## Search found 36 matches

- Sat Mar 17, 2018 10:56 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Strength of Oxidation/Reducing Agents
- Replies:
**2** - Views:
**277**

### Strength of Oxidation/Reducing Agents

What determines what is the "best" oxidation or reducing agent? How does this compare to a substances reduction potential?

- Tue Mar 13, 2018 5:43 pm
- Forum: *Enzyme Kinetics
- Topic: Collision Theory
- Replies:
**1** - Views:
**221**

### Collision Theory

Wondering if we have to know collision theory for the final? I'm not sure if he mentioned it in class but it is a part of chapter 15...

- Tue Mar 13, 2018 5:41 pm
- Forum: Student Social/Study Group
- Topic: 14BL LAB EXCHANGE
- Replies:
**1** - Views:
**273**

### 14BL LAB EXCHANGE

I currently have Casey for 14BL with a lab on Friday from 8am-10:50, but I'm enrolled in Prado's 14C lecture on MWF at 8am so they conflict. If anyone has lab for Casey for any other day/time and wouldn't mind switching PLEASE let me know...if I dont find another lab I'm going to have to drop the cl...

- Mon Mar 12, 2018 3:01 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Ignoring Slow Reverse Reactions
- Replies:
**1** - Views:
**148**

### Ignoring Slow Reverse Reactions

When creating a rate law from a proposed mechanism, how can we tell which reverse reactions are so slow we are allowed to ignore them?

- Mon Mar 12, 2018 2:53 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Steady State Approximation
- Replies:
**2** - Views:
**138**

### Steady State Approximation

Do we need to know how to do steady state approximation for the final, or simply the pre-equilibrium approach?

- Thu Feb 22, 2018 6:25 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: n
- Replies:
**3** - Views:
**220**

### n

For the example int he textbook : The potential of the Daniell cell for solutions of 1.00 mol/L copper and zinc ions is +1.04 V. What is the reaction Gibbs free energy for this cell? How did we know that n=2? In general, do we find n for any reaction? and do we HAVE to find the balanced reaction? Al...

- Wed Feb 14, 2018 5:02 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Practice Midterm #7
- Replies:
**2** - Views:
**145**

### Practice Midterm #7

Will someone share how they did #7 on the practice midterm?

I'm using the law Qsys= -Qsurr, translating that to Qice= -Qwater and MCAT= -MCAT, and I keep getting 26 degrees Celsuis. What am I doing wrong here?

I'm using the law Qsys= -Qsurr, translating that to Qice= -Qwater and MCAT= -MCAT, and I keep getting 26 degrees Celsuis. What am I doing wrong here?

- Wed Feb 14, 2018 4:22 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Practice Midterm #2C
- Replies:
**1** - Views:
**126**

### Practice Midterm #2C

Will someone explain the math for this question? I've done it over and over using (bonds broken)-(bonds formed), taking into account the 1/2 mol of N2 and 5/2 mol of H2 when I do my bond broken calculations. I keep getting the wrong answer, someone help please!

- Wed Feb 14, 2018 12:20 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: DeltaU and DeltaH
- Replies:
**4** - Views:
**419**

### Re: DeltaU and DeltaH

\Delta U=\Delta H occurs when the volume is constant. If you want to derive this, the equation for \Delta U is \Delta U=\Delta H-P\Delta V . Thus, when there is no change in volume, \Delta V=0 and so P\Delta V=0 . Thus, \Delta U=\Delta H . Not 100% sure, but I hope this helped. Hi, I'm looking back...

- Wed Feb 14, 2018 12:10 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Practice Test, Question 4
- Replies:
**3** - Views:
**165**

### Re: Practice Test, Question 4

Chem_Mod wrote:Hi, can you be more specific about which practice test and question you are referring to?

Referring to practice test w18, question 4

- Wed Feb 14, 2018 12:10 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Practice Test, Question 4
- Replies:
**3** - Views:
**165**

### Re: Practice Test, Question 4

referring to Practice Midterm w18, and question 4

- Tue Feb 13, 2018 10:21 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Spontaniety
- Replies:
**2** - Views:
**233**

### Re: Spontaniety

Spontaneity simply tells us whether or not a reaction will happen on it's own. It is independent from speed.

