Search found 50 matches
- Sun Mar 14, 2021 10:26 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Entropy
- Replies: 4
- Views: 397
Re: Entropy
I think for our purposes there is only one type of entropy. There might be more at a higher level of learning.
- Sun Mar 14, 2021 10:22 pm
- Forum: First Order Reactions
- Topic: Remembering Half Life Formulas
- Replies: 3
- Views: 275
Remembering Half Life Formulas
Does anyone have any suggestions for remembering the different half-life formulas for different order reactions?
- Sun Mar 14, 2021 10:21 pm
- Forum: General Rate Laws
- Topic: Intermediate
- Replies: 59
- Views: 4117
Re: Intermediate
A good way to recognize an intermediate is that it is made as a product and then used as a reactant in the next step.
- Sun Mar 14, 2021 10:20 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt Bridges
- Replies: 4
- Views: 500
Salt Bridges
How is a salt bridge represented on a cell diagram?
- Sun Mar 14, 2021 10:18 pm
- Forum: Student Social/Study Group
- Topic: Note Taking
- Replies: 145
- Views: 19801
Re: Note Taking
I like using Goodnotes 5! You can handwrite and then search your handwriting.
- Sun Mar 07, 2021 10:52 am
- Forum: General Rate Laws
- Topic: Youtube Review
- Replies: 17
- Views: 1054
Youtube Review
Any suggestions for Youtube channels that review chemistry topics (specifically 14B) well?
- Sun Mar 07, 2021 10:47 am
- Forum: Zero Order Reactions
- Topic: Overall order of the reaction
- Replies: 45
- Views: 2330
Re: Overall order of the reaction
I agree with what they said, for example if you have an equation A + B -> C and A is first order and B is second order, the overall order would be 3.
- Sun Mar 07, 2021 10:36 am
- Forum: First Order Reactions
- Topic: How to determine the Order of reactions
- Replies: 8
- Views: 430
Re: How to determine the Order of reactions
From my understanding, you can determine the order of a reaction by plotting concentration data. Depending on the order, the graph will be in a straight line, which alerts you that you have identified the right order.
- Sun Mar 07, 2021 10:32 am
- Forum: Balancing Redox Reactions
- Topic: Balancing Reactions Help
- Replies: 5
- Views: 346
Balancing Reactions Help
Does anyone have any good resources for reviewing the rules for balancing reactions?
- Sat Feb 27, 2021 2:37 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic vs electrolytic cells
- Replies: 1
- Views: 140
Galvanic vs electrolytic cells
Does anyone have a quick summary of the difference between galvanic and electrolytic cells?
- Sat Feb 27, 2021 2:35 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation vs Reduction
- Replies: 30
- Views: 1487
Re: Oxidation vs Reduction
I remember reduction is gaining electrons by thinking that the charge is "reducing" or becoming more negative.
- Sat Feb 27, 2021 2:32 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Shorthand
- Replies: 5
- Views: 316
Cell Shorthand
In lecture, we went over the shorthand for a cell, but it looked like this: w|x || y|z
In this week's sapling, there are two single lines on either side of the double. What do the sections of an expanded shorthand mean?
In this week's sapling, there are two single lines on either side of the double. What do the sections of an expanded shorthand mean?
- Sat Feb 27, 2021 2:28 pm
- Forum: Balancing Redox Reactions
- Topic: Stoichiometric Coefficients
- Replies: 1
- Views: 147
Stoichiometric Coefficients
When dividing Cl2+2Li⟶2LiCl into if half-reactions, Sapling accepts Li⟶Li+e− for the oxidation half-reaction. Why can we ignore the coefficients?
- Sat Feb 27, 2021 2:24 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Acidic Versus Basic Solutions
- Replies: 20
- Views: 1007
Balancing Acidic Versus Basic Solutions
When balancing reactions, I've noticed that we balance acidic solutions differently than basic ones. Why do we do this and what are the differences?
- Sat Feb 27, 2021 2:20 pm
- Forum: Balancing Redox Reactions
- Topic: Assigning Oxidation Numbers
- Replies: 3
- Views: 241
Assigning Oxidation Numbers
When assigning the oxidation numbers to KClO2, Sapling says we know O2 is 2- and K is 1+ and then we do subtraction to deduct the oxidation number for Cl. Does anyone have a good way of remembering which elements we use subtraction to infer the oxidation number rather than having a set value?
- Sat Feb 27, 2021 2:16 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: S.H.E. in Nonstandard Conditions
- Replies: 1
- Views: 125
Re: S.H.E. in Nonstandard Conditions
From my understanding, because the temperature is standard (298K), we can replace RT with 0.0592 V and proceed to use the Nernst equation as usual.
- Sat Feb 27, 2021 11:34 am
- Forum: Balancing Redox Reactions
- Topic: Sapling Week 7/8 #18
- Replies: 2
- Views: 162
Sapling Week 7/8 #18
I am being asked to balance this chemical equation. I am unsure why Sapling keeps telling me I am wrong.
