CHEMISTRY COMMUNITY

ayushibanerjee06

Eugene Chung 3F wrote:Does this class have a curve at the end?

there usually is, but I don't know if there will be one this time since the final was online.

ayushibanerjee06

sorry I meant ATP and not ADP. yeah I did everything that everyone else mentioned above.

ayushibanerjee06

sorry, I meant when*

ayushibanerjee06

Does anyone know approximately when we will know what our final grades will be released?

ayushibanerjee06

it said that all inorganic phosphate came from ADP so you can use the stoichiometry to find how much Pi you have. you can calculate Q from there

ayushibanerjee06

805383532 wrote:I was wondering this too!! I didn’t know if I should email him or not :/

Maybe it's not too late

ayushibanerjee06

I put none of these just to be safe, maybe it wasn't a typo.

ayushibanerjee06

You can calculate the concentrations by using the integrated rate laws. You can calculate k by using the overall rate expression or integrated rate law.

ayushibanerjee06

I don't think so

ayushibanerjee06

As everyone mentioned previously, bomb calorimeters have no change in volume. You should take note that since there is no change in volume, work = 0 and that the internal energy is only affected by changes in q.

ayushibanerjee06

Yes you add all of them up at the end. If you reverse a reaction, it is negative. You multiply/divide H by whatever you manipulate the reaction. Remember that you can do this because enthalpy is a state function!

ayushibanerjee06

You put it whenever the anode or cathode components are not solid. For example, if you have H+(aq)|H2(g), you will need to have Pt(s). This applies to when you have two aqueous solutions too. Another external electrode you can use is graphite: C(gr)

ayushibanerjee06

you can use it to find either: K1, K2, delta H, T1, or T2

ayushibanerjee06

For 5, why is the first SRP flipped? Shouldn't it be the cathode because it is the more positively charged one?

ayushibanerjee06

For #2, I used the E=Eo - (0.05196/n)logQ equation and got 1.7x10^-6 M. Did anyone else get this?

ayushibanerjee06

Will our final be multiple choice?

ayushibanerjee06

Matt Sanruk 2H wrote:Do you know if it also applies to TA review sessions and office hours too?

I am pretty sure it does.

ayushibanerjee06

Veronica_Lubera_2A wrote:As a last result: If you can't get your test back try asking some friends who had their discussion on Tuesday and look at the answers?

Fortunately, I have chem discussion on Tuesdays so I was able to receive my test yesterday. Thanks though!

ayushibanerjee06

Thank you for everything Lyndon!

ayushibanerjee06

For this question, you should look at the activation energies. It helps to draw it out. If it takes 39.7kj/mol for the forward reaction and only takes 25.4kj/mol for the reverse reaction, you can determine that the end of the forward reaction has higher energy than the start of the forward reaction...

ayushibanerjee06

Why is OH- the catalyst? I thought catalysts weren't consumed and OH- gets canceled out.

ayushibanerjee06

For 7D.7, why is the reaction endothermic if the reverse rate constant is larger than the forward rate constant?

ayushibanerjee06

Since all classes have been canceled, are UA review sessions for the final canceled as well?

ayushibanerjee06

Yes you can. An alternate way of thinking about this is you can use the half life equation to find k and use the integrated rate law for whichever order it is to find time. Here, you would set [A] to be [A]o/(desired value). For example, if you wanted to see how long it would take for a concentratio...

ayushibanerjee06

the difference between first order and second order rate laws is that a first order rate law will typically have one reactant that is first order and a second order rate law will have either one reactant that is second order or two first order reactants.

ayushibanerjee06

You have to use a property of logs to solve for l: l= ln(1.0)/ln(1.75) = 0, so C is zero order. Since C is zero order, [C]^0 is 1, so it essentially goes away and is not included in other calculations.

ayushibanerjee06

for the rate, it is usually M/s, but the rate constant's units depend on which order it is.

ayushibanerjee06

For 7A.15 a), how are we supposed to find the values of m and n when [C] is constantly changing?

ayushibanerjee06

When will we know what we got on Test 2 since we took it so close to our final?

ayushibanerjee06

You should use the following half-reactions: oxidation: Sn --> Sn2+ + 2e- reduction: 2H+ + 2e- --> H2 This will help you calculate E*. then you can combine the two to find the net which would be Sn + 2H+ --> Sn2+ + H2 writing the expression for Q should give you Q = [H2][Sn2+]/[H2]^2 why do we igno...

