Documentation listed below are from original planning and thoughts (9/28/2019). Much of the information including variables, materials, and procedure have changed during the course of STEM Fair. For the final procedure, materials, variables, and hypothesis, see the Experimental Research section.
The United States utilized approximately 15 billion kilograms of road salt during the winter of 2013-2014. Massachusetts averages about 44 inches of snow each year, and requires vast amounts of road salt for winter storm preparation. While rock salt is affordable and commonly used to de-ice roads, it does not work under temperatures below -7°C, poses a hazard to the environment by raising salinity levels of nearby bodies of water, and releases unwanted compounds such as lead, iron, and cadmium into the ecosystem. Recently, many cities are veering away from rock salt and experimenting with other alternatives including calcium chloride and beet juice. However, there is no “perfect” deicing substance on the market today because there are many needs for one product. While some products are environmentally friendly, they are expensive and hard to manage at home and while others are inexpensive, they corrode automobiles and create slick conditions. As a result, the main goal is to find the best product depending on preference to cost, availability, environmental effects, toxicity, and effectiveness in low temperatures. This experiment aims to answer the following questions: what are the effects of deicing substances on the rate of snow melting and what effect do different deicing solutions have on plant germination. This project’s findings would help raise awareness and mindfulness of road salt usage and impact on the environment, as well as alternate deicing solutions. In addition, the findings could help scientists and local governments further research the chemicals used as deicers and the consequences they have on nature.
The independent variable in this experiment is the type of deicing substance: sodium chloride, calcium chloride, calcium magnesium acetate, rock sand, and beet juice, and the dependent variable is the melting time and the length of germinating roots. The controlled variables are the type of bean seed, amount of deicing substance, time of germination, concentration of solutions, shape of ice cubes, and weight of ice cubes. The negative control group for the first experiment is no deicing substances used on the ice cube. For the second experiment, the negative control would be distilled water without any deicing substances.
Materials needed for this experiment include: (1) the deicing substances: sodium chloride (NaCl), calcium chloride, rock sand, calcium magnesium acetate, and beet juice, (2) 18 ice cubes, (3) 200 mL distilled water, (4)18 petri dishes, (5) filter paper, (6) lettuce seeds, (7) 1000 mL beaker, (8) 100 mL graduated cylinder, (9)18 cups, (10) balance, and (11) pipette.
Part I: The first experiment aims to test the efficiency of different types of deicing substances. Each cup will be filled with the same amount of water and put in the freezer to freeze. Once frozen, 15 mL of deicing substance will be added to coat the top of the ice. This will be done for all the types of deicing substances. The time taken to melt the ice and weight of amount of ice melted will be recorded in a table and this experiment will be repeated three times for an average.
Part II: The next part of this experiment tests the effect of different deicing substances on plant germination. Molar solutions of the deicing substances will be made at a concentration of 0.2M. The molecular weight of each deicing substance can be found by adding the atomic masses of each atom in the chemical formula. Knowing the molecular weight, it can be plugged into the formula: gram of chemical = (molarity of solution in mole/liter)*(molecular weight of chemical in g/mole)*(ml of solution) ÷ 1000 ml/liter, to determine the amount of deicing substance needed. Each petri dish will be labeled by the type of deicing substance and a filter paper will be placed in each. 2 mL of each test solution will be added using a pipette and for the control, distilled water will be added. Each dish will have 5 seeds that are placed so none are touching each other. The dishes will be kept at a constant temperature and humidified conditions for 5 days. After 120 hours, the number of germinated seeds in each dish will be counted and the root length of the germinated seeds will be measured. This data will be recorded into a table and repeated three times for an average.