Search found 120 matches
- Sat Mar 14, 2020 9:22 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Concentration cells
- Replies: 2
- Views: 259
Concentration cells
Why is the anode in the solution with a lower molarity? Is it because electrons from the cathode solution diffuse through the porous membrane to enter the anode solution?
- Sat Mar 14, 2020 9:11 pm
- Forum: *Free Energy of Activation vs Activation Energy
- Topic: Temperature vs. activation energy
- Replies: 33
- Views: 2689
Temperature vs. activation energy
How does temperature affect rate constant k? Does an increase in temperature cause an increase in the rate constant?
- Thu Mar 12, 2020 6:51 pm
- Forum: General Rate Laws
- Topic: Elementary reactions
- Replies: 4
- Views: 408
Elementary reactions
How are we able to tell whether or not something is an elementary reaction? Also how is writing the rate law of an elementary reaction different from a non-elementary reaction?
- Thu Mar 12, 2020 6:50 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: What was your favorite chem topic?
- Replies: 137
- Views: 13448
Re: What was your favorite chem topic?
I liked drawing Lewis structures!
- Thu Mar 12, 2020 6:20 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: 7E.7
- Replies: 2
- Views: 240
7E.7
In the solutions manual, it mentions that a catalyst provides a completely different reaction pathway. Is this different pathway due to the lowered activation energy?
- Thu Mar 12, 2020 6:12 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Last Q&A question
- Replies: 1
- Views: 147
Last Q&A question
Does anyone understand the last question on the Q&A PowerPoint that Dr. Lavelle posted? I don't understand how you are able to determine the rate limiting step.
- Thu Mar 12, 2020 6:09 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Arrhenius equation
- Replies: 5
- Views: 392
Arrhenius equation
What does the A value in the Arrhenius equation mean? Also when do we use this equation?
- Thu Mar 12, 2020 2:48 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Determining the slow step
- Replies: 4
- Views: 358
Determining the slow step
How are you able to tell which reaction is the slow step? Is the equilibrium reaction usually the slow step?
- Sun Mar 08, 2020 10:22 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Equations
- Replies: 2
- Views: 222
Equations
On the constants and equations sheet, one of the formulas is k= A exp(-Ea/RT) and another formula is lnK= -(Ea/RT) + lnA. Are these two formulas the same thing, except the first one has done e to the power of each term to cancel out the natural logs (ln)?
- Sun Mar 08, 2020 10:17 pm
- Forum: General Rate Laws
- Topic: Rate constant vs. rate
- Replies: 4
- Views: 312
Rate constant vs. rate
What is the difference between rate constant and rate? Does the rate constant of a reaction never change, while the rate is subject to change due to changes in molar concentrations?
- Sun Mar 08, 2020 10:14 pm
- Forum: General Rate Laws
- Topic: 7C.11
- Replies: 1
- Views: 219
7C.11
For part c, I understand that increasing the product or reactant concentration does not change the equilibrium constant, but does an increase in reactant cause an increase in the rate constant? Are these two concepts related?
- Sun Mar 08, 2020 5:41 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Units
- Replies: 2
- Views: 245
Units
How are you able to tell the units for k? Also, why do the units for k change depending on the order of the reaction?
- Sun Mar 08, 2020 5:19 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: 7A.15
- Replies: 3
- Views: 300
Re: 7A.15
Why don't concentrations for zero order reactions matter?
- Sun Mar 08, 2020 5:13 pm
- Forum: First Order Reactions
- Topic: Determining order
- Replies: 3
- Views: 268
Determining order
How are we able to tell the order of a reaction, and how do we know whether to use integrated or differential rate laws?
- Sun Mar 08, 2020 5:11 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: 7A.15
- Replies: 5
- Views: 410
7A.15
For 7A.15, how do we know which experiments for C to use when finding the orders for A and B (since none of the C experiments remain constant as the other two change)?
- Mon Mar 02, 2020 11:40 pm
- Forum: Balancing Redox Reactions
- Topic: 6K.1
- Replies: 1
- Views: 183
6K.1
When writing the half reactions, why don't we include the given H+ proton for our oxidation half reaction? Is this because the solution is acidic, so we ignore the extraneous H+ in the equation given?
- Wed Feb 26, 2020 10:13 pm
- Forum: Balancing Redox Reactions
- Topic: 6N.5
- Replies: 2
- Views: 267
6N.5
For 6N.5 part a, how do we determine the charges of the atoms in the compound Hg2Cl2?
