Search found 107 matches
- Sat Mar 14, 2020 3:10 pm
- Forum: Balancing Redox Reactions
- Topic: Redox Reaction in a Basic Solution
- Replies: 3
- Views: 383
Re: Redox Reaction in a Basic Solution
yes, for redox reactions in basic solution, you are supposed to add H2O to the side of the reaction that needs more hydrogens and then balance accordingly by adding an equal number of moles of OH- to the other side.
- Sat Mar 14, 2020 2:45 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Activation Energies
- Replies: 4
- Views: 342
Re: Activation Energies
So, is a condition of a reaction having "arrhenius behavior" having constant activation energy?
- Sat Mar 14, 2020 1:51 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: lnA
- Replies: 3
- Views: 244
Re: lnA
ln A is based upon the variable A, which is called the pre-exponential factor. The pre-exponential factor represents the frequency of collisions between reactant molecules in a particular reaction.
- Sat Mar 14, 2020 1:47 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Slow and Fast Step
- Replies: 7
- Views: 544
Re: Slow and Fast Step
yes, when determining the overall rate of reaction, you can use the slow step as the sole determinant of the rate by assuming that the other steps are so fast in relation to the slow step that their influence on the overall reaction rate is negligible.
- Sat Mar 14, 2020 1:45 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Activation Energies
- Replies: 4
- Views: 342
Activation Energies
Are activation energies always constant? If not, what variables change them?
- Sun Mar 08, 2020 10:50 am
- Forum: General Rate Laws
- Topic: Rate law
- Replies: 3
- Views: 330
Rate law
The book explains that we sometimes need to specify the specific species our rate refers to or write our rate law as “rate of consumption/production of A” instead of just rate. When would we need to be specific with species/processes we are referring to?
- Sun Mar 08, 2020 10:47 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Checking Answers
- Replies: 3
- Views: 373
Checking Answers
The book mentioned that a good way to check your calculated rate constant when given experimental data is to plug it into the rate law with the given data and see if you get the given rate. I was wondering what some other quick ways there are to check our answers in this kinetics section?
- Sun Mar 08, 2020 10:43 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: determine n
- Replies: 16
- Views: 1434
Re: determine n
n represents the order of the reactant, which in turn gives insight into the mechanism of the reaction. how do you know what the order is The order refers to the sum of all the exponents of the concentrations in the rate law. For example, if the rate law was rate=kr[A]^2[B]^3, the overall order wou...
- Sun Mar 08, 2020 10:40 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Terminology for reaction rate constant
- Replies: 3
- Views: 377
Re: Terminology for reaction rate constant
I believe that reaction rate constant and rate constant mean the same thing and can pretty much be used interchangeably, they will most likely always be referred to as one of the two. However, it is important to distinguish this from the reaction rate, which is the rate at any given moment in the re...
- Sun Mar 08, 2020 12:14 am
- Forum: General Rate Laws
- Topic: Units
- Replies: 3
- Views: 276
Units
the textbook gives units that your rate constants should be in for each reaction order, how do these work for non-whole number reaction orders?
- Sat Feb 29, 2020 10:41 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: 5G. 13
- Replies: 2
- Views: 251
Re: 5G. 13
The standard Gibbs of formation should only be used to calculate the delta G standard of a reaction at standard conditions (25C and 1 atm). If equilibrium isn't at those conditions, you should be using the given K to calculate the standard delta G of the reaction. In this case, they give you K so th...
- Sat Feb 29, 2020 10:35 pm
- Forum: Balancing Redox Reactions
- Topic: 6K.3 D)
- Replies: 2
- Views: 224
Re: 6K.3 D)
to your first question, I believe that Cl is acting as both a reducing and oxidizing agent because one of the Cls is giving an electron while the other is accepting that electron.
to your second question, I think someone told me that the Cl2 reactant is a typo and that it should be 2Cl
to your second question, I think someone told me that the Cl2 reactant is a typo and that it should be 2Cl
- Fri Feb 28, 2020 1:56 am
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: pH Electrodes, Corrosion, Etc
- Replies: 2
- Views: 216
Re: pH Electrodes, Corrosion, Etc
If those topics are reflected in the homework and/or lecture notes, they are fair game for test 2 so long as it is within the relevant section of thermodynamics or in our electrochemistry unit. I think the homework is probably a good indicator of what you should know regarding these, or any, topics.
