CHEMISTRY COMMUNITY

Silvi_Lybbert_3A

I forgot to thank my classmates on my slide, so thank you all so much for being such an uplifting group, giving many laughs, and of course for all the help on this forum:) Good luck with your other finals, and have a great spring break!

Silvi_Lybbert_3A

For example, for a mechanism with three steps and two intermediates, a reaction profile might show three different activation energies (the intermediates at the two dips between). I was thinking at first that the slow step would have the highest activation energy barrier seen on the profile (also se...

Silvi_Lybbert_3A

Hi! I am confused on which reduction potentials values and half reactions to use. Since not all half reactions for each substance have the same amount electrons transferred, which do we use? I thought that you could choose the half reaction, as long as the amount of electrons transferred is the sam...

Silvi_Lybbert_3A

Yes, I agree with the posts above. We want to provide cathodic protection for titanium; in other words, we want to protect it from getting reduced. By covering titanium with metals that are harder to become reduced (metals with more negative/less favorable reduction potentials), we will protect tita...

Silvi_Lybbert_3A

Thank you guys; I'm glad I could help!! Hopefully it's right..

Silvi_Lybbert_3A

I will try and give an analogy that helps me visualize this. Think about a very wealthy community. Imagine giving each individual $2000. Now think about a much poorer community. Imagine giving each individual $2000. The money will have a much greater impact on the poorer community than the wealthier...

Silvi_Lybbert_3A

Endothermic reactions have a greater activation energy of the forward reaction than the reverse reaction because the products of this reaction have more energy than the reactants. We know endothermic reactions require energy/heat... this energy is required to overcome the greater energy barrier. Als...

Silvi_Lybbert_3A

If the components are the same and the concentrations of the components of the reaction are also the same, I believe the reaction is at equilibrium and E=0. I agree with the above posts and want to add that, when the reactants are equal, there is not an imbalance of charge on either side of the cell...

Silvi_Lybbert_3A

This relationship can be seen through Le Chatelier's principle and the Nernst equation. You can think of it without doing any calculations by recognizing that increased reactant will mean the reaction will want to proceed more to the products to account for the change mentioned. This corresponds to ...

Silvi_Lybbert_3A

For a concentration cell as said above, Eº always equals 0 volts because concentration cells have the same components and therefore the same standard cell potentials regardless of differing concentrations at the anode or cathode. However, if these components are the same AND the concentrations of th...

Silvi_Lybbert_3A

Adding onto the posts above, I just want to note that you need to add an inert conductor into the cell even when only one side (one half reaction) doesn't have a conducting solid. So when you notice that one or both half reactions consist of only aqueous or gaseous phases, you should add an inert co...

Silvi_Lybbert_3A

Yes, I believe it connotes spontaneity, as the process is spontaneous when E is positive. You can see this when looking at the equation deltaG=-nFE. We know deltaG is negative for spontaneous reactions. With a negative deltaG, E must be positive: E= -deltaG/(-nF).

Silvi_Lybbert_3A

I believe it is because the dot means that the iron oxide molecule is hydrated with three water molecules, meaning these three water molecules are weakly bonded to the iron oxide to make it iron oxide trihydrate, so Fe 2 O 3 •3H 2 O is considered one molecule (waters are ligands to iron ions). So wh...

Silvi_Lybbert_3A

Yes, I was wondering the same thing, as well as why the answer would be different using PV=nRT to convert pressure to concentration and then using the concentration in the Q ratio. Does it have anything to do with the specifics in the way a standard hydrogen electrode is configured or how it works, ...

Silvi_Lybbert_3A

For this problem, you actually don't use the Nernst equation to find Eº but rather to find E. You use the table linked in the question to find Eº (cell) by finding the Eº of each half reaction and calculate the Eº(cell) using one of the two methods we used in class. Once you calculate Eº using the t...

Silvi_Lybbert_3A

I started writing the half reaction as N 2 H 4 --> NO. From here, I balanced the nitrogens which gave me N 2 H 4 --> 2NO. Next, I worked on balancing the oxygen and hydrogens by adding OH- ions and waters. The general rule sapling gave for a balancing a basic solution is if you need x more oxygen at...

Silvi_Lybbert_3A

To figure out which elements to focus on due to being reduced or oxidized, I would start out by writing out the oxidation states of the elements on each side of the equation. On the left side of the equation here, the oxidation states are: Au=0, H=+1, N=+5, O=-2, and Cl= -1. On the right side of the...

