In an endothermic reaction, increasing temperature will increase the forward rate constant, which increases the K constant.
For an exothermic reaction, would it be the opposite? Can someone explain this concept with exothermic reactions?
Search found 120 matches
- Sat Mar 13, 2021 7:55 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Effect of Temp. on K constant
- Replies: 8
- Views: 466
- Fri Mar 12, 2021 10:31 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneity in regards to Ecell and deltaG
- Replies: 1
- Views: 113
Spontaneity in regards to Ecell and deltaG
When K is greater than 1, Ecell is positive and deltaG is negative.
When K is less than 1, Ecell is negative and deltaG is positive.
Can someone explain the effect of K on Ecell and deltaG conceptually?
When K is less than 1, Ecell is negative and deltaG is positive.
Can someone explain the effect of K on Ecell and deltaG conceptually?
- Thu Mar 11, 2021 10:36 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts and Frequency Factor
- Replies: 3
- Views: 205
Re: Catalysts and Frequency Factor
I don't think they change.
For the most part, the frequency factor is pretty much constant in small temperatures.
It is, however, affected by temperature change! Increasing the temp will increase the frequency factor because molecules are more likely to collide.
For the most part, the frequency factor is pretty much constant in small temperatures.
It is, however, affected by temperature change! Increasing the temp will increase the frequency factor because molecules are more likely to collide.
- Thu Mar 11, 2021 10:23 pm
- Forum: First Order Reactions
- Topic: textbook 7C.7
- Replies: 2
- Views: 352
Re: textbook 7C.7
When given a multi-step reaction mechanism, we want to focus on the slow step. The slow step will determine our rate, not the overall reaction. Michael made a good analogy to explain this. For example, if my friend and I are both getting ready, and I get dressed lightning fast but my friend is still...
- Thu Mar 11, 2021 10:02 pm
- Forum: General Science Questions
- Topic: Water in combustion
- Replies: 3
- Views: 341
Re: Water in combustion
Water vapor is released in a combustion reaction so it should be written as H2O(g). The vapor can condense to liquid water after, but it is not because of the reaction itself and therefore we don't really focus on liquid water.
And you are correct about the change in moles!
And you are correct about the change in moles!
- Wed Mar 10, 2021 10:58 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Standard Molar Entropy
- Replies: 2
- Views: 224
Standard Molar Entropy
Can someone explain why standard molar entropy will never be zero?
- Wed Mar 10, 2021 10:45 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneity in regards to enthalpy and entropy
- Replies: 3
- Views: 259
Spontaneity in regards to enthalpy and entropy
When deltaH is positive and deltaS is positive, the reaction is spontaneous above a certain temperature.
Does this mean that for the reverse reaction, the reaction is spontaneous below a certain temperature? If yes, is that always the case?
Does this mean that for the reverse reaction, the reaction is spontaneous below a certain temperature? If yes, is that always the case?
- Wed Mar 10, 2021 9:35 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Sapling Homework #14
- Replies: 4
- Views: 229
Re: Sapling Homework #14
Ryan_Page_1J wrote:The equation to use is ln(K2/K1)=( Ea/R)(1/T1 - 1/T2)
K2/K1 is equal to "how many times faster" that the problem gives you.
Where is this equation derived from? I don't see it on the equation sheet :(
- Wed Mar 10, 2021 9:20 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Sapling Homework #14
- Replies: 4
- Views: 229
Sapling Homework #14
A certain reaction has an activation energy of 63.96 kJ/mol. At what Kelvin temperature will the reaction proceed 6.00 times faster than it did at 347 K?
Hello! I am not sure how to get the equation to do this problem, why is A not included? Moreover, how do we know k2/k1=6.00?
Hello! I am not sure how to get the equation to do this problem, why is A not included? Moreover, how do we know k2/k1=6.00?
- Wed Mar 10, 2021 9:09 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Is there a catalyst in this mechanism? [ENDORSED]
- Replies: 6
- Views: 308
Is there a catalyst in this mechanism? [ENDORSED]
ClO−(aq)+H2O(l)⇌HClO(aq)+OH−(aq) fast in both directions
I−(aq)+HClO(aq)→HIO(aq)+Cl−(aq) slow
HIO(aq)+OH−(aq)→IO−(aq)+H2O(l) fast
I can recognize the intermediates, but can someone confirm if there are no catalysts in this mechanism?
I−(aq)+HClO(aq)→HIO(aq)+Cl−(aq) slow
HIO(aq)+OH−(aq)→IO−(aq)+H2O(l) fast
I can recognize the intermediates, but can someone confirm if there are no catalysts in this mechanism?