- Fri Feb 28, 2020 1:52 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6M.1
- Replies: 1
- Views: 143
6M.1
The question asks to find the standard cell potential of (M2+/M) in the cell M(s)|M+ (aq)||Cu2+(aq)|Cu(s). I figured that since the cell has copper written on the right, that it was the cathode. But, the solutions manual treats the copper half reaction as the anode. How do we determine this?
- Fri Feb 28, 2020 1:48 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: 5G.17
- Replies: 2
- Views: 248
Re: 5G.17
To do this, you need to look at the relative rates of the product and reactant. You can see that I is being formed doubly as fast as I2 is being used up, due to the 1:2 ratio. To graph this, you just need to demonstrate this relationship using a graph of time on the x axis and concentration being on...
- Sun Feb 23, 2020 8:09 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: 5J.15
- Replies: 3
- Views: 290
Re: 5J.15
At different temperatures, delta G changes, which means that you cannot use the standard Gibbs free energy values at 100 degrees C, as those are only the values at 25 degrees C. This means in order to find the delta G at a different temperature, you would need to use the equation that relates delta...
- Sun Feb 23, 2020 6:25 pm
- Forum: Balancing Redox Reactions
- Topic: 6K.3 b)
- Replies: 2
- Views: 189
Re: 6K.3 b)
I think usually unless oxygen or hydrogen is written as it’s own molecule (I.e as shown in 6K.5A) we just put them as they are written in the half reactions of their respective molecules (I.e MnO4 - or H2SO3). They usually just allow us to determine the oxidation number of the species of focus.
- Sun Feb 23, 2020 6:22 pm
- Forum: Balancing Redox Reactions
- Topic: 6K.3 part d
- Replies: 3
- Views: 267
6K.3 part d
The problems asks to balance the redox reaction in acidic solution of : Cl2 (g) —> HClO (aq) + Cl2 (g) I understand why they broke the two reactions into Cl2 —> HClO and Cl2 —> 2Cl- But, I’m wondering why they were able to write the product in the second half reaction as chlorine ions (2Cl-) rather ...
- Sun Feb 23, 2020 1:40 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing redox
- Replies: 6
- Views: 520
Balancing redox
How do you know which method to use when balancing half equations? I.e. balancing Hydrogens by adding H+ to one side vs balancing hydrogens by adding H2O to one side and OH- to the other.
What tells are there in a reaction that lets you know which way to go?
What tells are there in a reaction that lets you know which way to go?
- Thu Feb 20, 2020 10:52 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: 5J.15
- Replies: 3
- Views: 290
5J.15
The question asks to calculate the equilibrium constant at 23 C and 100 C for two reactions using the data from appendix 2A. Even though the standard Gibbs of formation for the molecules is given in the appendix, the solutions manual says we have to use the enthalpies of formation and entropies of f...
- Wed Feb 12, 2020 12:07 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Delta S total vs regular delta S
- Replies: 1
- Views: 147
Re: Delta S total vs regular delta S
deltaS total is the sum of the delta S of the surroundings and the delta S of the system. Typically, when there is no subscript for a variable, as is the case with just delta S, that means it is referring to the system. So, deltaS is just the change in entropy of the system.
- Wed Feb 12, 2020 12:04 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Adiabatic
- Replies: 2
- Views: 193
Re: Adiabatic
when a system is adiabatic, there is no heat flow meaning:
q=0
deltaU=w
q=0
deltaU=w
- Wed Feb 12, 2020 12:00 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Cp and Cv
- Replies: 2
- Views: 200
Re: Cp and Cv
pretty much anytime the substance is an ideal gas in a problem and the C isn't explicitly given to you, you'll use either (3/2)R or (5/2)R to calculate q. Under conditions of constant volume, you would use the (3/2)R and under conditions of constant pressure, you would use (5/2)R.
- Tue Feb 11, 2020 11:52 pm
- Forum: Calculating Work of Expansion
- Topic: Midterm Q
- Replies: 1
- Views: 155
Re: Midterm Q
I believe you should know the meanings of the two terms as they might be used in an equation:
isobaric- constant pressure
isochoric- constant volume
isothermal- constant temperature
understanding these terms is important because they influence the values and calculations used in a problem
isobaric- constant pressure
isochoric- constant volume
isothermal- constant temperature
understanding these terms is important because they influence the values and calculations used in a problem
- Tue Feb 11, 2020 11:50 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Phase change’s effect on entropy
- Replies: 1
- Views: 105
Re: Phase change’s effect on entropy
I believe this statement refers to the equation for gibbs free energy (deltaG=deltaH- TdeltaS). This means that the magnitude of influence the deltaS, entropy, has on the change in Gibb's free energy is dependent on T. This is because, as T increases, because it is being multiplied by deltaS, the ma...
