<li><p>Why doesn’t H2SO4 react with NaNo3?What should we look for?</p></li>
<li><p>AlCl3 + NH3 + H2O (unbalanced) ->
Which of the following is one of the products obtained from the reaction above?
the answer is Al(OH)3</p></li>
</ol>
<p>not sure about 2, but for 1 i think they dont react becuase in order for a double replacement reaction to occur, a precipitate must be formed. in that reaction, you start with</p>
<p>H + SO4 + Na + NO3 becuase both those compounds ionize (solubility rules)</p>
<p>The products formed are:</p>
<p>H2SO4 + NaNO3 --> HNO3 + Na2SO4</p>
<p>and since both products are soluble and will form ions in a solution, you end with the same thing you started with:</p>
<p>H + SO4 + Na + NO3 --> H + NO3 + Na + SO4</p>
<p>Hydroxide usually forms insoluble compounds (exceptions: combined with Group 1 ions, Ca[2+], Ba[2+], Sr[2+], or NH4[1+]).</p>
<p>In aqueous solution, a substance is only considered a product if it forms a gas or solid (rxn. essentially going to completion).</p>
<p>All the other substances provided will just dissolve in water, so no real reaction occurs.</p>
<p>2) AlCl3 + NH3 + H2O (unbalanced) -></p>
<p>think of NH3 + H2O as NH4OH (this is one of the solubility eq. that always breaks down)
AlCl3 + NH4OH -> Al(OH)3 + NH4Cl</p>
<p>Are these questions from the "Real SAT II: Subject Tests"?</p>
<p>Well I have a couple of more questions. If anyone can help, that'd be great!</p>
<p>Questions 5-9 (it's kind of a series of reactions, so I can't really type it out here, but if you have the book, and know the answer, please explain it to me!)</p>
<ol>
<li><p>Again, this one you kind of need to see the diagram. But for those who have the book, I got E, 795 mmHg. Aren't you supposed to add 35+760? I don't understand why the answer is just 35.</p></li>
<li><p>Of the following, the element that does NOT react with hydrochloric acid to produce hydrogen gas is:
A. Zn
B. Fe
C. Hg
D. Ca
E. Mg
(the answer is C, Hg, but why?)</p></li>
<li><p>You kind of the need the book for this one as well.</p></li>
<li><p>Neutralization of 500 mL of 2-molar NaOH requires the smallest vlume of which of the following?
A. 1 M H2SO4
B. 1 M CH3COOH
C. 1 M HCl
D. 1 M NH3
E. 0.1 M H2SO4
(The answer is A, but why???)</p></li>
</ol>
<p>And just wondering, for those of you who took this test, who'd you do compared to the real SAT II?</p>
<p>THANKS!</p>
<p>I had trouble with 5-9 as well. The solution's somewhere in this forum. For #5, it's the dichromate ion (redox reaction). For #6, it has to be barium, because the next species present contains a barium compound.</p>
<ol>
<li><p>Yes. It's the pressure of the gas exerted AGAINST the atmospheric pressure. You can just find the difference for Fig. II (55-20)mmHg. Knowing that the atmospheric pressure is 760mmHg (or 1 atm) is not necessary.</p></li>
<li><p>I just know from a previous laboratory experiment that zinc and magnesium react with hydrochloric acid to produce hydrogen gas. The reaction is this (zinc): Zn + 2HCl --> ZnCl2 + H2(g) You can pretty much guess this. The reason why this single-replacement reaction occurs is because zinc is more reactive than hydrogen. From the ordered list, it is higher up in the reactivity series (with gold being the most unreactive - or least likely to oxidize). Compared to the other choices given, mercury is the most unreactive, and therefore is your answer.</p></li>
<li><p>The reaction is this: Pb(NO3)2 + 2NaI --> PbI2(s) + 2Na(NO3) The molar ratio between lead (II) nitrate and sodium iodide is 1:2. And Mixture II gives you the greatest yield of precipitate b/c the molar ratio is perfectly 1:2. I does not work because there is too little lead nitrate - it will only react with 4mL. III - NaI is the limiting reagent - 5/2 = 2.5 mL of Pb(NO3)2, IV & V by similar reasoning.</p></li>
