Search found 69 matches
- Sat Mar 14, 2020 9:47 pm
- Forum: General Rate Laws
- Topic: Initial Rate
- Replies: 5
- Views: 454
Re: Initial Rate
They will only change the concentration of one substance from trial to trial
- Sat Mar 14, 2020 9:45 pm
- Forum: General Rate Laws
- Topic: Factors Affecting k
- Replies: 83
- Views: 5149
Re: Factors Affecting k
I believe we only go over temperature changing rate, however it can be changed by altering activation energy as well(adding or removing a catalyst) It is related in the Arrhenius equation; k=Ae^(-Ea/RT) I think we have to understand the concept of catalysts, but not necessarily how to compute an equ...
- Sat Mar 14, 2020 9:41 pm
- Forum: General Rate Laws
- Topic: Rate Constant
- Replies: 31
- Views: 1229
Re: Rate Constant
Rate can be changed by altering temperature or activation energy (adding or removing a catalyst)
It is related in the Arrhenius equation; k=Ae^(-Ea/RT)
It is related in the Arrhenius equation; k=Ae^(-Ea/RT)
- Sat Mar 14, 2020 9:36 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Enthalpy
- Replies: 26
- Views: 1207
Re: Enthalpy
Ivan Tadeja 1G wrote:Fiona Latifi 1A wrote:Examples of state functions include density, internal energy, enthalpy, and entropy.
Could you also give examples of what would not be a state function?
Work is an example of a non-state (path) function
- Sat Mar 14, 2020 9:33 pm
- Forum: General Rate Laws
- Topic: Kr Units for Different Order Reactions
- Replies: 3
- Views: 576
Re: Kr Units for Different Order Reactions
Because rate is expressed in M/s, you have to adjust the units for k depending on the order. 0 order; units from [concentration (m/l)]^0 is removed, so k's units are M/s 1st order; units from [concentration (m/l)]^1 is present, so k's units are 1/s 2nd order units from [concentration(m/l)]^2 needs t...
- Sat Mar 14, 2020 9:21 pm
- Forum: Balancing Redox Reactions
- Topic: flipping equations
- Replies: 7
- Views: 594
Re: flipping equations
The E(cell) has to be positive, so the cathode will always be the larger (more positive) reduction potential value, and the anode will then "be flipped" so that it is giving off an electron (oxidized).
- Sat Mar 14, 2020 9:14 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: intensive vs extensive
- Replies: 12
- Views: 823
Re: intensive vs extensive
Intensive properties are not effected by the amount of the substance. For example boiling point or molecular weight.
Extensive properties are effected by the amount of the substance. For example mass or volume of a gas.
Extensive properties are effected by the amount of the substance. For example mass or volume of a gas.
- Sat Mar 14, 2020 9:10 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Grading Scale
- Replies: 16
- Views: 1087
Re: Grading Scale
From my understanding he will only curve up if the class average is significantly lower than expected. Otherwise It's as simple as adding all your points together and dividing by 500.
- Sat Mar 14, 2020 9:07 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final Exam Time
- Replies: 13
- Views: 942
Re: Final Exam Time
It opens Sunday at 11:15 AM and closes at 3 1/2 hours later at 2:45. 6 Questions.
- Sun Mar 08, 2020 10:13 pm
- Forum: First Order Reactions
- Topic: Graphing 1st order reaction rates
- Replies: 6
- Views: 402
Re: Graphing 1st order reaction rates
With a first order reaction graphing [A] vs t will produce a curve of exponential decay. By taking ln[A] we are able to make the graph a straight line.
- Sun Mar 08, 2020 10:11 pm
- Forum: Zero Order Reactions
- Topic: Identifying Zero vs. First vs. Second Order Reactions
- Replies: 7
- Views: 567
Re: Identifying Zero vs. First vs. Second Order Reactions
You can do so by looking at the graphs produced by modeling the system as 0th, 1st or 2nd order. Which ever order produces a straight line is the correct order.
- Sun Mar 08, 2020 10:09 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: K
- Replies: 11
- Views: 668
Re: K
In kinetics k is defined by the arrhenius equation, thus the temperature and activation energy.
