:

RATE= k[NH4+]n [NO2-]m

is n+m (if n=1 and m=1) the overall reaction rate is 2

But what do we call the individual orders (only n or only m)?
by Brandon Fujii 1K
Fri Feb 23, 2018 7:49 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Solving for Q when given molarity and partial pressure
Replies: 3
Views: 141

Solving for Q when given molarity and partial pressure

How do we solve for Q when we are given both molarity and partial pressure?

What if the partial pressures in 14.37a were different?
by Brandon Fujii 1K
Fri Feb 23, 2018 7:39 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Inert Electrode
Replies: 4
Views: 117

Re: Inert Electrode

Without an inert solid metal conductor, a cell with only aqueous ions would not be able to transfer electrons from the anode to the cathode.
by Brandon Fujii 1K
Fri Feb 23, 2018 7:34 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Finding n
Replies: 15
Views: 613

Re: Finding n

An example might be: if the oxidation half reaction produces 2 mol of e- and reduction half reaction produces 3 mol of e- you’d have to multiply the oxidation half rxn by a factor of 3 and the reduction half rxn by a factor of 2 because the moles of e- must cancel in this case 2mol e- * 3 = 6mol e- ...
by Brandon Fujii 1K
Sat Feb 17, 2018 8:38 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Adiabatic Reaction
Replies: 2
Views: 106

Re: Adiabatic Reaction

Additionally, if you were asked when does Delta U = q, your answer would be:

When w=0 because Delta U=w and q=0 under adiabatic conditions
by Brandon Fujii 1K
Sat Feb 17, 2018 8:34 pm
Forum: Balancing Redox Reactions
Topic: Cl2 and Cl -
Replies: 2
Views: 89

Re: Cl2 and Cl -

If you are wondering why Cl2 has an oxidation number of 0, it is because neutral uncombined atoms or atoms in pure element is assigned an oxidation number of 0.

ex. Cl2(g), Na(s), Hg(l)
by Brandon Fujii 1K
Sat Feb 17, 2018 8:20 pm
Forum: Balancing Redox Reactions
Topic: Oxidizing & Reducing Agents
Replies: 6
Views: 152

Re: Oxidizing & Reducing Agents

In the image below, the Reducing Agent (A) is oxidized because it loses its electrons. The Oxidizing Agent (B) is reduced because it gains electrons.
by Brandon Fujii 1K
Fri Feb 09, 2018 9:36 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.43 Using Cp vs Cv?
Replies: 2
Views: 123

Re: 9.43 Using Cp vs Cv?

You would only use the Cv,m and Cp,m values (3/2R, 5/2R, etc) as the heat capacity for ideal gases. Additionally, if water were a vapor, Cp,m would equal 4R not 5/2R because water is a nonlinear molecule.
by Brandon Fujii 1K
Fri Feb 09, 2018 9:18 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 9.57 [ENDORSED]
Replies: 1
Views: 89

9.57 [ENDORSED]

Can someone explain why the units for the answers are "kJ/mol"? Since we are decomposing 2 moles of Hydrogen Peroxide, shouldn't the answer be in just "kJ" because we already accounted for the 2 moles of Hydrogen Peroxide? In the Solutions Manual: for part A, delta G is -233.6 kJ...
by Brandon Fujii 1K
Mon Feb 05, 2018 12:24 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: 9.27 hypothetical (d)
Replies: 1
Views: 92

9.27 hypothetical (d)

If we were given 1mol Ar(g) @ 1atm and .5mol Ar(g) (instead of 1mol) @ 2atm would the entropy be the same or would 1mol @1 atm still have more entropy because of its larger volume?
by Brandon Fujii 1K
Fri Feb 02, 2018 9:13 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Assume ideal gas?
Replies: 4
Views: 112

Re: Assume ideal gas?

