Search found 54 matches
- Sun Feb 23, 2020 11:32 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Work
- Replies: 14
- Views: 1039
Re: Work
Work done on the system is positive. Work done by a system is negative.
- Sun Feb 23, 2020 11:28 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Kelvin or Celsius?
- Replies: 86
- Views: 6243
Re: Kelvin or Celsius?
Should use Kelvin so the units match the constant.
- Sun Feb 23, 2020 11:28 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: U vs H
- Replies: 15
- Views: 1290
Re: U vs H
Delta U is the change in internal energy while delta H is the change in enthalpy.
- Sun Feb 23, 2020 11:21 pm
- Forum: Calculating Work of Expansion
- Topic: Reversible vs Irreversible
- Replies: 13
- Views: 900
Re: Reversible vs Irreversible
For a system to be considered reversible, delta S must equal 0.
- Sun Feb 23, 2020 11:19 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Intensive vs. Extensive
- Replies: 15
- Views: 1384
Re: Intensive vs. Extensive
Extensive properties depend on mass and intensive properties do not.
- Wed Feb 05, 2020 10:36 am
- Forum: Phase Changes & Related Calculations
- Topic: Heating Curve
- Replies: 6
- Views: 1061
Re: Heating Curve
flat areas of the graph are where phase changes are occurring. At these instances temperature is constant because all energy is being used to change phases.
- Wed Feb 05, 2020 10:33 am
- Forum: Ideal Gases
- Topic: Temperature
- Replies: 17
- Views: 810
Re: Temperature
If the question asks for the change in temperature you can use either. If not, you need to look at what units are used in the question or which units are used in the constants.
- Wed Feb 05, 2020 10:29 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Shifts
- Replies: 6
- Views: 436
Re: Shifts
It depends on the circumstance but in general, the reaction will shift in the direction that allows for it to reach equilibrium. For example, if Q (reaction quotient)<K(equilibrium constant) the reaction will shift to the right because the concentration of reactants is greater than the concentration...
- Wed Feb 05, 2020 10:27 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Reaction Direction
- Replies: 19
- Views: 1074
Re: Reaction Direction
I know that K represents the equilibrium constant, but what does Q represent in this situation? In this situation, Q would represent the state of the reaction at a point where equilibrium has not been reached yet. This is why they are asking about which direction the reaction will occur ("left...
- Wed Feb 05, 2020 10:23 am
- Forum: Ideal Gases
- Topic: Ideal gas constant
- Replies: 4
- Views: 272
Re: Ideal gas constant
You need to use the constant that has the same units as the values given in the question as you need units to cancel out.
- Sun Feb 02, 2020 3:58 pm
- Forum: Phase Changes & Related Calculations
- Topic: Internal Energy, U
- Replies: 6
- Views: 324
Re: Internal Energy, U
Only when change in pressure and change in volume are zero.
- Sun Feb 02, 2020 3:57 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase Changes
- Replies: 17
- Views: 748
Re: Phase Changes
While a phase change is occurring the temperature is constant, but once the phase change is complete the temperature will continue to change.
- Sun Feb 02, 2020 3:53 pm
- Forum: Phase Changes & Related Calculations
- Topic: Calorimeters
- Replies: 8
- Views: 473
Calorimeters
Does the type of calorimeter affect the problem at all? Or do the equations work the same regardless of the type of calorimeter?
- Sun Feb 02, 2020 3:51 pm
- Forum: Phase Changes & Related Calculations
- Topic: Open vs Isolated System
- Replies: 15
- Views: 1345
Re: Open vs Isolated System
Energy can be transferred in a closed system while in an isolated system energy can't be transferred.
- Sun Feb 02, 2020 3:48 pm
- Forum: Phase Changes & Related Calculations
- Topic: Calorimeter
- Replies: 8
- Views: 594
Re: Calorimeter
A bomb calorimeter is able to withstand more pressure and is more precise.
- Sun Jan 26, 2020 11:33 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Gas Constant
- Replies: 13
- Views: 585
Re: Gas Constant
The constants will be given on the formula sheet during the exams.
- Sun Jan 26, 2020 11:26 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: ICE BOX
- Replies: 27
- Views: 924
Re: ICE BOX
If any of the K values are smaller than 10^-3 then they are considered negligible.
- Sun Jan 26, 2020 11:25 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kp to Kc
- Replies: 11
- Views: 611
Re: Kp to Kc
Liquid water is not included in equilibrium concentration calculations.
