Search found 32 matches
- Sat Mar 12, 2016 2:56 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Comparing heat capacities
- Replies: 1
- Views: 670
Re: Comparing heat capacities
Ethane has a single carbon-carbon bond, so it is able to have multiple different conformations, and energy has to go into all these different confirmations, which is why it requires more energy to raise the temperature. Ethene has a double C-C bond, so these different conformations aren't possible. ...
- Fri Mar 11, 2016 3:44 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: 2011 final 3B
- Replies: 1
- Views: 456
2011 final 3B
Why are there 2 sig figs in the final answer (.12V) when in the problem, the molarity given (0.6M) only has 1 SF?
- Thu Mar 10, 2016 11:45 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: combustion reactions
- Replies: 1
- Views: 437
combustion reactions
For a combustion reaction, when looking at the change in number of gas moles (for example when finding the change in gas moles to use in PV=nRT to find volume change), does the phase of H20 depend on the temperature at which the reaction takes place, or is it always liquid?
- Thu Mar 10, 2016 11:42 pm
- Forum: Calculating Work of Expansion
- Topic: work and state function
- Replies: 1
- Views: 484
Re: work and state function
work is a pathway function rather than a state function. Adding all of the steps is acknowledging that it is a pathway function; you are looking at all the steps it took to get to its final destination. If it were a state function; you wouldn't have to add all the steps, you could just subtract the ...
- Wed Mar 09, 2016 9:54 pm
- Forum: *Cycloalkenes
- Topic: double bonds and cycloalkanes
- Replies: 1
- Views: 500
double bonds and cycloalkanes
download/file.php?id=1239&mode=view
Related to this joke.... does the cyclohexane have to be a substituent even though it's longer because the double bonds need to be in the longest parent chain?
Related to this joke.... does the cyclohexane have to be a substituent even though it's longer because the double bonds need to be in the longest parent chain?
- Wed Mar 09, 2016 12:58 pm
- Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
- Topic: Potential Energy
- Replies: 1
- Views: 520
Re: Potential Energy
you know that if it is staggered, the anti conformation is most stable, and if you are choosing between 2 eclipsed conformations, then the more stable conformation is the one where the 2 largest substituents are not directly on top of each other
- Wed Mar 09, 2016 9:15 am
- Forum: *Cycloalkenes
- Topic: substituent numbering
- Replies: 2
- Views: 654
Re: substituent numbering
I wasn't sure because my TA said the opposite and then told me to ask on here to check because she was not sure!
- Wed Mar 09, 2016 8:58 am
- Forum: *Cycloalkenes
- Topic: substituent numbering
- Replies: 2
- Views: 654
substituent numbering
in terms of numbering preference on substituents(when the total number will be the same regardless), do you choose number preference based on alphabetical order or by greatest atomic mass when choosing the numbering for: 1. a halogen vs. a halogen 2. a halogen vs. an alkyl 3. an alkyl vs. an alkyl (...
- Wed Mar 02, 2016 9:12 am
- Forum: *Alkanes
- Topic: Intermediates
- Replies: 1
- Views: 510
Re: Intermediates
an intermediate occurs if it does not appear in the reactants or products of the overall reaction, but if there is a middle step. You need atlas 2 steps in the reaction for there to be an intermediate
Re: iso
any time you have 2 methyls branched off from a carbon at the end of a substituent chain
- Tue Mar 01, 2016 7:23 pm
- Forum: *Alkanes
- Topic: different structural formulas
- Replies: 1
- Views: 348
different structural formulas
on page 94 in the course reader, it says that pentane has 3 different structural formulas, but 2 of them are branched and the longest parent chain is no longer 5, so how can it still be considered pentane?
- Tue Mar 01, 2016 4:29 pm
- Forum: *Nucleophiles
- Topic: Identifying
- Replies: 2
- Views: 705
Re: Identifying
It depends on the molecule/atom, but F for example, and other halogens, are electrophiles because they prefer to have a full octet as an anion.
- Sun Feb 28, 2016 7:45 pm
- Forum: *Organic Reaction Mechanisms in General
- Topic: Transition States
- Replies: 1
- Views: 437
Re: Transition States
Br(-) will be part of the intermediates because if it was Hydrogen, it would actually be H- rather than H+, which is very unlikely to occur.
- Sun Feb 28, 2016 7:43 pm
- Forum: *Electrophilic Addition
- Topic: Electrophilic Addition Principles
- Replies: 1
- Views: 546
Re: Electrophilic Addition Principles
I think that you add the H first because it is okay for to have a Br(-) in the intermediate state, but very unlikely to have a H(-), so it will attach first.
- Sun Feb 28, 2016 7:41 pm
- Forum: *Electrophiles
- Topic: Neutral Electrophile?
- Replies: 1
- Views: 2209
Re: Neutral Electrophile?
The first thing you can do is see if there are lone pairs of elections on an atom in the molecule; if this is the case, and there's no other indication, it's likely a nucleophile.