Unless we learn how to calculate the entropy changes for non-ideal gases, I believe that --for this class-- we assume that all gases are ideal gases.
by Brandon Fujii 1K
Thu Feb 01, 2018 4:11 pm
Forum: Calculating Work of Expansion
Topic: Expansion
Replies: 3
Views: 117

Re: Expansion

In the internal energy equation

Delta U = q+w

our w value would be negative because the w is work done by the surroundings (system does work to expand)
by Brandon Fujii 1K
Thu Feb 01, 2018 3:58 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Adiabatic [ENDORSED]
Replies: 4
Views: 160

Re: Adiabatic [ENDORSED]

q=0 because heat is neither released nor absorbed by the system. Therefore, the only energy transfer is done by work (w).
by Brandon Fujii 1K
Sat Jan 27, 2018 12:30 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy Units
Replies: 2
Views: 59

Re: Entropy Units

Entropy is also represented by the equation

deltaS= Qrev/T

Therefore the units of Entropy are J * K-1
by Brandon Fujii 1K
Sat Jan 27, 2018 12:24 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy of gas vs liquid vs solid
Replies: 7
Views: 942

Re: Entropy of gas vs liquid vs solid

Whenever a substance is being heated AND is not going through a phase change, the temperature of the substance (average Kinetic Energy of each particle) increases. As the total kinetic energy of the particles of the substance increases, entropy increases. Therefore, because a gas has a higher temper...
by Brandon Fujii 1K
Sat Jan 27, 2018 12:10 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Systems in practice
Replies: 4
Views: 156

Re: Systems in practice

One can argue that the universe is an isolated system because matter and energy is neither created nor destroyed.
by Brandon Fujii 1K
Fri Jan 19, 2018 4:52 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: atm*L to J
Replies: 1
Views: 107

Re: atm*L to J

101.325 is the conversion of kPa to atm (101.325 kPa = 1 atm). 1 Joule = 1 Pa * m3 Work = Pressure * Volume For irreversible expansion W=-P ex * Delta V For this system, we would use 101.325 kPa to convert our units from atm to Pa. (Then we would convert our liters to cubic meters) Ex 8.11: w= -(1.0...
by Brandon Fujii 1K
Fri Jan 19, 2018 4:44 pm
Forum: Calculating Work of Expansion
Topic: 8.11
Replies: 1
Views: 68

Re: 8.11

101.325 is the conversion of kPa to atm (101.325 kPa = 1 atm).

1 Joule = 1 Pa*m3

1.20 L = 1.2x10-3m3

Therefore, w= -(101325 Pa)(1.2x10-3m3) = -122J
by Brandon Fujii 1K
Fri Jan 19, 2018 4:33 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Done By The System vs. Done On the System
Replies: 3
Views: 120

Re: Done By The System vs. Done On the System

Work = -Pressure external * Delta V When Delta V is positive, the system expands. This means that the work done on the system is negative (system is doing work on surroundings). When Delta V is negative, the system compresses. This means that the work done on the system is positive (surroundings doi...
by Brandon Fujii 1K
Fri Jan 12, 2018 9:42 am
Forum: Phase Changes & Related Calculations
Topic: Constant Temperature
Replies: 4
Views: 174

Re: Constant Temperature

Take the vaporization of water as an example. When we boil water at 100C= 373K the heat source provides energy to break the water molecules' bonds instead of heating up the temperature of the water. Thus, the temperature of the water remains the same during a phase change.
by Brandon Fujii 1K
Fri Jan 12, 2018 9:36 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 8.49
Replies: 5
Views: 181

Re: 8.49

We use 298K for the standard temperature for thermodynamics because 298K = 25C which is room temperature
by Brandon Fujii 1K
Thu Jan 11, 2018 10:28 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Ch 8 #57
Replies: 2
Views: 102

Re: Ch 8 #57

In 8.57 each individual enthalpy value is given in kJ/mol. Thus, I believe that the question is asking us to solve for the enthalpy for the hydrogenation of 1 mole of ethane. 8.61 gives each individual enthalpy value in kJ (possibly because it is not solving for the enthalpy of 1 mole of Bromide Gas...
by Brandon Fujii 1K
Wed Dec 06, 2017 10:14 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Drawing the Lewis structure for Coordination Compounds
Replies: 3
Views: 183

