Mr. Burrell's 8th Grade Science Class



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Identify each as a Chemical or Physical property: (1 point each)

|Rusted |Chemical |

|Color Change |Surprise = chem.; expected = phys |

|Evaporate |physical |

|Boiling |physical |

|Burning |chemical |

|Dissolving |physical |

|Rough texture |physical |

|Fizzed |chemical |

|Melted |physical |

|Density |physical |

|Exploded |chemical |

Answer each question with the best possible quick answer: (1 point each)

|Which property change involves a complete change in the substance?|Chemical |

|How would we know if two substances were the same based upon 2 |Compare test results; same results = same substance |

|chemical reactions? | |

|Which property change involves NO change in the substance? |physical |

|What would be an example of an indicator for a chemical change |Surprise color (ex: Blue + Yellow made Red) |

|(reaction) | |

Which of these reactions are the same pure substances?

Circle the two substances that are the same (1 point each)

|Substance |Added heat |Added Acid |Added Water |

|A |Melted |Fizzed |Rusted |

| B |Melted |Produced a gas |Rusted |

| C |Combusted |Turned green |Absorbed some water |

1) What did you look for to specifically match the two substances?

Same test results

2) Which test(s) would be a physical change?

Melted, absorbed some water, possibly turned green (depending on the starting colors)

3) Which test(s) would be a chemical change?

Combusted (another word for burned), Fizzed, Rusted, Produced a gas, possibly turned green (depending on the starting colors)

A crime scene has produced blood samples that we can analyze. Blood was also found at the home of a competing business owner. If blood has been moved from one place to another, the samples can often be contaminated. But if they react in very similar ways, we can argue that they are probably the same sample:

|Blood |Added Vinegar |Added Iodine |Added Water |

|Type O |Turned green |Fizzed |No change |

|Type AB |Became transparent |Turned Purple |Fizzed |

|Crime scene |Turned green |Formed Bubbles |No change |

|Suspect |color changed |Active fizzing |No change |

(1 point each)

4) What indicators would lead you to believe this suspect might be guilty?

Results from Vinegar test and Iodine test are identical

5) What indicators would lead you to believe this suspect might be innocent?

Result from Vinegar test is not specific (what color was it?)

6) Why might the results be difficult to tell for absolute certain?

Contaminated samples

7) Which tests are physical changes?

“No change” results (substances would have just mixed)

8) Which tests are chemical changes?

All of the results that showed a change on some sort (in this case; not the case ALWAYS)

List the phases and phase changes of water right on this diagram: (1 point each)

1) If a sample of water was measured to be at 65 degrees Celsius, what phase would it be? Liquid

2) If a sample of water was measured to be at 112 degrees Celsius, what phase would it be? Gas

3) What would be the indicator for a color change being a chemical change?

Unexpected result from mixing colors ex: Red + Yellow made Green

4) A pot of water is boiling on a stove. How do you know for sure that the pot and the water sample have different evaporation points?

Water is already changing phase (boiling); the pot hasn’t even melted yet

5) You open your freezer door and a small amount of your ice cubes instantly turn to water vapor. What kind of change is this?

Physical Change (solid water can also change phase when the air pressure changes suddenly; like when you open a freezer door)

6) In your kitchen, you mix baking soda and vinegar together. The solution begins to actively fizz. What kind of change is this?

Chemical Change

-----------------------

Solid

Melting

Time:

Temperature:

100°C

0°C

Liquid

Evaporating

Gas

Answer Key

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