- Tue Feb 11, 2020 11:44 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Homework Question 4I.1
- Replies: 2
- Views: 138
Re: Homework Question 4I.1
Yes, you would use that method. The reasoning behind this is that entropy is a state function, so the value is only dependent on its final state rather than the path taken to get there. Because of this, you are able to add together the change in entropy from each step and find the change in entropy ...
- Tue Feb 11, 2020 11:39 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Homework 4J.7
- Replies: 1
- Views: 139
Re: Homework 4J.7
I used the enthalpy of formation and gibbs free energy of H2O (l). The appendix doesn't even list an H2O aqueous. I see where you're looking, but the solutions manual used the values listed under H2O (l) despite writing H2O (aq) so it might've been a typo.
- Mon Feb 10, 2020 2:42 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Reversible vs. Irreversible reactions
- Replies: 1
- Views: 126
Reversible vs. Irreversible reactions
I know that work is different for reversible and irreversible reactions, so how does my calculation of work differ for a reversible vs. an irreversible reaction? Additionally, what other values/calculations differ for reversible vs. irreversible reactions and how do I accommodate those differences (...
- Thu Feb 06, 2020 5:28 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 4D.9
- Replies: 1
- Views: 95
4D.9
The questions asks to find the enthalpy change per liter for the reaction TNT and O2 to form CO2, H2O, and N2. I understand how they used the enthalpies of formation to find the enthalpy of the reaction to be -13168 kJ/mol. But, when they divide that by 4 to get the delta H per mole of TNT, they mak...
- Wed Feb 05, 2020 8:56 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Change in entropy for a monatomic ideal gas vs diatomic molecules
- Replies: 3
- Views: 608
Re: Change in entropy for a monatomic ideal gas vs diatomic molecules
As more atoms are in a molecule, the number of microstates (possible arrangements) increase and thus there are overall more ways to distribute the motional energy of the molecules within the gas sample. In lecture, Dr. Lavelle uses the number of microstates as the primary indication of change in ent...
- Wed Feb 05, 2020 8:48 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: Microstates
- Replies: 7
- Views: 217
Re: Microstates
Microstates are the varying possible arrangements for molecules. As motional energy (ie rotational, transitional, and vibrational energy discussed in the textbook pg.260) increases, the number of microstates tends to increase as well, which, in lecture, we take as a conceptual indication as a positi...
- Wed Feb 05, 2020 8:41 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: enthalpy of formation
- Replies: 2
- Views: 120
Re: enthalpy of formation
I believe so.
This is the case for most because no change is occurring in the reaction:
ie. O2–>O2
However, if you were to calculate the enthalpy change in a reaction such as:
2O—> O2
You would be calculating the heat of atomization(which is the heat released when the O2 bond is formed)
This is the case for most because no change is occurring in the reaction:
ie. O2–>O2
However, if you were to calculate the enthalpy change in a reaction such as:
2O—> O2
You would be calculating the heat of atomization(which is the heat released when the O2 bond is formed)
- Wed Feb 05, 2020 7:39 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy
- Replies: 2
- Views: 116
Enthalpy
I was doing problem 4C.3 and in the solution they said that at constant pressure, change in enthalpy is equal to q. Why is this?
- Thu Jan 30, 2020 7:48 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Test #1// #5
- Replies: 5
- Views: 256
Re: Test #1// #5
I had a different form but the gist should be the same. Use the given Molarity of hydrogen fluoride to set up an ICE table. Once that's set up, you should have equilibrium concentrations in terms of X. Use the equilibrium concentration values in terms of x to create an equation for the equilibrium c...
- Thu Jan 30, 2020 7:27 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Equipartition Theorem
- Replies: 2
- Views: 170
Re: Equipartition Theorem
Since it wasn't addressed in lecture, you won't be expected to know it. But, I think it'll be helpful to understand the foundations that go into forming the theorem.
- Thu Jan 30, 2020 7:24 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: When do we need to consider the calorimeter?
- Replies: 2
- Views: 155
Re: When do we need to consider the calorimeter?
Unless the question specifically states that you're considering the calorimeter as a system or as surroundings, I think it isn't counted as either. The main contribution of a calorimeter in a problem is its measurements of heat absorbed or released by a system.
