CHEMISTRY COMMUNITY

Naomi Jennings 2H

15.27 A substance A decomposes in a first-order reaction and its half life is 355 s. How much time must elapse for the concentration of A to decrease to (a) 1/8 [A] ; (b) one-fourth of its 80 initial concentration; (c) 15% of its initial concentration; (d) one-ninth of its initial concentration? How...

Naomi Jennings 2H

viewtopic.php?f=151&t=12747
This one helped me a lot!

Naomi Jennings 2H

I'm planning to go into a freezing chamber at -273.15 degrees C. My friends were worried but I told them I'd be 0K

Naomi Jennings 2H

Can someone define what an "Electrochemical series" is? The textbook uses this term in 14.7. Thanks!

Naomi Jennings 2H

Oops sorry didn't see someone else commented.

Naomi Jennings 2H

An electrolytic cell is a cell where an electric current drives a nonspontaneous reaction. A galvanic cell is an electrochemical cell where a spontaneous reaction is used to create an electric current.

Naomi Jennings 2H

14.17 (a) Write balanced half-reactions for the redox reaction of an acidified solution of potassium permanganate and iron(II) chloride. (b) Write the balanced equation for the cell reaction and devise a galvanic cell to study the reaction (write its cell diagram) I would look up the redox reactions...

Naomi Jennings 2H

∆G° = - n F E°
At standard conditions, the gibbs free energy is equal to the negative mols of electrons moving from the anode to the cathode x Faraday's constant x the standard cell potential.

Naomi Jennings 2H

Calculate the work that must be done against the atmosphere for the expansion of the gaseous products in the combustion of 1.00 mol C6H6(l) at 25 degrees C and 1.00 bar.
How would you start to do this problem?

Naomi Jennings 2H

When the system goes from solid to liquid, or liquid to gas, entropy also increases. If a reaction creates more mols of gas than were previously present then entropy increases as well.

Naomi Jennings 2H

If there's a change in volume and temperature, you use two different equations, which you can do because Entropy is a state function, so there's the same change whether both volume and temperature change at the same time, or whether volume changes, then temperature. First you can calculate the entro...

Naomi Jennings 2H

kaushalrao2H wrote:Cp for ideal gases is 4R. Cv for ideal gases is 3R. When in doubt, remember that Cp = Cv + R

I thought for an ideal gas Cp is (5/2)R and Cv is (3/2)R?

Naomi Jennings 2H

In addition, for entropy you have to use Kelvin, because in the equation you aren't using delta T, you are using T, so multiplying the other terms by 25 (degrees celsius) will get a much different result than multiplying the other terms by 298 (degrees kelvin). In contrast, for a problem asking for ...

Naomi Jennings 2H

Do we need to know the methods of reaching absolute zero in box 9.1 (page 336-337)?

Naomi Jennings 2H

I think it will indicate in the question. If it doesn't specify reversible or irreversible, it's probably irreversible. If "Work is done at a constant pressure" it must be reversible since the internal and external pressures won't be incredibly close together for most of the expansion.

Naomi Jennings 2H

Heat capacity is the amount of energy required to raise the temperature of the system/something by one degree celsius. Specific heat capacity is the amount of energy required to raise the temperature of one gram of a substance by one degree celsius. Heat capacity is mostly useful for calorimeters, b...

Naomi Jennings 2H

I know that for this chapter we're using enthalpy not energy, but I don't understand what the difference between the lattice enthalpy and the lattice energy even is. If anyone could explain this to me please do thank you!

Naomi Jennings 2H

I've been working based on the following and it seems to be working! If they give you multiple other reactions and their enthalpies, then you probably need to use Hess's law. If they refer you to Appendix 2A, you should use the enthalpies of formation. If they tell you to use bond enthalpies, then u...

Naomi Jennings 2H

Ishita Monga 1B wrote:
Sue Xu 2K wrote:Condensation, solidification and deposition are all exothermic phase change that release heat during the process.

follow up- what is deposition?

Deposition is the process of a vapor going straight from vapor to solid. It's the reverse of sublimation.

Naomi Jennings 2H

Yes, because enthalpy is a state function and heat is a path function. The enthalpy value will be determined by the current state of the substance, whereas heat is defined by the textbook as "the energy that is transferred as a result of a temperature difference between a system and its surroun...

Naomi Jennings 2H

Yet another way to think about it: The difference between a state function and a path discussion is the difference between the distance between point a and b and the distance walked. If you start at Pauley and walk to Hedrick and then to CS50, the distance between your start and endpoint will only b...

CHEMISTRY COMMUNITY

Search found 21 matches

15.27

Re: 15.67

Re: Post All Chemistry Jokes Here

Electrochemical Series Definition

Re: galvanic vs electrolytic

Re: galvanic vs electrolytic

Re: Exercise 14.17

Re: Cell potential

8.93

Re: Entropy [ENDORSED]

Re: Change in vol and temp

Re: The value of Cp

Re: When to use Kelvin or Celsius

Box 9.1 Absolute Zero

Re: reversible and irreversible reactions

Re: Heat capacity vs Specific Heat capacity

Difference between a lattice enthalpy and lattice energy

Re: Enthalpies [ENDORSED]

Re: Phase Changes

Re: enthalpy vs heat

Re: Heat and work not state functions