CHEMISTRY COMMUNITY

Ashe Chen 2C

The unique rate depends on the stoichiometric coefficients of the products or reactants, which differs from k, the rate constant.

Ashe Chen 2C

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.

Ashe Chen 2C

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.

Ashe Chen 2C

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.

Ashe Chen 2C

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.

Ashe Chen 2C

From the left, the order should be Solids|Gas, Liquid|Aqueous solutions||Aqueous solutions|Liquid, Gas|Solids

Ashe Chen 2C

The second test covers all material up to and including what was discussed in class on Friday 2/22

Ashe Chen 2C

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.

Ashe Chen 2C

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...

Ashe Chen 2C

Q doesn't mean anything until it is compared to K. The comparison helps to determine which direction the reaction will proceed given time.

Ashe Chen 2C

W is calculated by $(number of microstates)^{(number of molecules)}$
and then is plugged into the equation $S = K_{b} ln W$
to find the statistical/residual entropy

Ashe Chen 2C

$\Delta S = 0$ when q=0, or in free expansion.

Ashe Chen 2C

when pressure and temperature are constant, $\Delta S = \Delta Hsys/T$

Ashe Chen 2C

The brackets [Kc] is for calculating equilibrium concentrations (done in M) where (Kp) is for calculation equilibrium pressure (done in atm or barr)

Ashe Chen 2C

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 ...

Ashe Chen 2C

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.

Ashe Chen 2C

because of the ideal gas law, pressure and volume have an inverse relationship and thus when volume increases, pressure decreases.

Ashe Chen 2C

Boltzmann's equation solves for statistical or residual entropy, and is based on the number of microstates and number of molecules in a system.

Ashe Chen 2C

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.

Ashe Chen 2C

It is usually Cp unless the volume is changing

Ashe Chen 2C

If Gr $\neq$ Gp, then the rxn is not at equilibrium and:
$\Delta G = \Delta G^{\circ}+ RTlnQ$
At Equilibrium, $\Delta G$ = 0
Resulting in $\Delta G^{\circ} = -RTlnK$

Ashe Chen 2C

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.

Ashe Chen 2C

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.

Ashe Chen 2C

Delta T indicates a change in temperature where delta H indicates a change in energy, or enthalpy

Ashe Chen 2C

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.

Ashe Chen 2C

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.

Ashe Chen 2C

If the percent protonation is <5%, then the approximation is valid and allows for finding x without using the quadratic formula

Ashe Chen 2C

Kp refers to pressure where Kc refers to concentration

Ashe Chen 2C

ICE tables can be used for both pressure and molarity.

Ashe Chen 2C

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...

Ashe Chen 2C

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....

CHEMISTRY COMMUNITY

Search found 31 matches

Re: Unique rate?

Re: Slow Step

Re: Half-Life

Re: Acidic Solutions

Re: Pt inert electrode

Re: Order of Cell Diagrams

Re: Test 2

Re: Balancing redox reactions in basic solutions

Re: Rules for oxidation numbers

Re: Q and K

Re: How to calculate W

Re: delta S

Re: ΔS=q/t

Re: K constant

Re: Midterm

Re: pH and pOH

Re: Changes in Pressure

Re: Explaining Boltzmann's Equation

Re: Constant Pressure Calorimeter

Re: Calculating Delta S with a change in temperature

Re: Equilibrium Constant and Gibbs Free Energy

Re: State Function

Re: 3/2R vs 5/2R

Re: Delta H

Re: Water specific heat capacity

Re: Exothermic vs. Endothermic

Re: 5% rule

Re: Kp vs Kc

Re: ICE table

Chem 20A to Chem 14B

Re: Post All Chemistry Jokes Here