CHEMISTRY COMMUNITY

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Anode is on the left and Cathode on the right

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it is really helpful if you write down what you have. For example, like make a somewhat chart and then label what you are trying to find from there you can find an equation which will help you

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Enthalpy is the change in how much heat there is under constant pressure, while heat is the transfer of energy caused by a temp difference

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It takes energy to break bonds and energy is released to form bonds

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I chose a because the states of the reactants and products were similar thus an entropy change will not be too large, which implies a similar delta H and delta G

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anode/cathode

anode looses mass, cathode gains mass

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K is dependent on temperature.

K is not dependent on concentration (equilibirum)

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K is dependent on temperature.

REMEMBER it is not dependent on concentration!

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Sleep!!!

Throughout the week review all the material and the day before just do practice and make sure you are eating and sleeping

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An exothermic reaction is one where the reactants have more energy than products. Exothermic releases energy, which is why the reactants should have more energy.

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The rate limiting step is the slow step of the elementary reaction. This step determines the order of a reaction.

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Molecularity is the number of molecules as a reactant.
For example, N2 + O2 --> 2NO, this is a bimolecular example

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Basically all of electrochemistry and the gibbs free energy portion of thermochem

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Corrosion is when metals return to their natural oxidation states. It causes a loss in mass, which corresponds to the anode of a galvanic cell. To prevent this, another metal like zinc or chromium is used to prevent the corrosion

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You balance the half reactions and find out how many electrons are transferred.

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The oxidizing agent means that it is oxidizing the thing, it causes the oxidization

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K is the equilibrium constant and Q is when it is not at equilibrium

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Standard Temp: 273 K
Standard Pressure: 1 atm

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Also, review other thermo too because it may be implicitly tested.

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Oxidation is the loss of electrons. Think of the element getting more positive.

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Test 2 covers everything after the midterm. But there might be some questions that connect previous topics to the ones after the midterm.

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Commas means that the state did not change. One line represents state change. Two lines represent the salt bridge.

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A negative delta S means that the reverse reaction is spontaneous. A positive delta S means that the forward reaction is spontaneous. A negative delta H means that it is exothermic and usually exothermic reactions are associated with being spontaneous because they release energy.

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Finals week is week 11. We have our final about a week or so after.

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A closed system can only exchange energy with its surroundings.
An isolated system does not exchange anything.
Open can exchange heat and matter.

Think of a bomb calorimeter as an isolated system and a closed system would be like an open pan on stove, where energy is getting exchanged but not matter

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For a reversible equation Delta S is equal to -Delta S surr, which means that Delta S total is 0.
For irreversible Delta S is equal to Delta Stotal

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Spontaneous reactions have negative gibbs free energy. G= H-TS (include the deltas). If H is negative (exo) then the likelihood of the overall reaction being negative increases as long as entropy is positive. if entropy is negative then H (-H in this case) must be greater than TS

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I have heard that if the midterm/final scores are exceptionally lower than normal, he usually adjusts the grades bit. For 14A the final average was very high thus no curve, but after this midterm there might be one.

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Thermodynamically stable is equivalent to a negative value for Gibbs. This also means that the rxn is favorable.

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that is a very good question. I think that the sign of entropy is determined by how much disorder there is. If the substance is moving from solid to liquid, entropy is positive and vice versa.

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When does deltaH = q. I remember hearing that q always deltaH, but the reverse is not true? I am unsure if I heard correctly and why this is so/

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An isolated system cannot exchange any energy with its surroundings; however, a closed system can transfer energy (only).

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Endothermic means that there is energy going into the reaction. So if there is an increase of temperature endothermic is favored because the increased heat allows the reaction to favor the products.

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I would recommend going through each section and there are worked out problems that apply the concepts. This helps better understand the concepts and also find new ways of approaching problems

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Does anyone have any good recommendations for online review materials that explain thermodynamics/thermochemistry well? i.e.) khan academy.

if so can you guys link them below!! thanks!

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When Q < K, the forward reaction is favored.
When Q> K, the reverse reaction is favored.
Create a number line if you cannot remember this. if Q is to the left of K then it goes to the right towards K and if Q is to the right of K you go left towards K.

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Kelvin and Celsius increment by the same number, so in certain cases where units cancel out like q=mcdeltt it is valid. In a case where you are not sure, switch to kelvin.

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Hess's Law uses the enthalpies of intermediary reactions to calculate the total enthalpy. By using Hess's law , you are manipulating reactions to get rid of the intermediary reactants/products and up with the reaction you want. You then factor those manipulations into your calculations for enthalpy.

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Air pressure is the only pressure acting on the beaker and it does not change. The surroundings encompass a vast area, thus the pressure doesnt change.

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Water is not used because it is a liquid. Pretend it is not there

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Hess's law basically states that even though there may be intermediary steps in a reaction. The total enthalpy change is the sum of all changes because enthalpy is a state function

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Here is another video: https://www.youtube.com/watch?v=zQT6HKplzjY

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We use the delta H tables to find the standard enthalpies and subract reactants from products. Also remember that O2, N2 and such have values of 0 and are not on the table.

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i believe that sometimes we will only be given the individual bond lengths and will have to use method 2.

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If we are tested on this, we will be asked to find the pressure or even concentration and from there calculate the equilibrium constant.

