CHEMISTRY COMMUNITY

torieoishi1A

lnk(k'/k)=E/R((1/T)-(1/T'))
ln(k'/k)=(38kJ/mol)/(.08314kJ/K*mol)((1/298K)-(1/310K))-.59
k=1.5x10^10 L/mol*s
Solve for k'
k'=2.7 x 10^10 L/mol*s

torieoishi1A

Open:living plant, gas in a car engine
Closed: reusable ice pack, mercury in a thermometer, coolant in a refrigerator coil
Isolated:bomb calorimeter, high quality thermos

torieoishi1A

Compare rate 1&3 to find the order of concentration B because A conc and C conc remain constant between these two experiments.
Rate 3/rate 1=50.8/8.7=5.85
B conc3/B conc1=3.02/1.25=2.416
2.416^x=5.85
X=2
Therefore, the concentration B is a second order reaction.

torieoishi1A

First start with the equation: ln(A/A(initial)=-kt
Then plug in k(7.6x10^-3/min) and t (5 hours but use 300 min)
Second you will now have: ln(A/A(initial)=-2.28
Cancel out on by using e: (A/A(initial)=e^-2.28
A(initial)= 20mg
Solve for A which is 2.0 mg

torieoishi1A

It is a property of natural logs. When you subtract two natural logs, you can use division.
For example, lnA-lnB= ln(A/B)
So we are given lnA=-kt+lnA(initial)
Then you can change it depending on what you are solving for:
So lnA-lnA(initial)=-kt which is converted to ln(A/A(initial))=-kt

torieoishi1A

t=((1/[A])-(1/[A]"sub0"))/k=((1L/.080mol)-(1L/0.10mol))/0.015L/mol min=1.7 x 10^2 min
[A]=0.15 mol A/L- [(0.19 mol/L)-(1 mol A/ 2 mol B)] = 0.055 (mol A)/L=0.38[A]"sub0"

torieoishi1A

(a)t1/2=.693/k=.693/2.81 x 10^-3 min^-1=247 min (b) t=(ln([so2cl2]"sub0"/[So2Cl2]"subt")/k=ln10/(2.81 x 10^-3 min^-3)=819 min (c)[A]"subt"=[A]"sub0"e^-kt // masses and concentrations are proportional (b/c the vessel is sealed), therefore (mass left)"subt&...

torieoishi1A

15.1-15.6, assuming it's the same for whether you have discussion early in the week or later.

torieoishi1A

We mainly learned about Galvanic cells: they are cells in which chemical energy released by a spontaneous redox reaction are converted to electrical energy. For the overall cell reaction, deltaG should be less than 0 to indicate that the reaction is spontaneous. In an electrolytic cell, electrical e...

torieoishi1A

Using the Nernst equation with Ln and log should be interchangeable, but I had this same issue with this problem. I also got 3.27x10^6 rather than just 10^6.
There is an added constant for log. For ln: E = E-RT/nF(lnQ) but for log: E = E-2.303RT

torieoishi1A

N is the number of moles of electrons being transferred in a chemical reaction. Make sure to balance the equation for the chemical reaction before seeing how many moles of electrons are exchanged.

torieoishi1A

Looking at the cell:
Cu/Cu2+ electrode is the anode (oxidation is occurring)
M2+/M electrode is the cathode
Then use the formula: E=E(cathode)-E (anode)
-.689V=E(cathode)-(+.34V)
E(cathode)=-0.349V

torieoishi1A

Oxidizing Agent: its the species that is being reduced as it removes the electron from a substance
Some examples include: O2,O3,Fe3+
Reducing Agent: the species that is being oxidized as it supplies electrons to a substance
Examples include: H2, H2S

torieoishi1A

They are both an electrochemical cell in which a spontaneous chemical reaction is used to generate an electric current.
Galvanic and Voltaic are two different names for the same electrochemical cell, both converting chemical energy into electrical energy.

torieoishi1A

Nevermind, I reread the question

torieoishi1A

If deltaG is positive, how is the reaction spontaneous?

torieoishi1A

W=# of possible orientations^# of molecules.
The problem with either give you a specific amount of molecules or referring to the example 9.8 where it says one mole, you can use Avogadro's number to account for the amount of molecules in the one mole.