- Sat Feb 27, 2021 11:19 am
- Forum: Balancing Redox Reactions
- Topic: Sapling Week 5 Second Section
- Replies: 2
- Views: 224
Sapling Week 5 Second Section
I have been able to identify the oxidizing and reducing agent for this equation:
[Pb(OH)4]2−(aq)+ClO−(aq)⟶PbO2(s)+Cl−(aq)
Somehow I cannot balance the equation if anyone has any tips!
[Pb(OH)4]2−(aq)+ClO−(aq)⟶PbO2(s)+Cl−(aq)
Somehow I cannot balance the equation if anyone has any tips!
- Sat Feb 27, 2021 11:18 am
- Forum: Balancing Redox Reactions
- Topic: Sapling Question 5
- Replies: 1
- Views: 147
Sapling Question 5
Could someone walk me through how they balanced this equation:
Cl2O7(g)+H2O2(aq)⟶ClO−2(aq)+O2(g)
I have done it many times and can't seem to get it right.
Cl2O7(g)+H2O2(aq)⟶ClO−2(aq)+O2(g)
I have done it many times and can't seem to get it right.
- Sat Feb 27, 2021 11:16 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Sapling Question 17
- Replies: 2
- Views: 315
Sapling Question 17
The question I am given is "What would the potential of a standard hydrogen electrode (S.H.E.) be under the given conditions?"
[H+]=0.49 M PH2=4.5 atm T=298 K
How do I find E° and the Q value for the half-reaction to apply it to the Nernst Equation?
[H+]=0.49 M PH2=4.5 atm T=298 K
How do I find E° and the Q value for the half-reaction to apply it to the Nernst Equation?
- Sun Feb 21, 2021 10:06 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Calculating Disorder based on molecule size
- Replies: 12
- Views: 775
Calculating Disorder based on molecule size
Is it fair to say that larger molecules will always have more disorder than smaller ones?
- Sun Feb 21, 2021 10:04 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: interchanging q rev and deltaH
- Replies: 6
- Views: 615
interchanging q rev and deltaH
Under what conditions are we allowed to make deltaS=qrev/T into deltaS=deltaH/T?
- Sun Feb 21, 2021 10:03 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Using Pressure in a deltaS equation
- Replies: 4
- Views: 421
Using Pressure in a deltaS equation
In practice problem 4F.9 we are given the pressure changes to find the change in Entropy. How do we apply that to the equation: deltaS=nRln(V2/V1)?
- Sun Feb 21, 2021 9:40 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Trouton's rule
- Replies: 4
- Views: 360
Trouton's rule
What exactly is Trouton's rule? I saw it on a practice problem and can't remember if we learned it yet.
- Sun Feb 21, 2021 9:36 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Reversible vs Irreversible Entropy Calculation
- Replies: 5
- Views: 432
Reversible vs Irreversible Entropy Calculation
Wondering how we know which change in entropy equation to use in a reversible reaction versus an irreversible reaction.
- Sun Feb 07, 2021 10:44 am
- Forum: Calculating Work of Expansion
- Topic: q=-w
- Replies: 5
- Views: 195
q=-w
When does q=-w?
- Sun Feb 07, 2021 10:41 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: work in an isothermal system
- Replies: 2
- Views: 235
work in an isothermal system
I saw a post on chemistry community that said if there is no heat transfer q=0. Does this mean there is work done? or does work correlate to volume change?
- Sun Feb 07, 2021 10:38 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Cv and Cp
- Replies: 3
- Views: 150
Re: Cv and Cp
I am having the same confusion, I ran into this problem in Week 3/4 Sapling #18. I had never seen a Cv or Cp and am confused on what the difference is.
- Sun Feb 07, 2021 10:36 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Clarifying different q equations
- Replies: 1
- Views: 89
Clarifying different q equations
I am having trouble keeping track of the different equations and conditions for q. The ones I have identified are q=deltaH=nCpdeltaT, qsys=-qsurr, qv=deltaU, and deltaU=q+w=0.
Does anyone have a good way of remembering under what conditions these equations are used for?
Does anyone have a good way of remembering under what conditions these equations are used for?
- Sun Feb 07, 2021 10:32 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Sapling Week 3/4 Question 18
- Replies: 9
- Views: 459
Sapling Week 3/4 Question 18
I thought that deltaU = q+w, but I was unable to solve for the work in this problem. The feedback is saying that deltaU = nCvdeltaT. I guess I have two questions, when are these two equations used? and how do you derive Cv from Cp?
- Sun Jan 31, 2021 8:45 pm
- Forum: Calculating Work of Expansion
- Topic: reversible vs irreversible expansion [ENDORSED]
- Replies: 2
- Views: 219
Re: reversible vs irreversible expansion [ENDORSED]
I think it is because it does the maximum amount of work by pushing against the maximum external pressure.
- Sun Jan 31, 2021 6:38 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: definition confusion
- Replies: 5
- Views: 214
Re: definition confusion
From my understanding, they are not. I know that specific heat capacity is the amount of heat needed to raise the temperature of 1g by 1 degree celcius. I think specific enthalpy is just the energy in the system. It is confusing though that they seem to be used interchangeably.