- Tue Feb 13, 2018 10:19 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Constant Volume and work
- Replies:
**1** - Views:
**141**

### Re: Constant Volume and work

Under constant volume, work will always be equal to zero and q= delta U.

No question is irrelevant! Your thoughts are valid! You matter!

No question is irrelevant! Your thoughts are valid! You matter!

- Tue Feb 13, 2018 10:17 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Heat Transfer with no temperature given
- Replies:
**2** - Views:
**174**

### Heat Transfer with no temperature given

I'm doing a practice problem that is asking me to find the change in heat without giving me temperatures, and only the moles, the volume, and the pressure. Does anyone know how I go about solving this?

- Tue Feb 13, 2018 10:16 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: (DeltaU)=q+w Isothermal
- Replies:
**2** - Views:
**157**

### Re: (DeltaU)=q+w Isothermal

At constant volume, work=0, so q=delta U

At constant Temperature, q= -w, so delta U and delta H equal 0

At constant Heat, change in heat is equal to zero, so w= delta U. Also, entropy under this condition would be 0.

At constant Temperature, q= -w, so delta U and delta H equal 0

At constant Heat, change in heat is equal to zero, so w= delta U. Also, entropy under this condition would be 0.

- Tue Feb 13, 2018 9:49 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Calculating Degeneracy
- Replies:
**3** - Views:
**259**

### Re: Calculating Degeneracy

The equation for Degeneracy is the number of micro-states to the power of the number of molecules. When calculating moles, you would do the number of micro-states to the power of 6.022*10^23 times the number of moles. So, if you were calculating the degeneracy for 4 molecules with 6 different micro-...

- Tue Feb 13, 2018 5:51 pm
- Forum: Van't Hoff Equation
- Topic: Practice Test
- Replies:
**5** - Views:
**638**

### Practice Test

The practice midterm asks us to derive the Van't Hoff equation but I've been told that we don't explicitly need to do this...Is anyone positive on whether we'll have to derive this equation or not?

- Tue Feb 13, 2018 5:49 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Practice Test, Question 4
- Replies:
**3** - Views:
**165**

### Practice Test, Question 4

Can someone walk me through how to do number 4? I'm confused as to how there's a change in work if the system eventually goes back to its original volume and pressure, and I'm not sure how to break up each process and solve...

- Tue Feb 13, 2018 5:29 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Practice Test, Question 3A
- Replies:
**2** - Views:
**140**

### Practice Test, Question 3A

How are we able to use the equation deltaS=n*C*ln T2/T1 when the question gives us grams and not moles? Our units wouldn't be able to cancel out if we cannot find the moles.

- Tue Feb 13, 2018 1:13 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Delta H at constant pressure
- Replies:
**2** - Views:
**152**

### Delta H at constant pressure

Why is deltaH equal to 0 at constant pressure?

- Tue Feb 13, 2018 1:02 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Constant Volume
- Replies:
**2** - Views:
**100**

### Constant Volume

At constant volume, are q, deltaU, and delta H all equal?

- Tue Feb 13, 2018 12:59 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Change in Internal energy for Ideal Gas
- Replies:
**1** - Views:
**100**

### Change in Internal energy for Ideal Gas

What is the formula for deltaU of an ideal gas? Would we use MCAT and then replace Cp with 3/2R?

- Mon Feb 12, 2018 11:51 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: practice midterms
- Replies:
**2** - Views:
**182**

### practice midterms

Where is everyone finding the practice midterms? I'm looking on the class website and can't find them...

- Mon Feb 12, 2018 11:48 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Delta U Formulas
- Replies:
**3** - Views:
**214**

### Delta U Formulas

Can someone go over the delta U formulas for isobaric and isometric systems? would we use the same Cv and Cp values for ideal gases as we would when solving for enthalpies?