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Solids and Liquids do not contribute to the equilibrium constant, thus do not need to be included in ICE tables.

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Think of Pka and Pkb as being calculated pretty much the same exact way as pH, except in this case you could calculate -log(ka) and ka is the acid dissociation constant used for weak acids.

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The x is ignored because it is such a small value, thus will not affect the answer extremely. When doing calculations with small x, make sure you do not just plug in 0, but rather emphasize that it is negligible not 0.

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An inert gas is basically a noble gas. They are nonreactive as their octets are full

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Removing a product will cause the product concentration to increase because the reaction goes in the forward direction to make up for this product removal

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Q is calculated when the reaction is not at equilibrium and K is. K remains the same.

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Inert gases are noble gases that have a full octet so they are not that reactive.

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I believe that you can do either chemical equilibrium or acid bases. I believe Lavelle said if you have a discussion earlier in the week he doesn't expect you to do the acid and base homework.

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When K is closer to 1, then that means reactant and product concentrations are the same so that is thermodynamically stable

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yup one O2 and a histidine to create myoglobin

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CO2 increases the concentration of carbonic acid which decreases PH and causes acidosis

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if the ph is 7 at the equivalence point it represents that a strong acid and strong base titrated together

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you draw the lewis structure and then subtract the valence electrons from bonds and lone pairs. CN has a triple bond.

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delta x is the uncertainty in the position

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I would just know them just in case

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I am honestly not sure

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you would use bis tris and etc when the name already has prefixes like bi

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Amphoteric compounds are compounds that can react as an acid and base. If you react them with water, there would be 2 reactions. If you write this out then you can tell. Also it is general pattern. There is chart in the textbook which can help.

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I feel like the questions would be similarly formatted to the midterm. Reviewing the midterm can help a bit, but be prepared for anything.

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Usually in coordination compounds, the H20 becomes OH2. Since this is what bonds to the transition metal. I am not sure if we will be penalized for this.

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Cisplatin attacks the dna of the cancer cells and inhibits their repair. Transplatin cannot do that.

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Yup you can just draw them normally :)

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the first coordiantion sphere is made up of molecules and ions directly attached to the central transition metal

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A neutron walks into a bar. He asks the bartender, "How much for a beer?" The bartender gives him a smile and says, "For you, no charge."

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Old chemists never die. They just stop reacting!

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For single bonds there only exists sigma and then for double and triple there are sigma and pi bonds

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Yes it has to be transition metals

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Sigma bonds are found in double triple bonds and Pi bonds are found in single bonds. Sigma are stronger than pi

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The repulsion would be different which will lead to a difference in bond angles

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When hydrogen is bonded to N O or F then that is hydrogen bonding

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Lavelle has gone over bent, trigonal pyramidal, see-saw, and square planar in class

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How do I determine where each bond angle goes?

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Who is taking 14B with Dr.Lavelle next quarter? Anyone taking BL?

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What i would recommend doing is reading ur notes from lecture. Then attempting the hw problems for that section. And when u get stuck on a question write down the topics that correspond to it. Review those topics and reattempt the problem. This is a good way to assess your mastery of the material

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Sigma bonds are found in all type of bond. Pi are found in at minimum a double bond.

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LDF are also van der waals forces.

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H bonds are the strongest intermolecular force because of the great electronegativity difference between Hydrogen and NOF

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lewis acids accept electrons, while lewis bases donate electrons. An example of lewis acid would be H+ and an example of a lewis base would be OH-.

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An example of a radical would be OH- since it has 7 electrons

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I believe that Lavelle said that there might be some that show up as we are slowly learning more and more about naming.

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i am not sure, but the usual assumption is that the longer the bond, the weaker the bond.

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In the midterm, I believe that we only will have a basic periodic table. We should know the trends for electronegativity, electron affinity, ionization energy and such and be able to identify it.

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it is usually the least electronegative atom. Carbon is good

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How exactly would you guys recommend drawing a lewis structure

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A single bond is counted as one electron since it is shared hence the electrons in the equation are divided by 2

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Cations lose an electron, which means that their atomic radius is smaller. They oftentimes resemble the element before that which are smaller.

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Electrons must have different spin states so they can exist together in the same sublevel.

I'm pretty sure we just need to know how to draw the diagrams. so remember they must be in opposite directions

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Each photon must have enough energy to eject the electron. Increased intensity means that there are more photons. There must be an increased frequency.

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After a while, the electron will fall back down to a lower energy level/original one and release this energy in the form of photons. When an electron returns to the ground state, it no longer releases energy.

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these exceptions exist because a half-full or completely full d sub-level is more stable than the partially full one.

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The s shell fills up. Then the p shell fills up. Then d and f if they are applicable. The transition metals are where the d-orbital begins

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Molarity is moles/liters. if a question asks you to find moles of a certain substance. Then you could break down M1V1=M2V2 into moles/liters*volume.

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When electrons get excited they jump up to a higher energy level and they then release this energy in the form of a photon and eventually fall back to their original state.

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I would use M1V1=M2V2. I would start by making sure that all my numbers are in the correct units. Then I would plug in all the values that you know. From there I would solve for the unknown. Often times with dilutions you have to read the question carefully. In this case, just make sure that units a...

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