- Thu Jan 30, 2020 7:12 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Value of q
- Replies: 11
- Views: 587
Re: Value of q
In lecture, Dr.Lavelle showed us that perfect system equation which states that q(system)+q(surroundings)=0, which in turn means that q(system)=-q(surroundings) or vice versa.
- Thu Jan 30, 2020 7:04 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Test 1 Problem 5
- Replies: 1
- Views: 102
Re: Test 1 Problem 5
I think you would use the given molarity value of the triethylamine solution to make an ICE table. The equilibrium value for the N(CH3CH2)3, NH(CH3CH2)3+, and the OH- should come out to 0.2-x, x, and x respectively. Then use those equilibrium values to make an equation for the equilibrium constant t...
- Mon Jan 20, 2020 2:52 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Van’t Hoff Equation
- Replies: 4
- Views: 229
Van’t Hoff Equation
What do the vant hoff equation variables mean and what is it used for? Are we expected to use this equation? If so, in what scenario might we use it?
- Mon Jan 20, 2020 1:49 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: K value at a specific temp
- Replies: 6
- Views: 270
K value at a specific temp
In the “skills you have mastered” section of 5J, it says we should be able to predict the value of K at one temperature from its value at another temperature. Lavelle excluded part of this section from the assigned reading, but I just wanted to make sure. Should we be able to do this? Have we addres...
- Mon Jan 20, 2020 1:46 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: ICE table
- Replies: 3
- Views: 381
Re: ICE table
X is assigned to Change in molarity based on the balanced equilibrium reaction. In 5I.15, the reaction is 1:1:1 meaning all changes should either be +x or -x. If the reaction had a different ratio then the changes would be reflective of that ratio. Consider the equation 1AB2C2 —> 1A + 2BC. Since the...
- Mon Jan 20, 2020 1:33 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5 percent rule
- Replies: 2
- Views: 61
Re: 5 percent rule
The 5% rule basically allows us to determine the validity of an approximation by looking at the percent of ionization of the acid. Consider the reaction: [HA] —> [H+] + [A-]. If you’re looking for the Ka value, you’d need to use the equation Ka= x^2/([HA] - x). But, if the Ka is very small (Lavelle ...
- Mon Jan 20, 2020 1:19 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Inert Gas
- Replies: 6
- Views: 211
Re: Inert Gas
When talking about the effect of inert gases on a reaction at equilibrium, we are more focused on the fact that it is extremely stable and thus does not react. The inert gas wouldn’t interact significantly with the other reactants/products in the reaction and this has no net effect on the direction ...
- Sun Jan 19, 2020 8:52 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: homework 5G9
- Replies: 1
- Views: 103
Re: homework 5G9
So for these, you’re going to use your understanding of fundamental concepts and Le Chateliers to decide if they’ll stay the same or change: A) the amount of O2 will be different because there are different amounts of reactants and this different amounts of products B) the partial pressure of O2 sho...
- Thu Jan 16, 2020 7:21 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Acids and Bases, understanding the Ka value
- Replies: 3
- Views: 498
Re: Acids and Bases, understanding the Ka value
A larger Ka indicates a stronger acid, meaning the acid ionizes more than if it had a smaller Ka. So, that means the bonds in the acid are weak because they are more inclined to dissociate.
- Thu Jan 16, 2020 7:12 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Neutral Solutions
- Replies: 1
- Views: 112
Neutral Solutions
At the end of the last lecture, Dr.Lavelle explained that if [H3O+]<10^-7 then the solution is considered neutral, could someone explain why this is?
- Thu Jan 16, 2020 7:07 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6A.19
- Replies: 2
- Views: 127
Re: 6A.19
I believe that that is just a typo on the part of the solutions manual because, in order to get the OH- concentration, you just need to divide Kw (1x10^-14) by the respective H3O+ concentration, which they did correctly in all of the other parts. The answer I got is 3.23x10^-15.
- Thu Jan 16, 2020 6:44 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Converting between K and Kc
- Replies: 2
- Views: 147
Converting between K and Kc
In the book, they give an equation for converting between Kc and K: . How do I use this equation? Does Lavelle expect us to be able to practice this equation?
- Thu Jan 09, 2020 4:03 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equilibrium Constants with Ionic Compounds
- Replies: 2
- Views: 185
Equilibrium Constants with Ionic Compounds
The book mentions that, in reactions involving fully dissociated ionic compounds in solution, the equilibrium constant should be written for the net ionic equation by using the activity for each type of ion. First off, what does this fully mean in simpler terms? and is this something we should be do...
