Chemistry Blog

Law of Conservation Mass Lab

physchemchange_rxn1
Nicolette Kent
Class D
January 10th, 2012

Activity 1: When adding the lead nitrate and the potassium iodide together it turned yellow
Weight before- .553
Weight after- .599
Change in mass= .046
A chemical reaction occured and the sodium iodide reacted when the lead nitrate was added. The change did affect the mass because another solution was added.

Activity 2: We combined baking soda and vinegar in a plastic bag and watched the baking soda react with the vinegar. The plastic bag filled up with CO2 and got bigger.
CO2 is formed when combining baking soda and vinegar.

Activity 3: We placed steel wool over the Bunsen burner and it changed colors (blue, purple, and brown).
Dish before- 40.235
Wool before- 0.8
Weight after- 43.01
Change in mass= 0.81

The Law of Conservation of Mass: a relation stating that in a chemical reaction, the mass of the products equals the mass of the reactants.

In this lab I learned that some things are changed in their appearance and their mass changes, other things are changed in their appearance and their mass does not change at all. I also learned that the Law of Conservation of Mass is a relation stating that in a chemical reaction, the mass of the products equals the mass of the reactants.

Question from Activity 1: What do you think happened when you mixed the solutions? Did the change you observed affect the mass?
Answer: The two solutions reacted together and changed the substance. Yes the change affected the mass.

Question from Activity 2: What happened when the vinegar and baking soda were combined? Did this change result in a change in mass in the open flask? Did this change result in a change in mass in the closed flask? How could you account for both of these?
Answer: When the vinegar and baking soda were combined they reacted with each other and a new substance was created and that new substance expanded the plastic bag and created more air in the plastic bag. This change resulted in a change in mass in the open flask because it let the air out. In the closed flask there wouldnt be any air let out. You could account for both of these by measuring their masses.

Question from Activity 3: How did heating the steel wool affect its appearance? Did this change result in a change in mass? How could you account for this?
Answer: Heating the steel wool caused it to change color, to a blue, purple, and brown color. This change did not result in a change in mass.

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