CHEMISTRY COMMUNITY

Jasleen Kahlon

What equation are they using in this problem? Honestly I thought that the solution guide answer was confusing. To solve, use the equation ln(kr2/kr1) = Ea/R(1/T1 - 1/T2), found on page 623 of the textbook. You use .87 for kr2, .76 for kr1, 8.31•10^-3 for R, 1000 for T1, and 1030 for T2, and solve f...

Jasleen Kahlon

The email was sent! He said it will be a short, straightforward, open book, take home final. All other review sessions and lecture are cancelled.

Jasleen Kahlon

It is almost always seconds, but the problem typically specifies. It's usually best to write units with each step though, so that way it can easily be converted to another unit if necessary.

Jasleen Kahlon

If I'm not mistaken, it gives us the instantaneous rate of an equation via the slope

Jasleen Kahlon

I'm super confused on the steps to balancing redox reactions. Can someone explain it to me in simpler terms than the textbook, or does anyone know of a good resource explaining how it is done?

Jasleen Kahlon

I did not take 14A with Lavelle, so I only bought access for 1 quarter for now. Yes, I had to pay $64. According to the instruction sheet online, it said to use "use credit" to avoid paying, but I'm assuming that that meant if you had purchased access from a previous quarter...I couldn't f...

Jasleen Kahlon

Yes, because it is determined by looking at the slope at a given point, which is instantaneous.

Jasleen Kahlon

If you are talking about the G=-nFe equation, n is the number of electrons transferred...I was also confused on the examples in the book though

Jasleen Kahlon

Arrhenius theory states that acids dissociate in water to yield electrically charged atoms or molecules (ions), H+, and that bases ionize in water to yield hydroxide ions (OH−).

Jasleen Kahlon

I believe that E standard cell is the standard state cell potential, and then Ecell is the cell potential at non standard state conditions.

Jasleen Kahlon

I think that this is done to isolate one of the reactants in order to see the change

Jasleen Kahlon

I think that it just means simple reactions without a lot of complex molecules and numbers involved, basically nothing beyond the equation examples in the homework problems.

Jasleen Kahlon

I was also wondering how this would be done, I've seen it done with H2O, H+, and OH- and other elements, but I don't know how it would be done with just these three...

Jasleen Kahlon

I think that K' is the reverse rate constant of the reaction

Jasleen Kahlon

I assumed it is the same one that we've had on the last test, isn't that the same one on the website?

Jasleen Kahlon

It is determined by the rate, so a zero order reaction is one at a constant rate. A first order reaction is dependent on the concentration of only one of the reactants. A second order reaction is proportional to either the product of two concentrations, or a single reactant's concentration squared.

Jasleen Kahlon

I'm not entirely sure but I think it is when you are trying to determine the rate for one specific reactant, so you isolate it, and make the other reactants constant.

Jasleen Kahlon

I know that in the G=-nFe equation, n is the number of electrons transferred. Does that mean the electrons transferred from 1 compound to another? I'm confused because in a lot of equations, everything rearranges from one side to the other...

Jasleen Kahlon

How do concentration cells differ from galvanic cells? What is an example of one?

Jasleen Kahlon

How can you predict if a metal will dissolve in a solution?

Jasleen Kahlon

What is electromotive force?

Jasleen Kahlon

I'm having difficulty with determining rates of equations when a list of concentrations is given. How is the rate determined?

Jasleen Kahlon

How can you tell which side is the anode and which side is the cathode?

Jasleen Kahlon

What is the relationship between free energy and work?

Jasleen Kahlon

How can you determine if a reaction is zero, first, or second order?

Jasleen Kahlon

The Van't Hoff Equation shows temperature dependence of K, but I'm still a little confused on what that means, and does the equation in any way connect to ∆H, ∆S, and ∆G?

Jasleen Kahlon

It is said to be somewhat of a stepping stone, because it is less harmful than petroleum, coal, or natural gas in many ways, but still worse than solar or wind or other renewables. However, I do strongly feel that there is a lot more that the world can do in terms of investing straight into other re...

Jasleen Kahlon

What exactly does a reaction being spontaneous mean in terms of thermodynamics, and what occurs when ∆S and ∆H are either both negative or both positive?

