Search found 60 matches
- Tue Mar 12, 2019 9:25 pm
- Forum: First Order Reactions
- Topic: Graphs
- Replies: 2
- Views: 330
Graphs
Why does the graph of time versus concentration need to be linear?
- Tue Mar 12, 2019 9:22 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Kinetics and Thermodynamics
- Replies: 2
- Views: 584
Kinetics and Thermodynamics
How do kinetics and thermodynamics interact to control reactions? How do they each impact a reaction differently?
- Tue Mar 12, 2019 9:19 pm
- Forum: First Order Reactions
- Topic: Order of a Reaction
- Replies: 2
- Views: 296
Order of a Reaction
How can you tell what the order of a reaction is?
- Tue Mar 05, 2019 7:51 pm
- Forum: First Order Reactions
- Topic: First Order Reaction
- Replies: 3
- Views: 347
First Order Reaction
If [A]₀ is the initial concentration of A, then what does [A] represent?
- Tue Mar 05, 2019 7:48 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Rate Constant
- Replies: 3
- Views: 400
Rate Constant
Could someone explain what the rate constant (k) actually represents within a reaction?
- Tue Mar 05, 2019 7:46 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Activation Energy
- Replies: 2
- Views: 354
Activation Energy
How do temperature and activation energy impact the rate constant?
- Mon Feb 25, 2019 6:35 pm
- Forum: Van't Hoff Equation
- Topic: Equilibrium
- Replies: 6
- Views: 769
Equilibrium
How does the Van't Hoff equation relate to equilibrium?
- Mon Feb 25, 2019 6:28 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagrams
- Replies: 2
- Views: 272
Cell Diagrams
How do you know what order to put the reactants and products in when constructing a cell diagram?
- Mon Feb 25, 2019 6:27 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Electrons
- Replies: 3
- Views: 356
Balancing Electrons
How do you find the number of electrons to balance a redox reaction?
- Fri Feb 22, 2019 2:29 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt Bridges
- Replies: 3
- Views: 404
Salt Bridges
Do salt bridges and porous disks both allow ion transfer in the same way? Or would we use one instead of the other in certain situations?
- Fri Feb 22, 2019 2:24 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneity
- Replies: 8
- Views: 830
Spontaneity
How does Gibbs free energy relate to the spontaneity of a reaction?
- Fri Feb 22, 2019 2:22 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs Free Energy
- Replies: 2
- Views: 278
Gibbs Free Energy
Could someone explain what Gibbs free energy actually is? And how does that relate to entropy and enthalpy?
- Mon Feb 11, 2019 8:08 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Deriving Formulas
- Replies: 2
- Views: 369
Deriving Formulas
Will we need to know how to derive formulas for the midterm? Or is it just something he showed us in class in order to provide background for the concept?
- Mon Feb 11, 2019 8:04 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Determining of there is Change
- Replies: 2
- Views: 324
Determining of there is Change
Will we be told is there is changed/constant volume or temperature? Or is it something we will have to figure out using PV=nRT?
- Mon Feb 11, 2019 8:03 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Entropy Equations
- Replies: 2
- Views: 404
Entropy Equations
In what circumstances will we use equations with the Boltzmann equation versus nrtln(v2/v1) or nrtln(t2/t1)?
- Mon Feb 04, 2019 10:35 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: ΔU=q+w
- Replies: 1
- Views: 239
ΔU=q+w
Could someone explain conceptually why this equation works? I know what each of them means but I'm not sure why the internal energy is equal to the heat plus work.
- Mon Feb 04, 2019 10:33 pm
- Forum: Calculating Work of Expansion
- Topic: Converting between units?
- Replies: 2
- Views: 267
Re: Converting between units?
I'm pretty sure we would be given any constant we need to convert between units of pressure and volume. That being said, I think 1L*atm=101.325J is just like any other constant on the constant sheet we're given, we don't need to know where it comes from.
- Mon Feb 04, 2019 10:31 pm
- Forum: Calculating Work of Expansion
- Topic: Difference between reversible and irreversible expansion?
- Replies: 2
- Views: 882
Re: Difference between reversible and irreversible expansion?
