Nacl Mixture And Freezing Point Lab Results

Background Information

In this lab KCl, NaCl, and a mixture of MgCl2 and NaCl are the independent variables that all lower the freezing point of water. Ice is used as the controlled variable because it is what the salts are lowering the freezing point of. Salt (Na) weakens intermolecular forces of water, thus lowering the the freezing point. This is why in colder climates where icy roads and walkways are a liability, salt is often scattered over areas that are slick with frozen water. Ions (particles with a positive charge) are very effective at lowering the freezing point of water because they cause a large disruption in water molecules, weakening the intermolecular forces. The radius of the molecules particles also have an effect

Scientific evidence shows that the substance that lowers the freezing point the most will be the MgCl2/NaCl mixture, then second the KCl, and third the NaCl. This is because the MgCl2/NaCl mixture is positively charged. The particles charge has a greater impact on the intermolecular forces of the water than the radius of the particles, which is the other factor affecting freezing point. The radius of the particles composing the MgCl2/NaCl mixture are small, which decreases the disruption of intermolecular forces (making the freezing point higher) because there is less space for other atoms to gather around it. However, as stated before the particles charge has a greater impact on the intermolecular forces of the water than the radius. As a result of this the MgCl2/NaCl mixture lowers the freezing point the most. KCl has a larger radius than NaCl, allowing it to cause more disruption in intermolecular forces (thus lowering the freezing point) because more water molecules are able to be drawn to it. NaCl having a smaller radius than KCl and no charged particles places its ability to lower the freezing point of water at the least of the

After the data from our lab came out opposite of what is scientifically supported it was clear there were better, more relevant ways of measuring different salts ability to melt Ice (lower the freezing point) than time, which is what we used. Also, the Ice being crushed may have caused an additional error because it disrupted the distribution of salt throughout the ice. If this lab were to be performed again I suggest placing the salt on a block of ice, because the amount of Ice exposed to the sat would be less varied between tests than with crushed