ayushibanerjee06

The question is: a student was given a standard Cu(s)|Cu2+(aq) half-cell and another half-cell containing an unknown metal M in 1.00 m M(NO3)2(aq) and formed the cell M(s)|M2+aq)||Cu2+(aq)|Cu(s). The cell potential was found to be 0.689 V. What is the value of E(M2+/M)? When solving for E (M2+/M), I...

ayushibanerjee06

How many questions is Test 2 going to have?

ayushibanerjee06

Can someone explain the mechanism of pH meters? I am a little confused about how they work.

ayushibanerjee06

For 6O.3 d), why is Au3+ reduced when it's E value is +1.40 and water's is +0.82? Isn't the lower value reduced?

ayushibanerjee06

For 6O.1 b), why is the anode half-reaction 2H20(l) -> O2(g) + 4H+ (aq) + 4e- and not H2SO3(aq) + H2O(l) -> SO4 2- (aq) + 4H+(aq) + 2e-?

ayushibanerjee06

For maximum work calculations, why is Q = anode/cathode when the anode is the reactants and cathode is the products?

ayushibanerjee06

The question is: Calculate the potential of a cell constructed with two nickel electrodes. The electrolyte in one compartment is 1.0 m Ni(NO3)2(aq). In the other compartment, NaOH has been added to a Ni(NO3)2 solution until the pH 5 11.0 at 298 K. See Table 6I.1. I don't know how to start this probl...

ayushibanerjee06

The question is: A tin electrode in 0.015 m Sn(NO3)2(aq) is connected to a hydrogen electrode in which the pressure of H2 is 1.0 bar. If the cell potential is 0.061 V at 25 C, what is the pH of the electrolyte at the hydrogen electrode? I am confused about how to set up the cell diagram since I can'...

ayushibanerjee06

For 6N.3 a, Predict the potential of Pt(s)|H2(g, 1.0 bar)|HCl(aq, 0.075 M)||HCl(aq, 1.0 M)|H2(g, 1.0 bar)|Pt(s), why is Q = ( ((0.75)^2 (1.0))/((1.0)^2(1.0)) )? Isn't 0.075 M for the reactants/oxidation?

ayushibanerjee06

For 6N.1 part b), why does the book say In3+(aq) + 2e- -> In2+ (aq)? Shouldn't it be 1e-? I used one mole of e- in my calculations and K=1.07x10^2

ayushibanerjee06

I don't understand why reducing agents are the ones being oxidized (anode) and the oxidizing agents are the ones being reduced (cathode)

ayushibanerjee06

Why don't voltage energies of the cathode or anode change when you reverse the equation or multiply/divide?

ayushibanerjee06

For 6L.1, why do we use 9.6485x10^4 C/mol for Faraday's Constant instead of 96,485 C/mol?

ayushibanerjee06

Why is the oxidation number of O3 zero?

ayushibanerjee06

For 6K.3 part d), Reaction of chlorine in water: Cl2(g) -> HClO(aq) + Cl2(g), what is being reduced since Cl2 goes to Cl2 which both have an oxidation number of 0. Is this a typo? Should it be Cl2(g) -> HClO(aq) + Cl-(aq)?

ayushibanerjee06

I just realized I did 6K.2. Nevermind

ayushibanerjee06

For 6K.3, why is the equation in the answer different? Why is there no Te?

ayushibanerjee06

For 6K.1 a), why is C oxidized from +2 to +1 when C2 is +4 in C2H5OH and C2 is +2 in C2H4O? Also, if both C and Cr go to lower oxidation states, how do you know which one is oxidized and reduced?

ayushibanerjee06

Does anyone know what Test #2 will cover, especially since it is next week?

ayushibanerjee06

For 5J.15 part b), did anyone else get K=2.0*10^-18 for 273.15 K?

ayushibanerjee06

For 5J.15, why does the book say that 100 degrees Celsius is 423 Kelvins and not 373.15 Kelvins?

ayushibanerjee06

I really wish but no, unfortunately ):

ayushibanerjee06

if you use the deltag=-nrtlnK equation, it will equal zero because, at equilibrium, K=1 and ln(1)=0.

ayushibanerjee06

For 5G.21, what am I doing wrong? The question is" Calculate the equilibrium constant at 25.8C for each of the following reactions, by using data in Appendix 2A: (a) the combustion of hydrogen: 2 H2(g) + O2(g) -> 2H2O(g) (b) the oxidation of carbon monoxide: 2CO(g)+O2(g) -> 2 CO2(g) For a) I us...

ayushibanerjee06

For Gibbs Free Energy Calculations, why don't you multiply the standard GFE you get when using the delta G = -RTlnK equation by the number of moles of the product? For example, in 5G.13, why don't you multiply -19124.75 kJ/mol by 2?

ayushibanerjee06

Selena Yu 1H wrote:For G, I got -19.124 kJ instead of 19.33 kJ. You would use the equation G = -RTlnK to find what G is.

