CHEMISTRY COMMUNITY

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Can someone explain to me how I would determine the molecularity of each elementary reaction in C2H5Br +OH- > C2H2OH + BR-?

Is the answer bimolecular? If not, can someone explain how I would approach this question?

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Thank you so much! This cleared it up immensely.

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Conceptually, how do I know what order each molecule is going off of words? When NO is doubled, the rate of reaction of 2NO +O2 > 2NO2 increases by a factor of 4. When both O2 and NO are doubled, increases by a factor of 8. How can I figure out the reactant orders? The answers for NO is second order...

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Can someone explain to me how I can use the average rate to go from the production of one molecule to the consumption of another? For example, In the textbook, the example given is N2 + 3H2 > 2NH3 We are given that the average rate of rxn is 1.15 mmol/L*H NH3. a) How can I used this to find the cons...

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In question 14.85, in the 6th edition, it gives a list of metals being Al, Zn, Fe, Co, Ni, Cu, Ag, Au and asks to name the strongest reducing agent starting with the strongest reducing agent. The way I have written it above is the correct answer, however, the solutions manuel does not explain how th...

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Hi, I am having trouble knowing where to put the OH- and H2O when making my half reactions. I tried completing 14.5 in the 6th edition, but I just can't seem to figure it out. Can someone please explain?

An example is P4(s) > H2PO2^- +PH3

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How does one determine the driving force of dissolution?

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How does one one know the orientations of a cis versus trans molecule using MX2Y4?

The solutions manuel says cis has a total of 12 possible orientations and trans a total of 3 possible orientations.

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If Cell potential (E) is positive, what does that say about spontaneity and vice versa?

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Yes, K relates back to our topic of equilibrium so in essence, K is a value of products over reactants

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Internal energy does not change in an isolated system since it isn't able to exchange heat with its surroundings!

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Yes because it does not exchange heat with its surroundings!

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Hi, can someone please explain why is it that an exothermic reaction needs to be cooled in order to maintain that constant temperature?

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Hi, can someone please explain why is it that ab exothermic reaction needs to be cooled in order to maintain that constant temperature?

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Hi! Can someone please explain the idea of irreversible and reversible reactions to me? I don't understand how to differentiate from the two and how calculate work based on the type of reaction.

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Hi, I was just wondering how am I supposed to know that for me to calculate the change in volume for the finding work done using the given equation, I have to first use pi*r^2*d to find delta v? also, why is d 20.0 cm if that's how much the pump is depressed?

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It's not necessary, but it is certainly helpful to apply what you already know how to do. For instance, I like to draw them out because I like to see what is similar and what is different and compare the molecules I'm looking at. That way, I don't have to count every single bond in the reaction, jus...

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Refer to the constants and go from there. If the problem gives you torr, and whatever constant you're using uses atm, then make sure to use atm in order to be able to cancel them out properly.

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Both are good, just be careful and pay attention to units because sometimes a constant will be given in joules instead of kj so then you have to convert to joules in order to cancel out.

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Hi, I just wanted to confirm something. Since H2SO4 is a strong acid, we can automatically assume it dissociates completely, which is why when we are making an Ice table for the reaction H2SO4 +H2O -> HSO4^- + H3O^+, since we know that H2SO4 has an initial concentration of 0.15M, we can assume H30+ ...

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Hi can someone please explain how they got the equation Al(H2O)6 +H2O -> H3O + AL(H2O)5OH from the initial given concentration which is 0.055 M AlCl3? I know I have to make an acid/base reaction but why 6 h2os?

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Hi! Can someone explain how the stoichiometric coefficients are determined using the given graph? I understand that it is a dissociation reaction there for A will dissolve into B and C, but I dont understand how to calculate the stoichimetric coefficients and make a balanced equation.

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In question 11.69b, form the 6th edition, the formula given is CO + H20 > CO2 + H2. It asks what will happen to the partial pressure of CO2 if the partial pressure of CO is reduced. What I don't understand is why does reducing the partial pressure of CO decrease the amount of CO2. I thought using Da...

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How can I determine which reaction is more stable using K?

For example in 11.45, the question asks whether the dissociation of Cl2 or F2 is more stable. The k for Cl is 1.2*10^-7 and the k for F is 1.2*10^-4

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Hi, I had a question regarding how to determine whether an answer is neglible or not when using the quadratic formula and getting two separate answers. In this homework problem, I determined that x=5.5x10^-6 or x=-5.5x10^-6. I know that to find out whether the answer is neglible or not, I have to pl...

