Search found 69 matches
- Fri Mar 15, 2019 11:34 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt bridge
- Replies: 1
- Views: 311
Salt bridge
Can someone explain what ions would affect the salt bridge?
- Wed Mar 13, 2019 12:39 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Units of k
- Replies: 5
- Views: 924
Units of k
Can someone show how to derive the units of k for zero, first, and second order reactions?
- Wed Mar 13, 2019 12:37 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Catalyst vs. Intermediate
- Replies: 8
- Views: 813
Catalyst vs. Intermediate
Can someone explain how I would differentiate a catalyst from an intermediate in a reaction?
- Wed Mar 13, 2019 12:34 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Does reaction rate mean average reaction rate?
- Replies: 3
- Views: 491
Re: Does reaction rate mean average reaction rate?
If it says average rate, then it is average. If it just says rate, then they are referring to the instantaneous rate.
- Mon Mar 04, 2019 7:05 pm
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: Corrosion
- Replies: 2
- Views: 585
Corrosion
Can someone explain what happens to the electrons during corrosion?
- Mon Mar 04, 2019 7:03 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Order of Reaction
- Replies: 5
- Views: 700
Order of Reaction
Can someone explain the concept of order of reactions? I understand how to find the order based on the rate law, but I don't understand it conceptually. Can someone help me?
- Mon Mar 04, 2019 6:59 pm
- Forum: Zero Order Reactions
- Topic: Order distinction
- Replies: 9
- Views: 1111
Re: Order distinction
When you look at the rate law, you add the exponents of all the concentrations of the reactants.
- Mon Mar 04, 2019 6:58 pm
- Forum: Zero Order Reactions
- Topic: Order distinction
- Replies: 9
- Views: 1111
Re: Order distinction
When you look at the rate law, you add the exponents of all the concentrations of the reactants.
- Sun Feb 24, 2019 9:05 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagrams
- Replies: 2
- Views: 330
Cell Diagrams
When do we use commas in a cell diagram vs. a horizontal line?
- Sun Feb 24, 2019 9:03 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing redox reactions
- Replies: 1
- Views: 171
Balancing redox reactions
What role does water play if the original equation has water in the products? Does it just cancel out by adding hydrogens when balancing?
- Sun Feb 24, 2019 8:59 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Graphite
- Replies: 3
- Views: 365
Graphite
What role does graphite have in a galvanic cell?
- Sun Feb 24, 2019 8:58 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Redox Reactions
- Replies: 1
- Views: 229
Balancing Redox Reactions
Can someone go through the steps to balance a redox reaction? Which elements do I look at first, which part do I balance first?
Thank you!
Thank you!
- Sun Feb 24, 2019 8:55 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation numbers
- Replies: 1
- Views: 177
Oxidation numbers
For the compound C2H5OH, what is the oxidation state of C? I thought it was 2+, but the solutions manual is saying it is 2-?
- Thu Feb 21, 2019 12:20 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Stable vs Unstable
- Replies: 2
- Views: 330
Stable vs Unstable
Can someone explain the concept of stable and unstable in terms of the Gibbs free energy? Why does a negative free energy mean that its stable?
- Wed Feb 13, 2019 12:44 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Heat and Entropy
- Replies: 3
- Views: 378
Heat and Entropy
Why would you need to use the heat equation before solving for entropy with a temperature change?
- Wed Feb 13, 2019 12:39 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Calculating Delta S with a change in temperature
- Replies: 5
- Views: 591
Calculating Delta S with a change in temperature
If the problem does not specify, do you use C(@constant pressure) or C(@constant volume) when calculating delta S with a temperature change?
- Sun Feb 10, 2019 6:25 pm
- Forum: Calculating Work of Expansion
- Topic: Reversible vs Irreversible
- Replies: 9
- Views: 836
Re: Reversible vs Irreversible
Irreversible systems have a constant pressure. Reversible systems have a changing external pressure, and we use the integral to add up all the infinitely small work increments from each change in pressure
- Sun Feb 10, 2019 6:25 pm
- Forum: Calculating Work of Expansion
- Topic: Reversible vs Irreversible
- Replies: 9
- Views: 836
Re: Reversible vs Irreversible
Irreversible systems have a constant pressure. Reversible systems have a changing external pressure, and we use the integral to add up all the infinitely small work increments from each change in pressure
- Sun Feb 10, 2019 4:41 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Ways to find q
- Replies: 1
- Views: 297
Ways to find q
What are the different ways to find q in a reaction if you don't have a change in temperature to put in the mCdeltaT/nCdeltaT equations?
- Sun Feb 10, 2019 4:40 pm
- Forum: Phase Changes & Related Calculations
- Topic: Work equation
- Replies: 4
- Views: 529
Re: Work equation
You would multiply the amount of atm*L that you have by 101.325 J/atm*L to get your final answer in Joules.
