Search found 31 matches
- Sat Mar 17, 2018 5:21 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3006318
Re: Post All Chemistry Jokes Here
Why can't you trust atoms? They make everything up!!!!!!!
- Sun Mar 11, 2018 11:28 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts
- Replies: 3
- Views: 418
Re: Catalysts
I would also like to know the answer to this question
- Sun Mar 11, 2018 11:25 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: K and K'
- Replies: 4
- Views: 597
Re: K and K'
I don't think there is a way to numerically calculate k' from k without knowing the K because K is always involved in the equation K=k/k'
- Sun Mar 11, 2018 11:22 pm
- Forum: *Enzyme Kinetics
- Topic: Enzyme
- Replies: 6
- Views: 2429
Re: Enzyme
Enzymes are catalysts and their job is to lower the activation energy - the energy needed for the reaction to get between the products and reactants point.
- Tue Mar 06, 2018 11:50 pm
- Forum: Second Order Reactions
- Topic: molecularity
- Replies: 6
- Views: 903
Re: molecularity
Even though there are only NO molecules in the problem, using 2 of the NOs makes it bimolecular.
- Tue Mar 06, 2018 11:48 pm
- Forum: *Enzyme Kinetics
- Topic: Catalyst
- Replies: 6
- Views: 898
Re: Catalyst
I agree - usually the enzyme or catalyst is used in the rxn to change its rate. It wold go above the equation or be given in the word problem.
- Tue Mar 06, 2018 11:47 pm
- Forum: Second Order Reactions
- Topic: Rate of consumption vs concentration
- Replies: 2
- Views: 439
Re: Rate of consumption vs concentration
why would it be a less dramatic decrease?
- Wed Feb 28, 2018 9:21 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Hw 15.1 [ENDORSED]
- Replies: 7
- Views: 1058
Re: Hw 15.1 [ENDORSED]
it would make sense here because there is only one mole of N2 and 3 moles of H2 - in order to make a full 1, you would need 3 times more N2 to balance our for the amount of H2
- Wed Feb 28, 2018 9:15 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: units of K
- Replies: 5
- Views: 660
Re: units of K
why are these the units? does it have to do with each graph for first order, zero order, and second order reactions?Britney Alvey 1B wrote:For 0 order reactions, the units for k are are mol/(L*s). For 1st order reactions, the units of k are s^(-1). For 2nd order reactions, the units for k are L/(mol*s).
- Wed Feb 28, 2018 9:08 pm
- Forum: First Order Reactions
- Topic: Derivation
- Replies: 8
- Views: 1000
Re: Derivation
My TA said that if he asks us to derive on the exam, then it would be simple equations that we have gone over many times.
- Tue Feb 20, 2018 10:55 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Help on 14.15 half-reactions
- Replies: 1
- Views: 293
Re: Help on 14.15 half-reactions
I'm not sure about these either - also what is the difference between a solubility equilibrium, the Brønsted neutralization reaction, and the reaction in the nickel–cadmium cell??
- Tue Feb 20, 2018 10:50 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: When to include electrolyte in cell diagram
- Replies: 1
- Views: 248
Re: When to include electrolyte in cell diagram
I would also be intersted in knowing the answer to this question - thanks!
- Tue Feb 20, 2018 10:49 pm
- Forum: Balancing Redox Reactions
- Topic: Basic and Acidic conditions [ENDORSED]
- Replies: 11
- Views: 6931
Re: Basic and Acidic conditions [ENDORSED]
These statements are all right. OH is a negative charge, so you will use this with basic solutions while H3O is positive, so you will use this in acidic conditions. H2O is unlimited and you can always include this
- Tue Feb 13, 2018 10:51 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Practice Midterm [ENDORSED]
- Replies: 5
- Views: 870
Re: Practice Midterm [ENDORSED]
For this week's discussion, do we still have to hand in homework because the midterm is this week? I'm assuming we do but just checking!
- Tue Feb 13, 2018 10:50 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Derivation of Formulas
- Replies: 5
- Views: 775
Re: Derivation of Formulas
Last week, my TA said that we may need to know some but these would just be very simple equations we've gone over a lot of times during lecture.
- Tue Feb 13, 2018 10:49 am
- Forum: Phase Changes & Related Calculations
- Topic: Practice Problem
- Replies: 3
- Views: 455
Re: Practice Problem
I would also like to know how to do this problem! Thanks!