Drawing the Lewis structure for Coordination Compounds

If we are given a coordination compound, i.e. [HgF2(OH2))2]1+, do we use the total charge of the compound (1+) to find the formal charge of the lewis structure in addition to finding the oxidation state of the metal atom?
by Brandon Fujii 1K
Wed Dec 06, 2017 10:07 am
Forum: Determining Molecular Shape (VSEPR)
Topic: dipole moment chapter 4 test [ENDORSED]
Replies: 3
Views: 235

Re: dipole moment chapter 4 test [ENDORSED]

PO 4 3- has a resonance structure which creates a uniform negative polar charge around the Phosphate (in a tetrahedral). Because the negative polar charge and strength of each Oxygen is equal, the charges cancel each other out and there is no dipole moment. PCl 5 is the same in the sense that each C...
by Brandon Fujii 1K
Thu Nov 30, 2017 3:24 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Knowing VSEPR Shapes
Replies: 3
Views: 225

Re: Knowing VSEPR Shapes

Here's a table of all of the VSEPR Shapes that we need to know. I hope that this helps!
by Brandon Fujii 1K
Tue Nov 28, 2017 8:20 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Question 11.45 (c)
Replies: 1
Views: 121

Question 11.45 (c)

The solution manual states that the dissociation of Cl2 is more stable than F2 because F2 has a larger equilibrium constant. Why does a smaller equilibrium constant make a molecule more stable?
by Brandon Fujii 1K
Fri Nov 24, 2017 2:22 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Determining whether a complex is tetrahedral or square-planar?
Replies: 2
Views: 120

Re: Determining whether a complex is tetrahedral or square-planar?

Sorry I pasted twice, and I can't delete one of the images. I hope that the visual helps!
by Brandon Fujii 1K
Fri Nov 24, 2017 2:19 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Determining whether a complex is tetrahedral or square-planar?
Replies: 2
Views: 120

Re: Determining whether a complex is tetrahedral or square-planar?

A tetrahedral has 4 bonds and no lone pairs.

A square planar molecular shape has an octahedral electron structure with 4 bonds and 2 lone pairs about the central atom. (see image in link)

https://image.slidesharecdn.com/10lectu ... 1381918593
by Brandon Fujii 1K
Fri Nov 24, 2017 2:12 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Value of K
Replies: 1
Views: 82

Re: Value of K

For a small value of K (K< 1x10 -3 ) then the "equilibrium sits to the left" Because K=[products]/[reactants], a small K would have a large reactant concentration (left of the equation) and a small product concentration (right of the equation) at equilibrium. i.e. if K=[0.00110M]/[2.30M], ...
by Brandon Fujii 1K
Fri Nov 17, 2017 10:17 am
Forum: Hybridization
Topic: Triple bond sigma vs. pi
Replies: 3
Views: 117

Re: Triple bond sigma vs. pi

https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwj2gO_Am8bXAhXjh1QKHZevDo0QjRwIBw&url=http%3A%2F%2Fphilschatz.com%2Fchemistry-book%2Fcontents%2Fm51058.html&psig=AOvVaw06y99Sy5o2HwIBwz1IOUVH&ust=1511028916311529 We...
by Brandon Fujii 1K
Fri Nov 17, 2017 10:13 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angle
Replies: 7
Views: 254

Re: Bond Angle

Hello, unless we test it experimentally, we do not know the exact angles of bonds caused by electron repulsion. Thus, we just assume that the bond angles are slightly less than 109.5 degrees for a trigonal pyramidal molecular structures.
by Brandon Fujii 1K
Thu Nov 09, 2017 11:56 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: delta v
Replies: 4
Views: 212

Re: delta v

yes for example if our velocity is 20m/s \pm 5m/s our velocity would range from 15m/s to 25m/s. Delta v is the range of the velocity. This is found subtracting the upper and lower range of the velocity (25m/s-15m/s= 10m/s ). We can use the shortcut of multiplying the velocity found after the \pm (5m...
by Brandon Fujii 1K
Thu Nov 09, 2017 11:47 am
Forum: Trends in The Periodic Table
Topic: Noble Gases
Replies: 3
Views: 222

Re: Noble Gases

If we were to try to add or subtract an electron from a noble gas, it would require an extensive amount of energy.
by Brandon Fujii 1K
Thu Nov 02, 2017 10:48 pm
Forum: Bond Lengths & Energies
Topic: Bond Length
Replies: 5
Views: 225

