Search found 63 matches
- Sat Mar 16, 2019 10:57 pm
- Forum: General Rate Laws
- Topic: unique rate
- Replies: 3
- Views: 575
Re: unique rate
The unique rate is the rate of formation and disappearance of molecules in a reaction and it is divided by the coefficients. The unique rate will be the same for product and reactant.
- Sat Mar 16, 2019 8:57 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst Equation
- Replies: 3
- Views: 567
Re: Nernst Equation
It relates the reduction potential of an electrochemical reaction to the standard electrode potential, temperature, and concentrations of the chemical species going through reduction and oxidation.
- Sat Mar 16, 2019 8:38 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Activation Energy
- Replies: 3
- Views: 365
Re: Activation Energy
Activation energy and the rate are closely related. When we have a high activation energy the reaction will tend to be slower. Because fewer molecules will have enough energy to make it over the barrier.
- Sat Mar 16, 2019 8:34 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Exergonic
- Replies: 2
- Views: 244
Re: Exergonic
Yes, when Gibbs free energy is negative the reaction is exergonic because energy was lost.
- Sat Mar 16, 2019 8:30 pm
- Forum: Calculating Work of Expansion
- Topic: Work
- Replies: 1
- Views: 440
Re: Work
I depends on what kind of information is given. Sometimes you have to manipulate the equations to obtain something that will accommodate the values given.
- Sat Mar 16, 2019 8:27 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: half lives
- Replies: 1
- Views: 379
Re: half lives
The rate law let's us calculate the rate of a reaction from concentrations that are given to us from reactants. Then when derived it shows the reactants as a function of time. When we have a high k value it means that the reaction is proceeding quickly.
- Sat Mar 16, 2019 8:22 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Platinum
- Replies: 5
- Views: 513
Re: Platinum
When there is no metal present to conduct the flow of electrons from anode to cathode that is when we use an inert electrode like platinum.
- Sat Mar 16, 2019 8:18 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Frequency factor units
- Replies: 2
- Views: 683
Re: Frequency factor units
A would have the same units of k. So depending on what order the reaction is the units vary.
- Sat Mar 16, 2019 8:15 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Slow and Fast step
- Replies: 4
- Views: 751
Re: Slow and Fast step
From all the problems I have done the slow and fast steps were labelled. If we are asked to identify it, we would have to be given k of the overall reaction to see what step matches it and that would be our slow step.
- Sat Mar 16, 2019 8:12 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: concentration cell vs galvanic cell
- Replies: 3
- Views: 1572
Re: concentration cell vs galvanic cell
A concentration cell is made of two half-cells with the same electrodes, but differing in concentrations. The purpose for this is to dilute the solution that is more concentrated. This heavily relies on the concentration in order for the reaction to keep going. That is why the higher concentration i...
- Sat Mar 16, 2019 8:03 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Buffer solutions
- Replies: 1
- Views: 373
Re: Buffer solutions
Buffer solutions resist change to pH and this is because of the presence of an equilibrium between the acid and its conjugate base. Very little is used up in neutralizing the reaction which then pH increase.
- Sat Mar 16, 2019 7:59 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Collision model
- Replies: 3
- Views: 344
Re: Collision model
The collision model a occurs only when the reactants collide enough energy and in the proper orientation. It explains why certain chemical reaction happen more quickly at higher temps. The activated complex theory relates the rate of reaction to an equilibrium between the reactants and a transition ...
- Sat Mar 16, 2019 7:54 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Transition State
- Replies: 3
- Views: 390
Re: Transition State
The transition sates are the peaks of your profile. Let's say you have two steps and you have an intermediate. The first peak would be your reactants going to your intermediate that is your fist transition state. Your second would be your intermediates going to your products.
- Sat Mar 16, 2019 7:50 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Conjugate Base and Acid
- Replies: 4
- Views: 601
Re: Conjugate Base and Acid
A conjugate acid is a base with a hydrogen ion added to it. And a conjugate base is what is left over after an acid has donated a proton during a chemical reaction.
