Floral litmus solutions

In physical science laboratory thirteen the students use floral litmus solutions to determine whether household substances are acids, bases, or neutral.

Ashly, Osbert

The students bring in flowers. I do not provide guidance as to which flowers to bring in, there is no simple predictor for which flowers will work in any given term or at a particular time of day. Some flowers work better latter in the day (Hibiscus tiliaceus) while others work some terms and other terms do not work (Sphagneticola trilobata). Spathoglottis plicata tends to be reliable if freshly picked. And some flowers do not produce any pigment (Ixora casei, Saraca asoka).

Ashley, Lexus, Tricia

Each floral litmus solution is first tests against a known acid (local lime fruit) and a known base (baking soda) to determine whether the flower can detect acids and bases. The students are told to cue in on the hue angle and to ignore changes in saturation or luminosity. Changes in saturation or luminosity - terms from laboratory ten - are not reliable, reproducible indicators.

Lexus

Sphagneticola trilobata this term went from bright yellow to a deep orange for bases, but had only a shift in saturation for the known acid.

Philbert and Gayshalane

Once the lab partners have a working floral solution they work on determining whether household substances such as ammonia, bleach, cream of tartar, vinegar, hand soap, detergent, are an acid, base, or neutral.

Rayleen tests cream of tartar

Glenn DeShawn obtains more litmus fluid

Misko working with a litmus solution

Glenn DeShawn and Diane check for a hue angle change due to local lime juice

Nagsia testing for a hue change with baking soda

Glenn DeShawn and Nagsia working with the unknowns

Rubbing alcohol had a different density from Glenn DeShawn's litmus solution

Michelle Olter tests unknowns

Josey and Anster

Vandecia and Misko

Glenn DeShawn

Board notes from Wednesday

This term I used a variant on the traditional diagram to try to show the 2s and 2p orbitals and electron pairs. The 1s is the inside sphere.


Popular posts from this blog

Traditional food dishes of Micronesia

Box and whisker plots in Google Sheets

Engrade student reactions and comments