- Sun Jan 26, 2020 11:23 pm
- Forum: Ideal Gases
- Topic: Kc vs Kp
- Replies: 109
- Views: 5421
Re: Kc vs Kp
Kp is for gases and uses partial pressure. Kc uses concentrations.
- Sun Jan 26, 2020 11:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE
- Replies: 20
- Views: 963
Re: ICE
ICE is used when trying to the find the equilibrium concentrations.
- Sun Jan 19, 2020 10:24 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: ICE Tables
- Replies: 13
- Views: 523
Re: ICE Tables
H20 is not included when it is in liquid form.
- Sun Jan 19, 2020 10:21 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K for Gases
- Replies: 12
- Views: 395
Re: K for Gases
You would use Kp because you would use pressure to find the equilibrium constant of gases.
- Sun Jan 19, 2020 10:16 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K vs Q
- Replies: 14
- Views: 419
Re: K vs Q
K is a constant and is used when a reaction is in equilibrium. Q can be found at any point during a reaction and can be compared to K in order to find the direction of the reaction.
- Sun Jan 19, 2020 10:14 pm
- Forum: Ideal Gases
- Topic: ICE Tables
- Replies: 8
- Views: 534
Re: ICE Tables
It depends on whether the reaction is going forward or reverse. This is found by comparing the reaction quotient (Q) and the chemical equilibrium (K).
- Sun Jan 19, 2020 10:11 pm
- Forum: Ideal Gases
- Topic: homework #3
- Replies: 16
- Views: 956
Re: homework #3
Anything learned during the week should be the focus of the homework. Homework 3 should probably be on acid and base equilibria.
- Sat Jan 11, 2020 3:14 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: HW 5J.5
- Replies: 8
- Views: 208
Re: HW 5J.5
You would only use reactants and products that are in gas or aqueous phases when calculating the equilibrium constant.
- Sat Jan 11, 2020 3:10 pm
- Forum: Ideal Gases
- Topic: R in PV=nRT
- Replies: 34
- Views: 7096
Re: R in PV=nRT
R is the gas constant with a value of 8.314 (J)/((Mol)(K))
- Sat Jan 11, 2020 3:08 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Q
- Replies: 10
- Views: 500
Re: Q
Q, the reactant quotient, is calculated the same way as K, but Q is not in equilibrium.
- Sat Jan 11, 2020 3:04 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5I.13
- Replies: 3
- Views: 146
Re: 5I.13
Since the equation involves gases you would need to use Kp and partial pressures.
- Wed Jan 08, 2020 10:20 pm
- Forum: Ideal Gases
- Topic: Understanding Q
- Replies: 13
- Views: 561
Re: Understanding Q
When solving for Q you would leave out solids and liquids.
- Sat Dec 07, 2019 7:16 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: pH Calculation
- Replies: 3
- Views: 223
Re: pH Calculation
Since HCL is a strong acid, pH can be found by taking -log[HCL].
- Sat Dec 07, 2019 7:13 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Disobeying the octect rule
- Replies: 4
- Views: 300
Re: Disobeying the octect rule
elements with room in their d-orbitals usually can disobey the octet rule.
- Sat Dec 07, 2019 7:04 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: when to use what equation
- Replies: 5
- Views: 305
Re: when to use what equation
Also, 10^-ph gives you the H+ concentration.
- Sat Dec 07, 2019 3:00 pm
- Forum: Ionic & Covalent Bonds
- Topic: hydrogen
- Replies: 19
- Views: 1013
Re: hydrogen
The Hydrogen must be bound to an F, O, or N.
- Sat Dec 07, 2019 2:58 pm
- Forum: Significant Figures
- Topic: pH sig figs
- Replies: 9
- Views: 625
Re: pH sig figs
I think you would use the same rules so your answer should match the lowest number of significant figures that were given in the question.
- Sat Dec 07, 2019 2:22 pm
- Forum: Conjugate Acids & Bases
- Topic: studying
- Replies: 7
- Views: 650
Re: studying
Should probably prioritize strong acids and bases but also work on the problems posted in the syllabus.
- Sat Dec 07, 2019 2:21 pm
- Forum: Bronsted Acids & Bases
- Topic: Main Difference
- Replies: 8
- Views: 647
Re: Main Difference
Bronsted acids and bases accept or donate protons while Lewis acids and bases accept or donate electron pairs.
- Sat Dec 07, 2019 2:18 pm
- Forum: Lewis Acids & Bases
- Topic: Lewis acid
- Replies: 3
- Views: 395
Re: Lewis acid
Since NH4 has a full octet and doesn't want to accept any more electrons, it isn't considered a Lewis acid.