So, you use G=-RTlnK to find the standard GFE and not the ones in the back of the book?

ayushibanerjee06

Selena Yu 1H wrote:For 5G.15, for the standard GFE I got -12.35 kJ and for my final answer, I actually got -2.7 kJ/mol instead of -27 kJ/mol

How did you get -12.35 kJ? I used the one for NH3 in the back of the book that was -32.9 kJ/mol since the standard GFE for the reactants are zero.

ayushibanerjee06

For 5G.15, (a) Calculate the reaction Gibbs free energy of N2(g) 1 3 H2(g) S 2 NH3(g) when the partial pressures of N2, H2, and NH3 are 4.2 bar, 1.8 bar, and 21 bar, respectively, and the temperature is 400. K. For this reaction, K 5 41 at 400. K. (b) Indicate whether this reaction mixture is likely...

ayushibanerjee06

Can someone find where my error is? The question is: (a) Calculate the reaction Gibbs free energy of I2(g) -> 2I(g) at 1200. K (K 5 6.8) when the partial pressures of I2 and I are 0.13 bar and 0.98 bar, respectively. (b) Indicate whether this reaction mixture is likely to form reactants, is likely t...

ayushibanerjee06

When do you use q=mcdeltat and when do you use enthalpy of combustion/formation to find energy?

ayushibanerjee06

Why do exothermic reactions need to be cooled to stay at a constant temperature?

ayushibanerjee06

For 4.27 part b), why does q change from 1.4x10^4 to 1.4x10^7?

ayushibanerjee06

For phase change questions, when do you know to start off with q=mcdeltaT to find the heat and when to use the Hvap etc.? For example, why do you use q=mcdeltaT first in question 4.1 where as in 4C.13 you use H=6.01 kJ/mol first?

ayushibanerjee06

The question is: Oxygen difluoride is a colorless, very poisonous gas that reacts rapidly and exothermically with water vapor to produce O2 and HF: OF2(g) + H2O(g) -> O2(g) + 2 HF(g) delta H = -318 kJ What is the change in internal energy for the reaction of 1.00 mol OF2? Why can’t you assume that n...

ayushibanerjee06

Why are bonds that are formed negative in bond enthalpy calculations?

ayushibanerjee06

For 4A.7 a), why do you add the q of water and copper?

ayushibanerjee06

The question says: In an adiabatic process, no energy is transferred as heat. Indicate whether each of the following statements about an adia- batic process in a closed system is always true, always false, or true in certain conditions (specify the conditions): (a) deltaU= 0; (b) q=0; (c) q < 0; (d)...

ayushibanerjee06

For the reaction: CH3CHCH2(g)+ 1H2O(g) -> CH3CH(OH)CH3(g)
I calculated that the bonds formed were: -7(c-h), -1 (c-c), -1(c=c), -2(o-h) and the bonds broken were: 6(c-h) + 2(o-h) + 1(c-c) + 1(c=c). I don't know why this is wrong.

ayushibanerjee06

The reaction of 1.40 g of carbon monoxide with excess water vapor to produce carbon dioxide and hydrogen gases in a bomb calorimeter causes the temperature of the calorimeter assembly to rise from 22.113 8C to 22.799 8C. The calorimeter assembly is known to have a total heat capacity (calorimeter co...

ayushibanerjee06

For the Ka*Kb=Kw equation, does it make a difference if we say Kw=10^-4 or 1.0*10^-4?

ayushibanerjee06

You use Kp when all the products and reactants are gases and the question includes units like bar/atm/pa. You use Kc when the products and reactants are given in moles or molarity, even if the products and reactants are gases. If the question asks for Kp and the question only gives you information a...

ayushibanerjee06

You can ignore the Ka2 and Ka3 when they are much smaller in comparison the Ka1 and will no longer have an effect on the pH.

ayushibanerjee06

Remember that having a higher pH value means that it is not very acidic since it is closer to neutral pH = 7. Because of this, weaker acids have higher pHs because they are deprotonating less. Strong acids disassociate 100%, but since weak acids do not, their pH tends to be higher.

