Answers26-27 CFISD TX-Chemistry A CRLab: Physical and Chemical Changes

Lab: Physical and Chemical Changes Answers

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1
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Which reactions performed in the experiment involved chemical changes?

A
crushing calcium carbonate
B
mixing calcium carbonate and HCl
C
boiling water
D
heating copper (II) sulfate pentahydrate
E
separating iron filing and sulfur
F
mixing potassium iodide and lead nitrate
G
combining magnesium and HCl
H
burning the candle
3

Check all changes that you listed.

A
formation of a gas
B
formation of a precipitate
C
color change
D
temperature change
E
production of light
8

How did the experiement with the iron filings and sulfur compare with the experiment in which copper(II) sulfate pentahydrate was heated?

A
Both resulted in gas formation.
B
Both resulted in color change.
C
Both involved chemical change.
D
Both involved physical change.
E
One involved chemical change while the other involved physical change.
9

How did the experiement with boiling water compare with the experiment in which magnesium was added to hydrochloric acid?

A
Both resulted in gas formation.
B
Both resulted in temperature change.
C
Both involved chemical change.
D
Both involved physical change.
E
One involved chemical change while the other involved physical change.
12

Which real-world scenarios below represent physical changes? Check all that apply.

A
running a car engine
B
exploding fireworks
C
mixing water and powdered drink mix
D
combining oil and vinegar to make salad dressing
E
taking aspirin for a headache
F
diluting bleach with water
G
digesting Thanksgiving dinner
H
spreading peanut butter on bread
20

Based on the results of this lab, write a short paragraph that summarizes how to distinguish physical changes from chemical changes.

Answer:

Physical changes alter a substance’s form or appearance while its properties are retained, and the original materials may be recoverable. Chemical changes form a new substance. Evidence of a chemical change can include gas, a solid forming, light, or heat.

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