Chem Lab C

[g-omal]

Consider a Carnot engine (an insulated cylinder with a piston filled with a gas). Why must the cylinder expand during the isothermal phase of the Carnot cycle in which heat flows into the cylinder from a heat source?

[Nerd_Bunny]

Seeing as no one has posted here in a while, I'll re-start this.

What are london dispersion forces, and where are they found?

[dxu46]

Isn't this only a C event?

[Tailsfan101]

Isn't this only a C event?

Be confident in your answers. Say it like this: "This is a C only event."

[Sleepy]

What are london dispersion forces, and where are they found?

Answer

London dispersion forces are weak intermolecular forces that form when electrons in two adjacent atoms align in such a way that temporary dipole moments form. They are present between all molecules, but are stronger when the molecules have high polarization.

[Nerd_Bunny]

What are london dispersion forces, and where are they found?

Answer

London dispersion forces are weak intermolecular forces that form when electrons in two adjacent atoms align in such a way that temporary dipole moments form. They are present between all molecules, but are stronger when the molecules have high polarization.

Correct! Your turn.

[Sleepy]

Correct! Your turn.

Q: Name all intermolecular interactions in ammonia (NH₃).

[UTF-8 U+6211 U+662F]

(Just to clarify, yes, this is only a C event)

[Tesel]

Q: Name all intermolecular interactions in ammonia (NH₃).

LDFs - occur in all materials.
Dipole interactions - occur because of the partial negative on the lone electron pair and the partial positive on the hydrogen atoms.
Hydrogen bonds - occur specifically because of the N-H bond, special type of dipole interaction.

[Sleepy]

Q: Name all intermolecular interactions in ammonia (NH₃).

LDFs - occur in all materials.
Dipole interactions - occur because of the partial negative on the lone electron pair and the partial positive on the hydrogen atoms.
Hydrogen bonds - occur specifically because of the N-H bond, special type of dipole interaction.

Correct!

[Tesel]

What is the specific heat capacity of an ideal gas? Express this value using variables from this equation: PV=m/(mm)RT. Good luck

[dmis]

This question was on an invitational test: and I am pretty confident though my answer was marked wrong. What do you think:

As a substance undergoes a change from the solid to the liquid phase at constant temperature the average
kinetic energy of its molecules
a) decreases
b) increases
c) remains the same

[g-omal]

Answer:

C. Temperature is constant during a phase change and is proportional to average kinetic energy of the particles.

This question was on an invitational test: and I am pretty confident though my answer was marked wrong. What do you think:

As a substance undergoes a change from the solid to the liquid phase at constant temperature the average
kinetic energy of its molecules
a) decreases
b) increases
c) remains the same

[g-omal]

Answer:

Assuming we're talking about a monatomic ideal gas, you can use Cv = 3/2R and Cp = Cv + R. These come by setting U=3/2nRT equal to Q=nCvT in an isovolumetric process. Going way back, the 3/2 comes from some pretty neat degrees of freedom stuff, but I'm not exactly sure how far I should be going down this deriving rabbit hole.

What is the specific heat capacity of an ideal gas? Express this value using variables from this equation: PV=m/(mm)RT. Good luck

[Tesel]

I'd say that's far enough, I should have worded it better, but the main thing was Cv=3/2R.