Search found 23 matches

by Allison Young 1K
Sat Mar 17, 2018 3:33 pm
Forum: Balancing Redox Reactions
Topic: 14.15 Cell Diagram
Replies: 1
Views: 184

Re: 14.15 Cell Diagram

The reduction half reaction has H+ in it.
by Allison Young 1K
Sat Mar 17, 2018 3:29 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Homework 14.15c : KOH in cell diagram
Replies: 2
Views: 171

Homework 14.15c : KOH in cell diagram

In homework problem 14.15c) the cell diagram is
Cd (s)|Cd(OH)2 (s)|KOH (aq) || Ni(OH)3 (s)|Ni(OH)2 (s)|Ni(s)
- Is it correct if I just write OH- instead of KOH?
- Does the electrode have to be Ni? Can you use Pt (s) here?
by Allison Young 1K
Mon Mar 05, 2018 1:28 am
Forum: First Order Reactions
Topic: half life
Replies: 3
Views: 118

Re: half life

A half-life is like a unit of time. For example, if the half-life of something is 2 hours, then 3 half-lives would be 6 hours. After that point 1/8th of the reactant would be left.
by Allison Young 1K
Mon Mar 05, 2018 1:18 am
Forum: First Order Reactions
Topic: Half-life of first order reactions
Replies: 3
Views: 96

Re: Half-life of first order reactions

Yes, the half-life decreases as the rate constant increases.
by Allison Young 1K
Sun Mar 04, 2018 5:32 pm
Forum: Zero Order Reactions
Topic: Significance of Zero order reactions
Replies: 3
Views: 94

Re: Significance of Zero order reactions

For zero order reactions, the concentration of reactant [R] has no impact on the rate. This happens when the reaction is catalyzed by an enzyme and the enzyme becomes saturated, so adding more reactant will not increase the rate of reaction.
by Allison Young 1K
Sat Feb 24, 2018 8:22 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Determining k [ENDORSED]
Replies: 3
Views: 117

Determining k [ENDORSED]

How do you find k?
by Allison Young 1K
Sat Feb 24, 2018 8:17 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: When do you need to include Pt? [ENDORSED]
Replies: 5
Views: 154

When do you need to include Pt? [ENDORSED]

Do you always need to include Pt in the cell diagram?
by Allison Young 1K
Sat Feb 24, 2018 8:14 pm
Forum: Balancing Redox Reactions
Topic: Oxidation state
Replies: 5
Views: 151

Oxidation state

Is the oxidation number of molecules like O2 and H2 just 0?
by Allison Young 1K
Wed Feb 14, 2018 12:16 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Delta U Formulas
Replies: 3
Views: 132

Re: Delta U Formulas

Isometric/isovolumetric/isochoric are interchangeable.
by Allison Young 1K
Tue Feb 13, 2018 10:26 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.15 confusion
Replies: 2
Views: 117

Re: 9.15 confusion

Ahhh so I'm just blind lol. Thank you!
by Allison Young 1K
Tue Feb 13, 2018 10:11 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.15 confusion
Replies: 2
Views: 117

9.15 confusion

9.15 : Use data in Table 8.3 or Appendix 2A to calculate the entropy change for (a) the freezing of 1.00 mol H2O(l) at 0.00 $C; (b) the vaporization of 50.0 g of ethanol, C2H5OH, at 351.5 K. In the solution for part (b), delta H is found by multiplying the # of moles of C2H5OH by 43.5 kJ/mol. I cou...
by Allison Young 1K
Tue Feb 13, 2018 10:05 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.13 moles of gas
Replies: 1
Views: 90

Re: 9.13 moles of gas

I have a followup question: Why do we assume it is 1.00 mol?
by Allison Young 1K
Tue Feb 13, 2018 1:04 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Entropy of system vs surroundings
Replies: 1
Views: 112

Re: Entropy of system vs surroundings

I think that is entropy of the system.
by Allison Young 1K
Fri Feb 09, 2018 2:43 am
Forum: Balancing Redox Reactions
Topic: 14.5
Replies: 4
Views: 140

Re: 14.5

Ohh that makes sense. Thanks :-)
by Allison Young 1K
Thu Feb 08, 2018 9:11 pm
Forum: Balancing Redox Reactions
Topic: 14.5
Replies: 4
Views: 140

14.5

14.5a
The reduction half-reaction for O3 -> O2 is: H2O + O3 + 2e- -> O2 + OH-
Why do you add 2 electrons if the oxidation numbers of O3 and O2 are 0 and the charge doesn't change for O2? I'm confused as to where those 2 electrons are going.
by Allison Young 1K
Thu Feb 08, 2018 8:40 pm
Forum: Balancing Redox Reactions
Topic: 14.3d
Replies: 1
Views: 67

14.3d

In 14.3d, the redox reaction equation is 2Cl2 + 2H2O + 2e- -> 2HClO + 2Cl- + 2H+ + 2e- . Why are the electrons written on both sides of the equation? When do we include the electrons in the equation and when do we not?
by Allison Young 1K
Sun Jan 28, 2018 11:27 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Exothermic vs Exergonic and Endothermic vs Endergonic
Replies: 3
Views: 760

Re: Exothermic vs Exergonic and Endothermic vs Endergonic

Exothermic means the reaction releases heat. ΔH<0 Endothermic means the reaction requires heat. ΔH>0 Exergonic means the reaction is spontaneous, and releases energy. ΔG<0 Endergonic means the reaction is non-spontaneous, so it requires energy. ΔG>0 A reaction in an open system with positive ΔH woul...
by Allison Young 1K
Sun Jan 28, 2018 5:04 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Spontineity
Replies: 5
Views: 120

Re: Spontineity

Spontaneous reactions do not require energy input to occur, and that's why they will happen on their own. Vice versa for non-spontaneous reactions.
by Allison Young 1K
Sun Jan 28, 2018 5:02 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Relationship between entropy and volume in liquids
Replies: 5
Views: 139

Re: Relationship between entropy and volume in liquids

Liquids have a definite volume, so you can't expand the volume. Only gases can expand. In zero gravity, I think the total volume of the liquid is the same, but it would just be in different places, like if you had a bunch of separate containers of water.
by Allison Young 1K
Sun Jan 21, 2018 10:43 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 7
Views: 209

Re: Bond Enthalpies

Adding onto what Abby said. If something is harder to break, then it is more stable. If you need more energy to break something, then it is harder to break.
by Allison Young 1K
Sun Jan 21, 2018 10:39 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Constant Volume vs Constant Pressure
Replies: 2
Views: 81

Re: Constant Volume vs Constant Pressure

Using ΔU = q + w = q - PΔV
For constant volume, ΔU =qv. Because ΔV = 0, w= -PΔV = -P(0) = 0.
For constant pressure, ΔU = ΔH - PΔV, using ΔH = qp.
by Allison Young 1K
Tue Jan 16, 2018 1:35 am
Forum: Administrative Questions and Class Announcements
Topic: Discussion post due dates
Replies: 2
Views: 162

Discussion post due dates

Professor Lavelle said we need to post twice on Chemistry Community each week. What is considered the last day of the week in order for a post to be counted in our grades for the weekly 2-post quota? Basically what is the latest possible time each week for a post to be counted for that week? Is the ...
by Allison Young 1K
Sun Jan 14, 2018 1:25 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Systems
Replies: 7
Views: 256

Re: Systems

Another example of an open system is a car. Fuel goes into the engine, and exhaust gases and heat exit.

Go to advanced search