- Wed Feb 06, 2019 11:03 am
- Forum: Phase Changes & Related Calculations
- Topic: Negative work
- Replies: 11
- Views: 1086
Re: Negative work
Negative work is represented by a system doing work on its surroundings. When work is done on system, it is positive work.
- Wed Feb 06, 2019 10:57 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Irreversible/Reversible Processes
- Replies: 3
- Views: 405
Re: Irreversible/Reversible Processes
Reversible processes do more work because the work is the integral of many consecutive efforts of changing pressure. Irreversible processes has a constant pressure and only has one whole effort.
- Sun Feb 03, 2019 2:44 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Specific Combustion Reaction
- Replies: 2
- Views: 301
Specific Combustion Reaction
When you are writing a combustion reaction for H2, how do you know not to put CO2 on the product side? I thought all combustion reaction occur in the presence of oxygen and yields carbon dioxide and water?
- Mon Jan 28, 2019 12:44 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat Capacity
- Replies: 8
- Views: 778
Re: Heat Capacity
It’s important to note the difference between heat capacity and specific heat capacity. Heat capacity is not dependent on the amount of substance there is, and is an extensive property. Specific heat capacity does depend on the amount of substance there is, and is an intensive property.
- Mon Jan 28, 2019 12:41 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Water specific heat capacity
- Replies: 2
- Views: 266
Water specific heat capacity
Why is the specific heat capacity of water so high?
- Mon Jan 28, 2019 12:36 pm
- Forum: Phase Changes & Related Calculations
- Topic: Standard entalpy of formation
- Replies: 6
- Views: 1051
Standard entalpy of formation
Which molecules have a standard enthalpy formation of 0? And why?
- Mon Jan 28, 2019 12:33 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy signs
- Replies: 13
- Views: 1719
Re: Enthalpy signs
Enthalpy is the amount of heat absorbed in a reaction. If the reaction is endothermic, it absorbs heat, so the sign of enthalpy is therefore postitive. It is negative if the reaction is exothermic, and so it is releasing heat, therefore is going to have a negative enthalpy.
- Mon Jan 28, 2019 12:30 pm
- Forum: Phase Changes & Related Calculations
- Topic: State Properites
- Replies: 7
- Views: 642
Re: State Properites
State properties do not depend on the path taken. For example, for work, it depends on the distance traveled. A system that takes a shorter path will have performed less work than a system that a system that took a longer path. The final value is dependent on how the system was carried out.
- Wed Jan 16, 2019 5:36 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ice table coefficients [ENDORSED]
- Replies: 6
- Views: 956
Ice table coefficients [ENDORSED]
Is the coefficient of the change row in the ICE table always match the stoichiometric coefficients of the reaction?
Thanks!
Thanks!
- Wed Jan 16, 2019 5:35 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Using a Eq. table for questions
- Replies: 1
- Views: 152
Using a Eq. table for questions
How do you know which K value to use in an K eq. table when the equation you are looking at is comprised of two smaller equations with two different k values?
- Wed Jan 16, 2019 5:30 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: using ICE when you have a product concentration
- Replies: 1
- Views: 198
using ICE when you have a product concentration
If the only reactant is a solid, and the problem gives you a concentration for one of the products, can someone explain why for the initial change it is still positive x for both of the products?
Thanks!
Thanks!
- Wed Jan 09, 2019 8:33 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE chart
- Replies: 1
- Views: 164
ICE chart
Can someone explain what is the purpose of the ICE chart is? And, how to calculate the C portion of it?
- Wed Jan 09, 2019 8:31 pm
- Forum: Ideal Gases
- Topic: Units
- Replies: 19
- Views: 1165
Units
When we are calculating using the ideal gas law, should we put the temperature in Kelvins or in Celsius?
- Wed Jan 09, 2019 8:30 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equilibrium Concentrations
- Replies: 4
- Views: 230
Equilibrium Concentrations
Hi!
When we calculate K, are we using equilibrium concentrations or initial concentrations?
Thanks guys!
When we calculate K, are we using equilibrium concentrations or initial concentrations?
Thanks guys!
- Thu Dec 06, 2018 10:27 am
- Forum: Conjugate Acids & Bases
- Topic: Inverse Proportional
- Replies: 2
- Views: 307
Inverse Proportional
So the strength of the conjugate acid/base is inversely proportional to the strength of the acid/base?
- Thu Dec 06, 2018 10:26 am
- Forum: Lewis Acids & Bases
- Topic: Lewis and Bronsted
- Replies: 8
- Views: 831
Re: Lewis and Bronsted
Lewis acids/bases are a more general concept than the Bronsted acids/bases. Bronsted acids are proton donors and bronsted bases are proton acceptors. Lewis acids are electron acceptors and Lewis bases are electron donors.
