Search found 31 matches

by Ashe Chen 2C
Tue Mar 12, 2019 3:38 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Unique rate?
Replies: 7
Views: 85

Re: Unique rate?

The unique rate depends on the stoichiometric coefficients of the products or reactants, which differs from k, the rate constant.
by Ashe Chen 2C
Tue Mar 12, 2019 3:36 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Slow Step
Replies: 6
Views: 73

Re: Slow Step

On finals in previous years there has been questions where it is not given, I've heard, but because the slow step determines the overall rate law we should be able to figure it out with the given information if it is not given.
by Ashe Chen 2C
Tue Mar 12, 2019 3:35 pm
Forum: First Order Reactions
Topic: Half-Life
Replies: 7
Views: 79

Re: Half-Life

In addition, half life is often used for carbon dating of samples, for example fossils, to determine from the amount of decay the sample has undergone. There is no normal life because that would imply that it is the time it takes for the entire sample to decay.
by Ashe Chen 2C
Sun Mar 03, 2019 4:21 pm
Forum: Balancing Redox Reactions
Topic: Acidic Solutions
Replies: 7
Views: 124

Re: Acidic Solutions

Balance the equation first by adding H2O to the side that lacks oxygen, then add H+ ions to the other side to balance it overall.
by Ashe Chen 2C
Sun Mar 03, 2019 4:20 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Pt inert electrode
Replies: 9
Views: 157

Re: Pt inert electrode

Pt is added to a reaction that does not have a conducting solid, and is added on whichever side needs it, not on both sides.
by Ashe Chen 2C
Sun Mar 03, 2019 4:18 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Order of Cell Diagrams
Replies: 13
Views: 182

Re: Order of Cell Diagrams

From the left, the order should be Solids|Gas, Liquid|Aqueous solutions||Aqueous solutions|Liquid, Gas|Solids
by Ashe Chen 2C
Mon Feb 25, 2019 6:18 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Test 2
Replies: 4
Views: 127

Re: Test 2

The second test covers all material up to and including what was discussed in class on Friday 2/22
by Ashe Chen 2C
Sun Feb 24, 2019 5:26 pm
Forum: Balancing Redox Reactions
Topic: Balancing redox reactions in basic solutions
Replies: 2
Views: 50

Re: Balancing redox reactions in basic solutions

In acidic solution, balance O by using H2O and then balance H by using H+. In basic solution, balance O by using H2O; then balance H by adding H2O to the side of each half- reaction that needs H and adding OH- to the other side.
by Ashe Chen 2C
Sun Feb 24, 2019 1:53 am
Forum: Balancing Redox Reactions
Topic: Rules for oxidation numbers
Replies: 2
Views: 46

Re: Rules for oxidation numbers

1) The oxidation number for an atom in its elemental form is always zero. 2) The oxidation number of a monoatomic ion = charge of the monatomic ion. 3) The sum of all oxidation numbers in a neutral compound is zero. The sum of all oxidation numbers in a polyatomic ion is equal to the charge on the i...
by Ashe Chen 2C
Sat Feb 16, 2019 9:59 pm
Forum: Ideal Gases
Topic: Q and K
Replies: 13
Views: 185

Re: Q and K

Q doesn't mean anything until it is compared to K. The comparison helps to determine which direction the reaction will proceed given time.
by Ashe Chen 2C
Sat Feb 16, 2019 9:57 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: How to calculate W
Replies: 9
Views: 199

Re: How to calculate W

W is calculated by
and then is plugged into the equation
to find the statistical/residual entropy
by Ashe Chen 2C
Sat Feb 16, 2019 9:55 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: delta S
Replies: 7
Views: 120

Re: delta S

when q=0, or in free expansion.
by Ashe Chen 2C
Sat Feb 16, 2019 9:54 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: ΔS=q/t
Replies: 8
Views: 158

Re: ΔS=q/t

when pressure and temperature are constant,
by Ashe Chen 2C
Sat Feb 16, 2019 9:51 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: K constant
Replies: 5
Views: 276

Re: K constant

The brackets [Kc] is for calculating equilibrium concentrations (done in M) where (Kp) is for calculation equilibrium pressure (done in atm or barr)
by Ashe Chen 2C
Sat Feb 16, 2019 9:49 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Midterm
Replies: 12
Views: 194

Re: Midterm

I would say to just do as many homework problems as you can to familiarize yourself with the way these concepts take hold in actual problems, although it is also important to understand the ideas behind the problems as well. I didn't do enough homework problems and it totally screwed me over on the ...
by Ashe Chen 2C
Sat Feb 16, 2019 9:45 pm
Forum: Ideal Gases
Topic: pH and pOH
Replies: 18
Views: 327

