Conservation Of Mass Inquiry[1]

Chemistry I Proving a scientific law? Name: Question to be answered Can the law of conservation of mass which states; (during a chemical reaction matter is neither created nor destroyed, bonds are broken between atoms and new bonds between the atoms to create new substances while conserving the overall amount of matter) be proven? Can there be change without change? Purpose To accept, reject or modify our concept of the law of conservation of mass. Experiment (You may carry out your own experiment; use the one below or both.) Materials 1. Two empty (clean) vials with lids 2. 0.5M Pb(NO3)2 solution (can be toxic in large doses – handle with care) 3. 0.5M NaCl solution 4. Digital scale, 2 clean pipettes Directions 1. Fill one pipette full with the 0.5M lead (II) nitrate solution and do the same with the second pipette and sodium chloride solution. Next, empty the pipettes into each labeled vial for that particular solution. 2. Place the lids on both vials and mass them both at the same time and make note of the mass. (Make sure the digital scale is ‘zeroed’ prior to finding any mass.) Total Mass (before mixed): _________________ g 3. Next, Take the lids off and pour the contents of one vial into the other and replace the lids. Note any changes in the solutions.

4. After making note of any changes to the solutions, place both vials (w/lids on) onto the same scale used in #2 using the same massing procedure. Total Mass (after mixed): __________________ g 5. To clean up, place the contents of the vial into the beaker provide and clean the vials with soap/tap water and rinse with distilled water.

Questions 1. Did a chemical reaction take place? Explain. 2. Compare the total mass both before and after mixing the solutions. Make a claim as to the validity of the law of conservation of mass. 3. Was the evidence in line with what the law states? If so why? If not, why not? Explain your evidence. (Think of your procedure and how it may affect evidence gained.) 4. Explain your claim in #2. Shoot for the Stars 1. Why would the law of conservation of mass be so hard to accept if a gas, vapor or plasma was a result of a chemical change? Explain. 2. Why is it so easy to prove the law of conservation during physical changes and not necessarily for chemical changes? Explain.