CHEMISTRY COMMUNITY

Emily Burghart 1k

Dr. Lavelle, Although I know that my comment will be lost alongside many, I would like to say thank you. I switched majors over the summer from political science to a stem major and my first quarter was extremely rough; I didn't know how I was going to survive 14 B. Although I still struggled (and d...

Emily Burghart 1k

What was most helpful in understanding the mechanism functionality of an overall rate law?

Emily Burghart 1k

You're great! thank you for posting a comprehensive answer key despite not being able to have the review session!!

Your sessions were very helpful!

Emily Burghart 1k

This is a good video! I watched another of his videos on other general kinetics problems, and it was good. https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=15&cad=rja&uact=8&ved=2ahUKEwiOp82665voAhXMi54KHRqgAZsQtwIwDnoECAkQAQ&url=https%3A%2F%2Fwww.you...

Emily Burghart 1k

This is a good chart for reference.

Emily Burghart 1k

TanveerDhaliwal3G wrote:I think the k' is supposed to signify the combination of the first rate constant and the concentration of A

How did you get that from the problem? Is there a simple way of figuring that out?

Emily Burghart 1k

Does anyone have a good video/ website that helped them understand kinetics better?

I have been studying kinetics a lot, but seem to need some additional review!

Emily Burghart 1k

JasonLiu_2J wrote:Also to add on, remember that for a first order reaction, the slope of the graph ln[A] vs time is -k, so you would need to multiply it by negative 1 to find the value of the rate constant.

Why are we able to just multiply the slope by -1 to find the rate constant?

Emily Burghart 1k

Chem jokes

Emily Burghart 1k

the Nernst Equation relates cell potential with concentrations: E = E^naught - (RT/nF)*lnQ E^naught is the cell potential at standard conditions. R = Gas constant T = Temp in Kelvin N = mols of e- F = Faraday's constant Q = Reaction Quotient Another way of explaining n, is by saying it is the numbe...

Emily Burghart 1k

Is there a way of knowing if the metal will be oxidized? Do certain metals oxidize easier than others? Which metals are least likely to oxidize and dissolve into solution? Refer to the ordered electrochemical series. Metals with half-reactions that appear later in the table (more negative E^0) are ...

Emily Burghart 1k

205007651 wrote:The only order that matters is anode on the left and cathode on the right, and having aqueous next to salt bridge.

Why does it matter to have aqueous next to the salt bridge?

Emily Burghart 1k

Natalie Benitez 1E wrote:The cathode should be the one with the larger E value.

Why again is the cathode the one with the larger E value?

Emily Burghart 1k

When writing cell diagrams from a given reaction when do we separate species with a comma? is this due to the species being in the same phase? If this is true would you also separate products and reactants in the same phase with a comma as well? In addition to this, you separate the sides of the re...

Emily Burghart 1k

In a test style problem, would the question say something alongs the lines of "In the acidic rxn..." or must we be able to identify that? Otherwise, if we were to accidentally use OH- when we were supposed to use H+, would a significant number of points be taken off?

Emily Burghart 1k

When I took chem 14A with Caram, for the most part the Sapling was not that helpful. I do believe Lavelle has some problems he's pulled from there for test/exam questions. However, doing all the textbook problems is your better bet, along with going to step up sessions/ workshops.

Emily Burghart 1k

Test 2 will cover the information on the 2nd page of the Thermodynamics and the electrochemistry outline.

Emily Burghart 1k

Yes, due to their inverse relationship in the equation $\Delta G\cdot=$ -nFEcell, when the cell potential of the battery is positive, the $\Delta G\cdot$
becomes negative

Emily Burghart 1k

Is it important to have a detailed cell diagram for your answer/work in your problems, or is supposed to function as more of a basis for your equation?

Emily Burghart 1k

Found on Pinterest

Emily Burghart 1k

Ahh you Noble Gasses

Emily Burghart 1k

The activation energy of a reaction is the peak of an energy diagram. Beginning where the products are located to the height of the peak is how much energy is needed to cause the reaction to happen. Some reactions have very low activation energies, and others have high activation energies. It is imp...

Emily Burghart 1k

If an intermediate is formed during a reaction, and then used, do non-state functions include those changes and quantities?

Emily Burghart 1k

I end up doing the readings from the book and I make sure to do the example problems as I go along to make sure I have grasp the subject. The practice problems are helpful and the evening step up sessions are helpful if you need extra guidance on certain problems.

Emily Burghart 1k

What equation do you use if you are not sure if the equation has a $\Delta G$ equal to 0?

Is there a way to check that $\Delta G$ is 0 if it is not explicitly stated in the problem?

What happens if you use the equation for a reaction that is not at equilibrium?

Emily Burghart 1k

Ethanol is a byproduct of the fermentation of plants, which makes it readily available. We will always have a fuel source if we are producing plants. Although they still contribute to global warming, our society cannot immediately switch to fuel sources powered by solar, nuclear or wind/water becaus...