<li><p>Sulfuric acid is diprotic. It gives off two hydrogen ions to neutralize the sodium hydroxide. It is A b/c it has the higher concentration.</p></li>
</ol>
<p>Ok, 5 and 6 make sense now, does anyone know 7-9?</p>
<ol>
<li><p>But the question asks for the vapor pressure, doesn't that mean 760+35, since it's greater than the atmospheric pressure so you add. How would they rephrase the question so that the answer they want would be 795? I'm so confused.</p></li>
<li><p>Is there a trick/acronym to memorzing that chart? It's so hard. =[</p></li>
<li><p>Yay I understand now!</p></li>
<li><p>This may be a dumb question, but why would it need TWO hydrogen ions to neutralize the sodium hydrozide? I'm still a little lost here.</p></li>
</ol>
<p>THANK YOU SO MUCH blucheese!</p>
<ol>
<li><p>It asks for the vapor pressure exerted by the gas INSIDE the container. And from looking at the ruler, it's 35mmHg.</p></li>
<li><p>No. Just know your activity series. Keep in mind that the most reactive elements oxidize spontaneously. This is why iron rusts and gold doesn't.</p></li>
<li><p>The question asks for least amount of solution that you can use to neutralize NaOH. Since sulfuric acid gives off two acidic protons, it neutralizes twice as much NaOH than, say, HCl, which gives off once acidic proton. You take the highest concentration, because it contains the most H+.</p></li>
</ol>
<p>For 105, the SAT II Subject Tests book gives the answer as T,T, CE and I can't understand the last T and CE. WHY???!!!!!</p>
<p>Wait. Nevermind. :) Just figured it out.</p>
<p>I hope you're still up blucheese! I need you!</p>
<ol>
<li><p>Reaction of iron filings with powdered sulfur = Redox? Explain!</p></li>
<li><p>I know NOTHING about petroleum. Petroleum is an important source for all of the following EXCEPT:
A. paraffin wax
B. octane
C. ethylene
D. cellulose
E. lubricating cells
(Answer: D. I've never heard of any of the choices)</p></li>
<li><p>Why is it Zn and not Cu?</p></li>
<li><p>A 0.1-molar solution of which of the following compounds has the lowest hydrogen ion concentration?
A. HCl
B. AlCl3
C. NaHCO3
D. NaOH
E. HC2H3O2 (acetic acid)
The answer is D, but why?</p></li>
</ol>
<p>I promise this is all! So please help! </p>
<p>Btw, how much organic chemistry do we need to know?</p>
<ol>
<li><p>Oxidation numbers change in the reaction.</p></li>
<li><p>Cellulose is a compound found in plants.</p></li>
<li><p>NaOH is a strong base. Strong bases have low H+ concentration.</p></li>
</ol>
<ol>
<li>the manometer is measuring the total pressure of the gases in the flask. the total pressure = atmosphere pressure (as seen in fig1) + vapor pressure. the question is asking for just vapor pressure which is why you don't take the 760 mmHg into account.</li>
</ol>
<p>I guess this is too late now...</p>
<ol>
<li> Cellulose is something you should have known from Biology. It's like glucose (C6H12O6) except every other monosaccharide is flipped - the reason why we can't digest it -> fiber</li>
</ol>
<p>Another way to think of it is Vaseline - petroleum jelly :) </p>
<p>Today's exam had a lot of trivia - not too far from #28. Bah.</p>
<ol>
<li> The diagram shown is an electrolytic cell (spontaneous rxn.). Remember these mnemonics:
LeO (Lose e-, Oxidation), GeR (Gain e-, Reduction)
An Ox (Anode - Oxidation), Red Cat (Reduction - Cathode)</li>
</ol>
<p>Zinc is more reactive than copper according to the reactivity series, and therefore has a greater oxidation potential in a spontaneous reaction. In the real world, oxidation (loss of electrons) is spontaneous - this is why iron rusts. Zinc is the anode and oxidizes. And choice B is the only one that demonstrates the proper reaction.</p>
<p>Another note: this setup is standard. Most, if not all, Chemistry textbooks introduce electrochemistry with this. So it's not that random for CB to ask.</p>