Search found 49 matches
- Tue Mar 17, 2020 12:32 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: pH of acids
- Replies: 13
- Views: 1009
Re: pH of acids
pH=-log[H+] and strong acids cause there to be a high [H+] than weak acids this strong acids have a pH closer to 0 while weak acids are closer to 7 on the scale of 0-7
- Tue Mar 17, 2020 12:27 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Kelvin or Celsius?
- Replies: 86
- Views: 5162
Re: Kelvin or Celsius?
kelvin so it cancels out with the units of R
- Tue Mar 17, 2020 12:26 pm
- Forum: Zero Order Reactions
- Topic: 0 order
- Replies: 7
- Views: 641
Re: 0 order
zero-order rate isn't dependent on the reactant concentrations and has a linear graph when [A] is graphed vs time
- Tue Mar 17, 2020 12:24 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Redox from cell diagram
- Replies: 6
- Views: 451
Re: Redox from cell diagram
the left of the double line is being oxidized while the right is being reduced (you can remember this because of the two r's)
- Tue Mar 17, 2020 12:21 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: k
- Replies: 36
- Views: 1462
Re: k
a large k means a faster reaction rate
- Tue Mar 17, 2020 12:17 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Slowest step
- Replies: 38
- Views: 1376
Re: Slowest step
the slow step takes the most time and the reaction cannot be completed before this step is completed, it determines the reaction rate therefore
- Tue Mar 17, 2020 12:15 pm
- Forum: Calculating Work of Expansion
- Topic: Ideal gas
- Replies: 7
- Views: 633
Re: Ideal gas
that indicates that PV=nRT is applicable
- Tue Mar 17, 2020 12:13 pm
- Forum: Zero Order Reactions
- Topic: Equations for 0, 1st, and 2nd order reactions
- Replies: 4
- Views: 350
Re: Equations for 0, 1st, and 2nd order reactions
to get a linear graph for each type of order do the following:
0th- [A] vs time
1st- ln[A] vs time
2nd- 1/[A] vs time
0th- [A] vs time
1st- ln[A] vs time
2nd- 1/[A] vs time
- Tue Mar 17, 2020 11:49 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Delta G of ionization
- Replies: 3
- Views: 687
- Tue Mar 17, 2020 11:48 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Doubling the amount of reducer/oxidizer
- Replies: 2
- Views: 287
- Tue Mar 17, 2020 11:47 am
- Forum: General Rate Laws
- Topic: Axes labels
- Replies: 6
- Views: 835
Re: Axes labels
y-axis: 1/[A]
x-axis: time
x-axis: time
- Tue Mar 17, 2020 11:45 am
- Forum: Administrative Questions and Class Announcements
- Topic: Saying Thank You to Dr. Lavelle
- Replies: 490
- Views: 512902
Re: Saying Thank You to Dr. Lavelle
Dear Dr. Lavelle, Thank you so much for your positive energy this year. Your lecture is very clear and productive however, it is your evident love for teaching that makes it so amazing. Thank you for all of your resources and the quick and smooth transition to an online final, I cannot imagine how s...