- Sun Mar 08, 2020 10:07 pm
- Forum: General Rate Laws
- Topic: Rate limiting step
- Replies: 12
- Views: 861
Re: Rate limiting step
The slow step is equivalent to the rate law. If the rate law isn't given, it will specify which step is slow.
- Sun Mar 08, 2020 10:04 pm
- Forum: General Rate Laws
- Topic: units
- Replies: 12
- Views: 645
Re: units
The equilibrium constant does not have units
- Sun Mar 01, 2020 9:52 pm
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: Dissolved Metal
- Replies: 3
- Views: 338
Re: Dissolved Metal
If the metal is the cathode it will come out of solution and accumulate on the electrode. If it is the anode it will "dissolve" from the electrode and go into solution.
- Sun Mar 01, 2020 9:45 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: when to use K or Q
- Replies: 18
- Views: 1113
Re: when to use K or Q
K indicates the equation is at equilibrium. Q indicates that the equation is not at equilibrium.
- Sun Mar 01, 2020 9:44 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Electrochemical Series
- Replies: 5
- Views: 451
Re: Electrochemical Series
The electrochemical series are the tables of electrode potential.
- Sun Mar 01, 2020 9:42 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: How to determine anode and cathode in 6.57?
- Replies: 6
- Views: 456
Re: How to determine anode and cathode in 6.57?
The cathode will be the reaction with the larger E* value.
- Sun Mar 01, 2020 8:24 pm
- Forum: Balancing Redox Reactions
- Topic: oxidizing agents
- Replies: 11
- Views: 629
Re: oxidizing agents
Oxidizing agents cause Oxidation to a substance and get reduced in the process.
- Sun Feb 23, 2020 8:25 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: cell diagram
- Replies: 2
- Views: 188
Re: cell diagram
You have the oxidation reaction (anode) on the left side of the salt bridge and the reduction reaction (cathode) on the right side | indicates substances that are touching each other but in different phases || indicates the salt bridge You also need to include the inert conductor so; Cu(s) | Cu2+(aq...
- Sun Feb 23, 2020 8:18 pm
- Forum: Van't Hoff Equation
- Topic: Van't Hoff Equation
- Replies: 7
- Views: 547
Re: Van't Hoff Equation
You use it when you have a given equilibrium constant K at one temperature, and then you need to find the new equilibrium constant K at a new temperature.
- Sun Feb 23, 2020 7:53 pm
- Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Topic: 3rd law of thermodynamics
- Replies: 3
- Views: 340
Re: 3rd law of thermodynamics
Yes, at 0K atoms cease to move, have zero entropy and are in a solid state. 0K is theoretical, it is not actually possible to reach.
- Sun Feb 23, 2020 7:50 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Enthalpy
- Replies: 26
- Views: 1207
Re: Enthalpy
State functions only depend on initial and final values, thus intermediate steps are irrelevant when calculating enthalpy or entropy.
- Sun Feb 23, 2020 7:43 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Question 1 on Midterm
- Replies: 7
- Views: 575
Re: Question 1 on Midterm
Via Le Chatelier removing reactants from equilibrium causes the reaction to shift towards reactants, and removing products causes the reaction to shift towards products.
- Sun Feb 09, 2020 9:09 pm
- Forum: Phase Changes & Related Calculations
- Topic: closed vs isolated
- Replies: 10
- Views: 599
Re: closed vs isolated
A closed system can transfer energy with the surroundings while an isolated system cannot. Neither exchanges matter with the surroundings
- Sun Feb 09, 2020 8:59 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase Change Calculations
- Replies: 5
- Views: 188
Re: Phase Change Calculations
You can see what is included on the equation sheet here; https://lavelle.chem.ucla.edu/wp-conten ... ations.pdf
- Sun Feb 09, 2020 8:52 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: solids and liquids in the rxn quotient
- Replies: 8
- Views: 531
Re: solids and liquids in the rxn quotient
Solids and Liquids have an activity level of 1, so even if you include them in the calculations they will have no effect on the results.
