Properties and Changes Lab - Paint Valley Local Schools



Properties and Changes Lab

1. Purpose: The purpose of this experiment is to determine the physical and chemical properties and changes of three substances, to observe the physical or chemical reaction that occurs between the substances, to see a change in pH, and to test for the presence of a gas by using the wooden splint test.

2. Research: See MSDS sheets for background information on the substances tested.

3. Hypothesis: If I mix calcium chloride (CaCl2), baking soda (NaHCO3), and Bromothymol Blue/Phenol Red together, then the mixture will result in a physical change/chemical change (circle one).

4. Experiment

Materials and Supplies: Zip-loc bag, 1 teaspoon of baking soda (NaHCO3), 1 tablespoon of Damp Rid (CaCl2), small test tube with rubber stopper, Bromothymol blue or Phenol red, and Safety goggles

Procedure:

*Never open your plastic bag during this experiment!

1. The smaller granules are the baking soda and the larger granules are the calcium chloride. Your test tube contains Bromothymol Blue or Phenol Red.

2. Make observations about the physical and chemical properties of the substances in your bag. These have been written in your data table. It is your job to tell which sections of the MSDS it was found in and place this in the data table as proof that you found it.

3. Weigh the mass of the three contents in the Zip-loc bag before mixing them. Record this information in the data table.

4. Keeping the bag closed, remove the stopper from the test tube and mix the substances together.

5. Make observations about the physical and chemical changes the substances are undergoing and record them in the data table.

6. Weigh the mass of the unopened Zip-loc bag after the reaction is finished.

7. With a lit wooden splint, test to see if the gas generated from the reaction was oxygen (reignites the wooden splint) or carbon dioxide (makes the lit splint go out).

8. The contents of the bag will be disposed of once the test tube and stopper have been taken out of the bag. Wash the test and stopper with soap and water. If you handled the test tube and stopper, wash your hands with soap and water.

5. Data & Observations:

|Properties/Changes |Baking Soda |Damp Rid (CaCl2) |Bromothymol Blue or Phenol Red |

| |white powder or crystals, |White, odorless powder, |Deep, blue (red) liquid, |

|Physical Properties |odorless, dissolves in water, |crystals, or flakes, water |odorless |

|(Tell what section(s) of the MSDS|melting point loses CO2 at |soluble (dissolves in water), |Section(s) |

|this is in. You will have to |270˚C |melting point at 772˚C, | |

|read it!) |Section(s) |deliquescent (dissolves | |

| | |gradually by absorbing moisture| |

| | |from air) | |

| | |Section(s) | |

| |NaHCO3, reacts with strong |CaCl2, non flammable, non |Non flammable, non combustible,|

|Chemical Properties |oxidizers and acids, reacts |combustible, reacts with strong|used as an indicator for pH |

|(Tell what section(s) of the MSDS|with moist air, non combustible|acids |(turns yellow for an acid and |

|this is in. You will have to |Section(s) | |blue for a base) |

|read it!) | |Section(s) |Section(s) |

|Physical Changes | |

|(after mixing) | |

|Chemical Changes | |

|(after mixing) | |

Law of Conservation of Mass- matter cannot be created nor destroyed in a chemical reaction

|Mass of substances before mixing (g) | |

|Mass of substances after mixing (g) | |

6. Conclusions: (Please remember to communicate in sentences.)

1. Was your hypothesis supported or refuted?

2. Was there a change in the pH of the substances after mixing? How could you tell?

3. This equation tells us what chemical reaction happened in the bag. Identify and count the elements on each side of the arrow (yield) sign. Hint: You will need to use the periodic table in the back cover of your book to help you with this.

2 NaHCO3 + CaCl2 ----------( CaCO3 + 2 NaCl + H2O + CO2

5. Place a circle around the Calcium Chloride, place a square around the salt, and place a triangle around the water in the above equation in question 4.

6. What gas was produced in this reaction?

7. Was there a change in temperature? How could you tell?

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