Activity help

Janice M. Glime jmglime at MTU.EDU
Mon Aug 30 21:21:21 EST 1999


One fun activity is to use red cabbage juice as an indicator.  I may have
read it first on this discussion list.  It has various shades of color
from pink to green to blue as one subjects it to pH from acid to alkaline.
One could use it like litmus paper to test various buffers and household
items.  It really takes on unusual colors when the household item adds its
own color, but then it cannot be used to get a "litmus" reading.
Grind the cabbage and make a juice extract in water.  Amounts aren't
critical, but not much water is needed.  A set of buffers makes a nice
comparison set.
One could then examine a variety of flowers in pink, red, and blue and
subject them to acid and base to see if their colors change, indicating
that they are anthocyanin pigments.  These pigments are easily extracted
by grinding the petals in water.  Geraniums work well, and whatever else
is available to you.
Alternatively, one could see what Sphagnum does to the color of the water
if it starts out in a buffer.  (I haven't tried that.)

Janice
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 Janice M. Glime, Professor  
 Department of Biological Sciences
 Michigan Technological University
 Houghton, MI 49931-1295
 jmglime at mtu.edu
 906-487-2546
 FAX 906-487-3167 
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