What Soil Properties Cause the Biggest Sinkhole When Mixed with Water?

Overview

Objectives/Goals To find out which mineral causes the biggest sinkhole when mixed with water. Methods/Materials For my experiment, I covered the bottom of a container with six inches of sand. I punched two holes in each side of the container. Two tubes were placed in the holes of the container. I made a small pocket of the mineral in the sand. I placed the two tubes in the center of the mineral pocket. I covered the mineral pocket with sand until the container was 3/4ths full. Two syringes were hooked to the opposite ends of the tubes. I pumped 200 milliliters of water into the pocket (the water had to be pumped into the container at the same rate). Then I observed how much the sand had sunk and measured any sinkhole with a ruler. I repeated the experiment three times per mineral. I used the following materials: Two syringes, two tubes, limestone, gypsum, salt, sulfur, duct tape, plastic container, sand, water, ruler, pocket knife and a funnel. Results Salt worked the best. It averaged sinking 1 and 2/8th inches. Gypsum worked the second best. It averaged sinking 7/8th of an inch. Limestone worked the third best. It averaged sinking 3/8th of an inch. Sulfur did not cause a sinkhole. Conclusions/Discussion My conclusion is that salt caused the biggest sinkhole. I also discovered that gypsum and limestone caused sinkholes. However, sulfur did not cause a sinkhole. My hypothesis that salt would cause the largest sinkhole was correct, however, I was wrong in my hypothesis that limestone would work better than gypsum. Gypsum caused twice as big of a sinkhole as limestone. I achieved my objective of finding which mineral caused the biggest sinkhole because I discovered that salt, gypsum and limestone all caused sinkholes and sulfur does not.

Competition history

• CSEF 2006 Earth Sciences/ Planetary Sciences/ Physical Environments · Entry J0624

Resources

• CSEF project summary ↗

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