The conclusion

As the conclusion of our project, we want to answer the question of our hypothesis which was “Are there any salts more efficient or better for the environment than Rock Salt (NaCl) for use in melting urban snow?” Based on our data from experiments, we believe that CaCl2 may be the good choice. When we were studying our data, we found that CaCl2 did a good job in our experiments. Data shows the fact. However, we don’t think that our experiments are prefect. We might have made mistakes because our working condition was not good enough. We just tested 14 different salts and used only lentils as our plants. From the time being, we think that CaCl2 would be more efficient to better for the environment.
After we finished some researches, we found that CaCl2 is cheep which is a little bit higher than NaCl. It cost 8.95 per 500g. (NaCl: 6.20 per 500g). However, we did not know how much it is going to cost if we buy certain amount of CaCl2.
According to our data, CaCl2 is the best salt that can melt ice quickly. 20g of CaCl2 takes 48’40” to melt 20ml of ice, even faster than rock salt. We also focused on the CH3COOCH4 which is an organic salt. It takes 65 min to finish its job. K2SO4 takes longest time to melt ice. We also got the freezing point of the CaCl2 which is -8°C is a bit higher than -10°C which is the freezing point of Rock Salt. However, we think that is good enough to use it in real world conditions. The freezing point of the CH3COOCH4 is -7°C and CH3COONa∙3H2O is -6.5°C. It seems that Na2SO4 is useless because we just can use it when the temperature is above -2°C. (NH4)2SO4 can be used in the toughest condition. Its freezing point is -15°C.
When we tried to figure out which salt will affect the plants less, we found that CaCl2 is the best one as well. Based on the data we obtained, after we watered the plants with the salts, most of the plants were almost dead except the plant which was watered with CaCl2. However, we did not satisfy the data from this part. We will explain more at the end of the article.
While doing the project, we did not only water plants, we submerged iron nails in the salt solutions to measure how corrosive they were. Our data diagram shows that CaCl2 just corroded metal a little bit, less than most of salts. The mass of that nail just reduced about 0.01g, but mass of the nails that were in the Rock salt solution reduced objects about 0.02g. We can tell that if people use CaCl2 on the road, wheels of cars, bridges etc. may get less damage. We learned that organic salts will be use the airport because they just will damage metal a little bit. To our surprise, according to our data, the nails in the CH3COONH4 solution lost the most of mass. It reduced objects more than 0.03g. We don’t think that organic salts are good for using in the airport, but one thing we speculate is that not all organic salts are safe. It appears to our group, according to the data that CH3COONH4 should not be used.
To sum up our experience, we think that CaCl2 may be the best choice because in our experiments CaCl2 all did good jobs. In the watering plants part, base on the data diagram we created, we found that only the plants that were watered wiyj CaCl2 solution could grow. However, the other plant’s heights became small. It is possible the technique we used when measuring the plants could have been better, because during the measuring of the delicate plants, some were destroyed. If we have chance to improve our experiment, we want to have plants that are in the same condition because before we water the plants, they had different heights. It is hard to compare plants watered by different solutions. Also, we just used one kind of plant, lentils, in the experiments. Maybe the data will change if we have different species of plants. The freezing points of the salts may need some improvement in future trials, because the refrigeration temperature levels were unchangeable. We think that the data may not be as reliable as we wish. After we did some research, we found that all chloride salts with metal ions such as K, Na, Ca, and Mg are bad for the environment though this contradicts our experiment. Hence, in the future our studies may need more repetition.