Question

1. a student mixes two clear liquids. after a few minutes, yellow solid particles appear at the bottom.

what evidence supports that a new substance formed? (choose two.)
a. a solid (precipitate) formed.
b. the color stayed exactly the same.
c. the mixture could not be separated by filtering.
d. both liquids looked the same as before mixing.
e. the temperature did not change.

1. a student observes the following after mixing two substances:

a strong odor forms
the mixture turns cloudy
heat is released
what conclusion can the student make?
a. a physical change occurred
b. a new substance likely formed, showing signs of chemical change.
c. the materials simply mixed without changing.
d. the odor proves it was only a physical change.

1. a student wants to prove that a new substance formed. which evidence would best support this? (choose two.)

a. a color change occurred and gas was released.
b. the mixture separated into layers.
c. a new odor appeared after mixing.
d. one solid dissolved into another liquid.
e. the mixture could be separated with a strainer.

Explanation:

For question 5, a solid (precipitate) forming is a sign of a chemical reaction creating a new substance. Also, inability to separate by filtering can indicate a new substance formed as it may be a chemical - bonded mixture. For question 6, a strong odor, cloudiness, and heat release are signs of a chemical change indicating a new substance formed. For question 7, a color change and gas release or a new odor are signs of a chemical reaction forming a new substance.

Answer:

1. A. A solid (precipitate) formed., C. The mixture could not be separated by filtering
2. B. A new substance likely formed, showing signs of chemical change.
3. A. A color change occurred and gas was released, C. A new odor appeared after mixing