Emily Burghart 1k

Reduction and oxidation is how an electron is transferred. The notation taught in LS is OIL RIG. Oxidation is Loss of electrons Reduction is Gain of electrons When something becomes oxidized, the oxidation number becomes more positive. Being reduced means your oxidation number becomes more negative.

Emily Burghart 1k

Is there a way of knowing if the metal will be oxidized? Do certain metals oxidize easier than others? Which metals are least likely to oxidize and dissolve into solution?

Emily Burghart 1k

Are there any oxidation numbers of specific compounds that would be helpful to know?

Emily Burghart 1k

When work is done by a system, the system is affecting the surroundings. ex. exothermic rxn, - $\Delta H$

When work is done on a system, the surroundings are affecting the system. ex. endothermic rxn, $\Delta H$

Emily Burghart 1k

Are you asking about spontaneous reactions?

Emily Burghart 1k

What can we learn from the degeneracy of a system? when x=2 n=3 W=8, but what does that mean? Is it anything more than knowing that degeneracy is the number of ways of achieving a given state?

Emily Burghart 1k

Because the different micro states all have the same energies, is there any instance we would have to use a micro state in an equation and specify the one we are using?

Emily Burghart 1k

Yes, as temperature increases, entropy increases due to the excited nature of the molecules within a system.

Emily Burghart 1k

$\frac{300 kJ}{mol} \cdot .05 mol= kJ$

As you can see here, you will want to multiply the values to cancel out the mol, so you are left with kJ. You are left with 15kJ.

Emily Burghart 1k

In many of the problems covered in thermo, you have to calculate the energies expelled/absorbed for each part of the phase change, and then add those up to find your enthalpy, $\Delta H$ .

Emily Burghart 1k

Would irreversible reactions occur in open containers then? If the pressure is constant is it always a irreversible reaction? In open containers I believe you would use the irreversible equation since you are losing energy in the form of heat to the surroundings. According to the first comment, tha...

Emily Burghart 1k

Visible on the heating curve that we looked at in class, there is a significant amount of energy stored in vaporized water. When this vapor comes into contact with human skin (which is significantly cooler than the vapor) the vapor releases vast amounts of energy to return to its liquid state, which...

Emily Burghart 1k

In LS we learned that there is an input of energy to overcome the energy barrier, and that energy was released. But the energy put in or released depends on the type of bond that is broken. Determining enthalpy depends on the difference of energy between input to break and output to form these bonds.

Emily Burghart 1k

When a reaction has a negative enthalpy, it is considered ectothermic because it is releasing heat. You can think of how ecto sounds slightly like exit, and the negative sign as subtracting heat from a system and sending it into its surrounding environment. For endothermic, think of endo like enter....

Emily Burghart 1k

In a chemical reaction, if one reactant is increased in pressure, the other will decrease to try and balance it, but ultimately the concentration then becomes higher and the equilibrium shifts to the products where pressure increases.

Emily Burghart 1k

Adding an inert gas, a noble gas, has no change on the chemical system.

Emily Burghart 1k

When considering temperature, pressure, and concentration, it is important to note that pressure and concentration both only change where equilibrium lies on the equilibrium constant. If you were to increase pressure or concentration in one part of the equation, pressure or concentration would decre...

Emily Burghart 1k

$\frac{x}{initial concentration}*100$
then compare your % to 5%.

Emily Burghart 1k

The coefficients are taken into account when calculating the concentration of the reactants and the products. Once you have done that, I don't think you need to consider the coefficients again. For example, if you have calculated that there was x amount of product at equilibrium and y amount initia...

Emily Burghart 1k

A change in concentration does not cause Kc to change because equilibrium adjusts until the standard Kc rate is met. However, an increase in temperature will cause Kc to shift towards the reactants and vice versa.

Emily Burghart 1k

When Q=K the reaction is at equilibrium meaning that the forward and reverse reactions are happening at the same rate. This does not mean that they are not occurring, but rather [R] and [P] are being formed at the same time, and neither is being formed more than the other.

Emily Burghart 1k

P- Pressure
V- Volume
n- Amount in moles
R- The ideal gas constant (depends on the units you are using)
T- Temperature

P and V are inversely related. Assuming a constant temperature, when pressure increases volume decreases and so forth.

Emily Burghart 1k

For this problem we are only looking at the change in the P or R values of the Q equation, using K as a fixed ratio. Your K value is the fixed ratio between the left and right sides when at equilibrium. While Q is also a ratio between the [R] and [P] but the ratio might not be at equilibrium. This m...

Emily Burghart 1k

Is it appropriate to consider Le Chatelier's Principle as a ratio?
I.e. determining the change of one value would aid in determining the other values and thus, the equilibrium?

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