- Mon Mar 08, 2021 1:28 pm
- Forum: Balancing Redox Reactions
- Topic: Textbook Problem 6K.5 (a)
- Replies: 2
- Views: 160
Re: Textbook Problem 6K.5 (a)
For a reduction reaction, an oxidation number does not HAVE to decrease. For example in the case of O3 -> O2 the charges are neutral on both sides BUT the oxygens are not balanced. In this case you will have to add water to the right side and 2H+ on the left side. Then you will see that you need to ...
- Mon Mar 08, 2021 9:03 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Sapling #17
- Replies: 5
- Views: 312
Re: Sapling #17
What I did that helped me was drawing a curve and writing the numbers down. I'm not sure how to insert an image, but it is the typically energy barrier curves and Dr. Lavelle showed an image of it in the first lecture of kinetics. For this problem, you can look up endothermic energy barrier for ref...
- Fri Mar 05, 2021 7:36 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 5J.5 D
- Replies: 3
- Views: 413
5J.5 D
The question is asking if products or reactants will be favored by an increase of total pressure. E) 2HD(g)+H2(g) -> D2(g) The solution manual says no change because there is the same number of moles on each side of the equation. Can someone explain this? I thought it would shift towards the products.
- Wed Mar 03, 2021 7:36 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Textbook 6L.5
- Replies: 2
- Views: 162
Re: Textbook 6L.5
Yun Su Choi 3G wrote:I have the same question.. Also, if I2 is a solid, why would Pt(s) be necessary?
I2 is a nonmetal, so it is a very poor conductor! Because of this, you need the Pt :)
- Wed Mar 03, 2021 7:34 pm
- Forum: Student Social/Study Group
- Topic: Final Study Tips!
- Replies: 38
- Views: 1915
Re: Final Study Tips!
Time yourself while doing the textbook problems!! It will make you SO much more confident for the actual test, because you'll know that you'll be able to finish it on time or with time left over! I usually give myself about 3 minutes per problem, so if a set has 7 questions, I time myself for 21 min...
- Wed Mar 03, 2021 5:35 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Textbook 6L.5
- Replies: 2
- Views: 162
Textbook 6L.5
The textbook manual says the cell diagram of Ce4+(aq) + I−(aq) →I2(s) + Ce3+(aq) is
Pt(s)|I-(aq)|I2(s) || ...
Why does the I- (aq) come before the I2 solid? Shouldn't the aq be closest to the bridge?
Also, how do we write the half reactions for Au+ (aq) -> Au(s) + Au 3+ (aq)
Pt(s)|I-(aq)|I2(s) || ...
Why does the I- (aq) come before the I2 solid? Shouldn't the aq be closest to the bridge?
Also, how do we write the half reactions for Au+ (aq) -> Au(s) + Au 3+ (aq)
- Tue Mar 02, 2021 6:40 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst Equation
- Replies: 2
- Views: 197
Nernst Equation
"The dependence of cell potential on composition is expressed by the Nernst Equation"
Can someone explain this concept? Specifically, what is "dependence of cell potential on composition?"
Can someone explain this concept? Specifically, what is "dependence of cell potential on composition?"
- Sun Feb 28, 2021 7:51 pm
- Forum: Balancing Redox Reactions
- Topic: Sapling 3
- Replies: 5
- Views: 295
Re: Sapling 3
Gina Spagarino 3G wrote:So, looking at your final equation for that question, there should be no water in the reactants and only one water molecule in the products, but the 2OH- is correct!! sorry I made that more confusing with the incorrect first comment^^
Got it! Thank you :)
- Sun Feb 28, 2021 7:48 pm
- Forum: Balancing Redox Reactions
- Topic: hw #18
- Replies: 3
- Views: 207
Re: hw #18
Your answer is right! Sapling is just being a little weird so try formatting it in a different way. Try getting rid of the parenthesis and just leave the 2 in front of the Fe and also order it like this so that the placement of the reactants match the products:
Fe O2 H20 -> FeO3H2O
Fe O2 H20 -> FeO3H2O
- Sun Feb 28, 2021 11:49 am
- Forum: Balancing Redox Reactions
- Topic: Sapling 3
- Replies: 5
- Views: 295
Sapling 3
Hello! I am having a hard time getting the correct balanced equations. I learn best from making mistakes but I’m having a hard time finding where I went wrong. Can someone help me realize my mistake in these two? The top line is the original reaction.
- Sat Feb 27, 2021 9:19 pm
- Forum: Balancing Redox Reactions
- Topic: Sapling #3
- Replies: 3
- Views: 189
Sapling #3
This question is asking me to balance a reaction where NO is oxidized to NO3- and Fe3+ is reduced to Fe2+ in a basic solution.
Can someone tell me what I am doing wrong, I attached a picture :)
Can someone tell me what I am doing wrong, I attached a picture :)
- Mon Feb 22, 2021 9:02 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Question about Monday lecture (2/22/21)
- Replies: 5
- Views: 290
Question about Monday lecture (2/22/21)
Hello! In class Lavelle asked "How does cell concentration affect cell potential?"
