This Asia chemistry project can give we some clues. Question ; Which of the suggested test substances are soluble in water? ; Which of the suggested test substances are insoluble in water? ; Which of the suggested test substances makes ice melt fattest? Hypothesis ; The sugar and table salt are soluble in water. ; The sand is not soluble in water. ; The table salt makes ice melt fattest.
If we have ever made homemade ice cream the loadstone’s way using a handcraft machine, we probably know that we need ice and rock salt to make the cream mixture cold enough to freeze. Similarly, if we live in a cold climate, we have seen the trucks that salt and sand the streets after a snowfall to prevent ice from building up on the roads. In both of these instances, salt is acting to lower the freezing point of water, and changing what phase of matter the water is (i. E. Turning solid ice into liquid water). For the ice cream maker, because the rock salt lowers the freezing point of the ice, the temperature of the ice/rock salt mixture can go below the normal freezing point of water. This makes it possible to freeze the ice ream mixture in the inner container of the ice cream machine. For the salt spread on streets in wintertime, the lowered freezing point means that snow and ice can melt even when the weather is below the normal freezing point of water.
Both the ice cream maker and road salt are examples of freezing point depression Table salt (technically sodium chloride, or NCAA) when mixed with water is an example of a chemical solution. In a solution , there sis solvent (the water in this example), and a solute (the salt in this example). A molecule Of the solute dissolves (goes into solution) because the force of attraction between the solute molecule and the solvent molecules is greater than the force of attraction between the molecules of the solute. Eater (H O) is a good solvent because it is partially polarize (This 2 popularization is caused by the distribution of electrons in the water molecule: specifically, its hydrogen ends have a partial positive charge and the oxygen end has a partial negative charge v) Because water molecules are partially polarize, it is possible for them to arrange themselves around Ions (which are molecules or atoms that have a charge), like the sodium (An and chloride (CLC ) ions that make up table salt.
This is why there is a greater attraction between the water molecules and the molecules of salt than there is between the molecules of salt by themselves, and why the water can dissolve the salt to create a salty solution. Other substances when mixed with water can also lower its freezing point. The amount by which the freezing point is lowered depends only on the number of molecules dissolved, not on their chemical nature. This is an example of a colligating property . In this science project, we will investigate different substances to see how they affect the rate at which ice cubes melt. We will test substances that dissolve in water (i. . , soluble substances), like salt and sugar, as well as a substance that does not dissolve in water (i. E. , an insoluble substance), specifically sand. Which substances will speed up the melting of the ice? Temperature isn’t the only thing that affects how a liquid freezes-?and melts. If we’ve ever made homemade ice cream the loadstone’s way using a handcraft machine, we probably know that we need ice and salt to freeze the cream mixture. Similarly, if we live in a cold climate, we’ve probably seen the trucks that salt and sand the streets after a snowfall to prevent ice from building up on the roads.
In both of these instances salt is lowering the freezing point of water, which means that the water needs to be colder to turn from liquid into ice. For the ice cream maker, the temperature of the ice-?salt mixture can get much lower than if just using normal Ice, and this makes it possible to freeze the Ice cream mixture. For the salt spread on streets, lowering the freezing point means that ice can let even when the outdoor temperature is below water’s freezing point. Both of these events demonstrate “freezing point depression. Salt mixed with water is an example Of a chemical solution. In a solution there is a solute (salt in this example) that gets dissolved in a solvent (water in this case). When other substances are mixed with water they may also lower its freezing point. In this science activity we’ll investigate how salt, sand and sugar affect water’s freezing point. Materials ; Identical bowls or saucers (4) ; Ice cubes (12). They should all be the same size and shape. Salt TTS. ) ; Sugar TTS. ) ; Sand (3/4 TTS. ) ; 1/4 teaspoon measuring spoon ; Timer or clock ; Refrigerator. E will want an empty shelf that can hold all four bowls, unstained, at the Same time. ; 50 ml graduated cylinder, or smaller size. ; Large cup with a spout, such as some measuring cups. Alternatively we could use a funnel that fits in the graduated cylinder. ; Optional: Masking tape and a permanent marker for labeling the bowls ; Lab notebook Figure 1. We will need these household materials, and access to a refrigerator, to do this science project. . Get the salt, sugar, sand, and measuring teaspoon ready to use nearby.
Once we have set up the ice cubes in their bowls, we will want to quickly a. Add the substances to the ice cubes so that they do not melt before adding the e substances. 2. Into each of the four bowls, quickly place three ice cubes. Arrange the ice cubes so that only the corners are touching, forming a triangular shape, as shown in Figure 2, below. Tip: If we are using ice cubes from a tray, it helps to let the tray sit at room temperature a little (for about five minutes) so that the ice cubes more easily mom out of the tray and do not break into pieces. . Carefully sprinkle h teaspoon (TTS. ) of salt over the ice cubes in one bowl, a shown in Figure 3, below. Then sprinkle h TTS. Of sugar over the ice cubes in another bowl, and h TTS. Of sand over the ice cubes in the third bowl. Do not sprinkle anything over the ice cubes in the fourth bowl -? it will be were control 4. Move each bowl to an empty shelf in the refrigerator. If any of the ice cubes no longer form a triangular shape in their bowl, gently nudge the ice cubes to make a triangle again. Are doing this experiment in the refrigerator because it is easier to see the effects of colligating properties at colder temperatures. To think about who this is, imagine melting an ice cube on a hot, paved road compared to melting it in the refrigerator. The hot temperature of the road will make all of the ice cue Bess melt very quickly, which makes it harder to see the relatively minor effects of colligating properties on how fast the ice cubes melt. 5. Note the starting time in were lab notebook. 6. Now let the ice cubes completely melt in their bowls (we can leave them at mom temperature).
Once all Of the ice cubes are melted, repeat Steps 7-?8 (buy this time we will not need to worry about keeping the ice cubes in the bowls). Record the amount of liquid remaining in each bowl in were data table. 7. Calculate the total amount of water (originally in ice cube form) that was in each bowl. To do this, add the “amount melted” to the “amount remaining” of r each bowl. Record the total amount for each bowl in were data table. 8. Calculate the percentage of ice that was melted (when we first took the boo WISE out of the refrigerator) for each bowl.