- Tue Mar 17, 2020 11:38 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Increasing voltage of a cell
- Replies: 3
- Views: 321
Re: Increasing voltage of a cell
changing the size of the anode doesn't affect the voltage
- Tue Mar 17, 2020 11:38 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Increasing voltage of a cell
- Replies: 3
- Views: 321
Re: Increasing voltage of a cell
you can change the concentration to affect the voltage
- Tue Mar 17, 2020 11:36 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: n of concentration cell
- Replies: 3
- Views: 329
n of concentration cell
How do we know the value of 'n' for concentration cells
- Tue Mar 17, 2020 11:31 am
- Forum: Student Social/Study Group
- Topic: Coronavirus Joke
- Replies: 14
- Views: 1757
Re: Coronavirus Joke
thanks
- Tue Mar 17, 2020 11:28 am
- Forum: Balancing Redox Reactions
- Topic: Reversing the anode
- Replies: 10
- Views: 652
Re: Reversing the anode
the anode is being oxidized so you must flip the equation since all cell potentials are given in the reduction form
- Tue Mar 17, 2020 10:18 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Units for delta G
- Replies: 31
- Views: 1782
Re: Units for delta G
Your answer will be given in KJ
- Tue Mar 17, 2020 10:17 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Concentration Cells
- Replies: 9
- Views: 671
Re: Concentration Cells
concentration cells always have a smaller delta E than galvanic cells because the difference in the standard potential=0
- Tue Mar 17, 2020 10:16 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Concentration Cells
- Replies: 9
- Views: 671
Re: Concentration Cells
the difference in the standard potentials is zero because they have the same standard potential, they're the same solution
- Sun Mar 01, 2020 8:50 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Finding N
- Replies: 6
- Views: 442
Re: Finding N
to find n you must either balance the half equations to get the number or you can look at the standard enthalpy table to find number of electrons needed in both equations and set those equal to each other
- Sun Mar 01, 2020 8:48 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Units for delta G
- Replies: 31
- Views: 1782
Re: Units for delta G
delta G is given in kJ
- Sun Mar 01, 2020 8:46 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Rules for Writing Cell Diagrams
- Replies: 2
- Views: 144
Re: Rules for Writing Cell Diagrams
you shouldn't write the stoichiometric coefficients
- Thu Feb 27, 2020 9:14 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: homework 6N.1
- Replies: 1
- Views: 130
homework 6N.1
For part b what is the standard potential for In 3+ -> In2+? This value would be different than the transition from In3+ to In (s) right?
- Thu Feb 27, 2020 8:33 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: cells
- Replies: 5
- Views: 352
Re: cells
galvanic cells are positive while electrolysis is negative a helpful way to remember this is by knowing that electrolysis requires electricity to occur
- Thu Feb 27, 2020 8:31 pm
- Forum: Balancing Redox Reactions
- Topic: homework 6K.3
- Replies: 1
- Views: 159
homework 6K.3
what is the half-reaction in part d for Cl2 -> Cl2?
- Thu Feb 27, 2020 3:34 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Coefficients in Calculating Cell Potential?
- Replies: 3
- Views: 264
Re: Coefficients in Calculating Cell Potential?
the coefficients don't affect the standard potential but make sure to change the sign if you need to flip the equation given in the table
- Thu Feb 27, 2020 3:32 pm
- Forum: General Science Questions
- Topic: Test 2
- Replies: 16
- Views: 952
Re: Test 2
the last lecture it will cover is the start of class this Wednesday, it won't include kinetics
- Thu Feb 27, 2020 3:30 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Drawing Cell Diagram
- Replies: 7
- Views: 479
Re: Drawing Cell Diagram
make sure to write the state of the compound but you don't need to include the coefficient which means you don't need to find the balanced equation unless asked for separately
- Wed Feb 26, 2020 8:53 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Calculating Standard Potentials
- Replies: 4
- Views: 332
Re: Calculating Standard Potentials
the cell diagram should always have the cathode on the right so your method should be correct but to avoid getting the wrong answer due to an error in the set up of the cell diagram remember that it is E cathode - E anode
- Tue Feb 11, 2020 5:28 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Delta H and Delta U
- Replies: 2
- Views: 127
Re: Delta H and Delta U
For an ideal gas, in an isothermal process, ΔU=0=Q−W, so Q=W. delta H is zero for isothermal reactions with ideal gases.
- Tue Feb 11, 2020 5:22 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: 4H.7 partc c
- Replies: 1
- Views: 131
Re: 4H.7 partc c
you can guess that the entropy would be decreasing based on the state change of SO2 and BR2 from gas to aq, we know gas has a much larger entropy.
- Tue Feb 11, 2020 5:11 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Pizza Rolls 3b
- Replies: 1
- Views: 96
Pizza Rolls 3b
what formula is used to find the enthalpy of fusion in question 3b
- Tue Feb 11, 2020 4:57 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Pizza Rolls 4
- Replies: 1
- Views: 171
Re: Pizza Rolls 4
the easiest way to solve problems like these is to find chemicals that you want in your final equation that only appear once in the other equations. In 4a ginger ale only appears in the first equation so you know you must multiple that equation x2 to get the 2gingerale you see in the final equation....