- Wed Feb 26, 2020 12:41 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6M.11
- Replies: 1
- Views: 184
6M.11
For part 6M.11a, we are asked to draw the cell diagram with the given information: Co2+/Co and Ti3+/Ti2+. How are we able to determine the states of matter of these elements based off of the information given? Both Ti and Co are transition metals, so I thought they would both be solids; however, onl...
- Wed Feb 26, 2020 12:28 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: 5G.17
- Replies: 2
- Views: 246
Re: 5G.17
For the graph, why are the increase in I2 production and the decrease in I production curved rather than linear? Why would these rates change at a curved/exponential rate, rather than constant?
- Wed Feb 26, 2020 11:54 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6L.7
- Replies: 3
- Views: 307
6L.7
For 6L.7c, the solution uses Ni(s) as the electrode for the cathode in the cell diagram, but Ni(s) is neither a reactant or product of the reduction half reaction. Why do we have to use Ni(s)? Is it because Ni is already present in the solution/reaction and can act as a metal conductor? Would using ...
- Wed Feb 26, 2020 11:53 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6L.5
- Replies: 2
- Views: 249
6L.5
For part 6L.5d, the solutions manual splits two half reactions while including Au(s) in both half reactions. Why do we need to have a solid in each half reaction? Can we not have half reactions with just aqueous substances, thus causing us to have the solids in both half reactions?
- Wed Feb 26, 2020 11:50 am
- Forum: Balancing Redox Reactions
- Topic: 6L.9
- Replies: 2
- Views: 232
6L.9
The question asks us to write the balanced half reactions for potassium permanganate and iron(II) chloride; however, in the solutions manual, the steps to work out the problem do not include potassium or chlorine. Is this because they are spectator ions? Also, is this because it is in an acidic solu...
- Sun Feb 23, 2020 10:16 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: STP
- Replies: 13
- Views: 794
Re: STP
STP means standard temperature and pressure, during which the pressure is 1atm and temperature is 273K (or 0 degrees Celcius).
- Fri Feb 21, 2020 8:50 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Reaction quotient
- Replies: 3
- Views: 363
Reaction quotient
How does the reaction quotient affect our value for E in the Nernst equation? Does having a larger reaction quotient result in a smaller or larger value for E? Also, what is going on conceptually when this occurs?
- Fri Feb 21, 2020 8:47 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Relationship between Gibbs free energy and E
- Replies: 2
- Views: 228
Relationship between Gibbs free energy and E
Is Gibbs free energy only related to E using the equation (delta)G^o = -nFE^o? In addition, does the spontaneity of a reaction affect E?
- Fri Feb 21, 2020 8:45 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell diagrams
- Replies: 2
- Views: 209
Cell diagrams
In lecture today, Dr. Lavelle mentioned that there are some problems in the textbook where we have to tell what is wrong with a given cell diagram. One of the things that can be wrong with the cell diagram is the putting the anode (oxidation reaction) on the right. How are we supposed to be able to ...
- Fri Feb 21, 2020 8:37 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt bridge
- Replies: 1
- Views: 162
Salt bridge
I am having trouble understanding salt bridges. How do they work, and why are they needed? Do they make batteries last longer?
- Fri Feb 21, 2020 8:36 pm
- Forum: Balancing Redox Reactions
- Topic: Redox in Acid/ Basic Solutions
- Replies: 8
- Views: 547
Re: Redox in Acid/ Basic Solutions
For acidic reactions, we have to add water to the reduction and oxidation reactions to balance out the oxygens. Do we have to add water to balance oxygens in basic conditions, or do we only add OH- to balance oxygen molecules?
- Sun Feb 16, 2020 6:51 pm
- Forum: Balancing Redox Reactions
- Topic: Reduction vs. oxidation
- Replies: 29
- Views: 1246
Reduction vs. oxidation
How can you tell the difference between what is reduced and what is oxidized? Is it only dependent on proton transfer?
- Sun Feb 16, 2020 6:50 pm
- Forum: Balancing Redox Reactions
- Topic: Memorizing charges
- Replies: 11
- Views: 780
Memorizing charges
Will we have to memorize all of the charges of all of the elements, or just the ones that are in the most common groups (such as Groups 1, 2, 16, 17, etc.)? Is the only way to tell the charge of transition metals by seeing the whole compound the element is in?