Silvi_Lybbert_3A

For this problem, its easiest for me to work backwards from what we are asked to find. We need to find the change in internal energy, deltaU = q + w. Because it is a calorimeter, it will be constant volume and w=0 and so deltaU=q. So, we need to find q rxn to find change in internal energy. q rxn =-...

Silvi_Lybbert_3A

As an added note, if you did want to do calculations to confirm such conceptual reasoning, I think this is a good example of when the van't Hoff equation would be acceptable to use. If you plug in the values given to the equation and solve for the standard change in enthalpy, you will get a negative...

Silvi_Lybbert_3A

The wording of this question confused me at first, too, but I think it might help to point out that each container has 1 mol of atoms rather than molecules. This means that, because Container A has monatomic gas particles and container B has diatomic molecules, container B has half the amount of mol...

Silvi_Lybbert_3A

Hi! I am a little bit confused on the weight of certain factors when comparing entropies. Say we are asked which of the following reactions has the largest increase in entropy: H 2 (l) ---> H 2 (g) C 2 H 5 OH (l) ----> C 2 H 5 OH (g) This is probably a bad example, but I think it will reflect my con...

Silvi_Lybbert_3A

Make sure you take into account if the q is the heat being supplied to the calorimeter or the heat of the reaction. -q rxn = q calorimeter and q cal =C cal deltaT. So, q rxn = -C cal deltaT while q cal = +C cal deltaT. The question in this problem gives you the heat supplied to the calorimeter so we...

Silvi_Lybbert_3A

Does anyone know if it is common to open up more sections like Dr. Lavelle did for this class. Is it possible more spots might open for lec1 of 14C?

Silvi_Lybbert_3A

I believe it depends on the question. We have encountered homework questions where we have been asked to solve for the standard enthalpy of formation, so we may have to do so again. However, we are not expected to memorize any standard enthalpy of formation, standard entropy, or standard Gibbs free ...

Silvi_Lybbert_3A

Hi! I thought I'd start a post where we can organize which equations relate to each type of system; also, where we can explain why each does. I will list what I have organized so far. Please correct me where I am wrong if you don't mind. Thanks so much! Irreversible System: ΔS(surr) = 0 ... why? w= ...

Silvi_Lybbert_3A

Hi, adding onto the posts above, I just wanted to note that I learned a visual way to see this method in Justin's workshop last Thursday. I attached an image; I believe he called it the box method. Basically, you want to find the change in entropy going from the arrow from 31ºC in liquid form to 31º...

Silvi_Lybbert_3A

I found this confusing at first too, but visualizing the explanation Sapling gives helped me understand it better. First of all, take into account Trouton's rule which Sapling explains as the rule that states that the increase in positional entropy (disorder) is about the same for the vaporization o...

Silvi_Lybbert_3A

You cannot have a phase change with positive deltaH and negative deltaS because positive deltaH means it's an endothermic process and negative deltaS means entropy decreases. For a phase change, these two events cannot occur simultaneously. This is because endothermic processes require heat, so heat...

Silvi_Lybbert_3A

Notice that the water is at a lower temperature than the iron, so the water will absorb heat to reach the final equilibrium temperature while the iron will lose heat to reach the final temperature. So: q(water) = -q(iron) . --> (mass of water)(specific heat of water)(T f - T i ) = -(mass of iron)(sp...

Silvi_Lybbert_3A

The heat gained by a calorimeter is given by the equation q= (heat capacity of calorimeter)(change in temp), while the heat absorbed by reaction is q= mCdeltaT. Sometimes, you are not given the heat capacity of the calorimeter but you can find it by C= q/deltaT where q is heat gained by calorimeter.

Silvi_Lybbert_3A

You are given the amount of work done by the system, the internal energy, amount of substance, and temperature change. If you look at the equation for change in internal energy: deltaU= q + w, you realize you have all you need because q=mCdeltaT. So, deltaU= mCdeltaT - w ; work is negative because w...

Silvi_Lybbert_3A

Adding a visual picture to the explanations above, if the reaction produces more moles of gas than reactants, you can imagine those gas molecules pushing against the surrounding gas molecules in the atmosphere. Like Dr. Lavelle's bicycle pump analogy, you are doing work when you pump air into the ti...

Silvi_Lybbert_3A

Hi! Heat capacity is an extensive property because the heat required depends on the amount of the substance. The significance of heat capacity being an extensive property in the context of our class is simply to realize that the SPECIFIC heat capacity, which is an intensive property, is more useful ...

