CHEMISTRY COMMUNITY

Anne 2L

Why does maximum work of a battery = delta G at constant temperature and pressure? Doesn't maximum work occur for reversible processes, meaning that volume is changing and therefore pressure would not be constant?

Anne 2L

Thank you so much for all the help!

I was just wondering how having constant internal energy equates to energy being neither created nor destroyed.

Anne 2L

Can you elaborate on that?

Anne 2L

I read this in the course reader: The energy of an isolated system must remain constant because no matter or heat can be transferred and the system cannot be physically changed ( \Delta V=0). q=0 and w=0 then \Delta U=q+w=0 I just wanted to confirm that the internal energy of all isolated systems is...

Anne 2L

Solids and liquids are not included when determining the equilibrium constant K. I'm not sure if liquids are included in the rate law though.

Anne 2L

I just wanted to elaborate on Cristina's answer. The concept behind pseudo equilibrium is that having the fast step before the slow step results in a build up of products for the fast step. As a result, the reaction begins to reverse and create reactants, creating a fake equilibrium. As a result, we...

Anne 2L

Since the species are under standard conditions, we can refer to Appendix 2B for the phases.

Anne 2L

According to the Kinetics outline posted, I think we just need to know the following:

• Explain how the collision model and activated complex model account for the temperature dependence of reactions.
• Interpret or draw a reaction profile.

Anne 2L

Consider the following unbalanced half-reactions: Ag (s) + I [sup-][/sup] (aq) -> AgI (s) + e - E^{\circ} (anode) = -0.15V AgCl (s) + e - -> Ag (s) + Cl - (aq) E^{\circ} (cathode) = +0.22V Q = 26.8 E^{\circ} = 0.37V What is the value of E?

Anne 2L

Rank the following in order of increasing reducing power: I 2 , Br 2 , Al I 2 (s) + 2e - -> 2I - E^{\circ } = 0.54V Br 2 (l) +2e - -> 2Br - E^{\circ} = 1.07V Al 3+ (aq) + 3e - -> Al (s) E^{\circ} = -1.66V Correct Answer: Br 2 < I 2 < Al I understand that reducing powe...

Anne 2L

What is wrong with this cell diagram? Ag (s) I AgBr (s) II Br (aq) I Br 2 (g) I understand that the error we determined was that the left side of the cell diagram lacked a combatting electrode (Pt (s) ). However, I remember someone asking about the line separa...

Anne 2L

I was wondering if aldehydes and ketones are a subgroup of carbonyl?

Anne 2L

Which of the following plots will be linear? (f) initial rate against [A] for a reaction that is first order in A (g) half-life against [A] for a reaction that is zero order in A (h) half-life against [A] for a reaction that is second order in A I'm not sure how to conceptually or mathematically det...

Anne 2L

I've noticed that sometimes we use log instead of ln in the Nernst equation. I was wondering if there's a reason we would prefer to use log over ln or if there is no difference.

Anne 2L

throwback to simpler times [img]<iframe%20src="https://www.facebook.com/plugins/post.php?href=https%3A%2F%2Fwww.facebook.com%2Felitechatchemistrymemes%2Fphotos%2Fa.1807758922782274.1073741827.1807744196117080%2F2026968870861277%2F%3Ftype%3D3&width=500"%20width="500"%20height=...

Anne 2L

Assuming your asking about assigning oxidation numbers, there are a few rules to follow. 1) atoms in their natural state are assigned 0 (e.g., Al, H 2 ) 2) monatomic ions are assigned their charge (e.g., Na + = +1) 3) neutral compounds are assigned 0 (e.g., CO 2 ) 4) polyatomic ions are assigned the...

Anne 2L

This problem wants you to find the standard entropy of vaporization of water at 85 C reversibly. This takes much more work by the system than an irreversible vaporization of water at 85 C, which consists of one step and lots of energy lost as heat. To do it reversibly: 1.) reversibly heat the water...

Anne 2L

As explained above k b is the Boltzmann constant and does equal to R/Avogadro's number. It's applied in the Boltzmann equation S = k b lnW. This equation calculates the entropy of ideal gases in relation to their degeneracy W, the number of microstates of the molecule (so basically the number of pos...

Anne 2L

Isothermal means temperature does not change and therefore internal energy does not change. Delta U = q + w 0 = q + w Therefore -q = w Or w = -q Heat is transferred (not zero) but the same amount of energy is lost as work. Therefore internal energy is constant. If needed, ask during my Monday revie...

