***October 2013 - Chemistry***

<p>Got 8 on the CxHy question as well
There was a nasty equilibrium question. What do you add to shift it to the left?</p>

<p>That was pretty obvious , the carbonate one…
The ttces i got were

  1. reaction between na, k etc and water
  2. evaporation reduces temperature
  3. similarity in properties of na,k, li
    One more i dont recollect</p>

<p>You needed to add a compund with the formula containing one of the substituents of the right (which i believe was NaCO3? or NaNO3), in order for the equilibrium to shift to the left. This is referred to as LeChatliers principle.</p>

<p>No it was the same heat of formation I think</p>

<p>Atom with smallest radius, F-, O2-, Mg2+, Ne, Na+?</p>

<p>For the heat of formation, I was pretty sure that it was original x (-2)</p>

<p>Any guesses what the curve might be? Lenient or harsh?</p>

<p>Heat of formation question.
2Al + (3/2)O2 —> Al2O3</p>

<p>853 KJ of heat is released when 27 grams of Al is consumed. Find Heat of formation of Al2O3. First realize that 27 grams of Al of 1 mol of Al. Since in the reaction, 2 mols of Al is used, the delta H has to be doubled to 1706 KJ. To find the heat of formation. Since energy is being released, its -1706 KJ. (Numbers may be slightly off).</p>

<p>Yes Chessy!!! Thank u!!!
And the smallest radius is Mg2+</p>

<p>Was the titration equivalence point where the base and the acid mol numbers were equal??</p>

<p>To be honest, I don’t think the curve is going to be so lenient. Personally, I found that fairly easy</p>

<p>(Questions are not numbered they were they were numbered on the test. If I had such ability, I would kill the system)</p>

<ol>
<li>Contains a triple bond, N2 (Weird cause that question was on AP chem test this year)</li>
<li>Has 180 degree bond angle, I believe CO2</li>
<li>Cant remember</li>
<li>Seperate Ink, Paper chromotography</li>
<li>Seperate salt from salt water sltn. I believe evaporation</li>
<li>Seperate sugar and sand. It was the one where you mix it with water and do some weird thing…</li>
<li>Seperate methyl alcohol from water. Fractional distillation
…</li>
</ol>

<p>Aspirin questions, Kudos to everyone who knew that at the tops of their heads, (I did ahahah). C9H8O4</p>

<p>Was the density of ammonia or w/e near the end of the test the one that was .7 something?</p>

<p>I just hope that -3 is 800.</p>

<p>Isolated System :- Heat and mass can not leave the system.As the water vapor condenses
the kinetic energy is transferred to other molecules so the overall temperature ( Reflection of heat ) remains constant.</p>

<p>Am i right?</p>

<p>what was the question with the halogens and oxides (it was t/f question)
does anyone remember the other true false questions?
and for the one where it asked how many oxygen particles it was asking for moles of oxygen atoms or molecules? did you get 1.2 * 10 ^24?
was the k and h20 (t/f question) a t t ce?
the last t/f was t f because the two organic compounds were isomers, but the second statement was false?
what score does a person who leaves 15 blank and gets abt 3-4 wrong get?</p>

<p>what was the one that has had a high electrical conductivity? was it metallic or ionic?</p>

<p>yes it was 1.2*10^24 and the last was t,f. also I got that the sand and water would be different because both sand and sugar don’t react with water. I don’t remember what i put for it though. Also I put that the water and alcohol one would be gaseous diffusion because they have different boiling points</p>

<p>It was asking for no. of oxygen atoms. You are correct!The answer is 1.2 *10^24
Yes,the isomers one is - T, F.</p>

<p>Crap I just realized I mixed up diffusion and distillation</p>