ayushibanerjee06

Although adding an inert gas affects the total volume of the reaction, they do not interact with anything, thus causing there to be no change in concentration.

ayushibanerjee06

When the temperature is increased, K is higher. When the temperature is decreased, K is lower.

ayushibanerjee06

There will be no shift in the reaction.

ayushibanerjee06

For the question: What is the concentration of hydronium ions in a solution that is 0.20 m NH2NH2(aq) and 0.30 m NaCl(aq), do we assume that [OH-] is 0.30 M and not [NH2NH3+]?

ayushibanerjee06

Will there be UA sessions this Monday? Hi Ayushi, I had the same question! Unfortunately, I was told that there most likely will not because Office Hours and classes are not occurring on that day. If I hear anything else to the contrary, I will be sure to let you know! Good luck on the test :) -Reb...

ayushibanerjee06

When can we pick up our fall quarter final next week?

ayushibanerjee06

Will there be UA sessions this Monday?

ayushibanerjee06

Where can we find buffer questions to practice because none were assigned in the homework?

ayushibanerjee06

Please include the entire question with your post; this will better assist us in helping you The question is: A student added solid Na2O to a volumetric flask of volume 200.0 mL, which was then filled with water, resulting in 200.0 mL of NaOH solution. Then 5.00 mL of the solution was transferred t...

ayushibanerjee06

For 6B.11 a) ii), why do you multiply 0.18M by (500.0 ml/5.00 ml) and don't use the m1v1=m2v2 equation?

ayushibanerjee06

For 6B.9 i), when I solve for [OH-], I did Kw/[H3O+] (1.0x10^-14/1.50) and got 6.67x10^-15 instead of 1.50x10^-14. What am I doing wrong?

ayushibanerjee06

For 6A.21, why can you assume that [H3O+] and [OH-] are the same concentration?

ayushibanerjee06

For 5.35, how do you determine the coefficients of A, B, and C from just looking at the graph? Also, why do you divide the partial pressure by 100 in the equilibrium constant?

ayushibanerjee06

Consider the equilibrium 3 NH3(g) + 5 O2(g) <-> 4 NO(g) + 6 H2O(g). (a) What happens to the partial pressure of NH3 when the partial pressure of NO is increased? (b) Does the partial pressure of O2 decrease when the partial pressure of NH3 is decreased? Can someone explain why both NH3 and O2 increa...

ayushibanerjee06

The question is: The four gases NH3, O2, NO, and H2O are mixed in a reaction vessel and allowed to reach equilibrium in the reaction 4 NH3(g) + 5 O2(g) <-> 4 NO(g) + 6 H2O(g). Why is there less NH3 when NO is removed?

ayushibanerjee06

The question is: Consider the equilibrium CO(g) + H2O(g) <->CO2(g) + H2(g). c) If the concentration of CO is increased, what happens to the concentra- tion of H2?
Can someone explain why?

ayushibanerjee06

For 5I.13, why is Cl2 more thermodynamically stable than F2?

ayushibanerjee06

Can someone explain why if you start with a higher pressure of reactant, the equilibrium constant will be larger?

ayushibanerjee06

For 5I.13 a) and b), should we use K or Kc?

ayushibanerjee06

Their activities are actually 1, not 0.

ayushibanerjee06

You do not have to create an ice table. I find that if they give you the equilibrium concentrations of the product(s) and all of the reactants except for the one they are asking about and vice versa, you should set up K and solve for the concentration for you are trying to find.

ayushibanerjee06

You can use both but as everyone else mentioned, make sure to pay attention if you are given atms or mols.

ayushibanerjee06

I am confused about how to do 5H.3 because I am unsure of how to start the problem since it combines two equations. How do I set it up?

ayushibanerjee06

Would HOF or HOCl be a stronger acid? Since oxoacid strength is based on electronegativity, shouldn't HOF be stronger than HOCl?

ayushibanerjee06

Also, what would be an example of a molecule that would be amphoteric but not amphiprotic?

ayushibanerjee06

On the final, how would you show that a molecule is either amphiprotic or amphoteric through using reactions?

ayushibanerjee06

I'm kind of confused about acid/base reactions. So acids are classified as electron pair acceptors (Lewis) and proton donors (Bronsted) and bases are classified as electron pair donors (Lewis) and proton acceptors (Bronsted). When we do chemical equations for proton transfer, I always get confused b...

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