Re: pH and pOH

The problem should specify, but if not it is usually safe to assume you should calculate for what is given, ie if the reaction forms H+ ions you should solve for pH and if OH- ions are formed solve for pOH.
by Ashe Chen 2C
Sat Feb 16, 2019 9:44 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Changes in Pressure
Replies: 5
Views: 71

Re: Changes in Pressure

because of the ideal gas law, pressure and volume have an inverse relationship and thus when volume increases, pressure decreases.
by Ashe Chen 2C
Sat Feb 16, 2019 9:42 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Explaining Boltzmann's Equation
Replies: 6
Views: 187

Re: Explaining Boltzmann's Equation

Boltzmann's equation solves for statistical or residual entropy, and is based on the number of microstates and number of molecules in a system.
by Ashe Chen 2C
Sat Feb 16, 2019 9:40 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Constant Pressure Calorimeter
Replies: 5
Views: 135

Re: Constant Pressure Calorimeter

Calorimeters are considered isolated systems in problems, although it is very difficult to create a true isolated system in real life calorimeters are pretty close and are considered isolated.
by Ashe Chen 2C
Sat Feb 16, 2019 9:33 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Equilibrium Constant and Gibbs Free Energy
Replies: 3
Views: 55

Re: Equilibrium Constant and Gibbs Free Energy

If GrGp, then the rxn is not at equilibrium and:

At Equilibrium, = 0
Resulting in
by Ashe Chen 2C
Sat Feb 16, 2019 9:12 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: State Function
Replies: 2
Views: 70

Re: State Function

The change in internal energy during a process depends only upon the initial state and final state while work and heat depends on upon the path followed. Thus, internal energy is a state function and work and heat are not.
by Ashe Chen 2C
Sat Feb 16, 2019 9:06 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 3/2R vs 5/2R
Replies: 8
Views: 147

Re: 3/2R vs 5/2R

3/2 R is used for a monoatomic ideal gas at constant volume where 5/2 R is used is used for a monoatomic gas at constant pressure, or for a linear molecule at constant volume.
by Ashe Chen 2C
Mon Jan 28, 2019 4:12 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Delta H
Replies: 4
Views: 57

Re: Delta H

Delta T indicates a change in temperature where delta H indicates a change in energy, or enthalpy
by Ashe Chen 2C
Mon Jan 28, 2019 4:10 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Water specific heat capacity
Replies: 2
Views: 33

Re: Water specific heat capacity

Water has such a high specific heat capacity because of multiple hydrogen bonds between water molecules it takes a lot amount of heat energy to cause those molecules to move faster and raise the temperature of the water.
by Ashe Chen 2C
Mon Jan 28, 2019 4:08 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Exothermic vs. Endothermic
Replies: 10
Views: 135

Re: Exothermic vs. Endothermic

If the reaction gives a release of heat (-delta H), the reaction is exothermic. If the reaction requires heat (+delta H), the reaction is endothermic.
by Ashe Chen 2C
Mon Jan 21, 2019 8:27 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5% rule
Replies: 11
Views: 150

Re: 5% rule

If the percent protonation is <5%, then the approximation is valid and allows for finding x without using the quadratic formula
by Ashe Chen 2C
Mon Jan 21, 2019 8:25 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp vs Kc
Replies: 7
Views: 87

Re: Kp vs Kc

Kp refers to pressure where Kc refers to concentration
by Ashe Chen 2C
Mon Jan 21, 2019 8:24 pm
Forum: Ideal Gases
Topic: ICE table
Replies: 11
Views: 237

Re: ICE table

ICE tables can be used for both pressure and molarity.
by Ashe Chen 2C
Thu Jan 10, 2019 10:37 pm
Forum: General Science Questions
Topic: Chem 20A to Chem 14B
Replies: 3
Views: 75

Chem 20A to Chem 14B

Hi all, I took Chem 20A last quarter and my advisor said that there should be no issue for me in taking Chem 14B this quarter. However, I've noticed that the material differs drastically from the 20 series and I was wondering, realistically, how transferrable is the knowledge from the 20 series to t...
by Ashe Chen 2C
Thu Jan 10, 2019 10:32 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 889257

Re: Post All Chemistry Jokes Here

Two scientists sit down at a restaurant

The first scientist: I'll have H2O
The second scientist: I'll have H20, also.
The second scientist’s arch nemesis disguised as a waiter: [under breath] so close....

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