CHEMISTRY COMMUNITY

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In class Lavelle explained in the sense of throwing people throwing a ball trying to aim to hit the other ball. The probability of hitting eachother's ball is much more likely if you have two people, while with three people throwing three balls the likelihood of them all colliding with each other at...

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Khan academy has a whole section on kinetics with lots of good videos and resources!
https://www.khanacademy.org/science/che ... m-kinetics

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Yes I believe so

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A represents the reactant molar concentration. If its [a]0 then it's the initial concentration.

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One thing to get the slope is just to plot the concentration values and examine the straight line to see what the value of the slope is, as you would in a normal graphing class. This can also be done by using the integrated rate laws and using y=mx+b to derive m and see if its negative/positive.

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Like what was said above I think non rechargeable batteries have reactions that are one way (irreversible) while rechargeable batteries contain reversible reactions. The difference in products is that usually for stuff that needs a lot of power you would use rechargeable batteries and for stuff that...

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One example is:

2N2O⟶2N2(g)+O2(g)

And the rate will just = k, you won't multiply by any of the products or reactants.

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Was there an answer given I can check my work with?

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Would someone be able to explain to me how they found the half reaction for Cr and then how they balanced the full redox rxn. Thank you so much!

H+(aq) + (Cr2O7)-2(aq) + C2H5OH(aq) ---> (Cr)3+(aq) + C2H4O(aq) + H2O(l)

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This just means the reaction energy barrier is very high and but deltaG is negative

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He meant that this reaction was more dependent on kinetics because diamond is kinetically stable with respect to graphite but unstable with respect to thermodynamics. It will take longer for the reaction to happen because of the high activation energy barrier that has to be overcome.

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The n is how many electrons are gained or released in a reaction so with some it will just be the coefficient of e when you split it up into half reactions. Here is a good website for simple rules about oxidation numbers. Hope that helps. https://www.thoughtco.com/rules-for-assigning-oxidation-numbe...

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This is due to kinetic stability. For diamond to become graphite, there is a large activation energy barrier that needs a lot of energy to overcome and ultimately prevents the conversion to graphite in a forward direction

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an electrochemical series is just the order of redox reactions by their standard cell potentials
I don't remember exactly learning it in class either but we have used the concept of cell potentials?

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Also once you set the two equations equal to each other and E is on one side you can substitute the delta Go/-nF for Eo)

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The second half of outline4 and then outline 5.

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

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The textbook just does it using the positive reduction value for the anode instead of the one we went over in class. The two equations are ultimately the same, but it just gets confusing with the signs.
E= -E(anode) + E(cathode)
E= E(cathode) - (E(anode))

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The process doesn't differ much.
This video is helpful for balancing!
https://www.youtube.com/watch?v=mdHyyZf7XR8

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This is the equation at standard temperature
Ecell=E∘cell− ((0.0592 V)/n) (log Q)

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Yes redox reactions can happen in any phase including gas, and you can balance them with water. Example: Cr2O2−7(aq)+HNO2(aq) → Cr3+(aq)+NO3−(aq) You put the rxn into half rxns and balance them HNO2(aq)→NO3−(aq) Cr2O2−7(aq)→2Cr3+(aq) Then balance both the rxns with H20 Cr2O2−7(aq)→2Cr3+(aq)+7H2O(l) ...

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A conjugate acid has one one more + charge and H atom than the matching base while conjugate base contains one more - charge and one less H atom than the matching acid.

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Yes your delta G will be negative based on the equation ΔG∘=−nFEcell

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How does the standard entropy of a reaction depend on the state of a molecule(like whether it's a liquid or gas)? This question was asked much earlier but not really a concise answer was given. Thanks!

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Negative H means an exothermic reaction which means a net release of heat from reactants to products. This will cause the reactants to have less heat and therefore will be favored.

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I think they come from a formula in the first law of thermodynamics saying that the internal energy = 3/2nRT, which in turn comes from the kinetic energy equation. From there I unfortunately don't know how to further derive.

