Search found 25 matches
- Wed Feb 07, 2018 5:35 pm
- Forum: Phase Changes & Related Calculations
- Topic: Endothermic/exothermic
- Replies: 4
- Views: 494
Re: Endothermic/exothermic
A process is exothermic when it releases heat and a process is endothermic when it absorbs heat.
- Wed Feb 07, 2018 5:31 pm
- Forum: Calculating Work of Expansion
- Topic: Work Equations [ENDORSED]
- Replies: 9
- Views: 627
Re: Work Equations [ENDORSED]
You can use the equation w= -PdeltaV when pressure is constant
You can use the equation w= -nRt lnV2/V1 when temperature is constant
You can use the equation w= -nRt lnV2/V1 when temperature is constant
- Wed Feb 07, 2018 5:29 pm
- Forum: Calculating Work of Expansion
- Topic: Integral [ENDORSED]
- Replies: 4
- Views: 354
Re: Integral [ENDORSED]
The integrals were used in lecture as a way to show how the different equations were derived
- Wed Feb 07, 2018 5:28 pm
- Forum: Calculating Work of Expansion
- Topic: Irreversible expansion
- Replies: 4
- Views: 256
Re: Irreversible expansion
When pressure is constant, you can use the equation w= -PdeltaV, but when temperature is constant, you can use the other equation, w= -nRT lnV2/V1.
- Wed Feb 07, 2018 5:23 pm
- Forum: Calculating Work of Expansion
- Topic: Diagram of Reversible Expansion
- Replies: 3
- Views: 247
Re: Diagram of Reversible Expansion
A vacuum is a space that does not have any matter in it, not even air. Space is a vacuum
- Wed Feb 07, 2018 5:19 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Reversible systems
- Replies: 7
- Views: 444
Re: Reversible systems
Because both volume and pressure are changing, you would need to use both Cv and Cp
- Mon Jan 22, 2018 9:07 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: PdeltaV=deltanRT
- Replies: 4
- Views: 1634
Re: PdeltaV=deltanRT
Because w=PdeltaV, work could also be found using w=deltanRT when a value in the other equation is not known. This is because of the equation pV=nRT
- Mon Jan 22, 2018 9:04 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Open Beaker [ENDORSED]
- Replies: 5
- Views: 643
Re: Open Beaker [ENDORSED]
Because the system is open it can therefore remain at a constant pressure with its surroundings because it can exchange both energy and matter to come to an equilibrium pressure state.
- Mon Jan 22, 2018 9:02 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Calorimeter
- Replies: 10
- Views: 659
Re: Calorimeter
A calorimeter can measure energy that will be used in calculations.
- Mon Jan 22, 2018 9:01 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Adiabatic [ENDORSED]
- Replies: 8
- Views: 564
Re: Adiabatic [ENDORSED]
An adiabatic process is one in which there is no heat transfer between a system and its surroundings.
- Mon Jan 22, 2018 8:59 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Energy and matter?
- Replies: 6
- Views: 387
Re: Energy and matter?
yes, in an open system, both energy and matter can be exchanged between system and the surroundings. In a closed system, only energy can be exchanged. In an isolated system, neither energy nor matter can be exchanged between a system and its surroundings.
- Mon Jan 22, 2018 8:57 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Bomb calorimeter
- Replies: 7
- Views: 390
Re: Bomb calorimeter
A bomb calorimeter completely closes off its contents from the surroundings so that neither energy nor matter can be exchanged between the system and its surroundings, making it an isolated system.
- Mon Jan 22, 2018 8:56 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Difference between Closed and Isolated
- Replies: 10
- Views: 1247
Re: Difference between Closed and Isolated
A closed system can exchange energy with its surroundings, an example would be a closed test tube. An isolated system cannot exchange energy or matter with its surroundings, such as an insulated thermos.
