Chemical Reactions and Heat Lab

In this lab we were testing how fast an alka-seltzer would dissolve in heated, room temperature, and cold water. I had thought at the beginning that the hotter the water was, that faster the water would dissolve... lets see if I was right:

In our first test we used the hot water. We used a hot plate to get the temperature of to 50 degrees Celsius, then dropped in the alka-seltzer. We saw insta

nt bubbling as the chemical reaction started. The bubbling continued for 22.98 seconds until the alka-seltzer dissolved completely.

In our second test, we used room temperature water. The temperature was 26.1 degrees Celsius when we dropped in the alka-seltzer. The bubbling this time lasted 35.06 seconds, over 10 seconds longer than the first test.,

In our last test, we used cold water. We accomplished this by placing in the water, and stirring in for a minute, just to be sure the temperature was even. The temperature this time was 3.6 degrees Celsius. After the alka-seltzer was dropped in, it took a whole minute and 41 second to dissolve (1:41.81 seconds)! A funny thing happened this time though. Before the alka-seltzer was dropped in, the

temperature was at 3.6 degrees, but after it was dropped in, the temperature dropped over a full degree, to 2.3 degrees Celsius. A 1.3 degree change. The only thing that changed in between this drop in temperature was the alka-seltzer being introduced. I think the change in temperature had to do with the bubbles, because the alka-seltzer itself was not chilled.

Diagram of results:

*Here you can see how much time in took for the frozen (top) to the heated (bottom), and how much of a difference there was between the times.

Picture of reaction:

*Here you can see the very end of the reaction, right as the alka-seltzer completely dissolved. This test was the chilled test with the ice inside.

In the end, I accepted my hypothesis. The alka-seltzer took longer to dissolve as the temperature went down. I'm not exactly sure why this happened, but I think it has to do with the melting and freezing that comes with heating and cooling, and how it affected the alka-seltzer.