- Thu Jan 09, 2020 3:59 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kp v. Kc
- Replies: 5
- Views: 206
Re: Kp v. Kc
If the way the equilibrium constant was calculated is in no other way indicated, it is safe to assume that the K value was calculated using whatever form of given concentrations/partial pressures is in the question (meaning if they give you a partial pressure, it is probably Kp and vice versa). Plus...
- Thu Jan 09, 2020 3:56 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: determining shift in equilibrium
- Replies: 4
- Views: 241
Re: determining shift in equilibrium
Because the change in energy is negative, the reaction is exothermic. The answer is that the reaction shifts to the left because the reaction is exothermic and thus decreasing temperature would move the reaction in the forward. Therefore, increasing temperature would do the opposite.
- Thu Jan 09, 2020 3:53 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: solid/liquid
- Replies: 7
- Views: 200
Re: solid/liquid
when writing the K expression, you don't include it. But say the solid or liquid is the only product in the reaction, you'd still put a 1 in the numerator over your non-solid/liquid reactants.
- Thu Jan 09, 2020 3:52 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: calculating the equilibrium concentrations of products and reactants
- Replies: 1
- Views: 163
Re: calculating the equilibrium concentrations of products and reactants
First off, since the initial concentration of SO3 is 0 and you are adding 2X, the equilibrium concentration should only be 2X rather than c+2X. You would then proceed using your equilibrium equations you have set up (0.522-2X, 0.633-X, and 2X) in filling out your equation for K. With these equilibri...
- Sun Dec 08, 2019 11:19 am
- Forum: Air Pollution & Acid Rain
- Topic: Blood pH [ENDORSED]
- Replies: 1
- Views: 258
Blood pH [ENDORSED]
What are the roles that CO2, H2CO3, and HCO3- play in maintaining blood at a pH of 7.4? Lavelle said to look for it in the textbook but I was unable to find it.
- Sun Dec 08, 2019 11:18 am
- Forum: Conjugate Acids & Bases
- Topic: Bronsted vs Conjugate
- Replies: 3
- Views: 399
Re: Bronsted vs Conjugate
A bronsted acid is something that in it of itself is a proton donor. A conjugate acid is the acid resulting after a bronsted base accepts a proton. For example, NH4+ is the conjugate acid of NH3.
- Sun Dec 08, 2019 12:57 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Oxalate
- Replies: 2
- Views: 255
Oxalate
Why is oxalate bidentate and not tetradentate?
- Sun Dec 08, 2019 12:54 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Ph and poH of weak acids
- Replies: 8
- Views: 429
Re: Ph and poH of weak acids
No, 14a no longer requires student to do calculations based on weak acids and bases. I think we’ll learn more about that in 14B.
- Sun Dec 08, 2019 12:53 am
- Forum: Air Pollution & Acid Rain
- Topic: Options to reduce acid rain
- Replies: 8
- Views: 618
Re: Options to reduce acid rain
You should know the reactions behind acid rain. Acid rain is largely contributed to the interactions of water with nitrogen and sulfur oxides. So, solutions to acid rain would pretty much be anything reducing human activity causing the excessive release of sulfur and nitrogen into the environment. T...
- Wed Nov 27, 2019 4:49 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordinate covalent bonds
- Replies: 4
- Views: 215
Coordinate covalent bonds
What make a coordinate covalent bond differ from an ionic or covalent? I understand that, in coordinate covalent bonds, both electrons are donated by the same atom, but if that’s the case, how do they differ from ionic bonds?
- Wed Nov 27, 2019 4:44 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: polydente
- Replies: 2
- Views: 196
Re: polydente
Unless you know by memorizing a specific coordination compound, I don’t think you can just determine by looking at the formula. Drawing it out helps because it shows you the placement of the atoms and the compound’s structure.
- Wed Nov 27, 2019 4:43 pm
- Forum: Amphoteric Compounds
- Topic: Amphoteric Compounds other than Be, Al, Ga, Sn, Pb, and Sb
- Replies: 3
- Views: 269
Re: Amphoteric Compounds other than Be, Al, Ga, Sn, Pb, and Sb
I don’t think there is any set steps to determining whether or not something is amphoteric. However, it is helpful to think about the conjugate base and/or acid of something in determine whether it is amphoteric. If something doesn’t have a Hydrogen atom, it obviously doesn’t have a proton to donate...
