Search found 29 matches
Re: Final
I think the questions are going to ask us to identify functional groups within huge carbon chains.
- Sat Mar 17, 2018 1:39 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Spontaneity question
- Replies: 7
- Views: 1061
Re: Spontaneity question
Assuming delta H is postive,
The temperature is high enough it could overcome a positive delta H and make delta G negative (thus a spontaneous reaction). But if temperature is low it doesn't matter if you have a positive delta S, the reaction is not spontaneous.
The temperature is high enough it could overcome a positive delta H and make delta G negative (thus a spontaneous reaction). But if temperature is low it doesn't matter if you have a positive delta S, the reaction is not spontaneous.
- Sat Mar 17, 2018 1:32 pm
- Forum: *Enzyme Kinetics
- Topic: Catalysts in a reaction
- Replies: 12
- Views: 1715
Re: Catalysts in a reaction
If the substance shows up in the products and isnt cancelled out later by a reactant, then it can not be an intermediate.
- Sat Mar 17, 2018 1:26 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Slow Step Determining Overall Rate
- Replies: 3
- Views: 1158
Re: Slow Step Determining Overall Rate
the slow step itself makes up the rate law because it is rate determining step. In other words you could only go as fast as your slowest step. If the first step is your slow step then that is the rate law. But if the slow step is your second or third step in the reaction you have to include the rate...
- Wed Mar 14, 2018 10:46 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Question 15.47
- Replies: 4
- Views: 546
Re: Question 15.47
Another perspective to take on intermediates, is that are not present in the reactants of the first step and the products of the last step. Therefore Intermediates are produced by an elementary reaction but consumed in another one.
- Wed Mar 14, 2018 10:21 pm
- Forum: First Order Reactions
- Topic: Psuedo-Order Rate Laws
- Replies: 1
- Views: 378
Re: Psuedo-Order Rate Laws
It was covered in class, so there its likely.
- Wed Mar 14, 2018 10:19 pm
- Forum: General Rate Laws
- Topic: Rate Law
- Replies: 6
- Views: 1195
Re: Rate Law
When writing out the rate law equation, the exponents are the orders of the reaction. Therefore, the coefficient doesn't have an effect on the value of the of the exponents.
- Sat Mar 10, 2018 5:51 pm
- Forum: Balancing Redox Reactions
- Topic: 14.5 Part a
- Replies: 4
- Views: 605
14.5 Part a
If we are combining redox reductions and it has to be in basic solution, does the final answer have to include (OH-)?
I am asking this because the solutions manual for 14.5 part a does not have (OH-) in its final answer
I am asking this because the solutions manual for 14.5 part a does not have (OH-) in its final answer
- Sat Mar 10, 2018 5:08 pm
- Forum: First Order Reactions
- Topic: Log vs ln
- Replies: 9
- Views: 1275
Re: Log vs ln
There is no need to convert ln into log, and this could cause an answer to be wrong if you ever need to get rid of ln. Since e^ln cancels out smoothly the finding the reaction constant or time is made easier. In short, stick with ln
- Sat Mar 10, 2018 4:54 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: The universe as a thermodynamic system [ENDORSED]
- Replies: 3
- Views: 592
Re: The universe as a thermodynamic system [ENDORSED]
Since the universe contains everything by definition, and thus there can be no exchange of energy or matter with anything, thus the Universe is an isolated system.
- Sat Mar 10, 2018 4:49 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: The First Law
- Replies: 6
- Views: 990
Re: The First Law
I think the conservation of energy is another name to the first law so they are the same.
- Sat Mar 03, 2018 7:11 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3890961
Re: Post All Chemistry Jokes Here
I make bad chemistry puns, but only periodically.
- Sat Mar 03, 2018 7:10 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3890961
Re: Post All Chemistry Jokes Here
Q: What was the charge when NaCl was arrested?
A:Salt.
A:Salt.
- Sat Mar 03, 2018 7:08 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3890961
Re: Post All Chemistry Jokes Here
The only chemistry jokes that haven't been poster yet are the BORON ones,
*Ba Dum tsss*
*Ba Dum tsss*
- Sat Feb 10, 2018 11:54 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 9.13
- Replies: 1
- Views: 374
Re: 9.13
We use 5/2*R because the question says that the volume is changed from 3L to .5L so the reaction does not take place under constant volume. It does however take place under constant pressure.
