CHEMISTRY COMMUNITY

Myracle Franco 2G

Hi! I was wondering if anyone had tips on deriving or remembering the units of chemical kinetics. I know they usually include M and s. For example, could someone talk about the unit for Second Order, like how to derive it? Thank you!

Myracle Franco 2G

I believe that a voltaic cell is just another name for a galvanic cell. They both generate electricity from chemical changes and/or they utilize spontaneous a redox reactions create electricity.

Myracle Franco 2G

If I recall correctly, K is for equilibrium constant and k is for rate constants in kinetics. We have been using k within our rate laws.

Myracle Franco 2G

You determine orders of reaction by solving for your rate laws. They can be affected by time and concentrations, depending on the rate law. It would be best to also look at the examples of the order reaction graphs and see how their slopes affect their appearance.

Myracle Franco 2G

Hi, I hope this helps a bit, but for: cell shorthand notations/cell diagrams, you're given the reaction and if so the visual with the beakers/half cells. The anode is on the left and the cathode is on the right like how they would be in the visual. When you write the shorthand they are distinguished...

Myracle Franco 2G

Hi! Could someone explain why when determining the order of [A] & [B] in this problem, why don't we use the [C] column to help us calculate? My TA said the final/overall rate law was k[A][B]^2, thus it omits [C]. Thank you!

Myracle Franco 2G

Hi! I was wondering tips on maybe remembering the graphs for the order reactions?

Thank you!

Myracle Franco 2G

Hi! I was wondering if anyone could please explain the rate-determining step?

Thank you!

Myracle Franco 2G

Yes, galvanic cells can be recharged with external electrical energy, In order for the galvanic cell to be recharged, the external electrical energy that is applied would need to be an external electrical potential that acts in the reverse direction.

Myracle Franco 2G

I think that unique reactions and rates relate to whether a substance stays or doesn’t within a reaction and for a rate it would divided by the coefficient. Then a unique rate is identical for every reactant.

Myracle Franco 2G

Hi! I was wondering if someone could explain how to combine half-cell reactions so that electrons will cancel out on each side? Thanks!

Myracle Franco 2G

Hi! Does anyone have any advice or tricks to remember or identify the preferred oxidation states of common elements?

Myracle Franco 2G

I believe that in between solutions, a salt bridge, anions will be attracted to the anode, and the cations will do the same for the cathode. Porous disks are different in the sense that salt can be attracted to either side and not be attracted to a certain side. They are different in what they let t...

Myracle Franco 2G

An Ecell when positive is considered spontaneous because it goes hand in hand with delta G. If delta G is negative then the Ecell will be positive and spontaneous. This is due to the equilibrium constant which also relates to both. and vice versa.

Myracle Franco 2G

Is there a difference when balancing net ionic equations vs. the chemical equations that we are so used to balancing? If so, what are some good pointers to remember or look out for?

Myracle Franco 2G

Hi! I was wondering if anyone could please explain these and what their uses are?

Myracle Franco 2G

They are the same thing, just a different name. You would use them when you are generating electricity from chemical changes. They are a way to picture this process, and they contain the flow of electrons, the cathode, anode, and salt bridge.

Myracle Franco 2G

I believe that a voltaic cell is just another name for a galvanic cell. They both generate electricity from chemical changes and/or they utilize spontaneous a redox reactions create electricity.

Myracle Franco 2G

I believe in general, electronegativity on the periodic table of elements, when increasing will also increase at the same rate as the oxidation state of a certain element. For the ones that can bond to carbon that are non-metal, will have their carbon oxidation state increases by 1. However, not all...

Myracle Franco 2G

The equation for degeneracy should be: W = x^n. Where X is the number of (possible) particles and n is the number if molecules given. Then you would do Kb * ln(x^n).

Myracle Franco 2G

They all in a way go within each other, Gibbs Free Energy is basically the energy of a chemical reaction that does nonchemical work.

Myracle Franco 2G

For this equation, ln K= (-H/RT)+(S/R), K would be an equilibrium constant and not Kelvin.

Myracle Franco 2G

Hi! I have still been going over previous lectures and for Lecture 9, there is a last slide that mentions an example of how to calculate how much heat was released. I understand the equation, mass * specific heat capacity * change in temp. However, can someone explain how the mass part of the equati...

Myracle Franco 2G

I like to remember them. by looking over the equation and saying it as a funny word and finding a way to relate the variables. For example, you mentioned "work at a constant temperature", I try to remember that as just saying the whole equation as a word: PVnRT, (pronounced "PIVNERT&q...

Myracle Franco 2G

Hi! I have been looking over previous lectures and came upon the slide that mentions the methods of calculating delta H. Concerning Method 1 or Hess's Method: when the reactions were added, why weren't N2 and 2NO added together, and how come both their products not added together?

Myracle Franco 2G

Does anyone have tips on how to solve problems that relate to the change in enthalpy given change in intermediate reactions? Like we are given 3 reactions and their delta's h?

Myracle Franco 2G

Basically, a closed system is "closed" only for matter, and an isolated system is just fully closed so it cannot engage with energy or even matter.

Myracle Franco 2G

I am not sure if you were also talking about the types of systems. But if you were, An open system is where there is an exchange of energy and matter with its surroundings. Second would be an isolated system, there is no exchange of matter or energy with its surroundings. Lastly, there is a closed, ...