- Sat Feb 08, 2020 6:50 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hf and Hc
- Replies: 3
- Views: 121
Re: Hf and Hc
you can use Hc the same way you would use Hf mathematically but Hc stands for enthalpy of combustion
- Sat Feb 08, 2020 6:47 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Spontaneous vs Nonspontaneous
- Replies: 4
- Views: 169
Re: Spontaneous vs Nonspontaneous
I don't think that we've had a practice problem in which we weren't told if a reaction was reversible vs irreversible if that information was needed but an example of a irreversible reaction would be combustion. If a reaction is spontaneous the gibbs free energy value would be negative
- Fri Feb 07, 2020 6:06 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: negative Delta U
- Replies: 5
- Views: 272
negative Delta U
if you burn fuel what does it mean conceptually for the Delta U to be negative? can the system then not do work?
- Fri Feb 07, 2020 5:59 am
- Forum: Calculating Work of Expansion
- Topic: units
- Replies: 3
- Views: 98
units
if you can use equation -P deltaV to find work done from expansion how do you convert this to joules? my answer is in ATM x L
- Wed Feb 05, 2020 9:05 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Thermodynamically stable/unstable
- Replies: 2
- Views: 153
Re: Thermodynamically stable/unstable
It can but it is not a given that all thermodynamically unstable compounds will decompose. There are three types of decomposition reactions: Thermal, electrolytic, and catalytic.
- Wed Feb 05, 2020 8:59 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard State of Compounds
- Replies: 2
- Views: 140
Re: Standard State of Compounds
these compounds are not in their standard state, for example- C(s, graphite) + O2(g) → CO2(g)
C(s) and O2(g) are their standard states with standard enthalpies of formation=0
C(s) and O2(g) are their standard states with standard enthalpies of formation=0
- Wed Feb 05, 2020 8:56 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: q/T=H/T
- Replies: 1
- Views: 126
Re: q/T=H/T
This equation is used to find delta S of melting ice, delta H is the heat required to melt 1 mol of ice at 1atm divided by the melting point in Kelvin
- Wed Feb 05, 2020 8:51 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy
- Replies: 2
- Views: 96
Re: Enthalpy
This can be shown from:
deltaH = (qp + w) + PdeltaV -> deltaH = (qp - PdeltaV) + PdeltaV -> deltaH= qp
deltaH = (qp + w) + PdeltaV -> deltaH = (qp - PdeltaV) + PdeltaV -> deltaH= qp
- Wed Feb 05, 2020 8:49 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy
- Replies: 2
- Views: 96
Re: Enthalpy
Assuming that the only work done by the reaction is work of expansion gives an equation in which the P deltaV terms cancel.
- Thu Jan 30, 2020 2:56 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calorimeter q
- Replies: 2
- Views: 92
Re: Calorimeter q
q is negative if the reaction is exothermic a bomb this will be indicated by an increase in the thermometer of the bomb calorimeter
- Thu Jan 30, 2020 1:10 pm
- Forum: Calculating Work of Expansion
- Topic: 4B.5
- Replies: 1
- Views: 111
Re: 4B.5
The cylinder for the problem is in an environment that has 750 Torr. The conversion for Torr to atm is 760Torr/1atm so the environment we are working with would have a pressure slightly less than 1atm
- Thu Jan 30, 2020 12:45 pm
- Forum: Calculating Work of Expansion
- Topic: Reversible processes and greatest work
- Replies: 3
- Views: 181
Re: Reversible processes and greatest work
Reversible processes do the most work, because they have to push against more external pressure
- Sat Jan 25, 2020 5:39 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: standard enthalpy
- Replies: 3
- Views: 85
Re: standard enthalpy
the standard enthalpy is 0 because it takes no energy to form a naturally-occurring compound
- Thu Jan 23, 2020 9:16 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: homework 6A.23
- Replies: 2
- Views: 94
homework 6A.23
How are we supposed to find the concentrations of Ba2+, OH−, and H3O+ if we aren't given the Ka or pH?
- Thu Jan 23, 2020 2:05 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase change of water
- Replies: 2
- Views: 87
Re: Phase change of water
This happens for more than just water, you can google the phase change of other compounds to find examples.