- Sat Mar 16, 2019 7:48 pm
- Forum: Balancing Redox Reactions
- Topic: Half Reactions in Basic Solutions
- Replies: 1
- Views: 394
Half Reactions in Basic Solutions
When balancing half reactions in basic solutions do we need to add water to both sides and the add OH-? I just get confused because for acidic solutions you just add water and then H+.
- Fri Mar 15, 2019 9:10 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Midterm
- Replies: 4
- Views: 717
Re: Midterm
Thank You! Just saw it
- Fri Mar 15, 2019 7:43 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Midterm
- Replies: 4
- Views: 717
Midterm
Nanotechnologists have found ways to create and manipulate structures containing only a few molecules. However, orienting the molecules in specific ways to assemble such structures can be difficult. Calculate the entropy of a solid nano structure made of 64 molecules in which the molecules (i) are a...
- Fri Mar 15, 2019 1:07 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Test #1
- Replies: 3
- Views: 635
Re: Test #1
Thank you!
- Fri Mar 15, 2019 1:06 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Partial Pressure
- Replies: 4
- Views: 634
Partial Pressure
At 68. Celsius Kp=9.15×10^-3 for reaction
I2(s)--->I2(g).
What is the equilibrium partial pressure of I2(g) at 68 Celsius.
Do we use I2(s) when calculating?
I thought Kp was equal to PI2(g).
I2(s)--->I2(g).
What is the equilibrium partial pressure of I2(g) at 68 Celsius.
Do we use I2(s) when calculating?
I thought Kp was equal to PI2(g).
- Fri Mar 15, 2019 12:46 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Test #1
- Replies: 3
- Views: 635
Test #1
Does anyone have the final concentrations for question 3 part c in test 1? I don't know if I did my calculations right.
- Thu Mar 14, 2019 1:37 am
- Forum: General Rate Laws
- Topic: Rate Law
- Replies: 1
- Views: 218
Rate Law
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) one-eighth of its initial concentration; (b) one-fourth of its initial concentration; (c) 15% of its initial concentration; (d) one-ninth of its initia...
- Wed Mar 13, 2019 7:41 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalyst Problems
- Replies: 1
- Views: 183
Re: Catalyst Problems
I'm sure we will and it will probably look like the example we had in class today, where there were multiple steps and we had to figure out what was acting as a catalyst and what was an intermediate.
- Wed Mar 13, 2019 7:38 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts vs Intermediates
- Replies: 4
- Views: 463
Re: Catalysts vs Intermediates
So what I got form today is that catalyst are already present in the reaction, and in a later step they are removed. The intermediates are produced later and not originally present in the reaction. Only to be used up by the reaction in another step.
- Wed Mar 13, 2019 7:24 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat Capacity of Water
- Replies: 6
- Views: 898
Re: Heat Capacity of Water
A unit change in kelvin is the same change in Celsius. The equation states per kelvin/Celsius so if one unit of kelvin changes so does 1 unit of Celsius.
- Wed Mar 13, 2019 7:12 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Anode and Cathode
- Replies: 14
- Views: 1046
Re: Anode and Cathode
The anode is the oxidation and the cathode is the reduction in the reaction.
- Tue Mar 12, 2019 5:22 pm
- Forum: Van't Hoff Equation
- Topic: Test #2
- Replies: 5
- Views: 756
Re: Test #2
the ionic dissociation of water is given by the following reaction: the deltaH for the reaction is 58 kJ/mol. The Kw for the reaction at 25 degree Celsius is 10 ^-14. Is the pH of 7 acidic or basic at 10 degree Celsius? 2H20 --> H3O+ + OH- You have to start by using the Van't Hoff equation which is ...
- Tue Mar 12, 2019 12:24 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: instantaneous and unique rate
- Replies: 6
- Views: 1238
Re: instantaneous and unique rate
The average rate of reaction is an average rate which is calculated by taking the change in concentration over a time period. This is just an approximation of the reaction rate in the interval. It does not mean that the reaction has this rate throughout the time interval or even at any instant durin...