- Sat Jan 30, 2021 12:22 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Molar and Specific Heat Capacity
- Replies: 6
- Views: 293
Molar and Specific Heat Capacity
Are molar and specific heat capacity interchangeable? Are there any instances or equations where you must you one or can they be used in any situation where heat capacity is needed?
- Sat Jan 30, 2021 12:19 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat Capacity vs. Specific Heat
- Replies: 7
- Views: 306
Heat Capacity vs. Specific Heat
If both heat capacity and specific heat capacity measure heat, how is one an extensive property and the other is intensive?
- Sat Jan 30, 2021 12:09 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Finding the value of q
- Replies: 2
- Views: 236
Re: Finding the value of q
From my understanding the equation you would use is ΔU = Q − W. You then rearrange the equation to solve for Q. (remember that delta U is the change in internal energy and W is the amount of work done by the sysatem)
- Sun Jan 24, 2021 6:02 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy of a Phase Change
- Replies: 5
- Views: 207
Enthalpy of a Phase Change
In Method 2 (bond enthalpies) for finding total enthalpy change, we were told to incorporate the enthalpies of a phase change. How do we know when to include that and what the corresponding value is?
- Sun Jan 24, 2021 5:58 pm
- Forum: Phase Changes & Related Calculations
- Topic: Heat vs Temp
- Replies: 3
- Views: 236
Re: Heat vs Temp
From my understanding, heat is not a state property because the amount of heat used or released depends on the pathway taken. Whereas temperature is only dependent on the initial and final values.
- Sun Jan 24, 2021 5:55 pm
- Forum: Phase Changes & Related Calculations
- Topic: Work on vs by
- Replies: 4
- Views: 198
Re: Work on vs by
This is because the system has lost energy by performing this work and has therefore lost heat.
- Sun Jan 24, 2021 5:53 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: When enthalpy is zero
- Replies: 4
- Views: 408
Re: When enthalpy is zero
I like to think of it as a measure of change. In this case, there is no change because elements are in their most stable state naturally.
- Sun Jan 24, 2021 5:48 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies versus Standard Enthalpies of Formation
- Replies: 1
- Views: 90
Bond Enthalpies versus Standard Enthalpies of Formation
Can someone elaborate on the difference between using bond enthalpies and standard enthalpies of formation?
- Sun Jan 17, 2021 2:02 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Salt Solution
- Replies: 1
- Views: 109
Salt Solution
What makes a salt solution different from a regular one? Do we treat them differently when doing equilibrium calculations?
- Sun Jan 17, 2021 1:57 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Amphiprotic
- Replies: 8
- Views: 396
Amphiprotic
Can someone help define an amphiprotic molecule and how it relates to water?
- Sat Jan 16, 2021 10:22 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Weak versus Strong Acid and Base
- Replies: 10
- Views: 597
Weak versus Strong Acid and Base
Depending on if the acid/base is weak/strong we deal with them differently in equations, but how do we determine whether they are strong or weak? Is this something we just have to memorize?
- Sat Jan 16, 2021 10:18 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: pH of a Weak Acid
- Replies: 4
- Views: 146
Re: pH of a Weak Acid
Like they said above, if the x is less than 5% of the initial concentration then you can approximate the x value.
- Sat Jan 16, 2021 10:13 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Percent Ionization
- Replies: 2
- Views: 174
Percent Ionization
Can someone explain the formula for calculating percent ionization. I remember in lecture we learned that for an acid it is the concentration of the conjugate base over the initial concentration of the acid times 100. For example, [CH3OO-]/[CH3OOH]initial x 100. In a practice problem I was told that...
- Sun Jan 10, 2021 5:16 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Stable Reactants and Products
- Replies: 7
- Views: 261
Stable Reactants and Products
What does "Stability" imply? In lecture we learned that a large K means the product is more stable and conversely a small K means the reactant is more stable.
- Sun Jan 10, 2021 5:07 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Are there reactions that just do not/ can not ever reach equilibrium?
- Replies: 18
- Views: 1919
Re: Are there reactions that just do not/ can not ever reach equilibrium?
Is it ever necessary to know how long it will take for the reaction to create equilibrium in order to solve an equation?
- Sun Jan 10, 2021 3:53 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Changing volume
- Replies: 6
- Views: 375
Re: Changing volume
You can think of it as a sort of balance that the reaction is trying to achieve. If there are more moles on the left the reaction wants to get the same amount on both sides, so it will create more products in order to compensate.
- Sun Jan 10, 2021 3:49 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Change in Conc
- Replies: 8
- Views: 276
Re: Change in Conc
So does a change in concentration affect the system in the present? Meaning that it does not affect equilibrium because that constant will remain the same, but it will have an effect on the system before it returns to equilibrium.
- Sun Jan 10, 2021 3:46 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Delta H and its affect
- Replies: 5
- Views: 261
Re: Delta H and its affect
I am not sure if this has been taught yet, but how do we determine if a reaction is endo/exothermic?