A reversible reaction does more work than an irreversible reaction. This is because we change the volume infinitesimally, so we push against the force little by little to change the volume. This means a reversible reaction is slower, but more efficient. On the other hand, irreversible is fast but in...
- Wed Jan 30, 2019 8:29 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Thermodynamics vs Enthalpy
- Replies: 2
- Views: 367
Thermodynamics vs Enthalpy
How is thermodynamics different from enthalpy? I get that thermodynamics is heat transfer, but how does that differ from enthalpy, which is the heat absorbed or released?
- Wed Jan 30, 2019 8:27 pm
- Forum: Calculating Work of Expansion
- Topic: Reversible Process
- Replies: 1
- Views: 238
Reversible Process
What does calculating the infinitesimal change in volume mean? I get that it's when the volume is changing in very small steps, but what does that mean for the system in the big picture?
- Wed Jan 30, 2019 8:21 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Specific Heat Capacity
- Replies: 2
- Views: 258
Specific Heat Capacity
What is the difference between heat capacity and specific heat capacity? Why is one extensive and the other intensive?
- Tue Jan 22, 2019 10:30 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: acids and base
- Replies: 1
- Views: 238
Re: acids and base
To go from pH to concentration, you can do 10^-pH. You then use this concentration in the ICE box and solve for x to find Ka.
- Tue Jan 22, 2019 10:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Protonation
- Replies: 2
- Views: 248
Re: Protonation
Protonation is the addition of a proton (H+). Conversely, deprotonation is the removal of a proton (H+). Protonation occurs for bases, while deprotonation occurs for acids. The percent protonated is the amount of base that gets a H+ in the process of the reaction. If it's strong, the percent will be...
- Tue Jan 22, 2019 10:14 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Strong acids and bases
- Replies: 6
- Views: 602
Re: Strong acids and bases
I think we should be familiar with what strong acids/bases are going to be (for example, HCl/NaOH) so we can recognize them. Additionally, Lavelle said if the Ka is smaller than 10^-3, it means it's a weak acid. The same goes for bases I'm pretty sure.
- Sat Jan 19, 2019 11:48 am
- Forum: Identifying Acidic & Basic Salts
- Topic: Salts
- Replies: 1
- Views: 249
Salts
How do you know if something is a salt? How do you know if it will create an acidic or basic solution?
- Sat Jan 19, 2019 11:45 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: 6D.15
- Replies: 1
- Views: 154
Re: 6D.15
I'm pretty sure Ka values will be given to us either in the problem or in a table with other Ka values. For this specific problem, it's probably given in a table somewhere in the textbook. Hope this helps!
- Sat Jan 19, 2019 11:42 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Strong vs Weak Acids
- Replies: 2
- Views: 187
Strong vs Weak Acids
How do we know if an acid is strong or weak? Similarly, how do we know if a base is strong or weak?
- Fri Jan 11, 2019 7:33 pm
- Forum: Ideal Gases
- Topic: Ideal Gases
- Replies: 7
- Views: 541
Ideal Gases
How do we know if a gas is ideal? Do we just assume it is in most scenarios?
- Fri Jan 11, 2019 7:31 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Changes in Systems
- Replies: 3
- Views: 324
Changes in Systems
In lecture, Lavelle's slides said for changes in pressure, K does not change, whereas for changes in temperature, K does change. Was this just an example or is this always the case? If it's always the case, why does K change for temperature and not pressure?
- Fri Jan 11, 2019 7:28 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equilibrium Constant Values
- Replies: 3
- Views: 267
Equilibrium Constant Values
Will we always be given the numbers for the equilibrium constants of the products or reactants? Or will we have to find them ourselves?
- Sun Dec 02, 2018 1:56 pm
- Forum: Naming
- Topic: re: Bond Length and Resonance
- Replies: 2
- Views: 342
Re: re: Bond Length and Resonance
I don't think we'll be given a chart. I think we're just supposed to generally know how to name ligands and coordination compounds.
- Sun Dec 02, 2018 1:51 pm
- Forum: Lewis Acids & Bases
- Topic: Strong/Weak Acids & Bases
- Replies: 2
- Views: 324
Strong/Weak Acids & Bases
How can you tell if an acid/base is strong or weak?
