Pretty in pink -- or green

Jeff Benson

The pink and green mixtures that the Wilson Elementary School

fifth-graders held up in their test tubes Friday were good indicators

that each of them understood the assignment.

That’s exactly what they were -- indicators, or chemicals that

change colors in the presence of an acid or a base.

Students in Audrey Woolfolk’s class Friday mixed cabbage juice

separately with acetic acid (vinegar), potassium bitartrate (cream of

tartar), sodium hypochlorite (liquid bleach) and sodium bicarbonate

(baking soda) to witness the physical and chemical reactions that

occur.

“The students need to understand that scientists have ways to

identify chemicals,” Woolfolk said. “And today we’re learning these

ways by looking at acids and bases.”

Some of their mixtures fizzed, while some of them didn’t. And some

turned lighter shades of pink and green than others, depending on how

much of the different indicators were used.

The students compared their results with a color-coded pH scale.

Pinks and purples are lower numbers and denote the presence of acid,

while the shades of green are designated with higher numbers and

represent a base.

“I learned that if a pH is lower than seven, it’s an acid, and

it’s a base if it’s higher than 7,” said Fabiola Alonso, 10.

The students were urged to form educated guesses, document their

results, come up with questions, interpret their results and ask even

more questions, Woolfolk said.

If the students asked what color the chemicals would change to,

for example, the next step would be to get answers for that question

and write down what they saw.

“I mixed vinegar with cabbage juice,” said Alex Gartner, 10, as he

held up a test tube full of clear, pink liquid. “It was pretty easy.

I was expecting to see this color.”

Other students had mixed results. Abigail Vega, 10, and several

classmates ended up with a layered green-and-purple solution when

they blended the cabbage juice with vinegar and baking soda. The

product even stumped their teacher.

“I don’t know how it ended up that way, to be honest,” Woolfolk

said. “One of the chemicals is probably heavier than the other.”

* IN THE CLASSROOM is a weekly feature in which Daily Pilot

education writer Jeff Benson visits a campus in the Newport-Mesa area

and writes about his experience.