Anne 2L

Same. It seems like every problem referring to a reversible system also mentions that the system is isothermal. I was wondering if the fact that the system is isothermal makes it reversible, but that correlation doesn't seem to conceptually or mathematically add up for me.

Anne 2L

Mitch Mologne 1A wrote:If the pressure is constant, you known the process is irreversible.

How would you know if a process is reversible though?

Anne 2L

Why is W at its max when isolated systems are at equilibrium? And what does it mean for W to be at its max? It kind of sounds like there's a range of possible values for W and I thought there was just one set value calculated by W=2^n.

Anne 2L

It is important to specifically note that because when dealing with actual, complex molecules, it is difficult to know the exact number of microstates, W. It is often the case that we do not know the exact number of microstates, but that is okay because if we can estimate it, then we will still obt...

Anne 2L

I was reviewing the course reader and noticed that under the Boltzmann equation, S = k lnW, it's noted that a large error in W would result in a small error in S. I can see mathematically how that would work out. I just don't understand why it's important to specifically note that?

Thanks!

Anne 2L

Yes, Delta H (fusion) for water was given. We were supposed to treat the tea as if it was just water.

Anne 2L

I think we will have access to the same equations sheets during our midterm. Most of the basic equations we need are listed on there. Some of the equations he derived in class aren't listed, but it should still be possible to solve problems without those derived equations. The derived equations just...

Anne 2L

So in this question, is the system considered the contents of the cooler as well as the cooler itself, rather than just the contents being the system? In this question, the contents of the cooler alone should be considered the system. The cooler itself should be considered the surrounding. Since th...

Anne 2L

I've found that making flashcards based off lecture notes is enough for me to understand and apply the concepts.

Anne 2L

I understand why q(sys) + q(surr) = 0.

I was wondering how we can determine if we use

-q(sys) = q(surr)

or

q(sys) = -q(surr)

Anne 2L

Yes, the heat capacity should always be given. I don't think we have the means to calculate heat capacity outside of a lab setting.

Anne 2L

Yes, you can subtract all of the reactants from all of the products and still get the correct answer. Technically however the enthalpy of the reaction is the net of the energy released from forming bonds and the energy absorbed from breaking bonds.

Anne 2L

Sorry if I'm totally off, but wouldn't the negative sign be required and not arbitrary in this case. I believe freezing is the reverse reaction of melting/fusion. Since melting/fusion is endothermic and therefore has a positive enthalpy value, wouldn't freezing be exothermic and therefore have a neg...

Anne 2L

OH WOW YOU GUYS TYPE FAST.

Anne 2L

Can someone please explain to me why bond enthalpies (method 2) are always positive? Thank you! Yea np I gotchu girl! In method 2, the bond enthalpy values given are always positive, because the value given represents the amount of kJ/mol required to break the bond. Since breaking the bond requires...

Anne 2L

what did the ice cube say to his mom as he was melting

CHEMISTRY COMMUNITY

Search found 35 matches

Conditions for Maximum Work

Re: Internal Energy of Isolated Systems

Re: Internal Energy of Isolated Systems

Internal Energy of Isolated Systems

Re: Water in Mechanism

Re: Which equilibrium equation to use

Re: 14.29

Re: Section 15.12

Test #2 Question 8d

Test #2 Question 5B

Cell Diagram Question from Wednesday's (03/15/18) Lecture

Carbonyl -> Aldehydes and Ketones [ENDORSED]

Problem 15.99

ln vs log [ENDORSED]

Re: Post All Chemistry Jokes Here

Re: Oxidation state

Re: Homework 9.19 [ENDORSED]

Re: K_b

Re: isothermal system [ENDORSED]

Re: Reversible but not-isothermal expansion?

Re: Irreversible vs Reversible

Degeneracy (W) [ENDORSED]

Re: Boltzmann Equation

Boltzmann Equation

Re: test question 7 [ENDORSED]

Re: Midterm [ENDORSED]

Re: test question 5

Re: Concepts for Chapter 8 [ENDORSED]

q(sys) = -q(surr)

Re: Heat Capcity for Water

Re: Finding change in enthalpy when given bond enthalpies

Re: Enthalpy of Freezing

Re: Bond Enthalpies

Re: Bond Enthalpies

Re: Post All Chemistry Jokes Here