Does someone mind going over how we can use Le Chatelier's principles to qualitatively determine this? I can't wrap my head around the explanation from class.
Does someone mind going over how we can use Le Chatelier's principles to qualitatively determine this? I can't wrap my head around the explanation from class.
- Mon Feb 22, 2021 11:16 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: isobaric
- Replies: 20
- Views: 1061
Re: isobaric
Also remember our terms isothermal and isochoric! Isothermal means a constant temp, and isochoric means a constant volume.
- Mon Feb 22, 2021 11:12 am
- Forum: Student Social/Study Group
- Topic: Chem 14B Final
- Replies: 86
- Views: 4976
Re: Chem 14B Final
I would like to add on that you can also try timing yourself while doing the textbook problems. During midterms, we are given about 4.5 minutes per problem, so when I do the textbook problems I make sure to time myself that exact amount of time. Normally, I give myself 3 minutes per problem to make ...
- Mon Feb 22, 2021 11:08 am
- Forum: Balancing Redox Reactions
- Topic: Balancing
- Replies: 9
- Views: 442
Re: Balancing
The only time you will need to change E is when you flip the reaction! Then it will become negative. Other than that, multiplying or dividing the reaction will not affect the E.
- Mon Feb 22, 2021 11:04 am
- Forum: Balancing Redox Reactions
- Topic: Writing Half Reactions
- Replies: 3
- Views: 115
Re: Writing Half Reactions
A cathode is used for reduction reactions while anode is used for oxidation. In a cell diagram, the anode is on the left while the cathode is on the right. So we know that the left of the cell diagram will be our oxidation and the right of the cell diagram will be our reduction. So, we can write our...
- Mon Feb 22, 2021 10:51 am
- Forum: Student Social/Study Group
- Topic: Culinary Chemistry
- Replies: 239
- Views: 29344
Re: Culinary Chemistry
Yesterday, I brought a bag of sliced apples for lunch with me but by the time I got to eat it, it was already browning. Then I remembered how my mom used to cover apples with lemon juice to keep them fresh all day long! The acidity of the lemon slows down the browning because ascorbic acid reacts wi...
- Mon Feb 22, 2021 10:47 am
- Forum: Balancing Redox Reactions
- Topic: Inert Conductor
- Replies: 3
- Views: 189
Re: Inert Conductor
An inert conductor is not involved in the reaction, which is exactly why it's called an inert conductor! You would use an inert conductor when there are no solids involved in the reaction because the reaction itself won't be able to work as an electrode. It's really just there to keep the reaction m...
- Mon Feb 15, 2021 8:21 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: q in relation to delta H & delta U [ENDORSED]
- Replies: 3
- Views: 218
Re: q in relation to delta H & delta U [ENDORSED]
Yes! If there is only heat being exchanged and no work is being done, then deltaU=q. (like you mentioned, this would be at a constant volume because deltaV would be 0 so w=-PV would be 0). If there is only work being done and no heat exchanged, deltaU=w. (isothermal, deltaT=0, so q=0) If both is bei...
- Mon Feb 15, 2021 8:11 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Isolated System
- Replies: 16
- Views: 866
Re: Isolated System
An isolated system just means that matter and energy cannot be exchanged with the surroundings. That being said, we can still make changes to the system. For example, in a bomb calorimeter we observe combustion reactions. Though it’s not exchanging heat with the surroundings, it is still exchanging ...
- Sun Feb 14, 2021 3:40 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Sapling #5 Week 5/6
- Replies: 2
- Views: 117
Re: Sapling #5 Week 5/6
Rylee Mangan 1K wrote:Im not sure if this is a typo or not but you put "1037.15" instead of 1073.15 K ! Hope this helps
i———
omg thank you i would’ve never realized HAHA
- Sun Feb 14, 2021 11:05 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Sapling #5 Week 5/6
- Replies: 2
- Views: 117
Sapling #5 Week 5/6
The molar heat capacity for carbon monoxide at constant volume is C V,m=20.17 J/(K·mol) . A 7.00 -L fixed-volume flask contains CO(g) at a pressure of 4.00 kPa and a temperature of 25.0 C. Assuming that carbon monoxide acts as an ideal gas and that its heat capacity is constant over the given temper...
- Fri Feb 12, 2021 8:04 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hw 4D.1
- Replies: 1
- Views: 45
Hw 4D.1
Carbon disulfide can be prepared from coke (an impure form of carbon) and elemental sulfur: 4C (s) + S8 (s) -> 4CS2 H=+358.8kJ How much heat is absorbed in the reaction of 1.25mol S8 at constant pressure? (b) Calculate the heat absorbed in the reaction of 197 g of carbon with an excess of sulfur. (c...