- Tue Mar 12, 2019 12:17 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: rxn mechanisms
- Replies: 3
- Views: 402
Re: rxn mechanisms
If we know what the slowest step of the mechanism is, this let's us find the rate equation. This tells us how if we can increase the rate by increasing the concentration of certain reactants.
- Tue Mar 12, 2019 12:13 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Strong Acid/Base Concentration vs. Weak Acid/Base Concentration
- Replies: 2
- Views: 313
Re: Strong Acid/Base Concentration vs. Weak Acid/Base Concentration
Any acid that dissociates 100% into ions is a strong acid. If it does not dissociate 100%, it is a weak acid. Same goes for strong and weak bases.
- Tue Mar 12, 2019 3:06 am
- Forum: Calculating Work of Expansion
- Topic: Reversible Expansion
- Replies: 1
- Views: 415
Re: Reversible Expansion
Reversible reactions that occur in closed systems will somehow reach equilibrium. During this time the concentration of both P and R do not change. But that does not mean that the reaction has stopped. The forward and reverse reactions are continuing but at equal rates.
- Tue Mar 12, 2019 3:02 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Slow Step
- Replies: 6
- Views: 519
Re: Slow Step
I don't think this information will be given to us. During class we learned that the slow step if what determines the overall rate for the reaction, so we should be able to pinpoint that step.
- Tue Mar 12, 2019 3:00 am
- Forum: General Rate Laws
- Topic: Derivations
- Replies: 3
- Views: 349
Re: Derivations
You should be able to manipulate the formulas given on the formula sheet to accommodate the given information.
- Sun Dec 09, 2018 10:47 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: acids and bases in 14b
- Replies: 1
- Views: 350
Re: acids and bases in 14b
Yes, he spoke of doing calculation to find KA and KB of acids and bases.
- Sun Dec 09, 2018 10:45 pm
- Forum: Amphoteric Compounds
- Topic: Amphiprotic vs Amphoteric
- Replies: 2
- Views: 514
Re: Amphiprotic vs Amphoteric
These terms describe properties of both acids and bases. Amphiprotic refers to a substance that can either gain or lose a proton, and amphoteric refers to a substance that can act as either an acid or a base.
- Sun Dec 09, 2018 10:42 pm
- Forum: Conjugate Acids & Bases
- Topic: Definition of conjugate base
- Replies: 6
- Views: 669
Re: Definition of conjugate base
A Conjugate base is a substance formed when an acid loses a hydrogen ion. Considered a base because it can gain a hydrogen ion to reform the acid.
- Sun Dec 02, 2018 9:41 pm
- Forum: Bronsted Acids & Bases
- Topic: Bronsted vs Lewis
- Replies: 4
- Views: 484
Re: Bronsted vs Lewis
Bases and acids can be considered to fit in the Lewis and bronsted definition but not all fall in to this category. For example, "the HF molecule as a whole cannot be considered an electron acceptor as there is no room for more electrons,so HF first dissociates and then the H accepts the electr...
- Sun Dec 02, 2018 9:37 pm
- Forum: Naming
- Topic: 7th edition 9C.1
- Replies: 1
- Views: 252
Re: 7th edition 9C.1
For metals we sometimes use the Latin name when they are in complex so for iron it is ferrate.
- Sun Dec 02, 2018 9:33 pm
- Forum: Naming
- Topic: Polyatomic ions
- Replies: 1
- Views: 236
Re: Polyatomic ions
Yes I believe it would be important when finding an overall charge of a complex molecule .
- Sun Dec 02, 2018 9:31 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: 7th edition 9C.7
- Replies: 1
- Views: 200
Re: 7th edition 9C.7
The correct answer is the second one and that is because the NH2 groups are close together. Which means they can form the ring formation with another complex. The other combination don't have the groups close enough to form the ring.