- Sun Feb 09, 2020 8:49 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Strong acids and bases as gases
- Replies: 4
- Views: 231
Re: Strong acids and bases as gases
I believe we only need to know about how acids and bases behave in aqueous form.
- Sun Feb 09, 2020 8:48 pm
- Forum: Ideal Gases
- Topic: Change in pressure
- Replies: 7
- Views: 515
Re: Change in pressure
Because the system want to remain at equilibrium, increasing pressure will cause the equation to shift towards the side with fewer moles of gas.
- Mon Feb 03, 2020 6:24 pm
- Forum: Phase Changes & Related Calculations
- Topic: Steam?
- Replies: 8
- Views: 332
Re: Steam?
In order to break the hydrogen bonds found in liquid water, quite a bit of additional energy is required to be added to change water's phase from liquid to gas. This energy stays with the vaporized water molecules and it is released when it condenses back to liquid.
- Mon Feb 03, 2020 6:19 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Car Engine
- Replies: 4
- Views: 228
Re: Car Engine
It exchanges both heat and matter with the surroundings. It takes in gasoline and air and gives off exhaust. Heat is also exchanged with the air entering and exiting the engine, as well as radiation from the hot engine block.
- Mon Feb 03, 2020 6:15 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Specific heat capacity
- Replies: 7
- Views: 448
Re: Specific heat capacity
Specific heat capacity is per gram of substance. It can be converted to molar heat capacity by dividing it by the substances molar weight.
- Mon Feb 03, 2020 6:13 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Closed Systems
- Replies: 14
- Views: 940
Re: Closed Systems
An example of changing energy of a closed system would be adding or removing heat, or compression/expansion. An isolated system cannot transfer energy with its environment.
- Mon Feb 03, 2020 6:10 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated system
- Replies: 10
- Views: 1342
Re: Isolated system
It's my understanding that a perfectly isolated system is theoretical and impossible to create. A thermos is an example of a practically isolated system- it exchanges energy at a slow enough rate to be considered isolated for a question.
- Sun Jan 26, 2020 8:48 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess's Law
- Replies: 4
- Views: 170
Re: Hess's Law
Just the first
- Sun Jan 26, 2020 8:47 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Method 3
- Replies: 3
- Views: 187
Re: Method 3
Method 3 is more accurate than Method 2, you can use it as long as you know the standard enthalpy of formation of all the products and reactants. Something like O2 in gaseous form will not have a listed standard enthalpy of formation because by definition the standard enthalpy of formation for an el...
- Sun Jan 26, 2020 8:40 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy is said to be additive
- Replies: 10
- Views: 329
Re: Enthalpy is said to be additive
This is because Enthalpy is a state property. Only the initial and final values are relevant, the path taken to get to the final value does not matter.
- Sun Jan 26, 2020 8:36 pm
- Forum: Phase Changes & Related Calculations
- Topic: phase changes
- Replies: 2
- Views: 145
Re: phase changes
When calculating total enthalpy you have to account for whether or not the substance is its standard phase. For example if its a gas in its standard state and is currently a liquid, you would have to add the enthalpy of its vaporization to total enthalpy.
- Sun Jan 26, 2020 8:32 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase Changes
- Replies: 7
- Views: 241
Re: Phase Changes
When the substance is not in its standard state at the given temperature, you have to add the enthalpy of its phase changes. For example if its a gas in its standard state and is currently a solid, you would have to add the enthalpy of its sublimation.
- Sun Jan 26, 2020 8:24 pm
- Forum: Ideal Gases
- Topic: R Constant
- Replies: 18
- Views: 1107
Re: R Constant
R is the gas constant. It has different values depending on what units you are using.
- Sun Jan 19, 2020 8:53 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Not including solids and liquids
- Replies: 7
- Views: 302
Re: Not including solids and liquids
Pure liquids and solids have an activity level of 1, and thus do not need to be included in equilibrium equations.
- Sun Jan 19, 2020 7:56 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Stoichiometric coefficients for pH/pOH
- Replies: 3
- Views: 200
Re: Stoichiometric coefficients for pH/pOH
Raising concentrations to their stoichiometric coefficient is only required for the equilibrium equations.