- Fri Feb 12, 2021 9:56 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: HW 4A.7
- Replies: 4
- Views: 188
HW 4A.7
Calculate the heat that must be supplied to a copper kettle of mass 400.0 g containing 300.0 g of water to raise its temperature from 20.0C to the boiling point of water, 100.0C. (b) What percentage of the heat is used to raise the temperature of the water? Can someone explain part B? How do I find ...
- Sun Feb 07, 2021 10:21 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Atoms, Linear, Non- Linear Molecules?
- Replies: 9
- Views: 937
Re: Atoms, Linear, Non- Linear Molecules?
The book classifies CO2 as linear, since it has two double bonds and no lone pairs. To classify something as linear, nonlinear, or just atoms, we would have to figure out the shape using VSEPR models.
- Sun Feb 07, 2021 10:14 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Vocab. in thermodynamics
- Replies: 8
- Views: 283
Vocab. in thermodynamics
Will these terms ever come up in the problems we do in thermodynamics?
-adiabatic wall
-diathermic wall
-translational energy
-rotational energy
-vibrational energy
-adiabatic wall
-diathermic wall
-translational energy
-rotational energy
-vibrational energy
- Sun Feb 07, 2021 10:11 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: State Functions
- Replies: 4
- Views: 179
State Functions
If both q and w are NOT state functions, then how is it that the change in internal energy is one?
I can't seem to wrap my head around this haha
I can't seem to wrap my head around this haha
- Sun Feb 07, 2021 8:57 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Which q equation to use
- Replies: 3
- Views: 145
Which q equation to use
How do I know when to use q=CdeltaT VS. q=mCdeltaT?
- Sun Feb 07, 2021 8:56 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Bomb calorimeter
- Replies: 7
- Views: 469
Bomb calorimeter
How does a bomb calorimeter work?
- Sun Jan 31, 2021 8:24 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Sapling #15
- Replies: 3
- Views: 164
Sapling #15
Automobile airbags contain solid sodium azide, NaN3, that reacts to produce nitrogen gas when heated, thus inflating the bag. 2NaN3(s)⟶2Na(s)+3N2(g) Calculate the value of work, W, for the system if 17.0 g NaN3 reacts completely at 1.00 atm and 22C. I keep getting this wrong. Can someone explain how...
- Sun Jan 31, 2021 8:23 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Sapling #18
- Replies: 1
- Views: 101
Sapling #18
A 0.513 mol sample of Xe(g), initially at 298 K and 1.00 atm, is held at constant pressure while enough heat is applied to raise the temperature of the gas by 11.7 K. Calculate the amount of heat q required to bring about this temperature change, and find the corresponding total change in the intern...
- Thu Jan 28, 2021 9:36 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Textbook 6D.17
- Replies: 1
- Views: 80
Textbook 6D.17
The question asks to find the pH of 0.055M AlCl3
I know how to solve the problem, but how do I set up the chemical equation for the AlCl3 for the ice table?
I know how to solve the problem, but how do I set up the chemical equation for the AlCl3 for the ice table?
- Mon Jan 25, 2021 7:05 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Homework 5I.19
- Replies: 2
- Views: 98
Homework 5I.19
A reaction mixture that consisted of 0.400mol H2 and 1.60mol I2 was introduced into a flask of volume 3.00L and heated. At equilibrium, 60.0% of the hydrogen gas has reacted. What is the constant K? In this problem, why do we multiply 0.13M H2 by 40%? I understand that is how much H2 is left over bu...
- Mon Jan 25, 2021 7:00 pm
- Forum: Student Social/Study Group
- Topic: Culinary Chemistry
- Replies: 239
- Views: 29344
Re: Culinary Chemistry
This can also be extended to baking!! I like to experiment with cookies, because every single ingredient can completely alter your cookie! Since baking soda is a base (sodium bicarbonate as we know), it is often used in recipes that use some kind of acid like lemon juice in order for your product to...
- Sun Jan 24, 2021 11:12 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Focus 5 Exercise 35
- Replies: 2
- Views: 53
Re: Focus 5 Exercise 35
For a, I believe we will need to use the change in partial pressures to find the equation. First, we know that A will be the reactant because it is decreasing as B and C increase. For “A” the total partial pressure change is about 10, (27-17=10kPa). For C it is also 10 and for B it is 5. We can use ...
- Sun Jan 24, 2021 11:00 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Homework #7
- Replies: 10
- Views: 281
Re: Sapling Homework #7
The chemical formula would be ClO4- + H2O = HClO4 + OH-. Keep in mind that the Kb for this reaction would be 10^-14/Ka (Ka is given). Now you approach this problem like a regular ICE table equilibrium problem. Right, I know the equation will be that but how do I apply it to other problems? Is it be...