Re: Bond Length

First we must find the total number of electrons in the molecule. I usually make everything a single bond first and then adjust accordingly by adding double/triple bonds if I have too many electrons (more than the calculated total number of electrons that belongs in the molecule). Then we would calc...
by Brandon Fujii 1K
Thu Nov 02, 2017 10:38 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty Principle [ENDORSED]
Replies: 5
Views: 282

Re: Uncertainty Principle [ENDORSED]

Also if you use number 1.45 as a practice problem, the solutions manual is incorrect. The actual velocity given is 5.00 5.0m/s
Thus, =10.0m/s NOT 5.0m/s as the solution manual incorrectly states. Therefore, your answer is =6.7x10-37m
by Brandon Fujii 1K
Thu Oct 26, 2017 4:19 pm
Forum: Ionic & Covalent Bonds
Topic: covalent bond
Replies: 7
Views: 466

Re: covalent bond

Some examples of molecules that use covalent bonds are

Bromine (Br2)
Iodine (I2)
Nitrogen (N2)
Chlorine (Cl2)
Hydrogen (H2)
Oxygen (O2)
Fluorine (F2)

Carbon Dioxide (CO2)
Methane (CH4)
Water (H2O)
by Brandon Fujii 1K
Thu Oct 26, 2017 4:14 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 2
Views: 148

Re: Electron Affinity

Electronegativity is an atom's numerical value which measures its ability to form a covalent bond. Electron affinity is the amount of energy that an atom releases when an electron is added to it. Additionally, Electron affinity is a given value for each atom, but electronegativity varies based on di...
by Brandon Fujii 1K
Thu Oct 19, 2017 4:00 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Homework Problem 1.15
Replies: 4
Views: 234

Re: Homework Problem 1.15

We assume that n=1 because this is a Lyman Series, and the lowest possible energy level is n=1.

For Balmer, the lowest energy level is n=2
For Paschen n=3
For Brackett n=4
For Pfund n=5
by Brandon Fujii 1K
Thu Oct 19, 2017 3:56 pm
Forum: Properties of Light
Topic: the quantum world
Replies: 7
Views: 308

Re: the quantum world

Also, know which types of wavelengths correspond to higher or lower frequency.

i.e. x-rays have short wavelengths and therefore have a higher frequency than radio waves which have long wavelengths.
by Brandon Fujii 1K
Thu Oct 12, 2017 5:31 pm
Forum: Photoelectric Effect
Topic: Mass of an electron
Replies: 4
Views: 211

Re: Mass of an electron

Yes, for the mass of an electron use kg

Equation: E(kinetic)=(1/2)me-(ve-)2

Units: Joules = kg (m2/s2)
by Brandon Fujii 1K
Thu Oct 12, 2017 5:08 pm
Forum: Photoelectric Effect
Topic: Photoelectric effect example problem [ENDORSED]
Replies: 2
Views: 156

Re: Photoelectric effect example problem [ENDORSED]

Note the Photoelectric Effect equation: E (Photon) - Work Function = E (Kinetic) . E (Kinetic) = 1/2 (m e- v e- 2 ) The equation for E (Photon) = h v (Plank's Constant * Frequency) We know that the equation for the speed of light is: C= Wavelength * Frequency. Therefo...
by Brandon Fujii 1K
Thu Oct 05, 2017 10:44 am
Forum: General Science Questions
Topic: Sig Figs
Replies: 9
Views: 736

Re: Sig Figs

In addition, if we have to convert our calculated number of moles into grams, do not round off the number of moles. We only round to our number of significant figures at the very end of the problem. i.e. Say we are limited to 3 sig figs, and we calculated 3.45654 moles of Oxygen gas. We would multip...
by Brandon Fujii 1K
Thu Oct 05, 2017 10:30 am
Forum: Balancing Chemical Reactions
Topic: Combustion Question
Replies: 9
Views: 444

Re: Combustion Question

In addition, Oxygen must be present in order for a combustion reaction to occur. In most cases, Oxygen is in excess because it is found in the atmosphere. i.e. When we burn Butane in an outdoor barbecue, we have an excess Oxygen.

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