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If Q equals 1.0 for the reaction N2+O2>2NO at 25 degrees Celsius, will the reaction have the tendency to forms products, reactants or stay at equilibrium? It says to refer to the apendix where we're given delta H and delta G I know i need to find K in order to compare it to Q. Why do we use use gibs...

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The +x is determined by the stoichiometric coefficients. For example if the product has a 2 in front of it, it would have to be +2x. We're adding the x because its the change in the reaction and since we are assuming this a forward reaction, we are using up the reactants (thus the minus reactant) an...

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No they are not included in when solcing for Kc or Kp because and pure liquids don't have concentrations. Since solids and pure liquids aren't really mixed with other things, so that is why we can't really use them to calculate kc or kp. That is why it is ideal to use gases and aqueous solutions.

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Using the balanced equation is imperative because the stoichiometric coefficients are needed in order to solve for KC as they are what you raise each concentration to the power of. Therefore you need the correct balanced ratio for each reaction and the stoichiometric coefficients are necessary.

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Which is the stronger base, the hypobromite ion, BrO, or morphine, C17H19O3N? Justify your answer How can i tell which is stronger without pKb values? I already know HBrO is a relatively weak acid because it has a single bonded O-H and bromine is less electronegative so the electron cloud is fairly ...

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Hi, the original question asks what is the difference of pH if HCl- were diluted by 12%. I understand the pH equation is -log(H+) but in this case why is it that we divide the H+ concentrations? The solutions manuel says we would use the equation, pH = -log(0.12[H]+/[H+]) = -log(0.12) = 0.92 why do ...

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It also helps to think of the regions of electron distribution and whether one area is more localized with electrons. If the electron cloud is more localized, it is most definitely polar. If the electron cloud is evenly distributed, it is nonpolar.

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It's possible but be aware of that there are molecules with different shapes but same AXE Formula. This is because they have the same number of electron densities. For instance, tetrahedral and trigonal pyramidal are both AXE4 because they both have 4 regions of electron densities.

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The 2 corresponds to the quantum number!! So since, C, N, and O are in 2P and S is in 3P and so forth!

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If we were told to draw the lewis structure for C3H4, how would we determine which is best to draw if there are several possible structures you can draw with different hybridizations?

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Why is ClF3 considered polar if it doesn't have a partial positive and partial negative attraction?

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Hi! I know none of the molecules is a radical, but suppose one of them were how does one tell if it is a radical by looking at the configuration?

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Can someone describe what s-character is? Does it have to do with the s-orbital?

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Hi! I was wondering why in the cans of CH2^2-, why is the bond angle still less than 109.5 degrees if it has two lone pairs directly opposite of each other? I was under the impression that if we have an even amount lone pairs opposite to another, they will cancel out so the Lone Pair repulsions will...

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Hi! Can someone please explain to me why it is more favorable to take an electron from the p subshell if it is already half filled? I thought half-filled subshells were most favorable so taking an electron from something that is already half-filled will make the atom less stable? Problem: Sb3+ Answe...

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Hi ! Can someone explain to me why NH4CL is drawn separately?

I understand NH4 has a +1 charge and Cl by itself has a -1 charge so they are attracted to each other but why not draw them as a compound?

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Hi! Can someone explain to me why in the lewis structure for XeF2 why does Xe, the central atom have 3 sets of lone pairs? I know that noble gases have a valence electron number of 8 but in this example it has 10 and while I know Xe can exceed the octet rule, how do I know to add those extra electro...

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A permament Dipole moment is when the difference of electronegativity between two atoms is so large that it holds a partial positive and partial negative charge. Hope this helps! :)

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Hi! I have a question concerning ionic solubility. Can someone please explain why it is that increasing covalent of silver halides (AgF, AgCl, AgBr)makes them less soluble?

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Hi ! I kind of see this as a game of seeing what best works. "What best works" is determined by the formal charge. That is to say, if the formal charge of EACH individual element is close to zero then it is MOST stable. However, if the molecule as an entirety has a charge, you would want t...

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If you ever forget, the period trend of electron affinity genrally follows both Ionization energy and electronegativity. >> Increases as you go to the right and decreases down a group. Remember electron affinity is related to the energy released when an electron is added to a neutral atom in order t...