- Sun Jan 24, 2021 10:58 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Homework 5G.3
- Replies: 3
- Views: 165
Homework 5G.3
For a, the question asks us to find the K expression of
2 C2H4(g) + O2(g) + 4HCl(g) <-> 2 C2H4Cl2(g) +2 H2O(g)
Would we leave out the H2O and the O2 in the K expression? Moreover, would we write the K expression like P(C2H4Cl2) or [C2H4Cl2]
The book isn’t showing me the answers :(
2 C2H4(g) + O2(g) + 4HCl(g) <-> 2 C2H4Cl2(g) +2 H2O(g)
Would we leave out the H2O and the O2 in the K expression? Moreover, would we write the K expression like P(C2H4Cl2) or [C2H4Cl2]
The book isn’t showing me the answers :(
- Sat Jan 23, 2021 9:48 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: amphoteric vs amphiprotic
- Replies: 10
- Views: 251
Re: amphoteric vs amphiprotic
Aluminum Oxide acts as an acid and a base, so it is amphoteric, but since it has NO hydrogen protons to donate it is NOT amphiprotic.
- Sat Jan 23, 2021 11:13 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Homework #7
- Replies: 10
- Views: 281
Sapling Homework #7
The problem asks: HClO is a weak acid ( Ka=4.0×10−8 ) and so the salt NaClO acts as a weak base. What is the pH of a solution that is 0.024 M in NaClO at 25 °C? How do I set up the chemical formula for this problem? How do I know what will be the products vs the reactants? Just want to know how to d...
- Wed Jan 20, 2021 11:51 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Week 2 Sapling #5
- Replies: 9
- Views: 239
Week 2 Sapling #5
The problem asks: The Kb for an amine is 2.992×10−5. What percentage of the amine is protonated if the pH of a solution of the amine is 9.697 ? Assume that all OH− came from the reaction of B with H2O In this case, are we allowed to disregard the X in the Ka equation? So that it would just be Ka=X^2...
- Sun Jan 17, 2021 5:29 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: 6D7
- Replies: 1
- Views: 117
Re: 6D7
The textbook links you to a chart with aka/Kb values at the top of the page just above exercise 1, are the K values you need listed there?
- Sun Jan 17, 2021 5:21 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Textbook 6A.23
- Replies: 2
- Views: 83
Re: Textbook 6A.23
Ba(OH)2 is a strong base and ionizes completely. Start off by writing its chemical equation. Find the molarity of Ba(OH)2 in order to find the concentration of OH-. We did this in class I believe.
To find the concentration of H3O+, use the Kw constant equation!
To find the concentration of H3O+, use the Kw constant equation!
- Sun Jan 17, 2021 5:17 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Calculating K with multiple chemical formulas
- Replies: 3
- Views: 201
Calculating K with multiple chemical formulas
How do we combine K values? This question is pertaining to Sapling #5 where we are given four chemical formulas and have to combine K values
- Sun Jan 17, 2021 5:13 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: Sapling HW Q6
- Replies: 3
- Views: 239
Re: Sapling HW Q6
First write the bases and acids the salts are derived from. For example NaF is derived from NaOH and HF. A salt will be basic if it contains the conjugate base of a weak acid. In this case, HF is weak, so it’s conjugate base (F-) will be strong and therefore the salt is basic. Same process for acidi...
- Sat Jan 16, 2021 2:58 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kw constant
- Replies: 25
- Views: 670
Kw constant
When calculating Kw, why do we leave out [H2O]?
- Sat Jan 09, 2021 8:44 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Pressure Changes
- Replies: 3
- Views: 67
Pressure Changes
Can anyone summarize the concepts we need to know for change of pressure? Such as when you decrease the volume.
- Sat Jan 09, 2021 8:43 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: K Constant
- Replies: 3
- Views: 97
K Constant
Why does the K constant stay the same when adding more reactant?
- Fri Jan 08, 2021 1:29 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Using Activity for non-ideal gases
- Replies: 1
- Views: 76
Re: Using Activity for non-ideal gases
I have a feeling we won't be doing this for a while, maybe in upper div classes? The "real" gas law is quite complicated.
- Fri Jan 08, 2021 1:25 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Increasing Volume in Change of Pressure
- Replies: 7
- Views: 128
Increasing Volume in Change of Pressure
I have not quite grasped this concept yet, but what happens if we increase the volume?
- Fri Jan 08, 2021 1:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: lecture 3 question
- Replies: 4
- Views: 87
Re: lecture 3 question
The quadratic equation is just a quicker way to solve for X! When you cross multiply X^2/(3-x)=1.8, you get a quadratic function and the simplest way to solve it is through the quadratic equation.
- Wed Dec 09, 2020 12:59 pm
- Forum: Hybridization
- Topic: Composition of Bonds
- Replies: 1
- Views: 121
Re: Composition of Bonds
The first p orbital would be denoted as px (x being a subscript) because it lies on the x plane. The second would be py and then pz.