- Sun Feb 21, 2016 4:44 pm
- Forum: *Organic Reaction Mechanisms in General
- Topic: amident nucleophile
- Replies: 1
- Views: 573
Re: amident nucleophile
Something is an ambident nucleophile when more than one atoms in the compound have lone pairs of electrons. It is common for it to contain carbon and nitrogen, but I don' t think it's necessary
- Sun Feb 21, 2016 4:38 pm
- Forum: *Electrophiles
- Topic: Transition States
- Replies: 2
- Views: 562
Re: Transition States
On the graph since gibbs free energy is on the y axis, the distance between TS1 and the dotted line is the gibbs free energy at that transition state.
- Sun Feb 14, 2016 8:26 pm
- Forum: General Rate Laws
- Topic: Units for reaction rates
- Replies: 1
- Views: 415
Units for reaction rates
In the textbook, it says to choose multiples of units that minimize the powers of 10 shown explicitly. For example, converting from mmol to μmol. Are we expected to do this on quizzes/exams?
- Sun Feb 14, 2016 8:21 pm
- Forum: First Order Reactions
- Topic: First order vs zero order
- Replies: 2
- Views: 576
Re: First order vs zero order
Yes, if you are looking at the graphs of concentration of reactant versus time. For a zero order, the graph will be a straight line, and for a first order the graph will be a curve, starting off very steep and then becoming less steep.
- Sun Feb 14, 2016 8:15 pm
- Forum: Zero Order Reactions
- Topic: Order
- Replies: 1
- Views: 625
Re: Order
Order refers to what power of the concentration that the rate is proportional to. For example, for a second-order reaction, the rate is proportional to the second power of the concentration. It is significant to know this because if you know which type of reaction it is in terms of order, you know w...
- Sat Feb 06, 2016 4:47 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Enthalpy for isothermal reversible
- Replies: 2
- Views: 589
Enthalpy for isothermal reversible
Why is Enthalpy equal to zero for an isothermal reversible process?
- Sun Jan 31, 2016 5:14 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: max potential
- Replies: 1
- Views: 406
max potential
On page 48 of the course reader it says that there is "Maximum potential when process is reversible 'very little current'. How is the process being reversible related to the fact that there is little current?
- Sun Jan 31, 2016 5:11 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagram from lecture
- Replies: 1
- Views: 414
Cell Diagram from lecture
In lecture when discussing the cell diagram, it was said that when the Cu2+ is reduced to Cu, it is plated on the electrode. Is this the case for all reduction half reactions?
- Tue Jan 26, 2016 10:54 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.67
- Replies: 2
- Views: 421
Re: 8.67
Use the information in tables 8.3, 8.6, and 8.7 to estimate the entalpy of formation of each of the following compounds in the liquid state. (a) H2O
- Sun Jan 24, 2016 9:05 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.67
- Replies: 2
- Views: 421
8.67
For the condensation of water, do we assume that the gas condenses and then goes to a final temperature of 25 Celsius?
- Sun Jan 24, 2016 9:02 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy of atomization
- Replies: 1
- Views: 1806
Enthalpy of atomization
For problems such as part b. of 8.67, where are we able to find the values to "atomize" elements. Also, what exactly is meant by this, instead of just the energy to break/form bonds?
- Sun Jan 24, 2016 9:02 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy of atomization
- Replies: 1
- Views: 405
Enthalpy of atomization
For problems such as part b. of 8.67, where are we able to find the values to "atomize" elements. Also, what exactly is meant by this, instead of just the energy to break/form bonds?
- Mon Jan 18, 2016 8:01 pm
- Forum: Calculating Work of Expansion
- Topic: example 8.1
- Replies: 1
- Views: 495
example 8.1
For example 8.1 on page 264 where it says EVALUATE, it says that the internal energy decreases by 60.8 J when the gas expands and the system does 60.8 kJ of work on its surroundings. Why do the units change from Joules to Kilojoules here?
- Sun Jan 17, 2016 8:05 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: very general question about enthalpy
- Replies: 1
- Views: 426
very general question about enthalpy
Does enthalpy always refer to a change in heat, or can it also just refer to the heat of the system at a certain time?
- Sun Jan 17, 2016 8:04 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Diagram about ideal gases
- Replies: 1
- Views: 408
Diagram about ideal gases
In the diagram on page 33 of the course reader, does decreasing the mass slowly affect the volume or the pressure, and how exactly does it do this?
- Sun Jan 10, 2016 3:28 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: enthalpy definition
- Replies: 2
- Views: 623
Re: enthalpy definition
With a gas, I don't think it's possible to have a constant pressure and volume at the same time. In order to have constant pressure, the system is free to expand or contract(volume change).
- Sun Jan 10, 2016 3:19 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: bond enthalpies
- Replies: 2
- Views: 606
bond enthalpies
Why is bond formation exothermic?