<p>for significant figures do you keep the numbers stored w/o rounding in your calculator until the final calculation, and THEN do sig figures?</p>
<p>or do you do sig figures on every intermediate step?</p>
<p>dont round ur decimals or do sig figs till final calc i believe.... or thats how i was told to do it... and how i did it on review to get right answers</p>
<p>Do sig figs at end. I think they take 1 point off if you're sig figs are off by more than one figure, so I think 0.0020 is acceptable even though sig figs dictates the answer should be 0.002 Don't quote me on that though.</p>
<p>Can somebody tell me how to do complex ions please? I understand it except for Iron. It seems to not follow the "double the charge to find number of anions and keep the charge of a single cation for the complex ion charge" rule. For example:</p>
<p>Fe2+ + CN- -> (Fe(CN)6) 4-</p>
<p>Usually a complex ion would form (Fe(CN)4) 2+</p>
<p>True/false:</p>
<p>A catalyst will change the rate constant.</p>
<p>I don't think it does. For calculations do we have to put units on EVERYTHING? or can we leave it off until we write the answer?</p>
<ol>
<li><p>Is there some good resource for reviewing lab stuff on the net by any chance? I missed the days my teacher gave out old AP's (without me knowing) because i was taking other AP exams...</p></li>
<li><p>Is it worth memorizing some things if we know nothing about organic chem?</p></li>
</ol>
<p>Thanks.</p>
<p>About the rounding...</p>
<p>If the question's in a bunch of different parts (like part a, part b, etc...) then you round your answer to each part, and that's it.</p>
<p>Then you use your rounded answers for the next parts.</p>
<p>It's really not a big deal, though. As long as you show how you did the problem, they'll give you full credit.</p>
<p>No, there will probably be very little on organic chemistry.</p>
<p>For number 2, it would probably be a good idea to at least be familiar with some organic stuff. Know the difference between alkanes, alkenes, and alkynes, be familiar with the funtional groups, and know what an isomer is.</p>
<p>Actually, it's true. You were thinking of the equilibrium constant. The enzyme catalyzes the reaction in both directions so since the rate is increased by the same amount in both directions, then Keq does not change. </p>
<p>I said rate constant though, so there is no equilibrium and the reaction goes in one direction faster than it would without a enzyme.</p>
<p>Is it okay to do this?:</p>
<p>Give rounded answers for each part (a,b,c), but keep the non-rounded values in your calculator for the next steps.</p>
<p>Do we get a graphing calculator or scientific on the free response?</p>
<p>rate constant k= Ae^(-{Ea}/RT) Ea is the activation energy and A is a constant.</p>
<p>Is E naught cell at 25 degrees celsius? I"m sorry I still don't understand.</p>
<p>no. Ea is the activation energy, which is the threshold energy the reactants must have for the reaction to happen</p>
<p>
[quote]
Can somebody tell me how to do complex ions please? I understand it except for Iron. It seems to not follow the "double the charge to find number of anions and keep the charge of a single cation for the complex ion charge" rule. For example:</p>
<p>Fe2+ + CN- -> (Fe(CN)6) 4-</p>
<p>Usually a complex ion would form (Fe(CN)4) 2+
[/quote]
same question.
But is that a rule? I mean "double the charge to find number of anions and keep the charge of a single cation for the complex ion charge".</p>
<p>@andy_tok</p>
<p>No, I said E naught. Not Ea. You're getting things mixed up. E naught is hard to type out on a keyboard but is best represented as E (superscript 0). It is the voltage of galvanic or electrolytic cell.</p>
<p>oops, sorry. then yes the standard condition for E^0 (E naught) is 25, 1M, 1atm</p>
<p>Cool I'm looking over free response right now.</p>
<p>How do you identify a catalyst and/or intermediate in a mechanism?</p>
<p>Use 0 degrees only in gas problems? Yes</p>
<p>Also, what equation was it that you're not supposed to convert pressure into molarity? Was it Nernst?
? DO you mean concentration? That would be freezing-point depression and boiling point elevation</p>
<p>Can somebody tell me how to do complex ions please? I understand it except for Iron. It seems to not follow the "double the charge to find number of anions and keep the charge of a single cation for the complex ion charge" rule. For example:</p>
<p>Fe2+ + CN- -> (Fe(CN)6) 4-</p>
<p>Usually a complex ion would form (Fe(CN)4) 2+
[Fe(CN)6]3- is a complex ion with Fe3+, not Fe2+.</p>
<p>BTW, can someone confirm if a catalyst does or does not change the rate constant? I think I got that question wrong on the Mock.</p>
<p>@specify They are part of the reactant and product. Catalysts aren't consumed in a reaction I believe.</p>
<p>@wxmann I don't think catalyst should change the rate constant. Rate of reaction is dependent on temperature. How would catalyst affect it?</p>
<p>"Usually a complex ion would form (Fe(CN)4) 2+
[Fe(CN)6]4- is a complex ion with Fe3+, not Fe2+."</p>
<p>That's not what my PR book says. Is it wrong?</p>