- Sun Feb 16, 2020 6:47 pm
- Forum: Balancing Redox Reactions
- Topic: Charge of permanganate
- Replies: 5
- Views: 367
Charge of permanganate
How do we tell the charge of Mg in MgO4-? Is it because oxygen normally has a charge of -2, and the total compound is -1, thus causing us to determine that Mg has a charge of +7?
- Sun Feb 16, 2020 6:46 pm
- Forum: Balancing Redox Reactions
- Topic: Determining charge
- Replies: 5
- Views: 328
Determining charge
How are you able to tell what the charge what of each element is? Do all of the charges cancel each other out to make each side of the reaction neutral?
- Sun Feb 16, 2020 6:44 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Differences in (delta)G^o equations
- Replies: 3
- Views: 204
Differences in (delta)G^o equations
How do we know when to use the lnQ equation or the lnK equation? Is it dependent on whether the system is in equilibrium or not?
- Sun Feb 16, 2020 6:43 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs free energy
- Replies: 5
- Views: 343
Gibbs free energy
What is the difference between (delta)G and (delta)G^o in the equation (delta)G = (delta)G^o + RTlnQ?
- Sat Feb 08, 2020 11:42 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: State of molecules
- Replies: 3
- Views: 238
State of molecules
Does standard entropy of a reaction depend on the state of a molecule? For instance, would the standard reaction entropy of liquid water be different from that of water as a gas?
- Sat Feb 08, 2020 11:41 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: Entropy vs. moles
- Replies: 3
- Views: 639
Entropy vs. moles
Does having more moles of a molecule mean increased entropy? For instance, would 5 moles of H2O would have a higher entropy compared to 1 mole of H2O?
- Sat Feb 08, 2020 11:02 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Standard reaction entropy
- Replies: 3
- Views: 131
Standard reaction entropy
In the formula for standard reaction entropy, why is is S(products) and S(reactants) at standard conditions, rather than (delta)S(products) and (delta)S(reactants)? Are we looking at residual entropies, rather than the change in entropies?
- Sat Feb 08, 2020 10:58 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Lecture example
- Replies: 2
- Views: 110
Lecture example
In lecture during Monday of week 4, Dr. Lavelle did an example of a neutralization reaction. When he did the question, he used the Q= mC(delta)T equation, which I understand; however, he used 100g as his mass for the equation. In order to find the mass, did he add the 50ml of each solution and then ...
- Sat Feb 08, 2020 10:36 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: When to use internal energy equation
- Replies: 3
- Views: 334
When to use internal energy equation
On the constants and equations sheet, there is an equation for calculating just internal energy: U=(3/2)nRT. When do we need to use this equation? Were there any questions using this in the homework?
- Sat Feb 08, 2020 10:31 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs free energy
- Replies: 4
- Views: 263
Gibbs free energy
I don't really understand what Gibbs free energy is conceptually, and how it is related to enthalpy and entropy. I understand that, by looking at the equation, an increase in enthalpy increases Gibbs free energy and an increase in entropy decreases Gibbs free energy, but why is that?
- Sat Feb 08, 2020 10:29 pm
- Forum: Calculating Work of Expansion
- Topic: Irreversible vs. reversible work
- Replies: 2
- Views: 116
Irreversible vs. reversible work
Why do reversible expansions do more work than irreversible expansions? Does it have to do with constant or changing pressure?
- Sun Feb 02, 2020 10:53 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Enthalpy of formation vs. heat capacity
- Replies: 2
- Views: 127
Enthalpy of formation vs. heat capacity
Are these two concepts related? Are they opposites of each other, or are they two completely separate things?
- Sun Feb 02, 2020 10:52 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: 4C.1
- Replies: 2
- Views: 126
4C.1
Why does NO2 having more atoms give it a higher molar heat capacity compared to NO? The solutions manual says that it is because NO2 has more bonds to absorb added energy, but I am not really sure of what this means.
- Sun Feb 02, 2020 10:49 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: 4D.11
- Replies: 1
- Views: 103
4D.11
For part b, why is the heat positive? I thought that the energy (186.0 kJ) would be negative, because we are looking at the reverse reaction that forms N2.
- Sun Feb 02, 2020 10:46 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: 4A.11
- Replies: 1
- Views: 88
4A.11
For this question, why do we treat mass of the calorimeter as m= 1g? Why is the mass of the calorimeter not taken into account for solving the problem?