- Sun Dec 02, 2018 1:46 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Sphere
- Replies: 4
- Views: 387
Coordination Sphere
What does it mean if something is outside of the coordination sphere? How does that work structurally?
- Mon Nov 26, 2018 11:32 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone PR and Bonding PR
- Replies: 2
- Views: 257
Re: Lone PR and Bonding PR
There are quite a few molecular shapes we need to know for the test. I think it makes the most sense to look at them in terms of how many regions of electron density there are within the molecule. For molecules that have two regions of electron density, the molecule is linear. If there are three reg...
- Mon Nov 26, 2018 11:25 pm
- Forum: Dipole Moments
- Topic: Dipole Moment Calculation
- Replies: 3
- Views: 333
Dipole Moment Calculation
Do we need to be able to use the equation m=q x d to calculate the dipole moment? We took notes on this in class but never did any calculations with it. Is it just a concept we need to be familiar with or will we have to calculate the dipole moment within molecules?
- Sat Nov 24, 2018 8:11 pm
- Forum: Hybridization
- Topic: Sigma/Pi Bonds
- Replies: 5
- Views: 397
Sigma/Pi Bonds
Could someone explain how we know how many sigma/pi bonds there are within a molecule?
- Sun Nov 18, 2018 6:54 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 7th edition 2E. 21
- Replies: 4
- Views: 370
Re: 7th edition 2E. 21
It's not necessary for us to know the exact angle, I think it was just a specific example to show us the proof that the bond length was less. As long as you know it's less than 109.5, you should be good.
- Sun Nov 18, 2018 6:47 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E.1 7th Edition
- Replies: 2
- Views: 279
2E.1 7th Edition
Could someone explain why in part b the solution says it's possible to have lone pairs? If the two atoms have a bond length of 180 degrees, wouldn't the lone pair push them closer together and then the bond length would be less than 180 degrees?
- Sun Nov 18, 2018 6:43 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 7th edition 2E.13
- Replies: 3
- Views: 397
Re: 7th edition 2E.13
From what I understand, it shouldn't matter whether you draw it vertically or horizontally. The electron and bond positions would be the same, which is what is most important.
- Tue Nov 13, 2018 2:42 pm
- Forum: Bond Lengths & Energies
- Topic: Bond Lengths
- Replies: 4
- Views: 548
Re: Bond Lengths
Additionally, as a general rule, triple bonds are going to be the shortest because they are the strongest. Double bonds are the next shortest and strongest, and single bonds are going to be the longest and therefore the weakest.
- Tue Nov 13, 2018 2:40 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Electron Density
- Replies: 2
- Views: 232
Electron Density
Are single/double/triple bonds the only scenario in which there is high electron density that we need to know in terms of VSEPR model?
- Tue Nov 13, 2018 2:37 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Trigonal Bypyramidal
- Replies: 1
- Views: 174
Trigonal Bypyramidal
Could someone explain the bond angles in the trigonal bypyramidal shape? Specifically, how/where there are 120 degree angles?
- Sat Nov 03, 2018 10:22 pm
- Forum: Electronegativity
- Topic: Electronegativity Calculation
- Replies: 5
- Views: 612
Re: Electronegativity Calculation
There's also a periodic table with the elements and their electronegativity numbers, but I'm pretty sure Lavelle said we don't have to memorize the exact values. If we needed to know the precise numbers, it would be given to us.
- Sat Nov 03, 2018 10:14 pm
- Forum: Octet Exceptions
- Topic: Lewis acids and bases
- Replies: 4
- Views: 333
Lewis acids and bases
Could someone explain Lewis acids and bases? And how does it relate to coordinate covalent bonds?
- Sat Nov 03, 2018 10:11 pm
- Forum: Octet Exceptions
- Topic: Radicals
- Replies: 3
- Views: 347
Radicals
In what context would there be a radical? If they're so unstable, how do they exist?
- Sat Oct 27, 2018 1:15 pm
- Forum: Ionic & Covalent Bonds
- Topic: Lowest Energy
- Replies: 4
- Views: 349
Lowest Energy
What does it mean by achieving "lowest energy" when bonding?