- Wed Nov 27, 2019 4:36 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Relative Acidity (Noting a strong acid)
- Replies: 1
- Views: 163
Re: Relative Acidity (Noting a strong acid)
The trichloroacetic acid is stronger because the chlorine is an electron withdrawing group. This causes a withdrawal of electrons from both the carbon atom and the oxygen atom. Due to the withdrawal of electrons, the electron density in the O-H bond is diminished and this weakens the O-H bond, this ...
- Wed Nov 27, 2019 3:26 pm
- Forum: Lewis Acids & Bases
- Topic: Bronsted and Lewis Acids
- Replies: 4
- Views: 260
Re: Bronsted and Lewis Acids
Bronsted acids/bases focuses on the protons:
-bronsted acids- proton donors
-bronsted bases- proton acceptors
Lewis acids/bases focus on the electrons:
-Lewis acids- electron pair acceptor
-Lewis bases- electron pair donor
-bronsted acids- proton donors
-bronsted bases- proton acceptors
Lewis acids/bases focus on the electrons:
-Lewis acids- electron pair acceptor
-Lewis bases- electron pair donor
- Sun Nov 24, 2019 12:24 pm
- Forum: Naming
- Topic: HW problem 9C.3(d)
- Replies: 2
- Views: 97
Re: HW problem 9C.3(d)
I believe the rule is to write the neutral molecule first and then the anion. If there are multiple anions, they are listed in order of their atomic numbers.
- Sun Nov 24, 2019 12:13 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Hybridization
- Replies: 7
- Views: 456
Hybridization
What is the purpose of hybridization? Why does it occur?
- Sun Nov 24, 2019 12:08 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Identifying Polydentate Ligands
- Replies: 5
- Views: 299
Re: Identifying Polydentate Ligands
When determining whether or not a ligand is polydentate, you need to look at the location of lone pairs on the ligand and the shape of the ligand. If the lone pair locations are spread out between several atoms on a ligand, it is likely to be polydentate rather than when they are all located on one ...
- Sun Nov 24, 2019 12:00 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: homework
- Replies: 3
- Views: 126
Re: homework
I believe it also should include hybridization because that wasn’t a topic covered on our most recent test.
- Sun Nov 24, 2019 11:57 am
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Why are inorganic acids stronger?
- Replies: 8
- Views: 1316
Re: Why are inorganic acids stronger?
The strength of an acid is based upon its ability to lose hydrogen ions (ionize) when dissolved in water. Inorganic compounds lose hydrogens ions much more easily than organic, making them considered stronger.
- Wed Nov 20, 2019 10:36 am
- Forum: Hybridization
- Topic: electron promotion
- Replies: 1
- Views: 67
Re: electron promotion
Yes I believe it can be any atom that has an empty p orbital and a paired s orbital.
- Sun Nov 17, 2019 7:57 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: Electron repulsions
- Replies: 1
- Views: 99
Electron repulsions
How do electron repulsions relate to the Pauli exclusion principle?
- Sun Nov 17, 2019 12:51 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pairs
- Replies: 5
- Views: 323
Re: Lone Pairs
No, depending on the bonds and number of lone pairs that are also arranged about the central atom, a molecule with lone pairs can hold a wide variety of molecular shapes.
- Sun Nov 17, 2019 12:49 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pair location
- Replies: 3
- Views: 155
Lone Pair location
Why in some molecular shapes (like square planar) are the lone pairs on opposite sides of the central atom but in other molecular shapes (like bent or t-shape) the lone pairs are next to one another? How do you determine where the lone pairs are in relation to one another about the central atom?
- Sun Nov 17, 2019 12:44 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR
- Replies: 6
- Views: 397
Re: VSEPR
The valence shell electron repulsion theory is the model by which we determine molecular shapes by determining the form of the molecule which would minimize the electrostatic repulsion. This helps us to determine shapes because our Lewis structures tell us the bonds and line pairs in a molecule but ...
- Sun Nov 17, 2019 12:40 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E.25
- Replies: 2
- Views: 165
Re: 2E.25
The lone pair causes the S-F bonds to not be directly symmetrical from one another and therefore their dipole moments don’t cancel out.
- Sun Nov 17, 2019 12:37 pm
- Forum: Lewis Structures
- Topic: Drawing Lewis Structures (Multiple Atoms)
- Replies: 3
- Views: 203
Re: Drawing Lewis Structures (Multiple Atoms)
Usually it helps to know which atom will be the central atom. The central atom is the atom with the least electronegativity (except in cases where that atom is hydrogen). From there, you could just go about arranging the remaining atoms about the central.