Silvi_Lybbert_3A

You can determine bond enthalpy values from standard enthalpy of formation values by writing out the equations for the standard enthalpy of formation for the molecule the value is given about. For example, if you are given the standard enthalpy of formation of Cl (g), you can write out the equation ...

Silvi_Lybbert_3A

In this problem, there is technically two events that happen: AlCl3 dissolves in water and then the coordination compound gives off protons, acting as an acid. When AlCl 3 dissolves in water the Al +3 ions are surrounded by six water molecules each, as the Al +3 can accept the lone pair of electrons...

Silvi_Lybbert_3A

I will try make it clear in questions (but we will often accept both for the last reason below). If a question asks what is the enthalpy per mole of a reactant or per mole of a product, then it must be kJ/mol. Also, standard enthalpies of formation are always kJ/mol. When a balanced reaction is giv...

Silvi_Lybbert_3A

For part a, we can use method 3, the standard enthalpy of formation, to find the standard enthalpy of this reaction and determine if it is exothermic or endothermic. \bigtriangleup H_{RXN}^{\circ}=\sum \bigtriangleup H_{f}^{\circ} (Products) - \sum \bigtriangleup H_{f}^{\circ} (Reactant...

Silvi_Lybbert_3A

Hi! For exercise 5 of 4E in textbook it asks, Use the bond enthalpies in Tables 4E.2 and 4E.3 to estimate the reaction enthalpy for: (a) 3C 2 H 2 (g) --> C 6 H 6 I understand how to get the answer -597 kJ/mol, but I was wondering why the answer is in kJ/mol instead of just kJ. Aren't reaction enthal...

Silvi_Lybbert_3A

I do not believe you are doing anything wrong. I think this is either an error in the solutions manual or in Appendix2A in the book because the standard enthalpy of formation in the book for K 2 S (aq) is -471.5 kJ/mol while the solutions manual uses -417.5 kJ/mol in its calculations to get the answ...

Silvi_Lybbert_3A

I think the hardest part is just knowing where to start, as you said. Although normally we have done ICE tables for the equilibriums of weak acid, this question gives us a weak base and the process is the exact same. First, write out the equation for the weak base NaClO in solution. When dissolved ...

Silvi_Lybbert_3A

Yes, I believe so. Almost always, water is the solvent in the reactions we have looked at and especially in biochemistry. However, when water is not the solvent and its concentration is not large enough for a change in its concentration to be negligible, we do include it in the equilibrium equation....

Silvi_Lybbert_3A

Polyprotic acids are acids that can give off multiple protons, while polyphonic bases are those that can take more than one proton from water. The main takeaway from 6E I believe is to recognize this and become familiar with pH calculations of a solution with polyprotic acids or bases. The way to fi...

Silvi_Lybbert_3A

If you think back to coordination compounds you know when AlCl3 dissolves in water it becomes Cl- ions and Al(H2O)6 3+ ions because the Al can accept the lone pairs on the oxygens from six water molecules. It forms an octahedral complex. Once Al+3 dissolves in water by being surrounded by six water ...

Silvi_Lybbert_3A

I think the hardest part is just knowing where to start, as you said. Although normally we have done ICE tables for the equilibriums of weak acid, this question gives us a weak base and the process is the exact same. First, write out the equation for the weak base NaClO in solution. When dissolved i...

Silvi_Lybbert_3A

The stronger acid has a smaller pKa and a larger Ka. A weaker acid would have the larger pKa and the smaller Ka. The Ka is products/reactants so the smaller it is, the more of the acid (reactants) that does not dissociate and give off a proton, and therefore the weaker it is. To understand this conc...

Silvi_Lybbert_3A

As stated in the above post, when you add together two equilibrium equations, the constants will also be added. However, often when we add two equilibrium equations together, we make slight modifications to get the end reaction equation we want. For example, to ensure the end result is balanced we m...

Silvi_Lybbert_3A

To know if the X is negative or positive you have to look at what components of the reaction we have and what direction the reaction will proceed. For example, if we have a reaction vessel where we add in certain amounts of reactants, we will have initial concentrations of the reactants not yet reac...

Silvi_Lybbert_3A

When Q>K that means that there are more products than there should be. This is because if you look at what Q and K represent, it is the ratio of products/reactants. So if Q is larger than K, it means that there is a larger numerator and therefore more products than there should be at equilibrium, K....

Silvi_Lybbert_3A

The value of X you take from your two answers received from the quadratic equation needs to satisfy two conditions. As you know, it needs to be positive. It also has to be less than your initial concentrations. Intuitively, this makes sense because you cannot have a change in X concentration that is...