- Sat Oct 27, 2018 1:10 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: D-block Question
- Replies: 2
- Views: 247
D-block Question
Could someone explain why we write the 3d block before the 4s block when 4s occurs first on the periodic table? Which would get removed first when bonding?
- Sat Oct 27, 2018 1:07 pm
- Forum: Trends in The Periodic Table
- Topic: Atomic Radius
- Replies: 7
- Views: 721
Atomic Radius
Could someone explain why removing the second ionization energy of an element is always higher than the first?
- Sun Oct 21, 2018 9:39 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: S,P,D,F
- Replies: 6
- Views: 2693
Re: S,P,D,F
From what I understand, these are the five different ml numbers for a d orbital. Three of the ml numbers are similar to the way we've been writing them: d(xy), d(yz), and d(zx). Another is written as dx^2-dy^2. The final way is dz^2. I think the variances have to do with the different e- densities o...
- Sun Oct 21, 2018 9:32 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Wave Functions
- Replies: 4
- Views: 407
Re: Wave Functions
From what I understand, in the magnetic quantum number (ml), for l=1, ml= -1,0,+1. Because the subscript goes px, py, pz, py is the middle term, just as 0 is the middle term. Thus, py=0. I believe px and pz would be interchangeable for -1 and +1. Hope this helped!
- Sun Oct 21, 2018 9:25 pm
- Forum: *Shrodinger Equation
- Topic: Equation Question
- Replies: 2
- Views: 332
Equation Question
Could someone explain what the H in the Schrodinger equation represents? I can't seem to find it in my notes or the textbook.
- Mon Oct 15, 2018 1:14 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Heisenberg Indeterminacy Equation
- Replies: 4
- Views: 409
Heisenberg Indeterminacy Equation
Could someone explain why we have to account for the difference in position and momentum (why it's Δp and Δx instead of just p and x)? Why aren't we able to determine the precise value of the two?
- Mon Oct 15, 2018 1:02 pm
- Forum: DeBroglie Equation
- Topic: 1B.9
- Replies: 3
- Views: 299
Re: 1B.9
Watts is equivalent to Joules per second. So in this problem, 32 W=32J/s. Then you can find the amount of photons the lamp generates, and then convert the photons to moles by using Avogadro's constant. Hope this helped!
- Mon Oct 15, 2018 12:58 pm
- Forum: DeBroglie Equation
- Topic: Rest Mass?
- Replies: 4
- Views: 409
Re: Rest Mass?
In simple terms, resting mass is just when an object has mass when it's stationary. Hope this helped!
- Mon Oct 08, 2018 7:33 pm
- Forum: Properties of Light
- Topic: Wavelength vs Frequency
- Replies: 7
- Views: 632
Wavelength vs Frequency
Could someone explain how wavelength and frequency are different? Or are they related?
- Mon Oct 08, 2018 7:30 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric Effect
- Replies: 4
- Views: 288
Photoelectric Effect
Why was the photoelectric effect unexpected? What did they think would happen instead?
- Mon Oct 08, 2018 7:26 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric Effect
- Replies: 6
- Views: 470
Photoelectric Effect
Could someone explain what the formula Ek=1/2 Me- * Ve-^2 represents?
- Mon Oct 01, 2018 12:54 pm
- Forum: Limiting Reactant Calculations
- Topic: Limiting reagents
- Replies: 12
- Views: 867
Re: Limiting reagents
A one step chemical reaction can only have one limiting reagent because (as long as the 2 reactants are present in different amounts and/or you need different amounts for the reaction) you will run out of one first. Therefore, the reaction will not be able to continue because you will be out of one ...
- Mon Oct 01, 2018 12:47 pm
- Forum: Significant Figures
- Topic: Significant Figures [ENDORSED]
- Replies: 6
- Views: 473
Significant Figures [ENDORSED]
Could someone explain why we use significant figures? Wouldn't keeping more decimals be more precise in the answer, or should we just always go by how many sig figs are given in the question?
- Mon Oct 01, 2018 12:40 pm
- Forum: Balancing Chemical Reactions
- Topic: States of Matter
- Replies: 11
- Views: 2192
States of Matter
Can someone explain to me what an aqueous solution is? And why do we need to include the state of matter when we write and balance chemical reactions?