Salt experiments for kids – Salt for road
Go snow has fallen!
Some wonder why she has not thrown enough salt on the roads …
That is difficult to answer, here we will answer: why add salt when you check …
Pure water boils at 100 º C and freezes at 0 º C at one atmosphere of pressure, of course.
What happens when substances dissolve in water is the boiling point of freezing up and down. This is the principle we use antifreeze in the cooling circuits of vehicles. My dear Professor of Chemistry at school, Toni (a kiss for her.) Told us and taught how could an antifreeze manufactured to resist a given temperature, varying the concentration of solute.
So, yes, salt water freezes at a temperature below freezing. With the right concentration, it can be to lower the freezing point to 21.1 degrees below zero.
Salt Experiments For Kids
Put two plastic cups in the freezer, one saltwater and one did not and see what freezes first.
Salt experiments for kids – Adding salt to snow
Material: 1. Two glasses 2. Ice cubes 3. Tray of “Styrofoam” (the fruit, vegetables, etc..) 4. Salt (sodium chloride)
1. We put in the tray a little water, so as to form two separate pigs, and the two cups water.
2. We put in the glasses the same amount of ice cubes (crushed ice can be used).
3. In a vessel add a couple tablespoons of salt.
4. Within minutes we see that in the glass with salt cubes melt faster. 5. If you wait a half hour, we can touch the glasses and see that the temperature is lower than the glass with salt.
6. Finally, if we raise the two vessels, we see that the water under the glass with salt water and froze, and the tray is attached to the glass.
Explanation: On the surface of the cube is a layer of liquid water in equilibrium with ice. By adding salt, some of it dissolves in the fluid surrounding the cubes forming a saturated solution that breaks the equilibrium with ice. To restore the balance tends to dilute the solution and ice to cool, which is achieved by melting of the ice, which extracts the heat necessary to melt the solution, which is cooled below 0 ° C. The solution temperature can reach 9 degrees Celsius. The water was frozen under the glass and the tray is attached to the glass and can be lifted by pulling it. An important practical application of this phenomenon is the addition of large amounts of salt on icy roads. The addition of salt to icy roads make ice and snow melt while the temperature is below 0 ° C.
Thus, the freezing point of pure water is 0 º C. However, when a substance dissolves in it, the freezing point of the resulting solution is lowered. The decline that occurs depends on the amount of dissolved substance. With 22 g of salt per 100 g of water ensures that the freezing point drops to -21 º C.