For the fifth grade science student to be able to point out or name certain materials that will and will not dissolve in water. Students will be able to demonstrate how to slow the dissolving process and how to speed up the dissolving process. Standards/benchmarks:
SC.5.P.8.2- Investigate and identify materials that will dissolve in water and those that will not and identify the conditions that will speed up or slow down the dissolving process. Materials:
See through cups
Loose crystal sugar
Matrix graphic organizer
In order to teach the concept of “dissolving” I will have to explain what molecules are and what they do in different temperatures and how they react. All molecules have positive and negative charges and since the hydrogen atoms in the molecules carry opposite charges, nearby water molecules are attracted to each other like tiny little magnets. “The electrostatic attraction between the positive hydrogen and negative oxygen in adjacent molecules is called hydrogen bonding”. With these water molecules and charges the hotter the water the faster the molecules move to connect to each other, the colder the water molecules are the slower they move to connect to each other, when the water freezes the molecules move at a very slow pace almost hardly at all. Water is described as a “solvent”, “the partial charges that develops across the water molecules helps make it a solvent”. Water dissolves many substances by surrounding charges particles and “pulling” them into the solution. Materials can be dissolved in different ways by changing the temperature of the liquid, by stirring the material in the water, or if the material is a solid then crush the material and then stir. In order to understand the concept students should have the knowledge of knowing what a solid, liquid and gas are and have somewhat of a base meaning of what molecules are. Procedures:
What does it mean to dissolve?
Can everything dissolve in water?
Someone give me some materials or substances that you think can dissolve in water Ok sand
Ok you think oil
Well let’s try and see
I have two cups of water, and I have some sand, and I also happen to have some oil. When I put the sand in the water, what do you think will happen? Ok well let’s find out
What do you see happening?
Right! What do you think I could do to try and make it dissolve? Hmmmm, ok well let’s try it. So I am stirring and stirring and nothing is happening, is there anything else I could try? What happens to water molecules with different temperatures of water? Right the hotter the water the faster the water molecules move, so do you think that since molecules move faster in hot water that it will help the dissolving process? Some say yes some say no
Let’s try and increase the temperature of the water
So I increased the temperature of water so now I have sand in water with room temperature water and have sand in hot water. What do you see? That is exactly right! Nothing is happening to either cup of sand. We tried stirring the sand, we tried increasing the temperature of the water, so what can we conclude about the sand? Right! Sand is a material that does not dissolve!
Now someone said that oil will dissolve. Well let’s try it What do I do first?
I have my two cups of water, I pour some oil into one cup, and what do you see happening? Ok….. What do you think I could do to maybe make it dissolve? Stirring! Right! Ok so I am stirring and stirring, what is happening? Right! I don’t see much happening either; the oil and water stay separate from each other. Well stirring didn’t seem to help so what else could I do? Increase the temperature! Good answer! Raise your hand if you think the oil will dissolve So some of you think it will dissolve but most of you don’t think so, let’s check and find out Ok so I increased the water temperature and now I’m pouring oil...
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