Solubility LabThis presentation will show you how the Solubility Lab could have been written up correctly. Please make corrections on your own lab.

Purpose: The purpose is to see if temperature affects the rate of solubility.

Variable: Different temperatures of water (hot, room temperature, and cold)

Dependent Variable

Thing = RATE (TIME)

Unit = SECONDS

Tool = STOPWATCH

Some of you said that the thing was TEMPERATURE. Did you take the time to think about that? Think about how that would change the purpose. You would then be saying…..The purpose is to see if temperature affects temperature.

Does that make sense?

No!!!

Hypothesis: If a drop of food coloring is added to water of different temperatures, then it will become a solution fastest in the hot water.

Data Chart:

Water Temperature Time

Cold 40 degrees C 300 + secondsRoom

Temperature 60 degrees C 230 seconds

Hot 85 degrees C 53 seconds

Written Observations

Cold Water – When the food coloring was added to the cold water, it very slowly moved down towards the bottom of the beaker. Very little of the food coloring was spreading out around the beaker. After 300 seconds, the majority of the food coloring was mixed with only the water at the bottom of the beaker, and almost all of the water above it was still clear.

Written Observations

Room Temperature Water – When the food coloring was added to the room temperature water it still moved towards the bottom, but this time it was swirling down and a bit more of the top portion of the water was colored. Little by little, the food coloring moved upwards and around the sides of the beaker. At 230 seconds, the water was a solid color.

Written Observations

Hot Water – As soon as the food coloring hit the hot water it started moving around in all directions. Every place the food coloring went it turned the water to that color. The color of the water on the bottom of the beaker was the same as the color of the water on top. In only 53 seconds the water was a solid color.

Conclusion – Parts 1-3

The hypothesis was supported by the data and observations.The temperature of water does affect the rate of solubility. The

warmer the solvent is, the faster it will become a solution with a solute.During the experiment there was much more movement in the

beaker with hot water than there was in the other two temperatures. The warmer the water was, the faster the food coloring was moving, and the cooler the water was, the slower it was moving. The solution formed in the hot water in only 53 seconds, while it formed in 230 seconds in the room temperature water. The food coloring in the cold water did not become a solution during the time it was observed, even after 300 seconds.

Conclusion – Part 4A solute is a substance that is dissolved into another substance. In a solution there is

usually less of it. A solvent is the substance, usually a liquid, that is doing the dissolving. A solution is a homogenous (even) mixture of a solute and solvent.

In the solubility lab, the solute was food coloring, the solvent was water, and the solution was colored water.

A solution of food coloring and water could still be made without heating the water by stirring it. It could still be made without stirring it. It would just take longer.

Temperature can affect the rate of solubility in the same way that temperature affected the rate of the chemical reaction during the Alka-Seltzer lab. In both experiments, it was the behavior of the molecules inside the water that caused the different rates (times). Since molecules move faster in warmer liquids there are more collisions (crashes) between molecules. Those collisions helped break down the Alka-Seltzer faster. Cooler water causes molecules to move slower, causing less collisions and a longer reaction rate for the Alka-Seltzer to break down. In the Solubility Lab, the faster moving molecules in warmer water literally moved the food coloring along with them, acting very much like a spoon stirring the water. The cooler the water was, there was less movement of the molecules and less “stirring” of the solute and solvent, causing a longer time for them to become a solution.

Conclusion – Part 5

Oil and vinegar salad dressing is not a solution. A solution is defined as a homogenous (even) mixture between two or more things. Since the oil and vinegar do not distribute evenly, it is not considered a solution. Shaking the bottle will only temporarily mix the two liquids, and they immediately begin to separate.

Even if the temperature of oil and vinegar were increased they still will not become a solution. They still will not mix.

The scientific term that describes a mixture of oil and vinegar is an emulsion.