- Tue Feb 06, 2018 5:00 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Textbook 9.7
- Replies: 2
- Views: 400
Re: Textbook 9.7
For constant pressure, you use 5/2R in the equation and for constant volume, you use 3/2R.
- Tue Feb 06, 2018 3:53 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: 9.11
- Replies: 2
- Views: 356
Re: 9.11
Thanks!!!! :)
- Tue Feb 06, 2018 1:45 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: 9.11
- Replies: 2
- Views: 356
9.11
For chapter 9 question 11 it asks the entropy change with a change in pressure and given moles. What is the equation we use for this? Thanks!
- Wed Jan 31, 2018 10:06 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: bond enthalpies
- Replies: 3
- Views: 414
Re: bond enthalpies
These values are always given - we do not need to memorize them.
- Wed Jan 31, 2018 10:04 pm
- Forum: Phase Changes & Related Calculations
- Topic: Example in Lecture
- Replies: 4
- Views: 496
Re: Example in Lecture
The reason we put Delta G as 0 as well is because we didn't have that or T as givens for the equation: DeltaG= DeltaH-TDeltaS. We had H and S, but needed something for G in order to find T - when the reaction would be spontaneous. Putting it at 0 is a good first step and makes sense here because we ...
- Wed Jan 31, 2018 9:57 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat Capacity
- Replies: 8
- Views: 1010
Re: Heat Capacity
Why do liquids have a higher heat capacity?
- Tue Jan 23, 2018 10:25 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.49
- Replies: 1
- Views: 292
8.49
How do you find the change in internal energy with only a reaction and delta H given? It says "What is the change in internal energy for the reaction of 1.00 mol OF2? in the reaction OF2(g) + H2O(g) = O2(g) + 2H(g)." How do you find this for only 1 mole of one of the reactants?
- Tue Jan 23, 2018 10:22 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Why is enthalpy a state function? Why is heat not a state function?
- Replies: 5
- Views: 10055
Re: Why is enthalpy a state function? Why is heat not a state function?
How does this relate to Hess's Law? Does it have to do with how Hess's law is the sum of enthalpies?
- Tue Jan 23, 2018 10:17 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Week 3 Test Topic is endorsed
- Replies: 37
- Views: 4758
Re: Week 3 Test Topic is endorsed
Content from this week won't be on the exam, right? I'm pretty sure it's just material from Weeks 1 and 2
- Wed Jan 17, 2018 9:34 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess's Law
- Replies: 5
- Views: 458
Re: Hess's Law
Thanks! So how does this equation and idea relate to specific heat? Is specific heat involved in the equation to find enthalpy because it is needed in each step of a specific reaction?
- Wed Jan 17, 2018 9:28 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.51 energy "released"
- Replies: 4
- Views: 565
Re: 8.51 energy "released"
I agree; technically the energy is released so it makes sense that it would be a negative number (because exothermic reactions are negative) but since it is in relation to the outside receiving the energy, it is gaining a positive amount of energy.
- Wed Jan 17, 2018 9:21 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess's Law
- Replies: 5
- Views: 458
Hess's Law
What exactly does Hess's Law state?
- Thu Jan 11, 2018 10:39 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Equations
- Replies: 6
- Views: 569
Re: Equations
The heat of fusion uses unit of mass (the specific heat of fusion), and the molar heat of fusion is the enthalpy change per amount of substance referred to in moles. Using the example of H2O, you first find the mass of ice melted with the volume of melt. Then you calculate the energy (in joules) rel...
- Thu Jan 11, 2018 10:31 am
- Forum: Phase Changes & Related Calculations
- Topic: Phase Changes: Molecular Level [ENDORSED]
- Replies: 2
- Views: 306
Re: Phase Changes: Molecular Level [ENDORSED]
During the face changes, the part of the phase graph with a constant slope is when the phases are in the process of changing. For instance, the line between the slopes showing liquid water and ice is as the H20 is freezing into a solid.
- Mon Jan 08, 2018 7:30 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy and Temperature [ENDORSED]
- Replies: 4
- Views: 494
Re: Enthalpy and Temperature [ENDORSED]
When the temperature is greater, there is more heat and therefore more energy. I think that this would cause enthalpy to also increase.