- Mon Dec 07, 2020 9:51 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Ebook/Textbook problems
- Replies: 9
- Views: 584
Re: Ebook/Textbook problems
i have the same problem but with the solutions!! i have no idea why
Re: 9C.3d
You would use bis, tris, etc prefixes when referring to polydentates. You use the regular prefixes like bi for monodentate ligands.
- Mon Dec 07, 2020 8:27 pm
- Forum: Bronsted Acids & Bases
- Topic: acid strength
- Replies: 3
- Views: 229
Re: acid strength
A strong acid will yield a weak conjugate base. A weak acid will yield a strong conjugate base. Because the conjugate base in this case is more stable, we know it is weaker. Unstable molecules are more reactive, meaning they are stronger. With resonance, the molecule is able to handle the negative c...
- Mon Dec 07, 2020 8:19 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Cisplatin Question
- Replies: 1
- Views: 174
Re: Cisplatin Question
The chloride is favored because there is a low concentration of Cl within the cell, and the cisplatin goes under hydrolysis. Cisplatin is administered to a patient into the bloodstream. The cisplatin itself is contained within a solution with NaCl, so while it’s in the bloodstream, the chlorine rema...
- Mon Dec 07, 2020 7:40 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: CO32- why is it polydentate
- Replies: 1
- Views: 68
Re: CO32- why is it polydentate
CO3 2- has two oxygens, so it can bind to a metal in two place and therefore bidentate. Because of this, it technically CAN bind in two places, but this is not very common because of its size and shape (like you said).
- Wed Dec 02, 2020 6:15 pm
- Forum: Biological Examples
- Topic: Cr - insulin Example
- Replies: 2
- Views: 355
Re: Cr - insulin Example
I had to look at my old highschool notes for this but here is what I concurred: Chromium is a cofactor, a substance that aids in enzyme activity. Organic cofactors are ones we know very well, vitamins. Other cofactors are also group1+2 and transition metals. There are few ways that our body regulate...
- Wed Dec 02, 2020 5:54 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Number
- Replies: 2
- Views: 155
Re: Coordination Number
^^
And it is separate from oxidation numbers. The oxidation number refers to the charges of the atoms.
To figure out the oxidation number for a TM cation , you would have to look at the overall charge and the charges of the ligands.
overall charge= X(TM charge) + Y(charges of ligands)
And it is separate from oxidation numbers. The oxidation number refers to the charges of the atoms.
To figure out the oxidation number for a TM cation , you would have to look at the overall charge and the charges of the ligands.
overall charge= X(TM charge) + Y(charges of ligands)
- Wed Dec 02, 2020 3:49 pm
- Forum: Naming
- Topic: Oxidation State
- Replies: 4
- Views: 235
Re: Oxidation State
Yep. It’s just the number of electrons it gains or loses when forming a bond.
- Wed Dec 02, 2020 1:42 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Understanding coordination compounds
- Replies: 3
- Views: 165
Re: Understanding coordination compounds
In my notes, I have cisplatin written as square planar, not octahedral? If the complex’s coordination number is 4, it can either be tetrahedral or square planar. It’s a bit too complicated for us to distinguish which one it’ll be, so we would just have to memorize cisplatin as square planar due to t...
- Wed Dec 02, 2020 12:22 am
- Forum: Naming
- Topic: Memorizing ligand names
- Replies: 6
- Views: 262
Re: Memorizing ligand names
Lavelle said on the final we will need our periodic table, a calculator, and our equations sheet, so I do not think a ligand sheet will be allowed. We should know the basic ones, like Cl, NH3, H2O etc. For the bigger ones like edta, we do not need to know the structure but I believe it's important t...
- Mon Nov 23, 2020 11:26 pm
- Forum: Ionic & Covalent Bonds
- Topic: Textbook Question 1A.13
- Replies: 4
- Views: 322
Re: Textbook Question 1A.13
Hi! The way the compound is written out actually tells you the order you should draw them in. The parenthesis are there to emphasize a group. So the first carbon would have two hydrogens, an amine (NH2) group, and then connected to the next carbon. The second carbon would have an oxygen double bonde...
- Mon Nov 23, 2020 11:20 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: isoelectronic
- Replies: 12
- Views: 1001
Re: isoelectronic
Isoelectronic is used to describe atoms and ions with the same number of electrons
For example Na+ and Mg2+
For example Na+ and Mg2+
- Mon Nov 23, 2020 11:18 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E #7
- Replies: 3
- Views: 211
Re: 2E #7
Thionyl chloride has a trigonal pyramid shape because it has 3 regions of electron density as well as one lone pair. Because there are 4 total regions of electron density, we know the bonds should be equally 109 degrees based on our tetrahedral shape. However, the lone pair pushes the bonds down a b...
- Mon Nov 23, 2020 11:11 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Determining Molecular Polarity using VSEPR
- Replies: 8
- Views: 383
Re: Determining Molecular Polarity using VSEPR
The two oxygens are pointing exactly 180 degrees away from eachother. Since the dipoles are on exact opposite sides of the central atom, they will cancel out.
