Apple Mummy
This activity can be done in small groups or as a large group activity. Have the students make a prediction about what substance or mixture of substances will mummify the apple the best:
  1. ½ cup baking soda
  2. ½ cup table salt
  3. ½ cup Epsom salt
  4. 50:50 mix of Epsom and table salt
  5. 50:50 mix of table salt and baking soda
  6. 50:50 mix of baking soda and Epsom salts
  7. 1/3 baking soda, 1/3 Epsom salts, and 1/3 table salt
  8. Leave this cup alone as a control
Slice Apples Each student should get a slice and fill a cup with the "mixture" of his/her choice for mummification. Students will need to weigh their apple slice and write the starting weight on a piece masking tape taped on the cup. Student should also note on cup which "mummification" recipe they have used. Remind students they want to make sure that the apple slices are completely covered. Place the cups on a shelf out of direct sunlight and let them sit for seven days.
One week later:
Ask the students if they remember their predictions. Talk about why they chose the substance or mix of substances that they chose. Have students take each apple out of the cup and brush off as much salt as possible (do not rinse the apple off in water, that will re-hydrate the apple and defeat the purpose of the experiment). Have the students reweigh the apple slices and write down the finishing weight.
Calculate the moisture lost for each apple slice by dividing the difference in weight by the starting weight. Discuss with your students the following questions:
  • What was the point of leaving one of the apple slices in a cup without any salt at all?
  • Which compound or substance seemed to work best at making an apple mummy?
  • Which compound or substance do you thing is the most like natron?
  • Was the prediction you made at the beginning correct?

Activity courtesy of Erin Horton, Kirsten Evensen, Becki Ketterling - Idaho State University