<p>I didn’t say anything about an acid base equilibrium. It’s a dissociation equilibrium, and not all the carbonic acid necessarily decomposes.</p>
<p>carbonic acid <> carbon dioxide + water</p>
<p>Also wouldn’t it be favored to stay as carbonic acid because there is an excess of hydrogen ions?</p>
<p>The reverse reaction from CO2 to H2CO3 is very weak-only 0.2% of all molecules reform. So if you take into account sig figs, it’s still 1 mole.</p>
<p>Anyone want to create a consolidated list?</p>
<p>In all likelihood, the AP test is harder. The only difference between the AP Test and the SAT II, though, is that a decrease in score on the SAT II is noticeable after only 4 or 5 raw score off. You need to get a lot wrong to go from a 5 to a 4. </p>
<p>Also @people FMLing about 5 CE, I got 5 CE also…maybe we’re not wrong after all? One can only hope.</p>
<p>@ sententia- carbonic acid in water is not stable, it decomposes into carbon dioxide and water, and as carbon dioxide escapes the reaction is driven to the right and goes to completion (basically)</p>
<p>Wait… does anyone remember the exact wording of the answer?</p>
<p>Did it say 2 moles of Na+ or 1 mole Na2+?</p>
<p>I feel like there wasn’t enough information for the question. Yes if the carbon dioxide escapes then it would be driven to completion. But depending on the system, pressure, and temperature the carbon dioxide can stay dissolved. Were we just supposed to assume standard laboratory conditions and an open container?</p>
<p>I. 1 mol Na+
II. 2 mol CO2
III. 1 mol H2O</p>
<p>Would it be 2 mol Na+ or does it not matter?</p>
<p>Wait it’s Calcium carbonate.</p>
<p>So it’s 1 mol Ca2+ for the first answer choice. :P</p>
<p>Well, the reaction is 2H+ + CaCO3 –> CO2 + Ca(2+) + H2O. </p>
<p>So, given 1 mol of CaCO3, you should only get 1 mole of CO2, 1 mole of Ca(2+), and one mole of H2O.</p>
<p>was this true/false question:
I. Raising temperature will make equilibrium be achieved faster.
II. Raising temperature increases reaction rate.</p>
<p>TTCE? I know II is true but I wasn’t positive about I</p>
<p>^ Ya i was not sure too.I was thinking like when u change the temperature u change the equilibrium constant too…so…</p>
<p>I. is true but i don’t think II. is the CE for it. If you put the 2 sentences together: Raising temperature will make equilibrium be achieved faster BECAUSE reaction rate is increased. This is not correct because equilibrium will be achieved faster BECAUSE it will shift to the direction to relieve stress, not because reaction rate is increased. So the answer is probably TT.</p>
<p>Why isn’t it TTCE? The problem is talking about equations in general, so chances are that the delta H could be zero. In that case, there would be no shift when the temperature is increased.</p>
<p>II is the CE for I because as temperature goes up, the KE of the molecules goes up and more collisions occur, thus the reaction rate would also go up. That explains statement I because if reaction rates are high, equilibrium would be achieved faster.</p>
<p>Correct me if I’m wrong. Thanks.</p>
<p>The AP chem test is harder than the SAT II. You only need about 70% right for a 5 on it, which is not bad. The only problem with SAT II is time. Usually i get it done in 45 mins and still get an 800, but on this one it was a little more descriptive chemistry and it took a little more time</p>
<p>And everything exists in equilibrium, even HCl in water, even though it has a disassociation constant of like 1.0 x 10^6</p>
<p>Sorry I was wrong. I was thinking about how the equilibrium constant is changed by temperature and not about the rate at which it is achieved. I got that question wrong then =(</p>
<p>The AP Chem test was definitely harder. It seemed easier than other AP tests, but was definitely harder than the SAT. I think the reason that most people feel that the SATs were tough was because of the irritating time limit and the fact that the formats of the two tests are different. In the AP test you can redeem yourself in the free response section; in the SAT you only have multiple choice questions. I studied for the SAT using the AP Chem book I used for the AP test and would’ve done much better if I had used an actual SAT prep book. Oh well.
If you consider the Arrhenius equation,
K= Ae^ (-Ea/RT)
then you find that raising the T value decreases the negative exponent that e is being raised to, thereby increasing the K value and making equilibrium be achieved faster.
Hope that helps.</p>
<p>I always thought that changing the temperature changed concentrations of reactants and products based on whether the rxn is exo or endo, which would change K. But, I don’t think increasing temp would make it reach equil faster, just change the final concentrations at which equil. would be reached. Could be wrong though.</p>
<p>Well, it the reaction rate increased then equilibrium would be achieved faster.</p>
<p>@alexa - That is correct, it would change the concentrations of the products and reactants, but wouldn’t make it reach equilibrium faster. I think what College Board was trying to see was whether we can differentiate equilibrium reactions and completion reactions. In an equilibrium reaction, the only thing that can make the reaction reach equilibrium faster is a catalyst. However, in a completion reaction, a catalyst AND/OR an increase in the temperature would make the reaction go faster. So the answer would be T for statement I, and F for statement II.</p>