January 14, 2013
Class D
Date lab was performed: January 8,2013
LAW OF CONSERVATION OF MASS
- 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.
- The real mass changes and apparent ones due to the limitations of the balance are distinguished by the chemicals added to the substance. In this lab lead nitrate is added with potassium iodide. The apparent masses are the ones that are obvious. One may think that it has changed but it really has not.
- When I mixed the solutions in activity one, the change my partner and I observed did not affect the mass.
- In activity two, when the vinegar and baking soda combined it got lighter and made the Ziploc bag blow up. This did result in a change of mass in the open bag. This change resulted in change of mass in the closed flask because the baking soda was loose in the bag. Accounting for the changes in mass can be done by making sure to weigh everything very carefully.
- The heating of the steel wool in activity 3 affected its appearance by making it appear blue. This did not result in a change of mass. I could account for this because I weighed it before and after.
- Massing every material and doing accurate measurements the apparent changes in mass can be proved or disproved.
- Making sure all materials are massed correctly before doing anything with them it can modify such experiments.
What I learned: Throughout these activities I learned about the law of conservation of mass. Also I learned to be careful when massing materials before and after and throughout a experiment. Also I learned to account for the changes in mass between the differences of when mixing or burning substances. Learning these things will help me be a better scientist.
Activity one: lead nitrate
+ potassium iodide
35.53g(before and after mixing)
Activity two: Ziploc and vial w/lid= 113.12
Ziploc opened vial = 111.59
Activity three: steel wool(before and after burning)= 1.72g
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