<p>Okay, what’s the answer to the BaSO4 question? It asked about the addition of which ion would decrease its solubility. The choices were Ba^+2, SO4^-2 and NO3^-1.
I put Ba^+2 and SO4^-2 but I’m sure that’s wrong. Right? Because using the solubility law, this would increase the solubility wouldn’t it?</p>
<p>I didn’t take the Nov. Chemistry Subject Test, but if you added those two ions to a solution of those ions, wouldn’t BASO4 precipitate out, thus decreasing the solubility?</p>
<p>Apoc314 is correct.</p>
<p>“The common-ion effect is the effect of decreasing the solubility of one salt, when another salt, which has an ion in common with it, is also present. For example, the solubility of silver chloride, AgCl, is lowered when sodium chloride, a source of the common ion chloride, is added to a suspension of AgCl in water.” (Wikipedia)</p>
<p>What did you guys get for the question about “what is emitted by the earth’s surface?” (first section of the test)</p>
<p>I put microwaves but I’m not sure…</p>
<p>Yeah? YEAH! Yippee! 
That was my only doubt in chem till now.</p>
<p>no sorry it’s infrared, if it was microwave then we would all be fried ;)</p>
<p>Yes, its infrared. This question also came in OCT 2008 Chem (Not that I took it. I just chanced upon a discussion thread of theirs).</p>
<p>I got a string of C’s with one D in the middle.</p>
<p>Also, I got NO TTCE at all. Is that bad?</p>
<p>The question I’m confused about is the one where they claim the ratio of moles and volumes of an idea gas is the same, and that equal number of moles equal equal volume. That is TT and not TTCE right?</p>
<p>For the apparatus sets… the salt/sand is the filter, iron/copper is the magnet, and the HCl/H2 is the gas displacement in water equipment?</p>
<p>Twice the density is just twice the molar mass right?</p>
<p>Here are some of the ways I remember: SiO2 is tetrahedral, AlO3 is not possible, O2 & O3 are allotropes, K+ and Cl- are isoelectronic, H2O & OH- conjugate pairs, hydrolysis is 2H2O –> 2H2 + O2, ionization is 2H2O –> H3O + OH-, if partial pressure of 2 mols is 200, partial pressure of 1 mol is 100, infrared radiation</p>
<p>Yep. That’s bad. I think I got three or two TTCE. </p>
<p>And that is a TTCE. They explain the second theory(which is also a law) and the second one perfectly explains the first. </p>
<p>Yes, the gas displacement is in the water equipment. The last apparatus is what I’m talking about. I thought that out of HCl and H2, atleast one(I’m betting on H2) wouldn’t be soluble in water. I also thought the other apparatus didn’t make any sense for that question.</p>
<p>Yes, and Yes for the other two (salt-sand=filter pare, and magnet for Fe.)</p>
<p>some questions…
- Conjugate Acid-Base question: H20 and OH-?
- What determines amount of moles used up (or something like that): Limiting reactant or Excess reactant?
- There was a question with electron configuration… The atomic number was 18 i believe.
It asked. What happens when it is combined with Sodium?</p>
<p>Thanks :)</p>
<p>1) Yes.
2) Limiting Reagent.
3) Elaborate please? And I don’t recall any such question. An element with Atomic No. 18 is a noble gas (Argon to be specific) and it would not react with Na if it’s life depended on it!</p>
<p>perfectpixie, do you remember what are the other TTCE you got? I remember getting 2 or 3 TT but none of them had the relevant explanation.</p>
<p>Well the 2nd one says “IF two gases have the same number of moles, then their volume is the same”. But that doesn’t explain that two gases can have the same ratio of moles and volumes. Because the second statement does not offer an explanation for what happens when the mole ratio of two gases are different. So I just put TT.</p>
<p>Oh it was an atomic number of 16, which is sulfur. When it reacts with sodium, it becomes an -2 ion, so it was A.</p>
<p>Um, no. But I’ll be glad to answer if you can remember any questions!</p>
<p>The first statement stated that the moles and volume of a gas can be used in the same way utilising the stoichiometry. The second one stated the Law which states this- at the same temp and pressure, two gases with the same no. of moles have the same volume. This has nothing to do with the ratio? It only talks about the relation b/w moles and volume.</p>
<p>Oh really? Maybe the International and National tests was slightly different… but my first statement says something like: “Under the same temperature and pressure, the ratio of the number of moles of two gases is the same as the ratio of the volume of the two gases.” That is true because of the Ideal Gas Law, but the second statement is simply an instance of the first statement, the case when n1=n2.</p>
<p>Did anyone else get no TTCE for any of the problems? I looked pretty closely at all of the questions, but none of them yielded a TTCE.</p>
<p>15g?
only ba2+ and so4 2-?
Molarity 3 or 0.1? (i put 3, but pretty sure i got it wrong)</p>
<p>oh and btw, cali is done 1 hour ago ;)</p>
<p>can somebody contribute…</p>
<p>I think gamma radiation was one </p>
<p>There was also the one with something “A” (Li?) reacting with something else “B” in a 6:1 ratio, and but you only react 3 moles of A, and have 3 moles of B; they asked how much B was left. I put 2.5</p>
<p>Which consumes produces more H2 gas given excess H20, Li or Mg? I put Mg (probably wrong)</p>
<p>Burning glucose was one, but I do not remeber the question. something to do with moles consumed/produced.</p>
<p>One question was about which of the following compounds/molecules can not exist. I put F=F (Fluoride double bonded with another Fluoride.) Fluoride should be single bonded.</p>
<p>One question, near the end, was 60, but they put the answer as 2x30. I was freaked out.</p>
<p>Another near the end was about empirical formula of CH2-dont remember specifics. </p>
<p>One of the relationship questions was about Oxygen and Oxygen (-2) ion and radius.</p>
<p>There were two questions about pink Ph indicators. </p>
<p>Redox Question: Mn went from +7 to +2 I believe. </p>
<p>Thats what I can remember so far. </p>
<p>On a side note, this was my first time taking an actual SAT Chem test (aside from the blue book and all the PR and Barron’s tests I have taken). I though this was really difficult, or if anything, time consuming. There were like 5-7 “coefficiants” questions which just eat time. I generally finish with spare time, but I ran out of it here. Anyone else have a similar experience?</p>
<p>Li is right because Li produces a product with the coefficient of 2. It makes 1 mol instead of the 0.5 mol Mg would make
I also found that i had barely enough time to finish.
I put 2 times 30 or something too.
F is single bond like you said
Oxygen TTCE was FF i believe?
2.5 is correct.
One of the answers for Ph is “pink” and one “pink” was an “except” question.</p>
<p>^^ </p>
<p>Magnesium and water gives: Mg + 2H2O –> Mg(OH)2 + H2</p>
<p>Lithium and water gives: 2Li + 2H2O –> 2LiOH + H2</p>
<p>One mole of magnesium produces one mole of hydrogen gas, while one mole of lithium produces half a mole of hydrogen gas. Thus, magnesium makes more hydrogen, not lithium.</p>
<p>@ellegee</p>
<p>so is it true or false for that?</p>
<p>How many TTCE did you get?</p>