- Sun Nov 25, 2018 7:58 pm
- Forum: Octet Exceptions
- Topic: Understanding Expanded Octets
- Replies: 1
- Views: 346
Re: Understanding Expanded Octets
Since n=3 the d sub shell has 5 orbitals. Although the energy of empty 3d-orbitals is ordinarily higher than that of the 4s orbital, that difference is small and the additional d orbitals can fit more electrons. d orbitals participate in bonding with other atoms and an expanded octet is produced.
- Sun Nov 25, 2018 7:53 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: Dipole
- Replies: 3
- Views: 369
Re: Dipole
A polar molecule has to have a permanent dipole moment and the charges shouldn't fluctuate like they would in an induced dipole.
- Sun Nov 25, 2018 7:51 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: Dipole-Dipole forces
- Replies: 3
- Views: 405
Re: Dipole-Dipole forces
We have to see the difference in the charges. If the difference is big enough the molecule will have an overall dipole moment. But we do have to remember that nonpolar molecules can experience small disparities in their charge which is the Van der waal force. The molecule will be polar if it has a p...
- Sat Nov 17, 2018 9:15 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular shape vs electron geometry
- Replies: 4
- Views: 389
Re: Molecular shape vs electron geometry
The molecular shape doesn't take to account the lone pairs found on the central atoms, and thus results in the shape being the same. While electron geometry does take this into account and we know that lone pairs have a higher electron density so this changes the shape completely.
- Sat Nov 17, 2018 9:10 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: No central atom
- Replies: 7
- Views: 621
Re: No central atom
Each N will have one lone pair and 2 bond pairs and this will result in a "bent" shape.
- Sun Nov 11, 2018 9:39 pm
- Forum: Trends in The Periodic Table
- Topic: Atomic vs ionic radius
- Replies: 6
- Views: 971
Re: Atomic vs ionic radius
When it comes to the neutral atom both ionic and atomic radius is the same. But we know that many elements can lose or gain electrons converting them to anions or cations. We know that if an atom loses an electron the radius decreases, if the ion gains an electron the radius increases. This is where...
- Sun Nov 11, 2018 9:34 pm
- Forum: Bond Lengths & Energies
- Topic: Drawing resonance structures?
- Replies: 6
- Views: 716
Re: Drawing resonance structures?
When asking for a structure they are usually looking for the one that is most stable. If the compound is neutral you will draw the one with an overall charge of zero. You can identify the charge by using formal charge.
- Sun Nov 11, 2018 3:08 pm
- Forum: Bond Lengths & Energies
- Topic: Covalent Radius
- Replies: 3
- Views: 600
Re: Covalent Radius
When you have a covalent bond between atoms you can find the covalent radius. The distance between the two nuclei of the atoms will give you the diameter so you would have to divide by two. Atomic radius is just focusing on one atom.
- Sun Nov 11, 2018 2:52 pm
- Forum: Properties of Electrons
- Topic: Polar vs Non polar
- Replies: 15
- Views: 4790
Re: Polar vs Non polar
To figure out if something is polar or non polar we have to look at the dipole moments. If the dipole moments cancel each other out the compound is non polar. In contrast if there is a strong dipole moment the compound is polar.
- Sun Nov 11, 2018 2:48 pm
- Forum: SI Units, Unit Conversions
- Topic: Bond length
- Replies: 3
- Views: 731
Re: Bond length
When it comes to bond lengths we need to know that single bonds are longer and weaker than single and triple bonds. When it comes to resonance we know that the electrons are delocalized causing partial bonds. So a compound can have both single and double bond characteristics.
- Sun Nov 04, 2018 4:30 pm
- Forum: Lewis Structures
- Topic: 7th edition 2B.9
- Replies: 4
- Views: 400
Re: 7th edition 2B.9
When drawing the Lewis Structure for ionic bonds we have to remember that one atom is "giving away" its electron while the other is receiving it. And one atom will become positively charge while the other will become negatively charge and attract each other. That is why we don't draw the &...
- Sun Nov 04, 2018 4:22 pm
- Forum: Trends in The Periodic Table
- Topic: Ionization Energies
- Replies: 2
- Views: 261
Re: Ionization Energies
I don't think we need to know that for this midterm but you do need to know the periodic trend for ionization energy.
