From: Steve Gustafson (email@example.com)
Date: Thu Feb 06 2003 - 13:28:41 EST
Suggestion for the ziplock bag lab: I have my students put the liquids
together in a small regular sandwich bag which they then stuff into the
zoplock bag without spilling. Then they invert the whole thing and squeeze
out the liquid from the inside bag. You don't need quick reactions and if
the ziplock doesn't work just right, it doesn't matter.
on 2/3/03 9:19 PM, firstname.lastname@example.org at email@example.com wrote:
> We use a different activity to start discussions about chemical reactions that
> has worked well for us. The students do a quick experiment where they combine
> water, bromthymol blue, sodium bicarbonate and calcium chloride. They make
> observations of all four substances before they begin. They they combine the
> two solids in a plastic ziplock baggie, and make observations. They combine
> the two liquids in a beaker, and make observations, and finally add the
> liquids to the solids in the ziplock and quickly seal it. Heat is generated,
> gas is produced as well as a great color change from blue to yellow. After
> making all their observations, students are then told to determine exactly
> which combination of substances produces each change they noticed. The kids
> seem to like it and it really gets them talking about what is occurring.
> Would love any suggestions.