CHEMISTRY COMMUNITY

RachelCheung1A

I would use the equation of E=R*T/(nF)*lnK. Isolate K to solve, assuming you have values for the other variables or the information needed to solve them.

RachelCheung1A

The units in K should cancel out so there shouldn't be any units for K.

RachelCheung1A

Yes as long as it is the same formula and under same conditions (ex. temp)

RachelCheung1A

Not necessarily. As long as the units can cancel out, you can do seconds, minutes, hours, etc.

RachelCheung1A

Yep everything up to and including Wednesday

RachelCheung1A

They all have time on the x axis
Zero order has [A] on the y axis and slope is -k
First order has ln[A] on the y and slope is also -k
Second order has 1/[A] on the y and slope is k

RachelCheung1A

It is the number for the frequency of collisions between reactants.

RachelCheung1A

The Pre-equilibrium approach assumes that the reaction has steps in the order of a fast step, then a slow step. The fast step will produce intermediates needed for the slow step and because the slow step is slow, there will be a build up of intermediates and we can assume that it will be at equilibr...

RachelCheung1A

Ecell can be calculated by subtracting the reduction potential of the half reaction that is oxidized from the reduction potential of the half reaction that is reduced.

RachelCheung1A

In half reactions, balance elements first, H and O second, electric charges third and then electrons last.

RachelCheung1A

If the change in Gibbs free energy is negative, then it it spontaneous

RachelCheung1A

Doing hw problems

RachelCheung1A

All topics on Gibbs free energy and electrochemistry

RachelCheung1A

Standard gibbs energy is denoted by the little degree-like symbol and indicates the gibbs energy when the process is under 1 atm and 25 degrees C.

RachelCheung1A

In an isolated system, there is no exchange of energy with surroundings and therefore the internal energy stays the same and delta U is 0

RachelCheung1A

Heat and matter cannot be moved in or out of the bomb calorimeter

RachelCheung1A

When delta H is negative and delta S is positive, it will definitely be negative delta G.
A large negative delta H and a small negative delta at a low temperature can possibly result in a negative delta G

RachelCheung1A

Use deltaS=q/t when q (heat transferred) and temperature is given. Use deltaS=nRlnV2/V1 when moles and volume change is given.

RachelCheung1A

Use w=nRTlnV2/V1 when solving for work done by a reversible, isothermal gas expansion process with Volume change. Use w=-PdV for irreversible gas work. q is for heat transferred but I think that specific equation is not frequently used.

RachelCheung1A

Delta U only requires the Final and Initial numbers of U and anything that takes place in between (the path) does not matter. Because delta U just means the change of U from the beginning to the end, it is a state function.

RachelCheung1A

When the beaker is open, it experiences a constant pressure since the pressure it experiences is the atmospheric pressure around it which will not change since the atmosphere is too large for any change to be considered significant.

RachelCheung1A

State properties do not depend on the path taken; they depend on the state of the substance. Work and heat are not considered because they take into account the path taken. Ex. In work, the formula is force times distance. If you have two molecules at the same starting point, molecule A that reaches...

RachelCheung1A

when the K is less than 1x10-3, so if the K ends with 10^-4 or smaller. Ex 1.9x10^4 approximate but 1.9x10^-3 don't approximate

RachelCheung1A

They increase the rate of the reaction but does not cause any permanent chemical change in the reaction, so the concentrations are the same and equilibrium is the same

RachelCheung1A

They are both endothermic because they need to take in heat to break bonds and change phase

RachelCheung1A

Strong acid will have lower pH because it has a full dissociation into more H30+ than a weak acid. pH relies on the amount of H30+ ions (-logH30+) and so more H30+ ions will cause the pH to be lower since you are logging the molarity.

RachelCheung1A

If the % pronotation is less than 5, then approximation (disregarding the initial change of x in the denominator) is valid.

RachelCheung1A

Thanks that's really helpful. Just wanted to know why would 5/17 be used for the calculation of partial pressure instead of 6/11 from the earlier part B?

RachelCheung1A

Yes, water in gas form in included, however water in liquid form is not.

RachelCheung1A

We disregard solids and liquids because their concentrations are the same throughout the reaction. Concentration equals to density divided by molar mass and both solids and liquids' densities are pretty much constant, therefore concentrations of solids and liquids are constant.

CHEMISTRY COMMUNITY

Search found 30 matches

Re: Galvanic cells and K

Re: units

Re: Reaction Rate

Re: Units of Rate Constant

Re: Final Exam Topics

Re: First order rxn graphs [ENDORSED]

Re: Frequency Factor

Re: "Bottle Neck" Pre-equilibrium Approach

Re: Ecell

Re: Order to balance

Re: Spontaneous?

Re: How are you guys going to study for Test 2?

Re: TEST 3

Re: standard Gibbs Free Energy

Re: Internal energy (U) of an isolated system

Re: Isolated system

Re: Negative Delta G

Re: When to use deltaS=q/t versus deltaS=nRlnV2/V1

Re: When do you use w = -nRTlnV2/v1, q = nRTlnV2/V1, and w = -PdV?

Re: Delta U

Re: open system

Re: State Properites

Re: Approximations for ICE

Re: Catalysts in Kc

Re: Phase Changes

Re: pH of acids

Re: 5% rule

Re: 6th edition, 11.7?

Re: H2O

Re: Reaction Quotient