- Mon Nov 23, 2020 11:10 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Silver Electron Configuration
- Replies: 9
- Views: 2627
Re: Silver Electron Configuration
Elements in the same group as Cu would also “act” like Cu. Copper is one of our exceptions in electron configurations: its d-orbital will have a full shell (3d10 4s1). Any element under Cu will act the same so silver’s d orbital will also have a full shell.
- Mon Nov 23, 2020 12:34 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Why is CH2Cl2 polar?
- Replies: 6
- Views: 332
Why is CH2Cl2 polar?
Why is CH2Cl2 polar?
- Mon Nov 23, 2020 11:08 am
- Forum: Student Social/Study Group
- Topic: How have your study habits changed?
- Replies: 45
- Views: 1645
How have your study habits changed?
Since we have already taken two midterms in this course, how would you say your study habits changed throughout the term? I know a lot of folks had very different study habits in high school, so what have you done to adjust to this class? I think the biggest change for me was my style of notes. Afte...
- Tue Nov 17, 2020 10:37 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chem14B Waitlist Spots
- Replies: 6
- Views: 367
Re: Chem14B Waitlist Spots
Megan Singer 1F wrote:^regarding my previous post. All the last spots open are for a 6pm discussion session, which I'd rather not do but will take over no class at all. Should I just enroll in that to be safe?
Edit: nvm LOL it filled up
omg noooooo:(
- Tue Nov 17, 2020 10:37 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chem14B Waitlist Spots
- Replies: 6
- Views: 367
Re: Chem14B Waitlist Spots
Megan Singer 1F wrote:^regarding my previous post. All the last spots open are for a 6pm discussion session, which I'd rather not do but will take over no class at all. Should I just enroll in that to be safe?
I think it is def worth enrolling in that one!
- Tue Nov 17, 2020 10:13 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chem14B Waitlist Spots
- Replies: 6
- Views: 367
Chem14B Waitlist Spots
Is it possible for more waitlists spots to open in January? I had no other option but to sign up for chem 14B during second pass and it seems like it will fill up completely before then :((
To those of you who feel like they are not getting chem14b, what is your alternative plan?
To those of you who feel like they are not getting chem14b, what is your alternative plan?
- Mon Nov 16, 2020 6:59 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: chemical formula of compound
- Replies: 6
- Views: 268
Re: chemical formula of compound
From the periodic table, we know that the charge of Mg is 2+ and the charge of As is 3- We want to create a neutral compound, so you need enough of each atom to cancel out the charges. So we would need 3 Mg and 2 As in order for the charges to cancel out (6-6). Essentially, you are just switching th...
- Mon Nov 16, 2020 6:54 pm
- Forum: Ionic & Covalent Bonds
- Topic: textbook problem 2D3 and 2D5
- Replies: 3
- Views: 105
Re: textbook problem 2D3 and 2D5
Hi! You can figure this out by looking at the locations of each atom on the periodic table. The closer an atom is to F, the higher its electronegativity value is. For example, Ba is the farthest from chlorine, so the electronegativity difference will be the highest of the three.
- Mon Nov 16, 2020 5:31 pm
- Forum: Lewis Structures
- Topic: 2C.3
- Replies: 2
- Views: 138
Re: 2C.3
Because of the 2- charge, we know that this molecule is a Lewis base. Normally, bases have “-OH” so you know that the hydrogen will be attached to the oxygen. Another way to know is by just messing around with the structures themselves. When you attach H to the P, the lewis structure exceeds the num...
- Mon Nov 16, 2020 5:23 pm
- Forum: Lewis Structures
- Topic: 2C.5
- Replies: 3
- Views: 123
Re: 2C.5
Oxygen’s octet fills up first leaving the lone pair electron to be on the chlorine. You cannot put the lone e- on the oxygen since it cannot have an expanded octet.
- Mon Nov 16, 2020 5:15 pm
- Forum: Coordinate Covalent Bonds
- Topic: Lewis Structures for Coordinate Covalent Bonds
- Replies: 2
- Views: 290
Re: Lewis Structures for Coordinate Covalent Bonds
For this class, no you would not have to indicate where the bond came from. I can only see this happening if the question is specifically asking for it. As long as you get the final lewis structure correct, that’s all you need to show!
- Sun Nov 15, 2020 4:06 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: electron-electron repulsion
- Replies: 4
- Views: 248
Re: electron-electron repulsion
this might be more helpful
- Sun Nov 15, 2020 3:06 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: electron-electron repulsion
- Replies: 4
- Views: 248
Re: electron-electron repulsion
Hi, are you talking about electron-electron repulsion in reference to VSEPR theory? If so, electron-electron repulsion will actually make a molecule more stable, and therefore will be lower in energy. When electrons in a molecule are closer together, they are "excited" and are higher in e...