Silvi_Lybbert_3A

This reaction represents autoprotolysis because there is proton transfer between two of the same molecules and happens automatically. The water molecules are acting both like an acid, proton donor, and a base, proton acceptor. If you draw out the Lewis structures as the professor did in lecture, it ...

Silvi_Lybbert_3A

After an increase in temperature, the K of an exothermic reaction will decrease as the reaction will favor the reverse reaction (endothermic) more for it will use up the extra heat and minimize the effect of the change. After an increase in temperature, the K of an endothermic reaction will increase...

Silvi_Lybbert_3A

I don't think Q in relation to K tells us anything about stability. I believe this because Q represents the ratio of [P]/[R] when equilibrium is NOT yet reached (in other words, when the reaction is NOT yet favoring the correct amount of products/reactants, so not yet reflecting where the stability ...

Silvi_Lybbert_3A

I understand where you are getting at and I think it is a good point. However, I think even if lots and lots of inert gas was pumped in, the volume of the container would still not change. Even if each individual molecule of gas would have decreased space to freely move around about, the volume of t...

Silvi_Lybbert_3A

Yes Q is the ratio of [P]/[R] when the reaction is not at equilibrium and K is that ratio when the reaction is at equilibrium. They are calculated the same way with the same formula. Side note reminder, when Q<K reaction will proceed to the right (products) and when Q>K reaction will proceed towards...

Silvi_Lybbert_3A

Firstly, products and reactants can be favored when the reaction is already in equilibrium. When the equilibrium constant, k, is greater than 1, that means there are more products than reactants because K=[P]/[R]. Because the products are favored at equilibrium, this tells us that the products are m...

Silvi_Lybbert_3A

The answer is: i. increase in NO ; ii. increase in NO. ; iii. no effect in NO i. is increase in NO because when you increase the amount of the reactant NO2, there are now more reactants than there should be and the reaction will respond by using up some of the NO2 to form products to return to the e...

Silvi_Lybbert_3A

1) Balance equation 2) Convert grams of reactants into moles 3) Figure out how many moles needed for the given amount of one of the reactants. 4) Compare these needed amount with the amount given. Is it greater than or less than what you need? Identify the limiting reactant. If it asks for the theor...

Silvi_Lybbert_3A

Just as a note for the final, I've noticed we've had to use Avogadro's number a lot during questions about the photoelectric effect. For example, if the question says the energy needed to remove an electron is 490 kJ/mol, you have to concert this into J/photon using Avogadros's number. So, I'd say b...

Silvi_Lybbert_3A

This is because the equation for intermolecular energy is proportional to -(a1*a2)/(r^6), meaning that each increment in distance is raised to the power of 6. So even if the charge in the numerator, a1 and a2, increases by a bit, the increase in the distance in the denominator would far outweigh th...

Silvi_Lybbert_3A

So with CN, there is a triple bond which means there will be one sigma bond and two pi bonds (this is always the case with a triple bond, at least for our purposes I believe). The C and the N both have 2sp hybridization as you said. But there are three p-orbitals (px, py, and pz), and only one of th...

Silvi_Lybbert_3A

The reply is showing hydrogen bonding, not a Bronsted acid-base reaction. That said, I'm wondering the same thing; the solution says only N can accept protons that way, but I'm wondering why the double bonded O's don't do it as well. I believe it is because oxygen is stable with its double bond and...

Silvi_Lybbert_3A

Hi! I was wondering why size trumps difference in electronegativity. Is a difference in electronegativity less impactful than a difference in size, even if dipole-dipole interactions are stronger than LDF interactions? I don't know if that makes sense; I am a little confused. Thanks! This is becaus...

Silvi_Lybbert_3A

Hi! I was wondering why size trumps difference in electronegativity. Is a difference in electronegativity less impactful than a difference in size, even if dipole-dipole interactions are stronger than LDF interactions? I don't know if that makes sense; I am a little confused. Thanks!

Silvi_Lybbert_3A

The name is tetraammine dichloro cobalt (III) chloride. This is because the order of naming a coordination compound is ligands in alphabetical order (by ligand name not prefix), transition metal, and then anion name. NH3 is ammonia but when it is acting as a ligand, it is called ammine. Because ther...

Silvi_Lybbert_3A

I think another way to explain it is to look at the angles between electron densities in the two situations displayed in the diagram above. If the lone pairs were made in the axial positions (yielding trigonal planar shape), there would be three 90º angle interactions between each lone pair and the ...