- Sun Jan 19, 2020 7:51 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: When do we use the equilibrium sign?
- Replies: 7
- Views: 316
Re: When do we use the equilibrium sign?
Although only one arrow is required by strong acids/bases, I don't believe it's incorrect to use the equilibrium sign.
- Sun Jan 19, 2020 7:45 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5%
- Replies: 4
- Views: 190
Re: 5%
If you approximate the result with a small Ka (<10^-3) and end up with a change value of <5% of initial value then your approximation is valid. Otherwise you need to do the full quadratic calculation.
- Sun Jan 19, 2020 7:38 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Solids and Liquids
- Replies: 6
- Views: 262
Re: Solids and Liquids
Pure solids and liquids do not affect reactant amounts in the equation so they are not included in the equation. If you included them they would have an activity level of 1, thus not changing the equation.
- Sun Jan 12, 2020 7:33 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: increasing yield of NH3
- Replies: 3
- Views: 152
Re: increasing yield of NH3
By removing NH3 from the system, the numerator of the Qp equation will decrease, resulting in a smaller Qp value. When Qp is less than Kp the reaction moves forward, resulting in more NH3 being created. Yes it would decrease NH3 in the system, but overall you would have more NH3 (by adding NH3 in th...
- Sun Jan 12, 2020 7:27 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: increasing N2
- Replies: 5
- Views: 314
Re: increasing N2
Increasing N2 will result in a larger denominator for the Qp equation, resulting in a smaller value for Qp. When Qp is less than Kp, the reaction moves forward, meaning that more NH3 will be created from N2 and H2, resulting in H2 concentration decreasing.
- Sun Jan 12, 2020 7:23 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Inert gas
- Replies: 6
- Views: 173
Re: Inert gas
Reactant and Product concentrations will remain the same as volume does not change, therefore Kp is unchanged.
- Sun Jan 12, 2020 7:18 pm
- Forum: Administrative Questions and Class Announcements
- Topic: General HW question
- Replies: 9
- Views: 410
Re: General HW question
I believe it depends on the TA
- Thu Jan 09, 2020 6:53 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Homework 1
- Replies: 18
- Views: 656
Re: Homework 1
I believe it is graded on completeness, also you can check your answers with the solutions manual.
- Wed Jul 31, 2019 12:37 am
- Forum: Naming
- Topic: CO3(2-) Carbanato
- Replies: 2
- Views: 524
Re: CO3(2-) Carbanato
Hmm, I saw it stated as such when looking it up earlier. I see in our textbook it's only referred to as monodentate so I'm just going to go with that.
- Wed Jul 31, 2019 12:08 am
- Forum: Naming
- Topic: CO3(2-) Carbanato
- Replies: 2
- Views: 524
CO3(2-) Carbanato
Because CO3(2-) can either be monodentate or bidentate do we use bi- tri- etc as the prefix or bis- tris-?
- Tue Jul 30, 2019 11:58 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Angles
- Replies: 2
- Views: 433
Re: Angles
In the seesaw shape, the lone pair does not effect the axial angles. So the angles are 90, <120, and 180.
- Tue Jul 30, 2019 11:37 pm
- Forum: Conjugate Acids & Bases
- Topic: Delocalization of charge and stability
- Replies: 4
- Views: 1038
Re: Delocalization of charge and stability
One thing it can refer to is the electronegativity of the central atom of the conjugate base. For example; ClO4- vs H2PO4- Cl is more electronegative than P, so it handles the negative charge more effectively. HClO4 is thus a stronger acid than H3PO4.
- Tue Jul 30, 2019 11:19 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: how to draw lewis structure
- Replies: 9
- Views: 941
Re: how to draw lewis structure
With a radical you assign the lone electron to the atom with the lowest Electronegativity. For example in HOCO (17 e) the lone electron would be put on C.
I checked out ClO2, it involves something called a triple electron bond, which is beyond this class.
I checked out ClO2, it involves something called a triple electron bond, which is beyond this class.