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Hi, this is the UNCERTAINTY given so yes you would have to go 10 and 5 for the uncertainty because you're given the uncertainty of velocity in order to find the most accurate position (delta x) Think of it as a trade off, if you have the a certain momentum, then you must have an uncertain position, ...

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Hi all, I have a practice problem that I need help on. The question is: For the following molecules how many unpaired electrons are there for each molecule? O2 and C2^- So for this, I don't know why they gave us the molecules in diatomic form but I treated it as a normal atom and did a a drawn out e...

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Hi, to answer your question simply, an element has the tendency to seek stable energy levels. So, in this case stability would be filling the 4d energy level completely before starting to fill the 5s energy level. It typically is easier to fulfill an energy level completely before jumping to a highe...

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This is due to fact that elements have the tendency to look for more stable states. Therefore, to have a stable ground state, elements tend to follow the Pauli exclusion principle and Hund's rule. If these rules are not followed, then it is in an excited state.

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Hi, this has to do with the fact that ground-state electron configurations means numbers of electrons = number of protons. Add all the electrons in the ground-state electron configuration and find the same number on the periodic table and you will get the element predicted to have that configuration.

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Essentially, yes it is just a periodic table trend. Since the periodic table was organized by atomic number there is a discrepancy when it comes to organizing the energy levels, however, since 3d is a lower energy level than 4s, then we would write it as a 1s^2,2s^2,2p^6,3s^2,3p^6,3d^10,4s^2. It is ...

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Hi! Hi I need help interpreting number 39 in chapter 2 for the electron configuration arrow graphs. It says we have to identify which graphs represent excited states and which graphs represent ground states. This was a homework problem from the Quantum Mechanics in Chapter 2 part of the syllabus how...

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Hi! Electron spins are similar to orientation except it's just the way an electron spins whether that be clockwise or counter clockwise! It's not really a value that can be changed it is just a property that was found of electrons upon observing them. If you recall, in the lecture, we discussed the ...

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Hi!
Dr. Lavelle said we didn't have to worry about that in the test since it goes beyond the scope of the class. He won't give anything that messy, and as long as you understand the basics, you'll be fine. It's the same as the F subshell.

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Hi! Basically, to understand this, we have to think of it as what will give us a positive number in the end if you're dealing with Delta Energy. In this case, a negative is in front because you're subtracting nInitial-nFinal which will result in a negative number so adding a negative in the front wi...

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Hi! Can you clarify what you variables you want defined? As for what is the variable for the speed of light, the variable is c which is 3.00 * 10^8 m/s and it is found in the lambda = h*c/E equation lambda= wavelength h= Planck's constant which is 6.626*10^-34 J*S and E is the total energy emitted o...

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Hi, I need help answering part b of this problem. Here is the entire question; 33. Molybdenum metal must absorb radiation with a minimum frequency of 1.09 x 10^15 s-1 before it can emit an electron from its surface. Answer the following two questions. A. What is the minimum energy needed to produce ...

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This question is related to #28 and #29 but I have gotten stuck on #30. The Question is.. Light hits a sodium metal surface and the velocity of the ejected electron is 6.61 x 105 m.s-1. The work function for sodium is 150.6 kJ.mol-1. What is the frequency of the incident light on the sodium metal su...

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Hi! I'm still confused about how that got us the answer. I understand the equations we're supposed to use and where everything goes but the one part I am still confused about is the work function. If the work function is 150.6 KJ, shouldn't we first convert that to joules which would be 1.506x10^-5....

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Speaking from experience, it is possible to have more than one limiting reactant if you think of it this way, there are not always just two reactants. Sometimes you have more than two, in that case, you will have several limiting reactants and your greatest number will be the excess.

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Hi, Okay so this is a question that is testing your knowledge on polyatomic ions and acids which should've been a topic covered in your high school chemistry class. To start off, nitric acid has the word acid in it and knowing from general chemical rules, almost all acids begin with a hydrogen which...

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Hi, I just wanted to share something interesting I found. Another way to solve this problem, oddly enough, is by simply creating a balanced equation. Because they explicitly tell us the reactants and ultimate product, I simply combined Tin and Oxygen to make my product. In this case, the molecular a...

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In this example, yes. While it is standard that you always add up the masses to make sure they add up to the total mass, it is important to note that this is an example of combustion. In general, combustion questions always include what is being burned plus oxygen, so that oxygen should be an expect...

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