Silvi_Lybbert_3A

Hi! Just want to point out the number of bonds and number of ligands are not the same thing. The coordination number is the amount of bonds to the central transition metal atom, but that will not necessarily be the number of ligands. After all, polydentates can form multiple bonds; for example, one ...

Silvi_Lybbert_3A

Coordination numbers are the number of bonds to the central transition metal. It is not necessarily the number of ligands bonded to the TM because certain ligands can be polydentate. For example, in the example [Pt(en)Cl2], the coordination number is 4 even though there are only 3 ligands. (en) stan...

Silvi_Lybbert_3A

When nickel (II) chloride is dissolved in water, we saw in a lecture that it forms an octahedral complex with four water molecules coming in to bond with the central TM cation nickel. Because it is a salt and dissolves in water, I am assuming two other water molecules will end up displacing the chlo...

Silvi_Lybbert_3A

I agree with what is said above. The atoms do not cancel because of the tetrahedral shape causes the Cl dipole moments to add together and create a negatively polar side of the molecule. In a tetrahedral shape, the Cl atoms are not directly opposite each other, and therefore would not cancel.

Silvi_Lybbert_3A

For the T-shape, you want to put lone pairs opposite each other if possible to minimize the interaction between lone pairs for the most stable structure; therefore, they are on the same plane in a T-shape because they will be opposite each other. As for the seesaw shape, we make an equatorial positi...

Silvi_Lybbert_3A

Based on the Lewis structure and your knowledge of VSEPR theory, approximate the smallest bond angle in this molecule. I was wondering why the shape of this would be square pyramidal rather than trigonal bipyramidal because if you take the octahedral arrangement of electron density and make an equat...

Silvi_Lybbert_3A

Hello! I was a little bit confused with examples including unhybridized p-orbitals, regarding how many regions of electron density the carbon atoms have. For example, in ethene and benzene examples, Dr. Lavelle said in lecture that each carbon atom in these molecules has 3 regions of electron densit...

Silvi_Lybbert_3A

I agree with the answers above, and this image that I found helped me visualize this example. Hopefully, it interests others, too!

Silvi_Lybbert_3A

You do not have to know the exact electronegativities of the atoms to know whether the molecule is polar or non polar. You only need to know the periodic trend and, if looking at a molecule and not just a single bond, also the shape. The periodic trend is that electronegativity generally increases a...

Silvi_Lybbert_3A

I believe the only examples where Dr. Lavelle have added lone pair electrons to the central atom when the atom already has an octet is when that central atom is an element that can have electrons in the d-orbital. For example, when sulfur is the central atom of a molecule and you need a place to put...

Silvi_Lybbert_3A

Polarizability is the ability of the electron density of a molecule or atom to be distorted. Polarizability increases with the size of the atom; the bigger the molecule and the less tightly held the electrons are, the more polarizable they are and the more easily they can be distorted and vice versa...

Silvi_Lybbert_3A

You can assume the electron will be taken from the outermost shell (the valence shell) because these are the electrons with the highest energy and therefore will take the least amount of energy to remove. These outer electrons have the smallest effective nuclear charge and therefore are less strongl...

Silvi_Lybbert_3A

Even if the name of the molecule is only based on the bonding pairs of electrons, it doesn't mean that the shape of the molecule or the Lewis structure only includes/is based on only the bonding pairs of electrons. The two lone pairs of electrons on the sulfur central atom leads to a bent structure ...

Silvi_Lybbert_3A

Adding to the answers above, you can also solve for the mystery element by using the formal charge equation: FC= V + (L+ (s/2)). The formal charge of the other elements in the atom are 0, so the central atom must also be 0 because the overall net charge of the molecule is 0. The central atom has no ...

Silvi_Lybbert_3A

I know that molecules with polar bonds can accept electrons and be Lewis acids, but I was wondering about the specific example sulfur trioxide (SO 3 ) from Sapling. I understand that an electron pair can be accepted by an oxygen atom and its double bond could turn into a single bond. However, I was ...

Silvi_Lybbert_3A

The oxidation number of oxygens are -2 other when they are bonded to fluorine. The oxidation numbers of each atom in the molecule should add up to equal the overall net charge of the molecule. Therefore, with 4 oxygen atoms (4*-2) and an overall charge of -1, the oxidation number of Cl is +7. Now, i...

Silvi_Lybbert_3A

I am not sure this is exactly what you were asking, but 4s is written in electron configuration before 3d when 4s is lower in energy than 3D. This occurs for elements that have entered the s orbital, but not yet the d orbital on the periodic table, like Ca and K. However, after the 4s state/orbital ...