torieoishi1A

a) Entropy of a solid made of 64 molecules in which they are all aligned in the same direction. First you need to solve for W (orientation^#molecules). therefore, W=1^64=1. Then use the Boltzmann formula: S=klnW. (k=1.381x10^-23J/K #this is a constant that is given). Snce we know ln1=0, S=0. b) Entr...

torieoishi1A

In order to get entropy (-enthalpy(kJ/mol)/Temperature(K)) you need to change the grams to mol in order to cancel the moles in the enthalpy. Then your resulting entropy will be J/K.

torieoishi1A

The optimist sees the glass half full.
The pessimist sees the glass half empty.
The chemist see the glass completely full, half in the liquid state and half in the vapor state.

torieoishi1A

1ST: Law of Conservation of Energy-energy can't be created nor destroyed; it can only be transferred from one form to another. Equation: deltaU=q+w 2ND: Entropy of any isolated system always increases, going to maximum entropy. 3RD: Entropy of a system approaches a constant value as temperature appr...

torieoishi1A

The explanations above are great. Here is the math to maybe make it more clear. heat (ice cube)=(50g/18.02 gmol^-1)(6.01 x 10^3 J/mol) +(50g)(4.184JC^-1g^-1)(Tfinal-0)=1.67 x 10^4J +(209J/C)(Tfinal-0) heat (water)=(400g)(4.184J/Cg)(Tfinal-45)=1.67 x 10^3 J/C (Tfinal-45) then you set them equal to ea...

torieoishi1A

When using the enthalpy of formation equation, you should get -13168 kJ/mol. This is the amount of energy released per mole of reaction. In order to get the amount of energy released per mole of TNT consumed, you divide the total amount of energy released (-13158kJ/mol) by 4 (from looking at the bal...

torieoishi1A

Examples of these are: Closed: an reusable ice pack-->matter cannot be exchanged with the surroundings because it is sealed, but energy can when it is refrozen or melted. Isolated: insulated thermos-->matter cannot be exchanged with the surroundings because it is sealed. energy can also not be excha...

torieoishi1A

the state gr means graphite. It is the most stable form of carbon under standard conditions.

torieoishi1A

for part b, where they ask "what percentage of the heat is used to raise the temperature of the water?" you take the amount of heat used to raise the temperature of the water and divide it by the total heat. Then multiply it be 100 to get the percent. HEAT: q=mCdeltaT ((1.30 X 10^5J)/(1.45...

torieoishi1A

Heat(Q): the transfer of energy between a system temp. and its surrounding temperature. It can go in either direction, but is transferred from high temperature to low temperature. An object, itself, does not possess heat. Internal energy (U): the total amount of energy stored in a system. For a clos...

torieoishi1A

Step 1: (melting the ice at 0 degrees C) deltaH=amount of moles of water x the enthalpy of fusion at standard state deltaH=(80g/18.02g/mol)x(6.01kJ/mol)=26.7 kJ Step 2: (raising the temperature of the liquid water from 0 degrees C to 25 degrees C) deltaH=m(specific heat capacity)(deltaT) deltaH=(80g...

torieoishi1A

Yes, you use enthalpies of formation to find the enthalpy of reaction for the reaction. 28(-393.51kJ/mol)+10(-241.82kJ/mol)-4(067kJ/mol)=-13168kJ/mol (the energy released per mole of reaction) Since it is asking "per mole," 1/4 of the energy (3292kJ/mol) will be released per mole of TNT co...

torieoishi1A

Gas has two values for molar heat capacity because one accounts for the constant volume process (Cv) and the other is the constant pressure process (Cp). Cv is the change in internal energy (U) with respect to to change in temperature at a fixed volume whereas Cp is the change in enthalpy (H) with r...

torieoishi1A

Yes, using kJ/C would be ideal because it is the same units that are given in the problem. To solve this problem, you simply calculate the heat capacity of the calorimeter by dividing the amount of energy supplied (22.5kJ) by the change in temperature (23.97C-22.45C). Unless it says to calculate the...

torieoishi1A

Gas has two values for molar heat capacity because one accounts for the constant volume process (Cv) and the other is the constant pressure process (Cp). Cv is the change in internal energy (U) with respect to to change in temperature at a fixed volume whereas Cp is the change in enthalpy (H) with r...

CHEMISTRY COMMUNITY

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