After lab, chemistry class draws with homemade, washable chalk: Photo of the Day 1/8/18


Emily Reed

Sarah Buckley writes with homemade chalk.

by Emily Reed, Co-editor-in-chief

After a laborious lab, students in Mr. Scott Stair’s Honors Chemistry class got to enjoy writing washable messages on the lab tables with their final product: homemade chalk.

The challenge of this lab was to write, without a teacher’s guidance, a procedure to produce chalk and to determine with calculations how much of the materials should be used to make the fixed amount of chalk.

Using stoichiometric ratios, groups were able to calculate how much of each desired substance was needed to create four grams of chalk.

The lab group consisting of Sarah Buckley, Madison Cook, Abby Parker, and Emily Reed determined that 4.4 grams of calcium chloride (CaCl2) and 5.52 grams of potassium carbonate (K2CO3) would combine to form 4 grams of chalk.

Once the students measured the correct amount of each material, they placed the substances in separate beakers. Distilled water was added to both beakers and the solutions were stirred until the substances dissolved in the water, leaving it a murky white color.

Then, the calcium chloride solution was poured into the beaker containing the potassium carbonate solution. The students stirred the combined solution gently.

This lab group observed no change at first. All of sudden, the liquids started coalescing to form a gel. After a few minutes of waiting, the substance turned into a wet chalk.

Using filter paper, the group vacuum filtered the chalk twice to get rid of excess water. Then the chalk sat overnight to dry out further.

Once the mass of the chalk was collected, the group could finally enjoy the fruits of their labor!

Sarah Buckley, a member of the Class of 2019, “Drawing with the chalk we made was my favorite part of the lab.”

With chalk, this group drew shapes, wrote sentences, and even tried to write in cursive. And no worries, the chalk could be easily scrubbed off the table with a little bit of water and a paper towel.