Silvi_Lybbert_3A

Good afternoon! In the 11/11 lecture elaborating on induced dipole-induced dipole interactions, Dr. Lavelle explained how increasing molar mass/size of atom/ number of electrons results in stronger attractive interactions because the electrons are held more loosely and can be more distorted. However...

Silvi_Lybbert_3A

I don't believe we need to memorize the radicals, but I believe we do need to know what they are and what they mean. A radical is a compound with unpaired electrons, and this means that they are highly reactive (and often damaging to DNA, etc.) and therefore exist in such a state only for a short ti...

Silvi_Lybbert_3A

Would we be expected to know the difference in size of atoms that are hard to distinguish between, like for ex/ Na and Kr? In this example, Na is the largest atom in row 2, while Kr is the smallest atom in row 3. Is there a way to determine which one is greater in size just by looking at the trends ...

Silvi_Lybbert_3A

Hi! It seems as though cations are usually polarizing, while the anion is polarizable because cations tend to distort anions; however, I believe that it is possible for it to be the other way around and will explain this below. I would assume that polarizability does not relate exclusively to anions...

Silvi_Lybbert_3A

It seems to me that the concepts of electronegativity and electron affinity are very similar; is there a distinct difference?

Silvi_Lybbert_3A

Can total formal charge of a molecule be found, not only by summarizing individual atom's formal charges, but also by seeing how many electrons have been added on top of the total number of electrons the free atoms would have?

Silvi_Lybbert_3A

Electron affinity is the likelihood of gaining an electron, defined specifically as the difference in energy between a neutral atom and the anion (with an electron added) : energy of neutral atom - energy of anion. Electron affinity increases as you go up and to the right on the periodic table, with...

Silvi_Lybbert_3A

Why can't I use E=pv to find the energy of an electron instead of E=(1/2)mv^2? When I am given velocity of electron, E=pc from equations sheet becomes E=mv^2 to find the energy of the electron. However I am getting a different answer using the kinetic energy equation and the answer using this equati...

Silvi_Lybbert_3A

Thank you so much!

Silvi_Lybbert_3A

Hello! The question I am wondering about is: The electron in a hydrogen atom is excited to the n=5 shell and emits electromagnetic radiation when returning to lower energy levels. Determine the number of spectral lines that could appear when this electron returns to the lower energy levels. I know t...

Silvi_Lybbert_3A

Does anyone else get an answer of the wavelength being 1 m? In the back of the book it says the answer is 1 nm but I don't see how I'm getting it wrong somehow. I also am getting this, and I'm led to believe the book must have made a typo because they do say that the wavelength corresponds to micro...

Silvi_Lybbert_3A

I had the same question and would like further clarification, if anybody knows. Dr. Lavelle said that all matter (including classical objects) have wavelike properties but they are only detectable at the atomic scale. So, even classical objects have wavelike properties, but they are just immeasurabl...

Silvi_Lybbert_3A

Hi! In his office hours, I believe Dr. Lavelle said that there will only be modules for the first two outlines. This is because he wanted students to be able to start working on outline 1 in the summer, and he wanted to give additional help on outline 2 because the Quantum World is the hardest unit ...

Silvi_Lybbert_3A

Adding on to those comments above, amplitude is proportional to the intensity (intensity of light is then proportional to the number of photons). Frequency meanwhile is proportional to energy per photon.

Silvi_Lybbert_3A

Adding on to the reply above, because kg is the SI unit for mass, it is a part of the units for the constants. Plank's constant has units of J*s, and a joule is kg*m^2*s^-2. Because the units of Plank's constant incorporate kg, it is needed that the mass in de Broglie's equation is measured in kg so...

Silvi_Lybbert_3A

Roman numerals appear next to ions that often have different charged forms. For example, iron and copper often have different forms. Iron can have a charge of +2 or +3, while copper can have a charge of +1 or +2. The Roman numeral next to these ions corresponds to their charge (ex/ copper (II) sulfa...

Silvi_Lybbert_3A

Hello! I know that it is all multiple-choice, and we have a 50 minute period to take the test and a 5 minute period to "settle in." There will be partial credit for certain answers on the longer questions (some multiple choice answers will factor in doing certain steps but not all steps ri...

Silvi_Lybbert_3A

My TA said the same things as it seems others did. I just want to add that he also said you don't need to know specific cut-offs, but you should know the order of the type of light from area of higher to lower wavelengths so that you can compare.

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