Cp=5/2*R
Cv=3/2*R
Cp=5/2*R
Cv=3/2*R
- Sat Feb 10, 2018 11:49 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Concept of Second Law of Thermodynamics
- Replies: 6
- Views: 969
Re: Concept of Second Law of Thermodynamics
The 2nd law of thermodynamics relates entropy change to heat and temperature. For example if you connected two rooms that are at different temperatures, the temperature of the two rooms will reach an equilibrium
- Sat Feb 10, 2018 11:40 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3890961
- Sat Feb 10, 2018 11:25 pm
- Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Topic: Degeneracy (W)
- Replies: 4
- Views: 522
Re: Degeneracy (W)
To findthe degeneracy, you need to the formula W= number of states^(number of molecules)
- Sat Feb 10, 2018 11:22 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.99: Enthalpy Values
- Replies: 2
- Views: 432
Re: 8.99: Enthalpy Values
I think the solution manual has a mistake in when calculating the enthalpy of formation, because i notice that the enthalpy for HCL was used twice in their equation.
- Sat Feb 10, 2018 10:57 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Third law
- Replies: 3
- Views: 478
Re: Third law
Adding to the post above, another way to think about is that heat is created by the movement of particles. Thus as the temperature reaches closer to 0 kelvin, this absolutely no movement, thus we have exactly no entropy.
- Sat Jan 27, 2018 11:56 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Question regarding 8.39 homework question
- Replies: 5
- Views: 630
Re: Question regarding 8.39 homework question
In short, this problem requires two steps, the first step is calculating how much heat is needed to melt the ice at 0c, basically asking you to calculate the phase change with 80grams of ice (DeltaH=n(6.01kj*mol). The second part is calculating a change in temperature with the 80g of liquid water wh...
- Sat Jan 27, 2018 11:45 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Examples of work being done
- Replies: 7
- Views: 1014
Re: Examples of work being done
Another aspect of work to note is that work is not a state meaning that its value depends on the path taken. A quick example of this would be pushing a ball 100ft on a flat surface would require less work on the system than pushing that same ball uphill for a 100ft.
- Sat Jan 27, 2018 11:29 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: CV or CP
- Replies: 5
- Views: 651
Re: CV or CP
You use Cv when the reaction is going under a constant Volume (isometric) and Cp when the pressure is not changing in the reaction (isobaric).
- Sun Jan 21, 2018 11:13 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: 8.49
- Replies: 5
- Views: 621
Re: 8.49
I think you assume ideal gases, which is why we use Pv=nRT. Also in ideal gases tempature is always 25 degrees celsius or 298 kelvin
- Sun Jan 21, 2018 11:09 pm
- Forum: Phase Changes & Related Calculations
- Topic: heat vs ΔH vs work
- Replies: 2
- Views: 320
Re: heat vs ΔH vs work
Adding on the previous reply, work can only occur in a change in volume in the system, that is why in a bomb calorimeter work is always zero. A few examples that would cause a work change is a piston changing the volume of the system or pushing a box around a room. Another aspect of work is that it ...
- Sun Jan 21, 2018 10:57 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.67 gas to liquid
- Replies: 2
- Views: 271
Re: 8.67 gas to liquid
Changing a gas to liquid is an exothermic reaction and therefore the enthalpy is negative. In other words, the system which is the gas itself is losing energy to the surrounding this cooling can be seen in the physical change to a liquid.
- Sat Jan 13, 2018 8:37 pm
- Forum: Phase Changes & Related Calculations
- Topic: Constant temp
- Replies: 3
- Views: 307
Re: Constant temp
The heat is simply being use to get the substance through its phase change. After the phase change is completed then any addition of heat will result in higher temperature, until of course another phase change is begun and completed.
- Sat Jan 13, 2018 8:26 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Infinite Forms of Hess's Law
- Replies: 5
- Views: 357
Re: Infinite Forms of Hess's Law
Technically we could use Hess law to connect hundreds of equations, but I don't think we are going to see that in our problems because it would pointless since 2-4 equations shows that we know the concepts associated with Hess's law.
- Sat Jan 13, 2018 8:12 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calorimeters
- Replies: 3
- Views: 239
Re: Calorimeters
We use bomb a calorimeter to measure the change in Enthalpy at a constant volume (gas or solution). A coffee cup Calorimeter is used to measure the change in heat at a constant pressure (solution only).