## Search found 10 matches

Tue Mar 14, 2017 5:57 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Winter 2013 Midterm Q1B
Replies: 2
Views: 451

### Re: Winter 2013 Midterm Q1B

From what I understand, the entropy equation can only handle one change at a time. So in this case you need to solve for two separate values of entropy and add them together. The first equation is used when temperature is held constant and volume is changed, and the second is where volume is held co...
Sat Mar 11, 2017 6:39 pm
Forum: *Haloalkenes
Topic: Page 49 on course reader
Replies: 1
Views: 691

### Re: Page 49 on course reader

No, it should be called (E)-3-Bromo-4-chloro-3-hexene because the priority for numbering halogens is based on alphabetical order. Since B is before C, bromo gets the 3 and chloro gets the 4.
Sat Mar 04, 2017 9:12 pm
Forum: *Alkanes
Topic: Naming
Replies: 2
Views: 365

### Re: Naming

I believe Dr. Lavelle said both are acceptable unless the question specifically asks you to name the molecule according to one of them.
Sun Feb 26, 2017 7:41 pm
Forum: First Order Reactions
Topic: First Order Half life Independence
Replies: 1
Views: 318

### Re: First Order Half life Independence

The simple conceptual implication I get is that for first order reactions, the time it takes for [A] to decrease from, for example 2M to 1M, would be just the same as if it were to decrease from 0.5M to 0.25M. Otherwise, I would refer to this post for a more precise answer: https://lavelle.chem.ucla...
Sat Feb 18, 2017 10:08 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Rate of Reaction vs. Reaction Rate Constant [ENDORSED]
Replies: 2
Views: 355

### Re: Rate of Reaction vs. Reaction Rate Constant[ENDORSED]

The rate of the reaction is a measurement of the change in concentration of a reactant or product over a unit of time. For example, the equation to find a rate could be written as "rate = k[A]", where k is the reaction rate constant and A is a reactant. Within the rate law, the reaction ra...
Sun Feb 12, 2017 2:48 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Winter 2015 Midterm Question 2 and 3 D
Replies: 5
Views: 787

### Re: Winter 2015 Midterm Question 2 and 3 D

In calculating using bond enthalpies, the basic equation is enthalpy of rxn = bonds broken(reactant side) - bonds formed(product side). I find it easier to see exactly which bonds are broken if you draw out the structure of each of the molecules. Once you've done that, you can see that a C-I and H-O...
Sun Feb 05, 2017 7:26 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Inert Conductors
Replies: 1
Views: 239

### Re: Inert Conductors

Inert conductors are used when half reactions don't have conducting solids in them. Without these conducting solids, the electrons won't be able to transfer from the anode to the cathode. So the purpose of these inert conductors is to enable this electron flow without disrupting it or reacting with ...
Sun Jan 29, 2017 3:33 pm
Forum: Phase Changes & Related Calculations
Topic: Question 8.41
Replies: 2
Views: 309

### Re: Question 8.41

Hi, So first, I began by calculating the heat required to melt the ice, which is q1 = 50g/(18.02g/mol) * 6.01kJ/mol = 16,700J. Then I calculated the heat required to get the ice, now in liquid state, to get to the final temperature, which is q2 = (50g)(4.184J/g*°C)(Tf-0°C) or simplifying it, 209.2Tf...
Sun Jan 22, 2017 7:54 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Chapter 8 Question 65
Replies: 2
Views: 381

### Re: Chapter 8 Question 65

Hi, After getting the enthalpy of the reaction to be -169.2 kJ, it should be easier to understand if you write out the whole process. The enthalpy of the reaction should equal the enthalpy of the products minus the reactants of the equation 2NO + 3/2O2 --> N2O5. Thus, you get -169.2 kJ = deltaHfN2O5...
Sat Jan 14, 2017 10:02 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy
Replies: 4
Views: 574

### Re: Enthalpy

Expanding on the answer above, state functions are independent of how the final state of a system is reached. It's easier to understand if you think of an example such as hiking, which was what my TA told us. One hiker could take a winding path from point A to B, while another could make a straight ...