## Search found 23 matches

Thu Mar 15, 2018 5:08 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams for Concentration Cells
Replies: 1
Views: 129

### Cell Diagrams for Concentration Cells

For concentration cells, which concentration goes at the anode, the lower or higher one? Why?
Thu Mar 15, 2018 4:33 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 16.69: Pre exponential factor in catalysis
Replies: 1
Views: 153

### 16.69: Pre exponential factor in catalysis

What does it mean when the textbook questions say "in practice, the new pathway also has a different pre-exponential factor"? If this means that A for the new pathway with the catalyst changes, how does it cancel out when we try to find Ea?
Thu Mar 15, 2018 4:00 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 16.65 part b
Replies: 1
Views: 132

### 16.65 part b

is the only way to find out whether this is endothermic or exothermic by using the equation ∆G° = -RTlnK? How else would you be able to do this as this is thermodynamics?
Thu Mar 15, 2018 3:56 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: 15.65, part c
Replies: 3
Views: 246

### Re: 15.65, part c

can you answer this question only in terms of activation energies?
Sun Mar 04, 2018 9:44 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Test 2 Q5
Replies: 7
Views: 646

### Test 2 Q5

when it asks to rank the following elements in order of increasing reducing power, is this the same as ranking their ions in order of increasing reducing power? This question confused me because when you reverse the equations the sign of the standard potentials reverse too, and the answers were base...
Wed Feb 28, 2018 9:19 pm
Forum: First Order Reactions
Topic: 15.15
Replies: 4
Views: 248

### Re: 15.15

I think the book just gave a random increase to concentration to show that if rate increases by the same factor it is a first order reaction.
Wed Feb 28, 2018 9:15 pm
Forum: Zero Order Reactions
Topic: Zero Order Reactions and Rate of Reaction
Replies: 5
Views: 327

### Re: Zero Order Reactions and Rate of Reaction

it means that when you change the concentration, it does not have an effect on the rate.
Wed Feb 28, 2018 9:13 pm
Forum: Zero Order Reactions
Topic: Negative order
Replies: 4
Views: 294

### Re: Negative order

the concentration will appear in the denominator of the rate law. increasing the concentration would slow down the reaction because the negative order means it favors the reverse reaction.
Wed Feb 28, 2018 9:04 pm
Forum: General Rate Laws
Topic: 15.3 C
Replies: 8
Views: 801

### Re: 15.3 C

it's a positive value for b) because when you're finding the rate of the products (formation of O2), it's + 1/c ΔC/Δt.
Thu Feb 22, 2018 9:13 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 14.43
Replies: 1
Views: 179

### Re: 14.43

I don't think we've discussed how this works yet but it does! The exact reasons for this are quite technical and relate to the concept of standard states. In the end, if you want to use a "mixed" equilibrium expression, containing both concentrations and pressures, then the pressures must ...
Thu Feb 22, 2018 12:44 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 14.35
Replies: 3
Views: 246

### Re: 14.35

never mind, I just realized that the electron transfer is 2 not one :/
Thu Feb 22, 2018 12:42 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 14.35
Replies: 3
Views: 246

### Re: 14.35

for part b, I keep getting lnk = 4.67 which leads to a k value of 110, which is different to the textbook solution. Could someone please explain how they did this question?
Thu Feb 22, 2018 12:12 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 14.33
Replies: 1
Views: 164

### 14.33

What does it mean when it asks whether Tl3+ will disproportionate in the solution?
Fri Feb 09, 2018 10:33 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electrical energy to chemical energy
Replies: 2
Views: 175

### Re: Electrical energy to chemical energy

electrolysis: an electric current drives a chemical reaction that will separate an ionic substance. I don't think I saw it on the syllabus though so I don't know if we'll be learning about it.
Fri Feb 09, 2018 10:27 am
Forum: Balancing Redox Reactions
Topic: Standard Reduction Potential
Replies: 3
Views: 186

### Re: Standard Reduction Potential

because standard reduction potentials (E°)are intensive properties, they stay the same even when balanced so moles don't matter. however if the reduction half equations are reversed don't forget to change the sign of E°
Fri Feb 09, 2018 10:21 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.7
Replies: 2
Views: 184

### Re: 9.7

thank you!
Fri Feb 09, 2018 9:46 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Exothermic/Endothermic
Replies: 2
Views: 145

### Re: Exothermic/Endothermic

you can also think of this in terms of equilibrium: exothermic reaction: reactants --> products +heat - if temperature is lowered, heat decreases, and in order to maintain equilibrium more products will be formed. endothermic reaction: reactants + heat --> products - if temperature is increased, hea...
Fri Feb 09, 2018 9:37 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy Phase Change
Replies: 2
Views: 165

### Re: Entropy Phase Change

When a phase change occurs temperature (x axis) stays constant, while entropy (y axis) will keep increasing, causing a vertical line.
Fri Feb 09, 2018 9:31 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.7
Replies: 2
Views: 184

### 9.7

Can someone please explain which equations to use for this question and why?
Thu Jan 25, 2018 12:10 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Internal Energy
Replies: 5
Views: 264

### Re: Internal Energy

no change in pressure means ∆P=0, not P=0. the equation for work uses P not ∆P and it is unlikely P=0
Thu Jan 25, 2018 12:07 am
Forum: Administrative Questions and Class Announcements
Topic: Week 3 Test Topic is endorsed
Replies: 37
Views: 2341

### Re: Week 3 Test Topic is endorsed

what is an example of a conceptual question in terms of internal energy?
Wed Jan 24, 2018 11:35 pm
Forum: Phase Changes & Related Calculations
Topic: HW 8.1
Replies: 3
Views: 218

### Re: HW 8.1

the products would leave via the exhaust pipe into the surroundings and the reaction would heat up the surroundings as well. both matter and energy can be exchanged with surroundings so it is an open system
Thu Jan 18, 2018 9:58 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Question 8.43
Replies: 2
Views: 163

### Question 8.43

Can someone please explain why the answer to 8.43 is c, not b? thank you!!