- Sun Nov 10, 2019 2:31 am
- Forum: Dipole Moments
- Topic: Dipole Moments
- Replies: 3
- Views: 208
Dipole Moments
What is a dipole moment and how do they affect intermolecular forces?
- Sun Nov 10, 2019 2:26 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Electron Transitions
- Replies: 2
- Views: 271
Re: Electron Transitions
So for this problem, you could’ve used the rydberg formula to find energy at a specific level. I believe they gave us the change in energy, so you’d use the delta E= E(final) - E(initial). The only variable you should have left in the formula would be n(final) because they told us that it was a hydr...
- Sun Nov 10, 2019 2:21 am
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarisability and Size
- Replies: 3
- Views: 235
Re: Polarisability and Size
I think I remember Lavelle explaining it as those larger molecule have more electrons, resulting in stronger London dispersion forces due to the fact that they have stronger instantaneous-induced dipoles.
- Sun Nov 10, 2019 2:16 am
- Forum: Dipole Moments
- Topic: Homework Problem 3F.15
- Replies: 1
- Views: 121
Re: Homework Problem 3F.15
If you were trying to determine the answer to this question using Lewis structures, you would have to look at the molecular shapes. The AsF3 molecule has lone pairs pushing the three bonds down, this giving it a pyramidal shape, which is polarized as the less electronegative atom is on one side whil...
- Sun Nov 10, 2019 2:09 am
- Forum: Photoelectric Effect
- Topic: Wavelength from Work Function
- Replies: 1
- Views: 293
Re: Wavelength from Work Function
Assuming you’re talking about the wavelength of light, you would use the E= Kinetic Energy + work function formula in order to find the energy of the photon. I believe I remember the question asking for the wavelength of the photon which emitted the electron. If you’re looking for the wavelength of ...
- Tue Nov 05, 2019 10:21 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: Schrodingers Equation
- Replies: 1
- Views: 77
Schrodingers Equation
Can someone please explain the basic concepts we should know for schrodinger’s equation? It confuses me so much
- Sat Nov 02, 2019 11:25 am
- Forum: Bond Lengths & Energies
- Topic: Bonding
- Replies: 7
- Views: 450
Bonding
What are the general exceptions to the octet rule we should know? And how many electrons can those exceptions hold when bonding?
- Sat Nov 02, 2019 11:17 am
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Understanding Ionic Radius
- Replies: 3
- Views: 278
Re: Understanding Ionic Radius
Yes, as elements move to the right in a period, they have more protons, resulting in a high effective nuclear charge (in other words, a stronger pull) on each electron from the nucleus. This stronger pull leads to a smaller radius.
- Sat Nov 02, 2019 11:13 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Energy of orbitals
- Replies: 2
- Views: 68
Re: Energy of orbitals
The energy of an orbital refers to the amount of energy required of electrons to be in that orbital. In order for an electron to be in a certain orbital, it must have the discrete amount of energy required of that orbital. This higher energy is due to the fact that the higher energy orbitals are fur...
- Sat Nov 02, 2019 11:08 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Electron configuration rules
- Replies: 1
- Views: 111
Re: Electron configuration rules
Pauli’s principle states two things: there can be no more than 2 electrons in an orbital and electrons in the same orbital must be spin paired. This would be violated if you placed 3 electrons or more in an orbital or if your 2 electrons had the same direction of spin (ie both +1/2 or both -1/2). Hu...
- Sat Nov 02, 2019 10:57 am
- Forum: Octet Exceptions
- Topic: Odd number of valence electrons
- Replies: 2
- Views: 177
Re: Odd number of valence electrons
The electron is usually placed in a way that would allow our structure to be the lowest energy structure, meaning the least formal charges possible. So, it’s mostly the same as any other situation where you’re trying to figure out the best structure for bonding, except this time you happen to have a...
- Sun Oct 27, 2019 2:25 pm
- Forum: Resonance Structures
- Topic: Resonance
- Replies: 8
- Views: 212
Re: Resonance
Resonance is the blending of structures with the same arrangement of atoms but different arrangements of electrons. The actual structure is a hybrid of these resonant structures and is the most stable structure. The resonant structures all have the same energy and allow us to both visual and predict...
