CHEMISTRY COMMUNITY

Rebecca Doan 2L

For the final, how in depth do we need to know collision theory?

Rebecca Doan 2L

What does >> or << mean?

Rebecca Doan 2L

Are stoichiometric coefficients used for elementary reactions? In the book, it states that they are not. However, in lecture, Lavelle has provided examples where there are coefficients in the elementary reactions of a mechanism.

Rebecca Doan 2L

The question states "as it returns to the original internal energy". It was calculated, in step 1, that the change in internal energy was -158 so to return to the original internal energy, step 2 internal energy would have to be the opposite, +158J.

Rebecca Doan 2L

The temperature will not change during a phase change. All of the energy being lost is due to a substance changing from one state to another. The energy is used as work to break or form bonds of the molecule.

Rebecca Doan 2L

I am pretty sure you do not need to know the derivation of the equation, just the equation itself. So memorize the equation and you will be good to go.

Rebecca Doan 2L

you would use the data on the table just as you would for a positive whole number order.

Rebecca Doan 2L

What is the importance of half-lives? Like why is it significant to know the time needed for the concentration to be half of the initial, why not just calculate the time needed for the concentration to reach zero?

Rebecca Doan 2L

When solving for (a) in rate reaction problems, will the answer always be a whole number or 1,2,etc...?

Rebecca Doan 2L

I am still confused how to determine/calculate the a value of a reaction. can someone please explain this to me?

Rebecca Doan 2L

hydrogen's cell potential is zero so that it is possible to calculate the cell potential of the other electrode. Standard potentials only give us the overall cell potential and not just one electrode. Therefore, we arbitrarily set the standard potential of hydrogen to zero at all temperatures.

Rebecca Doan 2L

Anodes are always on the left and cathodes are always on the right. To figure out which is which you have to determine which reactant is being oxidized and which is being reduced, so look at the electrons.

Rebecca Doan 2L

how are rate constants calculated and what do they represent?

Rebecca Doan 2L

I think the unique average rate is just specific to the question/ reaction you are given. So when they ask for the unique average rate of the reaction, they are talking specifically about that certain reaction with those stoichiometric coefficients. When you calculate the average rate, the coefficie...

Rebecca Doan 2L

you are finding the average rate of consumption. So, because the reactants are being consumed the delta A or R is going to be negative. For chemical kinetics, the rate is always going to be positive, hence the negative sign.

Rebecca Doan 2L

Can someone please explain to me this concept: "True/False: One cannot calculate the entropy of vaporization for water at room temperature because water has a boiling point of 373K."?

Rebecca Doan 2L

How come you get two different Gibbs free energy values when you solve them using the equation G = H - TS vs G(products) -G(reactants) ?

Rebecca Doan 2L

What is the difference between S°m, S°r, and S°f?

Rebecca Doan 2L

In problem 9.65, what determines the stability of an element? Like what variable measures that and how are we supposed to calculate that?

Rebecca Doan 2L

If Dr. Lavelle doesn't allow calculators on exams, then how are we supposed to calculate any problem that requires solving an integral?

Rebecca Doan 2L

Think about entropy in a manner of disorder. If things are not vibrating, they are stuck in place and orderly. However, if they are vibrating, there is more movement in general, meaning that there is more disorder and entropy.

Rebecca Doan 2L

when heat is exiting the system, heat is being lost so it is negative. When additional heat is entering a system, heat is being added, hence the positive sign.

Rebecca Doan 2L

What does it mean by "ideal" when a system is an ideal cooler?

Rebecca Doan 2L

Can someone explain to me or give me an example of how energy could be transferred to or from a system as work in an adiabatic container?

Rebecca Doan 2L

I also was wondering what the relationship between the two was. Like are they completely different variables or do they work together?

Rebecca Doan 2L

Just for clarification, what is the difference between ΔH, work, and heat? (Conceptually)

Rebecca Doan 2L

Can someone please explain to me the difference between irreversible and reversible processes? I am still a little confused on the concept part of it.

Rebecca Doan 2L

what is the difference between delta H and delta U? also, what units do you use for each?

Rebecca Doan 2L

How do you know an element's standard state? are you just supposed to memorize them or...?

Rebecca Doan 2L

I understand that the temperature remains constant during phase changes, but then why does the temperature increase of water from when it melts to when it is boiling?

Rebecca Doan 2L

In Bronsted acid and Base equations will the proton always be in the form of H+ or could it be something else as well?

Rebecca Doan 2L

Can someone explain how NO2- is a Lewis base in the reaction HNO2 + HPO4(2-) --> & <-- NO2- + H2PO4-? like how does NO2- have two electrons to donate?

Rebecca Doan 2L

How can water act as a base and an acid?

Rebecca Doan 2L

What is the difference between Bronsted and Lewis acids?

Rebecca Doan 2L

whenever there is a decimal, there is a resonance structure meaning that the bond strength is between either a single bond and a double bond, or a double bond and a triple bond

Rebecca Doan 2L

the 2 is the principle quantum number (n)

Rebecca Doan 2L

How do you draw/fill orbitals? like in what order?

Rebecca Doan 2L

why can there only be one sigma bond?

Rebecca Doan 2L

With the molecular shape and VSEPR, would it be just easier to memorize the different angles and shapes and names for the test?

Rebecca Doan 2L

how do you know if a bond is ionic, polar, or nonpolar?

Rebecca Doan 2L

What is the relation between formal charge and stability of the structure?

Rebecca Doan 2L

I am still unsure about the concept behind the incomplete octet of boron trifluoride. I know what it says in the book, can anyone explain this in further detail?

Rebecca Doan 2L

Electron affinity is equal to the negative change in energy.

Rebecca Doan 2L

When writing the arrows denoting the spin of the electron, does it matter if you draw the arrow facing upwards or downwards first?

Rebecca Doan 2L

I am confused on the concept of a super octet. I thought there could only be up to 8 electrons in the outer shell. So, how is a super octet formed?

Rebecca Doan 2L

Will we need to know about the Lyman or Balmer series for the test?

Rebecca Doan 2L

Kayla Ikemiya 1H wrote:Can someone please explain how to start a new topic on this please? I also don't understand 30 C on the post module for Photoelectric effect

you have to go to board index --> chem 14a --> select which topic your question pertains to and then click post a new topic

Rebecca Doan 2L

Since 3.00 x 10^8 m/s is the constant that Dr. Lavelle uses in lecture, I think it is safe to use that on our homework and on tests since the TAs grade them and they know what Lavelle has taught us (i.e 3.00 x 10^8 m/s).

Rebecca Doan 2L

He did not go over it during lecture very much, so I am sure it is not needed for the test.

Rebecca Doan 2L

What is meant by the intensity of a wave or the intensity of the light?

Rebecca Doan 2L

How can we tell if something has wavelike properties?

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