5 - PS1.B - Mixtures - FINAL (WND 1-3-14)

DCI: PS1.B (B) Chemical Reactions – When two or more different substances are mixed, a new substance with different properties may be formed.

PE: 5-PS1-4 Conduct an investigation to determine whether the mixing of two or more substances results in new substances.

There are no clarification statements for this standard. 

The ideas we see in this standard are: 

- new substances with new properties form when two or more substances are mixed

- students should be looking at evidence from investigations to determine whether or not a new substance has been formed from the original substances. 

Although the title of this module is mixtures, here, we will be looking at chemical reactions and how they form new substances.  Students may have been taught that a mixture is formed when two substances are combined (gravel and sand), so this is taking it a step further.  We will need to be careful with this distinction. 

Possible Question Starters:

"Which of the following shows a mixture which results in the formation of a new substance?"

correct answer - a clear liquid is mixed with a yellow liquid and a white solid appears in the container

incorrect answer - a clear liquid is mixed with a white powder and the powder dissolves completely 

"Which of the following provides the best evidence that a chemical reaction has taken place?"

correct answer - two liquids are mixed, and a solid substance forms

incorrect answer - water, when boiled, evaporates and turns into vapor

"In a container, solid red crystals are mixed with a clear liquid and the following observations are recorded:

- the solid crystals dissolved into the liquid

-the color of the liquid changed to red

 - the volume of the substance increased

 - the temperature of the solution changed from 25C to 30C. 

Which of the observations indicate that a new substance was formed? 

correct answer - temperature change

incorrect answer - volume, etc.