Jasleen Kahlon

What exactly does Gibbs free energy tell us about an equation? How is it applied?

Jasleen Kahlon

I'm a little confused as to what exactly the Boltzmann equation is trying to explain in terms of entropy. When is it usually applied?

Jasleen Kahlon

How can a strong acid be identified from looking at a chemical equation? Is there a way to tell, or do they have to just be memorized?

Jasleen Kahlon

Can someone please explain what % dissociation means and how it is calculated?

Jasleen Kahlon

When volume decreases, the work of a system is positive as the surroundings have performed work on the system, creating energy. When volume increases, the opposite is true, as the system performed work, losing it, making it negative, as it has lost energy.

Jasleen Kahlon

A good example of state vs path functions is thinking of two points on a map, A and B, that are 100 km apart if you were to draw a straight line from one to the other. That 100km is representative of a state function. There are two roads to get from A to B, one road is 120km, the other is 180km. Thi...

Jasleen Kahlon

What is the difference between intensive and extensive properties, and what are some examples of each?

Jasleen Kahlon

The universe (supposedly) is not exchanging any energy or matter with something outside of the universe, therefore being isolated. Yes energy and matter exchanges happen within, but within the universe as a whole, no energy would be lost to something outside.

Jasleen Kahlon

Liquids and solids behave differently than gas. With solids, the volume is fixed so the typical way of calculating enthalpy would not work, and both solids and liquids behave differently than gasses when compressed. However, enthalpy of phase changes can be calculated.

Jasleen Kahlon

Enthalpy is the total heat quantity of a system, the internal energy (U) plus the product of pressure and volume (PV)

Jasleen Kahlon

If you mean by having mass be exchanged and energy conserved, I do not believe so. Isolated systems are the only systems in which energy is not exchanged with its surroundings, and those are difficult to come by as isolating anything from energy exchange is nearly impossible. I'm not sure that you w...

Jasleen Kahlon

Open system: exchanges energy and matter with surroundings Closed system: exchanges energy, but not matter, with surroundings Isolated system: exchanges neither energy nor matter with surroundings An example to help remember this is by thinking of cooking a liquid in a pot on a stove. If the lid is ...

Jasleen Kahlon

Can someone please explain what makes enthalpy a state property?

Jasleen Kahlon

Is looking at ∆H the only way to determine whether a reaction is exothermic or endothermic?

Jasleen Kahlon

I understand that autoprotolysis is the transfer of an H+ from an acid to a base in an equation (I think), I'm unclear on how pKW = pH + pOH is derived from it though.

Jasleen Kahlon

I'm a little confused on how you calculate the percent ionization of an acid or a base, and what that means.

Jasleen Kahlon

I don't fully understand how pKa and pKb are related to pH and Ka/Kb. Can someone please explain what pKa and pKb are?

Jasleen Kahlon

This occurs with gases. When pressure is applied to gas equations, the rate of reaction speeds up, therefore causing it to shift to the side with fewer molecules of gas.

Jasleen Kahlon

If you mean composition, as in concentration, it is because the forward reaction and reverse reaction are occurring at the same rate, so there is no net change in concentration/state/etc.

Jasleen Kahlon

Q, the reaction quotient, measures the amounts of reactants and products during a reaction at a specific point in time, and can be calculated before the reaction reaches equilibrium. So if the reaction has not reached equilibrium yet, the product/reactant ratio is Q, and is giving information that c...

Jasleen Kahlon

I took 14A a while ago and honestly don't have a strong foundation on acids and bases. How, when looking at an equation, do you identify the acid, base, conjugate acid, and conjugate base just by looking at it? Is that something that needs to be memorized?

Jasleen Kahlon

aq and g are state symbols. If a reaction has multiple sate symbols, it is heterogeneous, so yes, it can occur. If the state symbols are the same, it is a homogeneous reaction. Kp and Kc are just measures of concentration or pressure, so it depends what you are looking for in the reaction.

Jasleen Kahlon

K is representative of a ratio, products/reactants. It is used to compare rates of reaction and therefore does not have units.

Jasleen Kahlon

I was confused about the difference between Kc or Kp and Q. They are both [products]/[reactants], so how are they different?

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