- Tue Feb 06, 2018 11:45 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: 9.41
- Replies:
**1** - Views:
**123**

### 9.41

Can someone explain how we get the answer to part (b)? The solution manual multiples the deltaH/T by the value (10g/78.11 g*mol^-1), and I'm not sure why we do that.

- Sat Feb 03, 2018 2:44 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Formula Manipulations
- Replies:
**1** - Views:
**130**

### Formula Manipulations

I was given a "cheat sheet" in one of my peer learning sessions that went over ways to manipulate equations for each given situation. One of the equations say that at constant pressure, ndeltaH=q...but I'm just confused how this applies. I always think to use MCAT to solve heat? I was also...

- Wed Jan 31, 2018 8:11 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: 9.43
- Replies:
**5** - Views:
**166**

### Re: 9.43

We are given all the cp or cv values that we'll need for calculations! Don't worry about this too much

- Wed Jan 31, 2018 7:50 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 9.13
- Replies:
**2** - Views:
**134**

### Re: 9.13

I think that "ideal behavior" means we assume the gas molecules have negligible volume, so it would pertain to 1 mole of gas.

I know that for sure when a problem says to assume ideal behavior and they don't tell you the mass though, 1 mole of gas should be assumed.

I know that for sure when a problem says to assume ideal behavior and they don't tell you the mass though, 1 mole of gas should be assumed.

- Thu Jan 25, 2018 8:38 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: DeltaU and DeltaH
- Replies:
**4** - Views:
**419**

### DeltaU and DeltaH

When does deltaU equal deltaH?

Does this happen in isochoric or isobaric conditions? What about at constant heat?

Does this happen in isochoric or isobaric conditions? What about at constant heat?

- Thu Jan 25, 2018 8:36 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Calculating internal energy in isobaric reaction
- Replies:
**3** - Views:
**321**

### Calculating internal energy in isobaric reaction

If we use the formula nCpDeltaT, where 5/2R can be replaced for Cp to calculate the change in internal energy for an ideal gas at constant pressure , how would we calculate the change in internal energy for just a normal isobaric reaction that did not involve a gas?

- Thu Jan 25, 2018 8:32 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Formulas Under Different Conditions
- Replies:
**2** - Views:
**134**

### Formulas Under Different Conditions

What is the formula for calculating heat in a reversible isothermal reaction?

- Thu Jan 18, 2018 10:23 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Q. 8.65
- Replies:
**2** - Views:
**96**

### Re: Q. 8.65

Make sure to double the equation 2NO+O2==>2NO2 and double the enthalpy as well. Cancel NO2 on both sides and then once you have a resulthing equation, use the bond enthapies to calculate the kJ. Ensure to account for moles!!

- Thu Jan 18, 2018 12:13 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Homework Problem 8.41
- Replies:
**1** - Views:
**107**

### Homework Problem 8.41

I have calculated the kJ needed to heat the ice by calculating q=m*c*deltaT with the specific heat capacity of ice, then calculated the deltaH of fusion, and then calculated the kJ needed to cool the water from the ice being put in. I was told to add those values together to get the total energy nee...

- Sun Jan 14, 2018 10:14 pm
- Topic: 8.61
- Replies:
**4** - Views:
**197**

### Re: 8.61

Thank You!!

- Sun Jan 14, 2018 10:07 pm
- Topic: Calculating Enthaply with Changing Pressure
- Replies:
**1** - Views:
**116**

### Calculating Enthaply with Changing Pressure

We have a formula for how to calculate enthalpy with the pressure is constant, but how would you calculate it when the pressure or temperature is changing?

- Thu Jan 11, 2018 9:56 pm
- Topic: 8.61
- Replies:
**4** - Views:
**197**

### 8.61

Has anyone figured out how to manipulate the equations to create the equation needed for the problem? So far, I have reversed and doubled the enthaply of the first reaction in order to cancel the NH4Br from equation (c) and the NH3 from equation (b). I'm stuck at what to do now, as we need to end up...