- Tue Jul 30, 2019 11:09 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar v. Nonpolar
- Replies: 11
- Views: 2127
Re: Polar v. Nonpolar
Yes, the vectors would cancel out with that shape, but more importantly C-H is not a polar covalent bond, they both have similar Electronegativities. CH3+ would also be a symmetrical shape with canceling vectors, but again, the bonds are not polar.
- Tue Jul 30, 2019 11:03 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Hydrogen Bonding
- Replies: 5
- Views: 742
Re: Hydrogen Bonding
CH4 would only have London. This is why it has a low boiling point
- Tue Jul 30, 2019 10:57 pm
- Forum: Conjugate Acids & Bases
- Topic: Water as an Acid/Base
- Replies: 20
- Views: 1559
Re: Water as an Acid/Base
You can recognize it because it will have a H+ to give, and be able to receive an H+.
An example would be HPO4 (2-)
An example would be HPO4 (2-)
- Tue Jul 30, 2019 10:54 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Strength of Acids vs. Number of Oxygens
- Replies: 6
- Views: 1479
Re: Strength of Acids vs. Number of Oxygens
Yes, if the acid is polyprotic, it will be strongest when it has the most H. For example, H3PO4 is a stronger acid than H2PO4-
This is because it is easier to remove the first H.
This is because it is easier to remove the first H.
- Tue Jul 30, 2019 10:47 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: shape
- Replies: 2
- Views: 458
Re: shape
Chem_Mod wrote:Because there are 6 ligands, 3 from the Na and 3 from the oxalate, it will have an octahedral shape.
I thought oxalate was bidentate, and thus 3 of them would provide the 6 areas.
- Mon Jul 29, 2019 11:31 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: What are polydentate ligands ?
- Replies: 4
- Views: 764
Re: What are polydentate ligands ?
Hexadentate is 6 binding sites.
- Mon Jul 29, 2019 11:28 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic vs covalent
- Replies: 8
- Views: 884
Re: Ionic vs covalent
If the difference is between 1.5 and 2 does the bond exhibit qualities of both ionic and covalent bonds?
- Mon Jul 29, 2019 12:38 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Oxidation states
- Replies: 5
- Views: 684
Re: Oxidation states
I think they might be referring to finding the oxidation state of a metal in a coordination compound.
- Mon Jul 29, 2019 12:30 am
- Forum: Formal Charge and Oxidation Numbers
- Topic: charges and roman numerals
- Replies: 5
- Views: 944
Re: charges and roman numerals
The Roman Numeral indicates the Oxidation State.
- Mon Jul 29, 2019 12:25 am
- Forum: Coordinate Covalent Bonds
- Topic: Why can h20 only donate 1 lone pair?
- Replies: 5
- Views: 2267
Re: Why can h20 only donate 1 lone pair?
In my understanding with coordinate covalent bonding the element can only donate one pair to another element, no matter how many lone pairs it may have.
- Fri Jul 05, 2019 2:56 pm
- Forum: Photoelectric Effect
- Topic: kinetic energy of electron
- Replies: 8
- Views: 1163
Re: kinetic energy of electron
How can something be released with a KE of 0? That would mean it has no velocity, so its position would not change.
- Thu Jun 27, 2019 10:12 am
- Forum: SI Units, Unit Conversions
- Topic: Use of Kelvin
- Replies: 6
- Views: 884
Re: Use of Kelvin
Temperature is the measure of the average kinetic energy of the particles of a substance. At absolute zero the kinetic energy of the particles is zero, ie they stop moving. Because you can't have negative kinetic energy, you can't go past zero.
- Thu Jun 27, 2019 10:06 am
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Moles and Molarity HW Problem E.29b
- Replies: 2
- Views: 377
Re: Moles and Molarity HW Problem E.29b
In each molecule of CuCl2 there will be two ions of Cl, hence you need to double the amount of moles found of CuCl2 to find the number of moles of Cl- ions.
- Thu Jun 27, 2019 9:59 am
- Forum: Molarity, Solutions, Dilutions
- Topic: the mole
- Replies: 4
- Views: 577
Re: the mole
Grams per cubic centimeter is also commonly used.