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It might be because they are asking for the formation of 1 mol of a specific product or reactant so you would use fractions to keep that product's coefficient 1. I know in discussion last week that's what the TA did to balance an equation for calculating work.

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I believe they should always give you K but I'm not completely sure. Also in the review session today, the K was smaller than 10^-3 but we still couldn't discard the x so I'm slightly confused.

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For your second question: Changing the concentrations of products and reactants would change Q which is apart of the second equation

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Enthalpy (which equals H) is amount of heat released divided by what is absorbed(at constant pressure)

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In the question from review guide it ask what the Kc will be when the constants are halved. I think the new Kc will just be square root(Kc). Is this true, and if so is it still true if the temperature isn't at 400 K? Thanks!
(Refer to pizza rolls question 1d)

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It means that it will keep constant independent of the state of the system. So if it is liquid or solid it will stay the same enthalpy.

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It is because of latent heat of vaporization, so steam has a lot more heat energy, so much it makes more severe burns than boiling water does.

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Degeneracy means if it corresponds with two or more states of a quantum system that are measurable

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Internal energy is the total energy of a closed system

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It’s important so all the forces can balance so you can calculate all the energy from work. This is because you have to multiply the force by the distance to get work

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The first way is to add or remove the amount of substance in a system. This can only be used for an open system. The second way is to heat or cool the system, which can be used for a closed system. The third way is do either do work on the system or let the system do the work on the surroundings. Th...

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In addition, icreasing the temperature will shift the reaction equilibrium to the left.

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When the temperature is increased in an endothermic reaction, the equilibrium constant increases.

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After you've found your balanced equation, you have to find internal energy. This can be represented as U = q+w. Because it says bomb calorimeter you know that volume is constant so w=0. Then you have to calculate how much heat was released when the carbon monoxide was burned to find q. The equation...

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The answers should be that at constant pressure your temperature = 343 and at constant volume your temperature = 373

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I think he means that you have to add it to the final delta h of the reaction. In the example he wrote below he said for Br2 --> 2Br the deltaH= deltaH of vaporization + deltaH of the bonds. Hope that helps

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Method 2 uses bond enthalpies to calculate the change in H of the reaction. The left side of the enthalpy equation represents the bonds broken(reactants) and therefore show the energy required, a positive value. The right side will be your the bonds formed(the products) and therefore show the energy...

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Yes, you will only use the other three compounds in an ICE table.

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To calculate it you just do (equilibrium concentration/initial concentration) * 100. It is valid if it's less than 5%.
If you get around 5% professor Lavelle said it might be due to approximation during calculations so you should try to do them again.

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There is also a helpful explanation of how composite k multiplication is done in section 5H.2 Composite Equations, pg. 411.

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It is applicable to an reaction where one or more physical parameters changes (including temperature, concentration, and pressure). It tells us what happens but not why it happens.

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You can look at PV=NRT to know the answer to this. If you keep temperature and moles constant and double pressure, then the volume has to halve. It gets trickier if you change more than one variable.

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Usually we will assume the units for concentrations will be in mol/L if not stated, and the ratio of that cancels out the units. Therefore the reactant quotient is unitless.

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Just to add on to the previous reply, the only reason k will change will be because of a change in temperature.

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The ideal gas law deviates because of two things usually. Primarily, intermolecular forces are always present and although very small/negligible in high heat, are increasingly important in lower temperatures. In addition, the fact that even as pressure continues to increase, the gas volume will neve...

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From previously in the question you foudn that chlorine favors its reactants more than fluorine because the K of chlorine is smaller. Since Cl2 is on the reactants side it is more stable there than flourine is in F2

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Le Chatelier's principle is used solely to figure out the outcome when you change reaction conditions when it is in equilibrium as said above. The important thing to note is that Le Chatelier's just tells you what happens not why it happens.

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