Myracle Franco 2G

I know for the solid phase there is low entropy, but what is the type of entropy for liquid and gas phases? In addition, could you please explain why they have that entropy? Thanks!

Myracle Franco 2G

An open system is where there is an exchange of energy and matter with its surroundings, and for isolated, there is no exchange of matter or energy with its surroundings.

Myracle Franco 2G

Hi! I was checking my answer for 6B.5, and I am unsure why my answer was different from the textbook. For Part C I did, -log(0.0092) and got about 2.04 as the PH and then did 14-2.04 = 11.96 for POH. However, both these answers are incorrect. What step am I missing? The textbook says the answers are...

Myracle Franco 2G

Hi! I had just been going over my work before the midterm, but I had forgotten I had skipped over this problem since I was unsure. How would I go about starting this problem? "A sample of ozone, O3, amounting to 0.10 mol, is placed in a sealed container of volume 1.0 L and the reaction 2 03(g) ...

Myracle Franco 2G

If I remember correctly from my discussion section, there are not exact factors that affect Q. Because when thinking of equilibrium, Q has to depend on K to shift to the left or the right. So in the sense that, the temperature is a factor that affects Q, but not directly since if the temp is higher ...

Myracle Franco 2G

Water autoprotolysis is basically when two h2o molecules create [OH-] and [H₃O]⁺ or [H+]. But in terms of pH + pOH = pKw, you know pH is -log([H₃O]⁺ or [H+]) and PoH is -log([OH-]). Together the sum of PoH and PH should be 14 at room temperature. Kw=([H₃O]⁺ or [H+])*[OH-], which is equal to 10^-14, ...

Myracle Franco 2G

Hi! You should always round your final answer at the end and not during the steps to get to it. It can cause your calculations to be off. However, if a value is given, don't round when calculating just round your answers. In addition, I was also told by one of the UAs that the sig figs in the lectur...

Myracle Franco 2G

Hi, I was wondering for Achieve #9 and #10, when it comes to a weak acid and weak base are “the rules” the same when comparing the given PH to the given Pka? Or are they opposites? Ex: For a weak base, if the given PH is less than the given Pka, it would be charged and it would be neutral for a weak...

Myracle Franco 2G

Hi! For your problem, we had different values but our ICE tables are similar. For your Change portion, you should use the ___ Mol of SO3, which based on your photo is 0.800. You were not given any other values for SO2 and O2 so those are 0. For the change portion use the "at equilibrium ___ mol...

Myracle Franco 2G

Hi, I was wondering if anyone could explain "percent ionization" more? It was talked about in yesterday's lecture, but I wanted more help on how to go about starting calculations for this type of problem. Any advice is appreciated, thank you!

Myracle Franco 2G

Hi! If I remember correctly from the section last week, my TA said that the equilibrium won't shift since both sides have equal molecule amounts. But if partial pressures are given when their molecule numbers are equal, the shift would be towards the side with higher partial pressure. Or you can loo...

Myracle Franco 2G

Hi! Does anyone have any advice or tricks to remember or identify the acidic, basic, or neutral substances (Weak and Strong)? Thanks!

(sorry the topic forum is from last week but not sure where to find the acids/bases topic forum. This one is the most recent)

Myracle Franco 2G

Hi! We really use this principle for concentrations and not for temp or pressure. However, for its meaning, its is when the equilibrium moves to balance out a type of stress that is applied. (tries to be equilibrium again after the stress) Like if a volume increases then it will shift to the side th...

Myracle Franco 2G

Hi Y'all, My question is that when solving for the Ka using Ka = [H+][A-]/[HA], What would the "[H+] and [A-]" look like when we are writing out our ICE tables, since it is not given? I am not sure, but since H+ has "+" the change would be "+x" and for A- with the "...

Myracle Franco 2G

hi! I'm not sure if this is what you are asking. However, I will answer this using the Pka equation that pKa = -log(Ka). Based on this, "Ka" can be found by using: Ka = [H+][A-]/[HA]. Thus Pka will be affected by the hydrogen ions' concentration, the conjugate base concentration, and the a...

Myracle Franco 2G

Hi! You would have to use stoichiometry to solve for moles and use the molar masses on the periodic table, based on the compound or element the problem or reaction gives you. Pay attention to the coefficient of the compound and the subscripts.

Myracle Franco 2G

hi! To get x for this problem (My #4 was different from yours), but if I remember correctly you can use the ice table to look at the changes in your problem. Since the left side of your reaction has two items that turn into one item, the changes in your table for "C" are +x, +x, -x. Then y...

Myracle Franco 2G

Hi! You have to take note of the signs in the changes in enthalpy (delta H), (+ or -), because it will determine what type of reaction you have, either exothermic or endothermic. So for #7 if the temperature is positive or increasing, then K will also increase and the system response will shift to t...

Myracle Franco 2G

Hi, I believe brackets are preferred when one is using an amount of a concentration, and they have set units. So basically they are solved or given. But since your TA is asking your class to use parentheses, this is them showing that when you are solving your equation or substituting, the values in ...

Myracle Franco 2G

Hi, from what I remember: changes in temperature impact the pH and pOH because if the temperature is warmer or higher, the Ph will lower and the opposite will occur to the pOH, it will increase and vice versa if the temperature is lower or colder.

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