CHEMISTRY COMMUNITY

Charles Hood Disc 1C

Is there anything other than temperature that will change the value of an equilibrium constant K?

Charles Hood Disc 1C

You can't just make it first order. The order of a reaction is determined empirically and cannot be changed. However, if you had a reaction that was simply first order the rate law would appear as Rate = k[A]. Also, a second order rate law is rate = k[A]².

Charles Hood Disc 1C

It is not in the outline so most likely not, however you should always have an understanding of any material covered in class.

Charles Hood Disc 1C

A value with less than 10^-3 means that we can approximate the x value.

Charles Hood Disc 1C

E^o is a state function. E is not a state function.

This is because E^o is related directly to ΔG^o (-nFE^o = ΔG^o)

Charles Hood Disc 1C

Eventually the reaction that occurs between the two sides will complete/ be at equilibrium.

Charles Hood Disc 1C

I got the same answer, it seems as though they chose to round early from 14.7 to 15. However, this would not explain the discrepancy.

Charles Hood Disc 1C

For the cathode, try to imagine the Oxygen as being the electrons supplied to make the OH^-. When it is added to water it will increase the number of electrons and form OH^-. (Really it is the electrons adding on with the oxygen)

Charles Hood Disc 1C

Check the E values. A lower (more negative) E value has a higher reducing ability.

Charles Hood Disc 1C

I don't understand how to split up the half reactions for this equation. In the solution manual, it reduces a random Ag + ion and I don't know where it comes from. Does anyone understand where the silver ion came from? It also seems as though silver has just been added in as an electrode in the prob...

Charles Hood Disc 1C

In a galvanic cell, when do you use an electrode? (As in an added on one, it seems to most commonly be platinum).

How do you decide which element to use as the extra electrode?

Charles Hood Disc 1C

You will also probably need to know if a reaction is exergonic or endergonic based on the value of G.

Charles Hood Disc 1C

When you want to find the relation between a change in temperature and a change in K_eq.

Charles Hood Disc 1C

You will most likely have to calculate entropy and enthalpy in order to use it with Gibbs free energy.

Charles Hood Disc 1C

They are both trigonal planar, so try to find which one is the least symmetrical, as in when you rotate the molecule, which has the more states. This will have the most entropy.

(COF₂ in this case)

Charles Hood Disc 1C

This question needs to be done in parts, remember that entropy is a state function, so as long as you end up with 85 being your final temperature, you can do whatever you want along the way. Try splitting up the entropy into 3 parts: what it takes to go from 85-100, at 100, then back down again.

Charles Hood Disc 1C

If you were unable to get them after the lecture, you can go to your TA's office hours as well.

Charles Hood Disc 1C

A Positive ΔH is an endergonic reaction. A negative ΔH is an exergonic reaction.

Charles Hood Disc 1C

If an ideal gas is "isothermal" then you can assume ΔU = 0.

Charles Hood Disc 1C

When do I use ΔS=q/t instead of ΔS= nC(ln(T₂/T₁))

Charles Hood Disc 1C

Look at the units you are dealing with, the constants have different units. So if you don't know try looking at what units you are using and comparing them to the units of the gas constants.

Charles Hood Disc 1C

When you don't have Avogadro's number you get a different result than the gas constant.

Charles Hood Disc 1C

An open cup of tea can have its matter and energy changed. It fully interacts with the surroundings.

Charles Hood Disc 1C

Delta refers to the change between the final and the initial of value. When you have a negative delta H this is due to the fact that you have lost enthalpy, so it makes sense that the reaction would be exothermic (give off heat). The reverse is true for a reaction with positive delta H. It is an end...

Charles Hood Disc 1C

Atmospheres. (atm).

Charles Hood Disc 1C

Enthalpy is a state property, which means that it measures the total of an object at a specific moment. It is a value that is not influenced by how it was achieved, all that matters is what it is.

Charles Hood Disc 1C

It can help to draw a Lewis structure and look for any lone pairs, or any hydrogens that could be donated.

Charles Hood Disc 1C

You would add the hydronium created in the first equation to the initial value of hydronium of the next equation.

Charles Hood Disc 1C

You can also get a clue based on the K_a or K_b given. A large number means it will dissociate strongly.

Charles Hood Disc 1C

Use PV=nRT, then convert it to P=MRT, (n/v = concentration = M) Then proceed to use the values given in concentrations to solve for the pressures individually. These are the partial pressures.

Charles Hood Disc 1C

They are, it's just that they have a hydroxide with them in table 12.2. Use the K_b given in the table to convert into K_a.

Charles Hood Disc 1C

The others are acids, not bases so they can be found in table 12.1, except bonded to another element (generally hydrogen) this gives you the K_a value instead of the K_b value. This means that you can can subtract the pK_a from 14 to find the pK_b.

Charles Hood Disc 1C

The reaction quotient is calculated during the reaction, rather than at the end. Depending on its value it can give you information about how the reaction will proceed (e.g. if Q>K then there are too many products and it will favour the left).

Charles Hood Disc 1C

Most likely it's because inert gases won't react (because they have full valence shells), therefore they won't change the chemical equation in any way.

Charles Hood Disc 1C

This is because you raise the concentration or partial pressure to the power of its respective coefficient in the equation. When you divide an exponent by 2 it is the same thing as square rooting. Or when you multiply it by 2 it is the same as squaring it. As an example: 2 (3/2) = sqrt(2 3 )...

Charles Hood Disc 1C

That number will be equal to the concentration of ADP and Pi. This is due to the fact that the coefficients for ATP and ADP and Pi are all the same (1) so when you lose a certain concentration of ATP, you lose the same concentration of ADP and Pi.

Charles Hood Disc 1C

If you mean P = (n/V)*R*T, you would use that in order to solve for concentration (n/V is the concentration) when given a pressure.

If you mean k = (P.products)/(P.reactants) you would use that to solve for the equilibrium constant or partial pressures, depending on your initial information.

Charles Hood Disc 1C

The square brackets refer to the concentration of Cl2 which is its molarity.
The "P" refers to the partial pressure of Cl2, which is generally given in atm.

Charles Hood Disc 1C

Which Equation?

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