- Tue Nov 10, 2020 7:08 pm
- Forum: Electronegativity
- Topic: Electronegativity values
- Replies: 4
- Views: 112
Electronegativity values
In highschool, I was taught electronegativity values as:
ionic bond >1.7
polar covalent bond 0.5-1.7
nonpolar covalent bond <0.5
Why do we do it differently?
ionic bond >1.7
polar covalent bond 0.5-1.7
nonpolar covalent bond <0.5
Why do we do it differently?
- Tue Nov 10, 2020 6:57 pm
- Forum: Student Social/Study Group
- Topic: Exercising Our Minds and Bodies
- Replies: 120
- Views: 14551
Re: Exercising Our Minds and Bodies
Learning the choreo for "I Cant Stop Me" by twice B)
- Tue Nov 10, 2020 6:56 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: electron-electron repulsion
- Replies: 4
- Views: 248
Re: electron-electron repulsion
Hi, are you talking about electron-electron repulsion in reference to VSEPR theory? If so, electron-electron repulsion will actually make a molecule more stable, and therefore will be lower in energy. When electrons in a molecule are closer together, they are "excited" and are higher in en...
- Tue Nov 10, 2020 6:03 pm
- Forum: Dipole Moments
- Topic: Debye
- Replies: 2
- Views: 135
Re: Debye
I believe Debye is just the unit used to measure the magnitude of a dipole dipole moment. The SI units of Debye would be written in coulomb meters. It’s used to measure the charge difference.
- Tue Nov 10, 2020 5:56 pm
- Forum: Dipole Moments
- Topic: Ionic Character
- Replies: 3
- Views: 276
Ionic Character
What does it mean if a bond has a “higher” ionic character?
- Wed Nov 04, 2020 2:27 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic v. Covalent Bonds`
- Replies: 10
- Views: 829
Re: Ionic v. Covalent Bonds`
Ionic bonds are between nonmetals and metals. They involve a TRANSFER of electrons. So atoms either fully gain or lose electrons.
Covalent bonds are between nonmetals and nonmetals. These involve SHARING of electrons.
Both are similar in that they lead to creation of stable molecules.
Covalent bonds are between nonmetals and nonmetals. These involve SHARING of electrons.
Both are similar in that they lead to creation of stable molecules.
- Wed Nov 04, 2020 2:24 pm
- Forum: Octet Exceptions
- Topic: Limit to octet exception
- Replies: 2
- Views: 150
Re: Limit to octet exception
I believe it depends on the number of valence electrons. For example, P can only hold 5 bonds due to its 5 valence electrons. The d orbital allows it to have more than an octet but it cannot exceed past its 5 valence electrons.
- Wed Nov 04, 2020 2:17 pm
- Forum: Ionic & Covalent Bonds
- Topic: London Dispersion Forces
- Replies: 5
- Views: 105
Re: London Dispersion Forces
Hello! All molecules have London Dispersion forces. These forces are intermolecular, interactions between molecules (intramolecular is within molecules). LDF is the weakest type of intermolecular force.
- Wed Nov 04, 2020 2:14 pm
- Forum: Coordinate Covalent Bonds
- Topic: Coordinate covalent bond
- Replies: 3
- Views: 106
Re: Coordinate covalent bond
Yes, you are right about both! I think it is also good to point that yes coordinate covalent bonds happen when an atom does not have enough electrons to fulfill an octet, but it can happen in more than one way. For example, a double bond between C and O fulfills the octet of the O but not the C. The...
- Wed Nov 04, 2020 2:07 pm
- Forum: Coordinate Covalent Bonds
- Topic: Coordinate covalent bond lecture example
- Replies: 4
- Views: 224
Re: Coordinate covalent bond lecture example
Hi! The fluoride can come from the reaction itself depending on the reagents. Fluoride is considered a leaving group (albeit a really bad one) and can "detach" from a structure. So if BF3 was reacting with let's say X-F, the bond in X-F is broken and the electrons are transferred to F crea...
- Sun Nov 01, 2020 12:16 am
- Forum: Trends in The Periodic Table
- Topic: Electron Affinity #23
- Replies: 4
- Views: 112
Re: Electron Affinity #23
Gerardo Ortega 2A wrote:I used 4 sig figs for both my first answer and my second answer
thank you so much i was able to fix it!!!
- Sat Oct 31, 2020 11:59 pm
- Forum: Trends in The Periodic Table
- Topic: Electron Affinity #23
- Replies: 4
- Views: 112
Re: Electron Affinity #23
Gerardo Ortega 2A wrote:Your setup is the same way I solved it and I ended up getting it right. Maybe it's the number of sig figs?
True, how many sig figs did you use? I have tried four, three, and even tried using *10 but its still not working LOL