- Sun Oct 27, 2019 2:15 pm
- Forum: Ionic & Covalent Bonds
- Topic: Valence Electrons
- Replies: 4
- Views: 244
Re: Valence Electrons
When counting the number of valence electrons an element has, you only count the number of electrons held in the outer shell. This usually doesn’t include those from the d-orbital because electrons aren’t placed in the d-orbital until there are some in the next shell s-orbital, but by then the s-orb...
- Fri Oct 25, 2019 11:04 am
- Forum: Ionic & Covalent Bonds
- Topic: Ionization Energy
- Replies: 5
- Views: 185
Re: Ionization Energy
When thinking about ionization energy comparisons between several elements, you have to take both the period and the group into account rather than just the groups. Therefore the ionization energy trends can’t just be described with one direction, such as down. The ionization energy increases in the...
- Fri Oct 25, 2019 10:57 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Sulfur bonding
- Replies: 5
- Views: 244
Re: Sulfur bonding
Although most elements need exactly 8 electrons in a bond to be stable, there are some exceptions to the rule. Some elements, like Boron, can be stable with less than 8 electrons, while some other elements, like Sulfur, can be stable with more than 8 electrons. This is due to the expansion of valenc...
- Fri Oct 25, 2019 10:43 am
- Forum: Electronegativity
- Topic: Molecular Geometry
- Replies: 4
- Views: 218
Re: Molecular Geometry
The topic hasn’t really been brought up yet in specifics as to the shapes, so as of what we have learned so far, probably not. But, if it’s addressed by the midterm then yes.
- Sun Oct 20, 2019 5:10 pm
- Forum: DeBroglie Equation
- Topic: DeBroglie Equation
- Replies: 11
- Views: 375
Re: DeBroglie Equation
You use de Broglies equation to find the wavelength of an object with mass when given the mass and velocity of the object. The units for the equation are: Joules•seconds for plancks constant, kg for mass, meters/second for velocity, and meters for wavelength.
- Sun Oct 20, 2019 4:55 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Homework week 4
- Replies: 4
- Views: 257
Re: Homework week 4
yes, our homework is to be done on the topic we are currently working on. So since we are still on quantum world, you just pick five other problems from the topic to turn in.
- Sun Oct 20, 2019 4:51 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Matter and wavelike properties
- Replies: 3
- Views: 150
Re: Matter and wavelike properties
Wavelength is inversely proportional to mass. This means that, the higher the mass, the shorter the wavelength. For larger objects, the wavelength becomes so small (the rule is generally any wavelength less than 10^-15 m) that it is unnoticeable. We just have to assume that it have wavelike properti...
- Sun Oct 20, 2019 4:38 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Uncertainty in Speed
- Replies: 2
- Views: 128
Re: Uncertainty in Speed
The uncertainty in velocity would be 10 m/s. The uncertainty is given by the total range of what it could be. So, in this case, since the velocity could be anywhere ranging from 0 m/s to 10 m/s, your uncertainty in velocity would be 10 m/s.
- Sun Oct 20, 2019 4:36 pm
- Forum: Properties of Electrons
- Topic: Mass of an Electron
- Replies: 14
- Views: 562
Re: Mass of an Electron
This is a set mass. Electrons don’t gain or lose mass through any process. It is given to us on our constant sheet.
- Sun Oct 20, 2019 4:33 pm
- Forum: Properties of Electrons
- Topic: Hund's Rule
- Replies: 5
- Views: 226
Re: Hund's Rule
Hund’s Rule basically states that, due to electron repulsion, each orbital in a sub shell is occupied by a single electron before any electrons within that orbital are paired. It also explains that each of the single electrons have the same spin. The rule helps us to figure out electron configuratio...
- Sun Oct 13, 2019 8:26 pm
- Forum: Properties of Light
- Topic: Electron energy levels
- Replies: 2
- Views: 103
Electron energy levels
Why can’t electrons exist between energy levels? I remember Lavelle mentioning this in class but I’m confused as to why
- Sun Oct 13, 2019 8:20 pm
- Forum: Significant Figures
- Topic: Tests and Significant Figures
- Replies: 6
- Views: 352
Re: Tests and Significant Figures
On the class website, there’s a list of a bunch of helpful links and one of them is titled “everything you want to know about sig fig” which is a document with all of the sig fig rules and I’m assuming Lavelle accepts these rules.
- Sun Oct 13, 2019 8:17 pm
- Forum: Properties of Light
- Topic: SI units
- Replies: 3
- Views: 99
Re: SI units
Lavelle has chemistry constants and equation documents listed on the class website and they have helpful information for conversions and constants.