- Thu Dec 06, 2018 10:09 am
- Forum: Lewis Acids & Bases
- Topic: Resonance and acids
- Replies: 2
- Views: 518
Resonance and acids
If a molecule has resonance, does that mean they are a stronger or weaker acid?
- Thu Dec 06, 2018 10:08 am
- Forum: Lewis Acids & Bases
- Topic: Metal oxides
- Replies: 1
- Views: 163
Metal oxides
Can someone explain in detail the properties of metal oxides? and which ones are acids and bases?
- Thu Dec 06, 2018 10:06 am
- Forum: Bronsted Acids & Bases
- Topic: Donating H protons
- Replies: 2
- Views: 391
Donating H protons
So if a molecule contains 2 hydrogen atoms does that mean it can donate 2 H+ and be a strong bronsted acid?
- Wed Nov 28, 2018 4:37 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: ClO2+
- Replies: 7
- Views: 1634
Re: ClO2+
This molecule has a bent shape. There are three electron densities and one lone pair, making the molecular shape bent.
- Wed Nov 28, 2018 4:32 pm
- Forum: Hybridization
- Topic: pi bonds
- Replies: 3
- Views: 366
Re: pi bonds
Sigma bonds are involved in hybridization, but pi bonds are not involved in hybridization.
- Wed Nov 28, 2018 4:28 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Equatorial axis
- Replies: 1
- Views: 134
Equatorial axis
Can someone explain more in detail about the equatorial and axial axis?
- Wed Nov 28, 2018 4:27 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Identifying intermolecular forces
- Replies: 4
- Views: 600
Re: Identifying intermolecular forces
Every interaction between two molecules have London Dispersion Forces. Hydrogen bondings occurs when an H comes into contact with either an F, O, or N atom. Dipole-dipole forces occur that two polar molecules come into contact.
- Wed Nov 28, 2018 4:21 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar and Non-Polar
- Replies: 2
- Views: 261
Re: Polar and Non-Polar
You have to look at the electronegativities of the atoms. In a bond, one atom's electrons will be pulled towards the atom that has a greater electronegativity, resulting in a net partial charge. Do this for each atom. If all of the attached atoms are the same and their partial charges cancel out, th...
- Sun Nov 25, 2018 12:58 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Naming
- Replies: 5
- Views: 502
Naming
If a molecule does not have lone pairs in the Lewis structure, then does that mean that both the electron arrangement and the molecular shape are going to be the same?
- Sun Nov 25, 2018 12:55 pm
- Forum: Hybridization
- Topic: Equatorial lone pair
- Replies: 2
- Views: 266
Equatorial lone pair
Can someone explain in detail the importantance of an equatorial lone pair ?
- Sun Nov 25, 2018 12:52 pm
- Forum: Hybridization
- Topic: Atomic orbitals
- Replies: 1
- Views: 215
Atomic orbitals
Can someone explain how to find out the number of atomic orbitals in a molecule?
- Fri Nov 16, 2018 11:42 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Repulsion and Stability
- Replies: 3
- Views: 264
Re: Repulsion and Stability
If the repulsion is low, that means that the electrons won’t be close to each other to have repulsion. Therefore, the electrons are farthest from each other. The closer the electrons, the more repulsion.
- Fri Nov 16, 2018 11:40 am
- Forum: Ionic & Covalent Bonds
- Topic: Polar/non polar molecules
- Replies: 5
- Views: 652
Re: Polar/non polar molecules
A main thing to look out for is if the pulls from the electronegative atoms cancels out. If they do, it’s non polar, if they don’t it’s polar. You need to look at the shape and see if there is an uneven distribution of electrons.
- Tue Nov 13, 2018 10:22 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Determining the polarizability
- Replies: 4
- Views: 561
Determining the polarizability
Is charge relevant when looking at which anion is more polarizable? Or do we just look at the size of the atom?
- Wed Nov 07, 2018 11:54 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge
- Replies: 11
- Views: 1331
Re: Formal Charge
Formal charge is dependent on the molecule the atom is in! There is no predetermined formal charge for an atom or element, it will vary based on what it is reacting with and whether that molecule is stable or not.
- Wed Nov 07, 2018 11:52 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Electron distortion
- Replies: 3
- Views: 738
Electron distortion
Can someone explain the concept of how bigger atoms have more electron distortion and how that leads to a higher polarization?
- Wed Nov 07, 2018 11:49 pm
- Forum: Lewis Structures
- Topic: Double Bonds
- Replies: 7
- Views: 568
Re: Double Bonds
You need to check the formal charges of the atoms. The number of electrons drawn might be correct, but it will not be the most stable lewis structure until you make the formal charges as low as possible. A double bond can make the formal charges lower.
