AP Chem Important Questions!

Test Preparation AP Sciences
1

<p>Hey guys,</p>

<p>I have a question if any of you is taking or has taken AP Chemistry.</p>

<p>So today we were doing a lab to calculate the # of moles of an unknown substance, by measuring the temperature changes in two substances and their mixture.
(i.e. we had NaClo and an unknown substance) And we were supposed to record the initial temperature of each of them and mix them together and record the temperature change.</p>

<p>So here's the question. The initial temperature of the two substances was supposed to be the same, I don't know why, but we got different numbers.</p>

<p>My teacher says I need to make a correction, but I am wondering how? I've used all the available sources but couldn't find out how to make a correction in such a case.</p>

<p>By the way, correction is required because I'm calculating the temperature change of the final solution and the initial substances. I have attempted to add them up and divide by two, but it somehow doesn't sound true.</p>

<p>So I would really appreciate if any of you know how.. </p>

<p>a lot of thanks.</p>

2

<p>Hi,</p>

<p>If the two initial temperatures were supposed to be the same, but change once you added the two solutions together, they would have to react and change the temperature causing a change in the number of moles. I believe that’s what the lab is trying to teach you. It’s possible that some of one of the initial solutions could have already reacted some and that caused the temperatures to be different. There are literally a thousand different possibilities for this error. Sorry, but I don’t think there is a way to solve this problem without re-doing the lab.</p>

<p>-Bryce</p>