Search found 11 matches

by Maya Schnall 3J
Sun Feb 21, 2016 8:58 pm
Forum: *Electrophiles
Topic: Standard Entropy of Activation
Replies: 2
Views: 519

Re: Standard Entropy of Activation

If you're referring to page 89 in the course reader where it explains our pseudo-equilibrium constant and our the signs for ∆H and ∆S for our ∆G equation than it is referring to the energy going from the products to the peak of the activation energy needed for the process to occur. In other words, i...
by Maya Schnall 3J
Sun Feb 14, 2016 1:56 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: zero order reaction
Replies: 2
Views: 514

Re: zero order reaction

Normally, with other order reactions, when we graph the change in concentration over time, the graph shows a curved line with a negative slope that shows the concentration first decreasing quickly and then slowing down. However, with zero order reactions, because the rate of the reaction is independ...
by Maya Schnall 3J
Sun Feb 14, 2016 1:25 pm
Forum: General Rate Laws
Topic: half life
Replies: 1
Views: 330

Re: half life

Because we know that 1/64=(1/2)^6, we know that 6 half lives occur to get to 1/64th of the initial concentration. Therefore, we multiply our half-life time by 6, 6*0.43=2.58, to get an answer of 2.58 seconds.
by Maya Schnall 3J
Mon Feb 01, 2016 7:49 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Chapter 14 IN-TEXT Example 14.4: Self-Test 14.5A
Replies: 2
Views: 406

Re: Chapter 14 IN-TEXT Example 14.4: Self-Test 14.5A

Although it's not technically incorrect to have fractions when balancing an equation, unless it specifically states that you're balancing for a specific number of moles of a molecule, just put integers in your final balanced equations.
by Maya Schnall 3J
Fri Jan 29, 2016 7:26 pm
Forum: Balancing Redox Reactions
Topic: Redox Reactions
Replies: 3
Views: 532

Redox Reactions

Does anybody know of any pneumonic device or anything else to help me remember the cathode's role vs the anode? I always seem to mix them up.
by Maya Schnall 3J
Fri Jan 29, 2016 7:24 pm
Forum: Balancing Redox Reactions
Topic: Oxidation States
Replies: 8
Views: 881

Re: Oxidation States

He hasn't mentioned any more yet since the first day of electrochemistry in the course reader, so hopefully not.
by Maya Schnall 3J
Sun Jan 24, 2016 3:15 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Quiz 1 Preparation
Replies: 1
Views: 313

Quiz 1 Preparation

Question 9a requires that we calculate the standard reaction entropy for a reaction using standard molar entropies. The Standard molar entropies for O2,CO2 and H2O are given in the front of the packet; however, the standard molar entropy for C6H6 isn't provided. Should it be or are we supposed to ca...
by Maya Schnall 3J
Sat Jan 23, 2016 1:49 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneous Reactions at certain temperatures
Replies: 2
Views: 465

Re: Spontaneous Reactions at certain temperatures

So for these types of situations, you'll want to look at the equation for delta G, but in a conceptual, not quantitative manner. ∆G=∆H-T∆S First, we know that a system is spontaneous if ∆G is negative, so we now want to look at qualities of enthalpy and entropy that will make that true. If ∆S is pos...
by Maya Schnall 3J
Thu Jan 14, 2016 8:14 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Homework Problem 8.73
Replies: 4
Views: 720

Re: Homework Problem 8.73

It's extremely helpful to draw the Lewis Structures of these molecules before finding enthalpies because that will illustrate the specific bonds you have to break so that the product may be formed with its bonds. For the reactants, you'll see that the Lewis structure is H-C:::C-H meaning that you ha...
by Maya Schnall 3J
Thu Jan 14, 2016 8:01 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: System and Surroundings
Replies: 2
Views: 677

Re: System and Surroundings

That’s correct. Assuming that we’re dealing with a perfect system guarantees that the heat gained/lost by the system will be equal to the negative heat lost/gained by the surroundings, which Lavelle outlines below that “perfect system” mention by putting heat given off by the reaction equal to heat ...
by Maya Schnall 3J
Wed Jan 06, 2016 8:52 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Understanding Bond Enthalpies
Replies: 3
Views: 1815

Re: Understanding Bond Enthalpies

Hi Leah! This idea seemed a bit weird to me at first as well; however, if we think about the example in the course reader where CH2 combines with HBr to form CH3 and CH2Br, we’re looking specifically at the energy required or released to break or create every bond changed. Each of these energies add...

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