- Sun Feb 02, 2020 10:45 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: 4A.1
- Replies: 2
- Views: 134
4A.1
For question 4A.1b, why is coolant in a refrigerator coil a closed system? Also, for 4A.1f, why is a living plant an open system?
- Sun Feb 02, 2020 10:39 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Heat capacity vs. specific heat capacity
- Replies: 3
- Views: 387
Heat capacity vs. specific heat capacity
What is the difference between heat capacity and specific heat capacity? Is it a matter of whether they are intensive or extensive properties?
- Sun Jan 26, 2020 5:59 pm
- Forum: Phase Changes & Related Calculations
- Topic: Method 3
- Replies: 1
- Views: 97
Method 3
In the method 3 example done during lecture, were the values used to calculate (delta)H(rxn) standard/given values, or do we have to calculate them using a formula?
- Sun Jan 26, 2020 5:57 pm
- Forum: Phase Changes & Related Calculations
- Topic: Standard reaction enthalpy vs. Standard enthalpy of formation
- Replies: 2
- Views: 103
Standard reaction enthalpy vs. Standard enthalpy of formation
I do not really understand the difference between standard reaction enthalpy and standard enthalpy of formation. What makes them different, and how would we be asked to use them?
- Sun Jan 26, 2020 5:54 pm
- Forum: Phase Changes & Related Calculations
- Topic: Method 2 for calculating enthalpy changes
- Replies: 1
- Views: 114
Method 2 for calculating enthalpy changes
If method 2 is the least accurate method for calculating the net enthalpy change, would we ever be asked to use it, or should we just understand it conceptually and know why it is inaccurate?
- Sun Jan 26, 2020 5:53 pm
- Forum: Phase Changes & Related Calculations
- Topic: Physical or Phase Changes
- Replies: 7
- Views: 202
Physical or Phase Changes
When calculating this such as the enthalpy of vaporization or sublimation, will the enthalpies for the physical states (such as H(vapor) and H(liquid) for vaporization) be given to us, or is there some formula for how to calculate these values?
- Sun Jan 26, 2020 5:51 pm
- Forum: Phase Changes & Related Calculations
- Topic: Why does steam cause burns?
- Replies: 29
- Views: 1338
Why does steam cause burns?
I know Dr. Lavelle went into quite a bit of depth as to why steam causes burns worse than boiling water, but I am still a bit confused. Why does this occur? In my notes, I wrote that steam has a large enthalpy of condensation: is that the reason why?
- Sun Jan 26, 2020 5:49 pm
- Forum: Phase Changes & Related Calculations
- Topic: Why is enthalpy additive?
- Replies: 3
- Views: 157
Why is enthalpy additive?
I understand that enthalpy is a state property (meaning that only the current state determines its value), but why aren't the intermediary states taken into account?
- Sun Jan 19, 2020 8:53 pm
- Forum: Ideal Gases
- Topic: When to use PV=nRT
- Replies: 5
- Views: 174
When to use PV=nRT
How do we know when to use the PV=nRT equation? Do we just use it to calculate initial concentration for pressure before creating our ICE table? Were there any homework questions that showed us an example of when/how to use it? Also, do the units for pressure (bars vs. atm) matter when using this eq...
- Sun Jan 19, 2020 8:51 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5I.13
- Replies: 4
- Views: 169
5I.13
For part c, how are we able to tell which reaction is more thermodynamically stable? Does it have to do with whether we would get more monatomic molecules or diatomic molecules for the reactions, and them comparing the K values of each equation?
- Sun Jan 19, 2020 8:48 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5% rule
- Replies: 8
- Views: 287
5% rule
When approximating, how do we test to make sure that our approximation violates the 5% rule? Do we have to do (equilibrium concentration)/(initial concentration)?
- Sun Jan 19, 2020 8:45 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatelier's Principle
- Replies: 7
- Views: 207
Le Chatelier's Principle
I am a little confused as to what the significance of Le Chatelier's Principle is. Is it applicable to all chemical reactions?
- Sun Jan 19, 2020 8:44 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Relationship between pressure and volume
- Replies: 10
- Views: 434
Relationship between pressure and volume
Are pressure and volume inversely related to each other? If the pressure of a system doubled, would the volume halve?
