Search found 9 matches

Wed Mar 09, 2016 10:43 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Final 2010 question 1C
Replies: 2
Views: 418

Re: Final 2010 question 1C

The heat capacity of a molecule increases when the molecule is more complex. Because ethane consists of carbon-carbon single bonds and hydrogens, the atoms have more freedom to move around than those in ethene do because the double bond creates a fixed structure. Because the atoms have more freedom,...
Wed Mar 09, 2016 10:21 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Calculating residual entropy
Replies: 3
Views: 1092

Re: Calculating residual entropy

I thought that BF3 would have a greater residual entropy too, but on page 176 of the course reader, winter 2011 final exam question 1C, the answer says NO would have a greater residual entropy.
Tue Mar 01, 2016 12:52 am
Forum: *Nucleophiles
Topic: halogens as nucleophiles
Replies: 1
Views: 355

halogens as nucleophiles

On page 152 in the Introduction to Organic Chemistry book, it states: "halogens are also stable as anions due to their electronegativity, and organic reactions will often show curved arrows pointing towards them as they gain a pair of electrons and become negatively charged...as anions, halogen...
Sun Feb 28, 2016 11:34 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Difference between equations for calculating Ecell
Replies: 3
Views: 700

Difference between equations for calculating Ecell

There are two formulas in the course reader for calculating E: E = E standard - ((RT)/(nF))(lnQ) E = E standard - (0.0592/n)(logQ) And I was wondering what the difference between the two was, i.e. what are the circumstances when you use each one and why are there two different equations for the same...
Wed Feb 10, 2016 11:12 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: deciding which cell is the cathode/anode
Replies: 3
Views: 559

deciding which cell is the cathode/anode

How do you know which one is the cathode and which one is the anode? For example in midterm 2014 question 8, the E standard values are given as +3.03 and +2.87. I thought that the smaller positive number was the one where the reaction should be switched and the E standard value changed to a negative...
Tue Jan 19, 2016 7:49 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Reversible/Irreversible Process
Replies: 1
Views: 502

Re: Reversible/Irreversible Process

Can someone explain what the difference between a reversible and irreversible process is? Does it have any affect on calculations of work? A reversible process is one that can be reversed by an infinitely small change in a variable. For example, if a reaction takes place in a container with a pisto...
Sun Jan 17, 2016 2:39 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Reversible Reactions vs. Irreversible Reactions
Replies: 2
Views: 485

Re: Reversible Reactions vs. Irreversible Reactions

Reversible reactions are ones that can be reversed by an infinitely small change in a variable. In all of the problems we have done thus far, you were able to tell a reaction was reversible because the external pressure equaled the internal pressure. Because both pressures are equal, a change in eit...
Sun Jan 17, 2016 2:31 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Relationships of Enthalpy with Change in Internal Energy
Replies: 1
Views: 291

Re: Relationships of Enthalpy with Change in Internal Energy

Work = -(Pressure external)(change in volume), so if the reaction is done under a constant volume, the change in volume would be 0, making work = -(Pressure external)(0) = 0. And going back to the equation for internal energy, change in U = w + q, if w = 0, then the change in internal energy = 0 + q...
Sun Jan 10, 2016 5:35 pm
Forum: Phase Changes & Related Calculations
Topic: Phase Changes- Melting/Boiling
Replies: 4
Views: 647

Re: Phase Changes- Melting/Boiling

The temperature remains constant even though heat is being supplied because of where the temperature being applied goes to. At the temperature of the phase change, the heat added to the system goes into breaking the bonds, therefore allowing a phase change to happen. Due to this heat being used for ...