- Wed Oct 31, 2018 6:14 pm
- Forum: Electronegativity
- Topic: Periodic Trends [ENDORSED]
- Replies: 3
- Views: 462
Re: Periodic Trends [ENDORSED]
Electronegativity increases as you go to the right on the periodic table because it is continuously getting more stable when you add more valence electrons to the outermost shell, and therefore the atom will have a higher tendency to want to keep those electrons. Therefore, the more the atom wants t...
- Wed Oct 31, 2018 6:12 pm
- Forum: Resonance Structures
- Topic: Resonance
- Replies: 8
- Views: 976
Re: Resonance
The bond length allows to have more insight on how strong the bond is as well!
- Wed Oct 31, 2018 6:11 pm
- Forum: Trends in The Periodic Table
- Topic: Atomis Radius Trend
- Replies: 2
- Views: 422
Re: Atomis Radius Trend
Use the periodic trends of atomic radii, and why this is what it is, to formulate your answer. As we go towards the right of the periodic table, the effective nuclear charge increases, and therefore, has a stronger pull on the electrons, making the radius of the atom smaller. As we go down the perio...
- Tue Oct 23, 2018 5:30 pm
- Forum: Properties of Electrons
- Topic: Difference between electron's particle like and wave like characteristics
- Replies: 5
- Views: 387
Re: Difference between electron's particle like and wave like characteristics
The photoelectric effect demonstrates how electrons and light (little packets of energy called photons) have particle like properties. Their interaction is based on a one electron one photon interaction. According to De Broglie, anything that has rest mass has wave like properties, they can diffract...
- Tue Oct 23, 2018 1:08 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric Effect original purpose
- Replies: 2
- Views: 358
Re: Photoelectric Effect original purpose
Another purpose of the photoelectric effect is that it demonstrates how electrons and light have particle like properties, since there is a one electron one photon interaction in this experiment.
- Mon Oct 22, 2018 10:07 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: When to double the parameter to get delta v
- Replies: 3
- Views: 578
When to double the parameter to get delta v
In the homework, there are questions that asked for the minimum uncertainty of the object's position, and when it said minimum, the solution's manual did not double the parameter of the velocity. Although, when it does not say minimum, they double the parameter? Does the word "minimum" pla...
- Wed Oct 17, 2018 6:56 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Nodal Planes
- Replies: 3
- Views: 286
Re: Nodal Planes
In a nodal plane, there is 0 probability of finding an electron, therefore the electron density goes to 0 approaching a nodal plane.
- Wed Oct 17, 2018 6:51 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg equation
- Replies: 4
- Views: 429
Rydberg equation
Can someone explain what the rydberg equation tells us conceptually?
- Wed Oct 17, 2018 4:53 pm
- Forum: Properties of Light
- Topic: energy equation
- Replies: 4
- Views: 437
energy equation
How do I know when to use just the equation E=hv or when to use E=(hc)/v to find the energy of a photon?
- Tue Oct 09, 2018 5:12 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Finding the volume of stock solution to dilute
- Replies: 13
- Views: 1351
Re: Finding the volume of stock solution to dilute
I would suggest always converting to Liters because molarity is moles/liters and the units always have to be consistent!
- Tue Oct 09, 2018 5:10 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Week 2 Homework
- Replies: 4
- Views: 395
Re: Week 2 Homework
The homework is due in the discussion sessions every week.
- Tue Oct 09, 2018 5:08 pm
- Forum: SI Units, Unit Conversions
- Topic: Formula Units
- Replies: 2
- Views: 209
Re: Formula Units
It is the same method as finding the amount of atoms in an element, you use avogrado's constant. Formula units are applied to molecules and compounds!
- Tue Oct 09, 2018 5:07 pm
- Forum: Significant Figures
- Topic: Sig Fig zero rules
- Replies: 7
- Views: 2359
Re: Sig Fig zero rules
Pay attention to decimal points! Those indicate whether you count the zeros as significant figures in some cases.
For example 5000 has one significant figure, but 5000. has 4 significant figures!
I hope this helps!
For example 5000 has one significant figure, but 5000. has 4 significant figures!
I hope this helps!
- Wed Oct 03, 2018 11:23 am
- Forum: Molarity, Solutions, Dilutions
- Topic: Concentration Calculations
- Replies: 15
- Views: 8062
Re: Concentration Calculations
How do we know when not to use the formula M(initial)V(initial) = M(final)V(Final)? That was my plan for this problem, but it does not work out.
- Mon Oct 01, 2018 3:46 pm
- Forum: SI Units, Unit Conversions
- Topic: Naming Compounds
- Replies: 8
- Views: 616
Naming Compounds
Is there a trick in knowing how to write out Calcium sulfide in molecular terms?
- Mon Oct 01, 2018 3:18 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Calculating the amount of atoms in a sample
- Replies: 2
- Views: 214
Calculating the amount of atoms in a sample
How do you find the amount of formula units for a compound that are present in a given sample (in grams)?