- Sun Jan 19, 2020 8:40 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Exothermic vs. endothermic
- Replies: 2
- Views: 117
Exothermic vs. endothermic
How does an increase in temperature affect exothermic reactions differently from endothermic reactions? If you apply heat, does the endothermic reaction favor formation of products, and does the exothermic reaction favor the formation of reactants?
- Sat Jan 11, 2020 6:25 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5G.9
- Replies: 3
- Views: 120
5G.9
For part c, why does the ratio of P(O2)/P(O3) change between the two experiments? I understand that the equilibrium constant K= (P(O2)^3/P(O3)^2) does not change, but why would the ratio P(O2)/P(O3) based off of the amount of moles present?
- Sat Jan 11, 2020 6:22 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kc vs. Kp [ENDORSED]
- Replies: 4
- Views: 317
Kc vs. Kp [ENDORSED]
How do we know when to use Kc or when to use Kp? Does it need to be specified which we are using, or do we have to assume that Kp applies to things in the gas phase (since it deals with partial pressure), while Kc typically is used for aqueous solutions?
- Sat Jan 11, 2020 6:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: States of matter [ENDORSED]
- Replies: 4
- Views: 180
States of matter [ENDORSED]
I know that it was touched upon in lecture, but I am still having trouble with this concept. Why don't solids and liquids affect the value of K?
- Sat Jan 11, 2020 6:19 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Meaning of K [ENDORSED]
- Replies: 4
- Views: 217
Meaning of K [ENDORSED]
I understand that at equilibrium the rates at which the reactions occur are equal, but is the equilibrium constant K the rate at which these reaction occur? In addition, how can you speed up the rate at which a reaction occurs?
- Sat Jan 11, 2020 6:17 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Difference between K and Q
- Replies: 6
- Views: 288
Difference between K and Q
What is the difference between the equilibrium constant K and the reaction quotient Q? Does K remain constant, while Q is subject to change?
- Sat Jan 11, 2020 6:14 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: When to do ice tables [ENDORSED]
- Replies: 4
- Views: 300
When to do ice tables [ENDORSED]
How do we know when to use an ICE table to find the composition of the mixture, or when we have to use only the K=[products]/[reactants] equation? Is it dependent on whether initial concentrations or equilibrium concentrations are given?
- Sat Dec 07, 2019 6:01 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Conjugate Seesaw
- Replies: 2
- Views: 182
Re: Conjugate Seesaw
Based off of that, how would you determine the pH for each of those scenarios?
- Sat Dec 07, 2019 5:57 pm
- Forum: Amphoteric Compounds
- Topic: Amphoteric vs amphiprotic
- Replies: 4
- Views: 430
Amphoteric vs amphiprotic
What is the difference between amphoteric and amphiprotic compounds? Why is something that is amphiprotic also amphoteric, but not the other way around?
- Sat Dec 07, 2019 5:54 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Alkaline vs. acidic solutions
- Replies: 2
- Views: 159
Alkaline vs. acidic solutions
Under acidic conditions, when pH is higher than the pkA, why is the acid protonated as HA? In addition, when the pH is higher than the pkA, why does the solution become more basic and give off an H+ to form A-?
- Sat Dec 07, 2019 5:49 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Conjugate Seesaw
- Replies: 2
- Views: 182
Conjugate Seesaw
If you have a conjugate seesaw (the equilibrium arrows), what would the pH of the solution be? Are we able to tell, or do we need the kA and kB values to determine this?
- Sat Dec 07, 2019 5:23 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Determining acidity of solution
- Replies: 1
- Views: 193
Determining acidity of solution
If you have a reaction between a strong acid and a strong base, why does that result in a neutral pH? In addition, why does a reaction between a strong acid and a weak base make the solution acidic, and why does a reaction between a strong base and a weak acid make the solution basic?
- Sat Dec 07, 2019 5:18 pm
- Forum: Bronsted Acids & Bases
- Topic: Bronsted vs. Lewis Acids/Bases
- Replies: 2
- Views: 284
Bronsted vs. Lewis Acids/Bases
Why is it that a Bronsted acid/base is a Lewis acid/base, but a Lewis acid/base is not always a Bronsted acid/base?
- Sat Dec 07, 2019 5:17 pm
- Forum: Biological Examples
- Topic: Polydentate
- Replies: 3
- Views: 147
Polydentate
When talking about EDTA, would you say that it is hexadentate or polydentate? Can you use polydentate to describe anything that is not monodentate?