- Sat Dec 07, 2019 2:15 pm
- Forum: Lewis Acids & Bases
- Topic: Water
- Replies: 63
- Views: 3162
Re: Water
Water can act as either an acid or a base.
- Sat Dec 07, 2019 2:14 pm
- Forum: Properties & Structures of Inorganic & Organic Bases
- Topic: 6B.5
- Replies: 8
- Views: 1514
Re: 6B.5
Osvaldo Sanchez Fernandez -4F wrote:You can start to approach this by simply knowing that the addition of pOH and pH Is equal to 14 so (pOH+pH=14). So if you find the pH of the molecule using the molarity you found in each problem you can just subtract it to 14 and get pOH or vice versa.
How do you solve for (c)?
- Sat Dec 07, 2019 12:54 pm
- Forum: Properties of Electrons
- Topic: Mass of an electron
- Replies: 9
- Views: 786
Re: Mass of an electron
The mass of an electron was provided on the formula sheet given out during midterm 1.
- Sat Dec 07, 2019 12:54 pm
- Forum: Properties of Light
- Topic: 1b.
- Replies: 1
- Views: 218
Re: 1b.
energy from the lamp = 32 J/s * 2s = 64J. Also 420nm should be converted to m (420 x 10^-9). Use the equation: E=hc/wavelength which gives you 4.73 x 10^-19 J per photon. Then 64/4.73 x 10^-19 gives you 1.4 x 10^20 J.
- Sat Dec 07, 2019 12:47 pm
- Forum: Significant Figures
- Topic: Sig Figs on Tests
- Replies: 24
- Views: 2285
Re: Sig Figs on Tests
Usually your answer should match the lowest amount of significant figures given in the question.
- Sat Dec 07, 2019 12:45 pm
- Forum: Significant Figures
- Topic: Sig Figs on Midterm Q4 Part 2
- Replies: 3
- Views: 425
Re: Sig Figs on Midterm Q4 Part 2
You would use the lowest amount of sig figs present in the problem which is 3 because of the 100 kJ
- Sun Nov 24, 2019 11:23 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: AXE Format
- Replies: 34
- Views: 1307
Re: AXE Format
The 1 is unnecessary.
- Sun Nov 24, 2019 11:22 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 7
- Views: 506
Bond Angles
Why can bond angles be slightly smaller than a given value? For example, why are some bond angles "slightly smaller" than 109.5?
- Sun Nov 24, 2019 11:21 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pairs on Cenrtral Atom
- Replies: 11
- Views: 672
Re: Lone Pairs on Cenrtral Atom
Lone pairs repel other bonds and therefore cause the bond angles to decrease.
- Sun Nov 24, 2019 11:17 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: T-shape
- Replies: 21
- Views: 1761
Re: T-shape
AX3E2 would be a T-shape with bond angles of 90 and 180.
- Sun Nov 24, 2019 11:15 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Final
- Replies: 10
- Views: 603
Re: Final
Yes, the final is cumulative.
- Sun Nov 17, 2019 8:56 pm
- Forum: Ionic & Covalent Bonds
- Topic: Character of Bonds
- Replies: 7
- Views: 531
Re: Character of Bonds
Maddie wrote:Will he give us the actual electronegativity values on the tests though?
Using trends, you need to know the electronegativity of atoms relative to other atoms.
- Sun Nov 17, 2019 8:50 pm
- Forum: Ionic & Covalent Bonds
- Topic: Homework for Week 7
- Replies: 2
- Views: 115
Re: Homework for Week 7
I believe chemical bonds are part of the second test so yes, you can turn in work on chemical bonds.
- Sun Nov 17, 2019 7:32 pm
- Forum: Ionic & Covalent Bonds
- Topic: Hydrogen Bonds
- Replies: 6
- Views: 416
Re: Hydrogen Bonds
Hydrogen bonding occurs when a hydrogen atom is covalently bound to an oxygen, fluorine, or nitrogen atom.
- Sun Nov 17, 2019 7:29 pm
- Forum: Ionic & Covalent Bonds
- Topic: London Dispersion
- Replies: 13
- Views: 707
Re: London Dispersion
Anokhi Patel 4G wrote:what exactly is london dispersion?
LDF is the weakest of the intermolecular forces. LDF occurs when electrons in two adjacent atoms form temporary dipoles.
- Sun Nov 17, 2019 7:19 pm
- Forum: Ionic & Covalent Bonds
- Topic: Dipole-Dipole Interactions
- Replies: 3
- Views: 251
Dipole-Dipole Interactions
What type of molecules contain dipole-dipole interactions?