2. Why is CaCl2 better than NaCl?
11After we finished some research, we found that CaCl2 is still cheap,though a little bit higher than NaCl. It cost $ 8.95 per 500g. (NaCl:$ 6.20 per 500g).Based on the price, CaCl2 is a good choice.
11According to our data, CaCl2 is the best salt that can melt ice quickly. 20g of CaCl2 takes 48'40Ħħ 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.
11We 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 consider it is good enough to use CaCl2 in the real world. The freezing point of CH3COOCH4 is -7°C and CH3COONa is -6.5°C. It seems that Na2SO4 is useless because we can only use it when the temperature is above -2°C. (NH4)2SO4 can be used in the toughest condition because its freezing point is -15°C.
11When we tried to figure out which salt would affect the plants less, we found that CaCl2 was the best overall. Based on the data we obtained, after we watered the plants with different salt solutions , most of the plants almost died except those which were watered with CaCl2 and water.
11While doing the project, we not only watered plants, we submerged iron nails in the salt solutions to measure how corrosive they were. Our data diagram showed that CaCl2 corroded metal a little, less than most of salts. The mass of that nail just got reduced about 0.01g, but masses 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 used at 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.