- Sun Dec 01, 2019 10:25 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Acid strength relative to kA
- Replies: 2
- Views: 163
Acid strength relative to kA
In lecture, Dr. Lavelle said that a stronger acid would have a lower pkA. Is this trend the same for kA, or is kA different from pkA? Also, is this true for bases, too?
- Sun Dec 01, 2019 10:18 pm
- Forum: Bronsted Acids & Bases
- Topic: Acid/Base strength
- Replies: 2
- Views: 227
Acid/Base strength
How are we able to compare strengths between two different acids or bases? For instance, how are we able to tell whether acetic acid (CH3COOH) is a stronger/weaker acid than trichloroacetic acid (C2HCl3O2)? Are we able to tell based off of the electronegativities of the atoms within each compound?
- Sun Dec 01, 2019 10:15 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Equilibrium constants
- Replies: 3
- Views: 165
Equilibrium constants
What does an equilibrium constant (kA) mean? Also, is there a difference between kA and pkA? In addition, when do we know to use this formula in a given problem? Are there any instances of it in the homework?
- Sun Dec 01, 2019 10:12 pm
- Forum: Amphoteric Compounds
- Topic: 6A.17
- Replies: 5
- Views: 471
6A.17
How are we able to tell that As2O3 and Bi2O3 are amphoteric compounds? I drew the Lewis structure for the compound, but I do not understand how we can tell that they possess both acidic and basic abilities.
- Sun Dec 01, 2019 10:07 pm
- Forum: Lewis Acids & Bases
- Topic: 6A.13
- Replies: 1
- Views: 220
6A.13
For part b, how are you able to tell that BF3 is a Lewis acid? Where would the newly accepted electrons go on the Lewis structure? Would the new bond be formed with boron or with fluorine?
- Sun Dec 01, 2019 10:06 pm
- Forum: Amphoteric Compounds
- Topic: Determining amphoteric compounds
- Replies: 2
- Views: 283
Determining amphoteric compounds
How are you able to determine if something can be an amphoteric compound without knowing the chemical reaction equation? Does it have to do with the number of hydrogen atoms attached to the molecule?
- Sun Nov 24, 2019 12:46 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination compounds
- Replies: 2
- Views: 183
Coordination compounds
I feel like the term "coordination compound" has been used a lot throughout lecture, but I am still a bit confused as to what the actual definition fo a coordination compound is. Is it a complex formed between a ligand and a transition metal?
- Sun Nov 24, 2019 12:44 am
- Forum: Bronsted Acids & Bases
- Topic: Bronsted vs. Lewis Acids
- Replies: 4
- Views: 277
Bronsted vs. Lewis Acids
Are Bronsted acids different from Lewis acids because they deal with accepting protons, rather than electrons?
- Sun Nov 24, 2019 12:42 am
- Forum: Hybridization
- Topic: Hybridization
- Replies: 1
- Views: 158
Hybridization
One of the lecture slides said that an unhybridized 2p orbital is perpendicular to the in plane sp2 orbitals, but I am not really sure what this means and how to visualize it.
- Sun Nov 24, 2019 12:40 am
- Forum: Hybridization
- Topic: Strength of sigma and pi bonds
- Replies: 8
- Views: 711
Strength of sigma and pi bonds
In one of the UA sessions, the UA mentioned that sigma bonds require more energy to break than pi bonds. Why is that?
- Sun Nov 24, 2019 12:34 am
- Forum: Naming
- Topic: Coordination sphere
- Replies: 1
- Views: 117
Coordination sphere
During lecture Dr. Lavelle said that everything inside the square brackets is in the coordination sphere. How are you able to tell if something is not in the coordination sphere (not inside the brackets)?
- Sun Nov 17, 2019 3:50 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E.21
- Replies: 1
- Views: 121
2E.21
For part a, how do we know that the bond angles for H-C-H and H-C-C are 120 degrees? Is it because each central atom has a trigonal planar shape, and the bond angle for trigonal planar is 120 degrees?
- Sun Nov 17, 2019 3:48 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone pairs and bond angles
- Replies: 4
- Views: 247
Lone pairs and bond angles
Does having a lone pair on the central atom decrease the bond angles of the other attached atoms?
- Sun Nov 17, 2019 3:47 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E.13
- Replies: 1
- Views: 115
2E.13
How do we know that the shape of I3- is linear and not bent? Is it because of lone pair-lone pair repulsion that causes the shape to be linear (to reduce repulsion)?