- Sun Nov 04, 2018 4:10 pm
- Forum: Lewis Structures
- Topic: HW 3.39
- Replies: 1
- Views: 240
Re: HW 3.39
Potassium Hypochlorite (NaClO) is known has an ionic bond. It is composed of a potassium ion (Na+) and a hypochlorite ion (ClO-). So if we put that together we get Na+ [Cl--0]- plus the lone pairs around Cl and O to complete the octet.
- Sun Nov 04, 2018 4:02 pm
- Forum: Trends in The Periodic Table
- Topic: 7th Edition 1F 11
- Replies: 1
- Views: 221
Re: 7th Edition 1F 11
This trend either increases or can decrease when going across a period, this all depends on the electron configuration of an atom. For example a half filled p sub-shell can be identified as more stable, carbon has higher electron affinity in comparison to nitrogen.
- Sun Oct 28, 2018 9:23 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Equation
- Replies: 2
- Views: 381
Equation
When using the heisenberg indeterminacy equation do we use the radius or diameter for delta x?
- Sun Oct 28, 2018 9:20 pm
- Forum: DeBroglie Equation
- Topic: De Broglie
- Replies: 12
- Views: 1468
Re: De Broglie
You use it when the question asks you for a wavelength and the known object has a mass and velocity.
- Tue Oct 23, 2018 10:05 pm
- Forum: Photoelectric Effect
- Topic: Wavelength Calculation
- Replies: 2
- Views: 413
Re: Wavelength Calculation
Thank you
- Tue Oct 23, 2018 7:00 pm
- Forum: Photoelectric Effect
- Topic: Wavelength Calculation
- Replies: 2
- Views: 413
Wavelength Calculation
The velocity of an electron that is emitted from a metallic surface by a photon is 3.6 x 10^3 km/s . (a) What is the wavelength of the ejected electron? (b) No electrons are emitted from the surface of the metal until the frequency of the radiation reaches 2.50 x 10^16 Hz. How much energy is require...
- Sat Oct 20, 2018 11:41 pm
- Forum: Properties of Light
- Topic: Visible Light
- Replies: 5
- Views: 481
Visible Light
What is the wavelength range of visible light? I've seen many ranges but I don't know which one is correct.
- Tue Oct 09, 2018 10:12 pm
- Forum: Limiting Reactant Calculations
- Topic: Percent Yield [ENDORSED]
- Replies: 13
- Views: 2904
Percent Yield [ENDORSED]
I know that the equation for percent yield is Actual Yield/Theoretical Yield...but I still confused on which value is which. Can someone please explain the difference between actual and theoretical?
- Tue Oct 09, 2018 8:58 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Molarity
- Replies: 4
- Views: 580
Molarity
I have attempted this problem multiple times and keep getting the same answer; which is not one of the answer in the module. I have used the formula M1*V1=M2*V1. For M1 I got .211, V1 is .150L, V2 is .250L, and we are trying to find M2. Did I do a miscalculation? 5.00 g of KMnO4 is dissolved in a 15...
- Sun Oct 07, 2018 10:52 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: To find the amount of water used
- Replies: 1
- Views: 140
Re: To find the amount of water used
If you have already found both the initial and final you can use that formula. If you are missing one of the volumes you can use M1V1 = M2V2, M1 is the molarity (moles/Liters).
- Sun Oct 07, 2018 10:46 pm
- Forum: Significant Figures
- Topic: knowing how many sig figs to use
- Replies: 17
- Views: 2221
Re: knowing how many sig figs to use
What helps me when it comes to sig figs I usually put the numbers given into scientific notation. This helps when the numbers are too big or too small to tell the appropriate sig figs.
- Sun Oct 07, 2018 10:43 pm
- Forum: Empirical & Molecular Formulas
- Topic: when to multiply empirical formula [ENDORSED]
- Replies: 9
- Views: 4567
Re: when to multiply empirical formula [ENDORSED]
You multiply by the smallest possible value; that will give you a whole number.