<p>I ran into these problem in my practice books because i was studying for an electro/thermo chemistry exam tomorrow, and due to the long nature of both problems, the likelihood of something like this being asked on the exam is very high. Could someone help me through each one? I can do half, and get stuck. Thanks for your help! </p>
<p>THIS IS NOT A HOMEWORK HELP THREAD; IT IS A QUESTION THAT AROSE FROM INDEPENDENT STUDY</p>
<p>Thermodynamics: </p>
<p>1) Consider the reaction N(2) + 3 H(2) <-> 2NH(3)</p>
<p>a) Is the nitrogen oxidized or reduced in the above reaction?
(I said it was oxidized because it was losing electrons)
b) Write the equilibrium constant K(p) for the above reaction.
(I'm not sure which formula to use, and since I can't solve this, the entire problem was rendered unsolvable)
c) Consider the following in relation to the above reaction :
[Delta]G(f) NH(3) = -16.66
[Delta]H(f) NH(3) = -46.19
aa) Calculate [Delta]G for the reaction at 298 K
ab)Calculate [Delta]S for the reaction at 298 K. Include the units.
ac) Assume that [delta]s and [delta]h do not change with temperature. Calculuate [delta]g at 400 C
d) Calculate K(p) for the above reaction at 25 C and at 400 C
e) Is the reaction spontaneous at 25C?</p>
<p>ELECTROCHEMISTRY:
a) Under standard conditions, Zn (s) reacts with Co (2+) to produce Co.
aa) Write the balanced equation for the oxidation half reaction.
ab) Wite the balanced net-ionic equation for the overall equation.
ac) Calculate the standard potential (E) at 25 C.</p>
<p>Thanks in advance!</p>
<p>a) reduced....i think. Its losing electrons, ive always been bad at oxidation equations but i thought losing was reduction and gaining was oxidation
b) Kp = (NH(3))^2/ (H2) ^3 (N2)
c) I refuse to do the math, but use (delta) G = (delta) H - T(in Kelvin) (delta) S (divide by 1000 to get kj/k instead of j/k)
d) use PV=nRT then plug in the pressure into the Kp equation
e) if (delta) g is negative, it is spontaneous</p>
<p>1 (a). N(2) becomes a part of NH(3) where N has a charge of +3.</p>
<pre><code> So think about it, it goes from 0 --> +3, so it has to lose 3 electrons. In other words, it is getting oxidized
</code></pre>
<h2>(remember: Oxidation Is Loss, Reduction Is Gain which give u OILRIG) :)</h2>
<p>2 (b) </p>
<p>K(p) = [NH3]^2
---------
[H2]^3 x [N2] </p>
<p>Remember: [something] is the concentration if the chemical something.</p>
<hr>
<p>Gotta go, bye... hope this much helps</p>
<p>In NH3 the nitrogen has a charge of -3, not +3.. It is getting reduced.
I am pretty sure it would look like this
6e- + N2 --> 2N-3</p>
<p>For Kp it is the partial pressure of the gas in the brackets, not the concentration, that would be Kc.
Kp = Kc(RT)^n change (number of gas moles product - reactant)
n would be -2 in this case (2 - -4)</p>
<p>Electrochem, is a) supposed to say Co and Zn+2?
If so,
aa) Zn --> Zn+2 + 2e-</p>
<p>ab)
Zn --> Zn+2 + 2e-
Co+2 + 2e- --> Co
-------------------
Zn + Co+2 --> Zn+2 + Co</p>
<p>ac) Look up their standard reduction potentials on the chart, and take the opposite of the value for the oxidation reaction, then add.</p>
<p>The Nitrogen is being reduced. Going from 0 (free state) to -3. Here is an easy way to remember oxidation and reduction</p>
<p>LEO::Losing Electrons Oxidation
GER::Gaining Electrons Reduction</p>
<p>LEO (the lion) goes GER.</p>
<p>this is my crazy way of remember it...works everytime.</p>
<p>1a) So i guess they explained it well that N2 has no charge, but when it becomes 2NH(3), u gotta remember that 3H x 2 = 6+, therefore 2N = 6-, N=3-... so 0-> 3- is reduced.... OILRIG, oxydation is loss, reduction is gain... loss and gain electrons of course. Since we are gaining electrons, it is reduction. Then just follow what esmitty said, i refuse to do math as well.</p>