- Sun Nov 17, 2019 3:46 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 3F.19
- Replies: 2
- Views: 113
3F.19
For part c of 3f.19, how do we know that CH3(CH2)CH3 is rod-shaped, while C(CH3)4 is spherical, since they have the same number of carbons and hydrogens? Is it because of the notation of how the molecular formulas are given?
- Sun Nov 17, 2019 3:43 pm
- Forum: Dipole Moments
- Topic: 3F.3
- Replies: 2
- Views: 155
3F.3
For part c of question 3F.3, why does CH2Cl2 have dipole-dipole interactions? If we were to draw the two chlorine atoms opposite from each other, wouldn't the dipoles cancel out, making it nonpolar?
- Sun Nov 17, 2019 3:39 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: lone pairs
- Replies: 3
- Views: 204
Re: lone pairs
I believe that we put the lone pairs across from each other in order to minimize electron repulsion for octahedral shapes. For instance, Dr. Lavelle used the example of XeF4 in lecture and placed the lone pairs opposite from each other because that is the shape with the least amount of repulsion for...
- Sun Nov 10, 2019 3:39 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: Polarizability
- Replies: 3
- Views: 144
Polarizability
How does polarizability affect intermolecular forces? Do things with high polarizability form stronger bonds?
- Sun Nov 10, 2019 3:38 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: Strengths of bonds
- Replies: 3
- Views: 269
Strengths of bonds
How are we able to determine how strong each of the bonds are relative to one another?
- Sun Nov 10, 2019 3:37 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: States of matter
- Replies: 2
- Views: 125
States of matter
How do bonds affect the states of matter (whether it's a solid, liquid, or gas) for a molecule?
- Sun Nov 10, 2019 3:35 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: Interaction Energy Calculation
- Replies: 3
- Views: 118
Re: Interaction Energy Calculation
Are these alpha values for polarizability given, or will we have to calculate them ourselves?
- Sun Nov 10, 2019 3:32 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: How to Draw Dipole Arrows
- Replies: 8
- Views: 2777
Re: How to Draw Dipole Arrows
Dipole arrows are drawn on Lewis structures and point towards the more electronegative atom, since they pull electrons towards them. This is why in water the dipole arrows are drawn going from hydrogen (low electronegativity) towards oxygen (higher electronegativity). Due to this pulling of electron...
- Sun Nov 03, 2019 1:41 pm
- Forum: Bond Lengths & Energies
- Topic: Resonance bond length
- Replies: 4
- Views: 280
Resonance bond length
For resonance structures, is the bond length an average of the experimental bond lengths because of delocalization?
- Sun Nov 03, 2019 1:38 pm
- Forum: Coordinate Covalent Bonds
- Topic: Coordinate covalent bond?
- Replies: 12
- Views: 1412
Re: Coordinate covalent bond?
Debora Fernandez Clemente_ 4H wrote:I know understand what a coordinate covalent bond is but, how did you know what compound was a base or an acid?
A Lewis acid accepts electrons, while the Lewis base donates electrons, usually as lone pairs.
- Sun Nov 03, 2019 1:33 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizability
- Replies: 3
- Views: 271
Polarizability
If an atom has high polarizability, does that mean that that the atom pulls the electrons, or are the electrons being pulled from it? In addition, what are the trends for polarizability? Does it follow the same trend as ionization energy, electronegativity, and electron affinity?
- Sun Nov 03, 2019 1:25 pm
- Forum: Lewis Structures
- Topic: Radicals
- Replies: 5
- Views: 217
Radicals
When drawing a radical, do we put the radical on the atom that is less electronegative, since it does not pull electrons towards it as strongly?
- Sun Nov 03, 2019 1:23 pm
- Forum: Dipole Moments
- Topic: Polarity
- Replies: 4
- Views: 173
Polarity
When labeling the dipole moment on a Lewis structure, how are we able to tell if the structure is polar or nonpolar? How are we able to tell if there is no net dipole?
- Sun Oct 27, 2019 8:00 pm
- Forum: Octet Exceptions
- Topic: Expanded octet
- Replies: 3
- Views: 147
Expanded octet
During lecture, Dr. Lavelle mentioned expanded octets, but I am unsure of what he meant by that. What is an expanded octet, and can atoms that follow the octet rule have expanded octets (or is that a violation of the octet rule)?