- Mon Jan 22, 2018 8:54 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated vs Closed system
- Replies: 3
- Views: 806
Re: Isolated vs Closed system
An isolated system is completely closed off from its surroundings and cannot exchange matter or energy with its surroundings. A closed system is closed off from its surroundings and cannot exchange matter, but this system can exchange energy with its surroundings.
- Mon Jan 22, 2018 8:52 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: System Types
- Replies: 7
- Views: 396
Re: System Types
In an open system, both energy and matter can be exchanged between the system and the surroundings. In a closed system, only energy can be exchanged between the system and the surroundings, and in an isolated system neither energy or matter can be exchanged between the system and the surroundings.
- Sun Dec 03, 2017 10:39 pm
- Forum: Lewis Structures
- Topic: Central Atom? [ENDORSED]
- Replies: 7
- Views: 1120
Re: Central Atom? [ENDORSED]
Hydrogen cannot be the central atom because it only can form one bond, therefore it cannot bond to multiple different atoms or satisfy the octet rule.
- Sun Dec 03, 2017 10:35 pm
- Forum: Lewis Structures
- Topic: Lewis Structure of IO2F2 (-2) Problem 4.23 [ENDORSED]
- Replies: 3
- Views: 4467
Re: Lewis Structure of IO2F2 (-2) Problem 4.23 [ENDORSED]
The closer the formal charge is to zero, the more stable it will be. So drawing the structure where more of the formal charges are closer to zero would be more stable and more preferred.
- Sun Nov 12, 2017 10:36 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Central Atom
- Replies: 4
- Views: 337
Re: Central Atom
For the most part, use the atom with the lowest electronegativity as the central atom unless the problem tells you otherwise
- Sun Nov 12, 2017 9:56 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Drawing lewis structures
- Replies: 5
- Views: 393
Re: Drawing lewis structures
Usually, if all the atoms have a formal charge of zero in the drawn structure, then that is the most stable form of the molecule.
- Sun Oct 22, 2017 11:05 pm
- Forum: Photoelectric Effect
- Topic: Post Module #17 [ENDORSED]
- Replies: 3
- Views: 391
Re: Post Module #17 [ENDORSED]
Increasing the intensity of the light, the amplitude of the wave, would not eject electrons, which showed that light had particle like properties because they were just increasing the number of photons rather than increasing their energy. If more photons were shone onto the metal with the same energ...
- Sun Oct 22, 2017 7:09 pm
- Forum: Properties of Light
- Topic: Light travels as a "wave"
- Replies: 5
- Views: 385
Re: Light travels as a "wave"
The way the way would travel, like diagonally or up and down etc, would be dependent upon the direction of the electric field and the magnetic field.
- Tue Oct 10, 2017 7:43 pm
- Forum: Properties of Light
- Topic: Problem 1.4
- Replies: 3
- Views: 265
Re: Problem 1.4
I'm confused with this problem as well because A. all waves travel at the speed of light, which is a constant, B. The wavelength of visible light increases as it changes from blue to green (but the frequency does decrease), and when you calculate the frequency of infrared radiation and radio waves, ...
- Tue Oct 10, 2017 7:27 pm
- Forum: Properties of Light
- Topic: Question 1.23
- Replies: 2
- Views: 352
Re: Question 1.23
An eV is an electron volt, which is another unit of energy. 1 eV = 1.60218x10^-19 J.
- Sun Oct 08, 2017 9:16 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Molarity unit [ENDORSED]
- Replies: 11
- Views: 1071
Re: Molarity unit [ENDORSED]
It is usually easiest to convert all of your units to SI units at the beginning of a problem so that you are less likely to make an error in the calculation and answer, which in this case the SI unit is mol/L.
- Tue Oct 03, 2017 4:25 pm
- Forum: SI Units, Unit Conversions
- Topic: Molecules [ENDORSED]
- Replies: 10
- Views: 758
Re: Molecules [ENDORSED]
A mole is an amount of something, similar to how a dozen is 12 units of something, a mole is 6.022x10^23 units of something. A mole of molecules would be 6.022x10^23 molecules, where a single unit, in this example, would be a molecule.