Chemical Properties--Testing Unknowns with Vinegar, Iodine, and Red Cabbage Juice

Big Idea: Chemical Properties--Testing Unknowns with Vinegar, Iodine, and Red Cabbage Juice

Focus question:  How can we use properties to identify chemicals around us?

Prediction:  Which unknown will have a reaction?       

	Vinegar	Iodine	Cabbage Juice
Red	Smell, bubble	Color change	Smell
Yellow	Smell, bubble	Color change	Smell
Green	Smell, bubble	Color change	Smell
Blue	Smell, bubble	Color change	Smell
Orange	Smell, bubble	Color change	Smell

Planning:  1) Add controls to the test mats. 2) Next, place one spoonful of each unknown on the test mat. 3) Add six drops of vinegar to each unknown. Stir using the toothpicks. Record your observations on your recording sheet. Compare with the control circle. Record findings. 4) Continue with each unknown. ***Remember to change your test mat for each new liquid chemical.

               

Data :  Unknown Test—Changes (Class Properties Chart)

(Color, change, texture, odor change—science properties)

	Vinegar	Iodine	Cabbage Juice
Red	Hard, crystallizing, change in smell	Change in color-brown, no change in consistency	Dissolved, slight color change, odor change-sour
Yellow	Tacky, smells like vinegar	Changes texture-mash potatoes and color-red/orange/brown	Texture change-pasty, sticky, (should have seen color change—most change dark purple)
Green	Pasty, change in smell, no color change	Pasty, color change-burnt yellow-hardens over time	Dissolved, Pink, paint-like
Blue	Bubbled over, then stopped-no color change--clumpy	Changes color-dark brown and	Change in texture-chunk mash, (no color change-should have to green)
Orange	Solid, smooth	Changes color-black—most color change	Texture change-Like glue

Claims and evidence:

We found that liquid chemicals can cause our unknowns to change color, shape, and texture. When we add certain liquids to chemicals, reactions may occur.

Conclusion/Reflection:  We discovered that some unknowns had more of a reaction than others did. We also learned that time influences chemicals and their possible reactions. We learned that physical properties are changed by other chemicals. This is called a chemical reaction.

Questions:  How does time affect cabbage juice?

Literacy Connections:  Using the “The Crystal Story,” discuss growing sugar crystals with boiling water and sugar.