science-this is urgent, plz help me! its easy too.

we did a lab on chemical change, where we had to see how a chemical change affcts mass. so we measure the mass of 20ml of copper solution, and 2cm(cubed) of steel wool, and then we mixed them into a flask. soon the steel wool turned rusy, and broke apart. and the duofilm(which is a strtchy rubery lid) popped up as tho gas was produced.

then we had to answer some questions:here is the question i need help with.

sometimes in an experiment there are flaws due to lack of design and materials, therefore causing mistakes. what are 3 sources of air flaws and name 3 ways to fix them.

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asked by haya
  1. You need to be somewhat more specific about your experiment. There IS no gas produced, or at last there should not be, when steel wool (iron) and copper(II) solution are mixed. The rusty color you see is due to the iron going in to solution (forming iron(II) ions) while copper plates out. The copper is what you see that looks like rust. No gas in that reaction. Was the solution acid? An acid solution would produce gas. Did you test for the kind of gas? Did you weigh the resulting material and compare that with the original mass of the reactants? What conclusions did you draw concerning the changes in the chemical mass?

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    posted by DrBob222
  2. yah we weighed the resulting material and it turned out to weigh more than the starting material

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    posted by haya
  3. I can help with some things that might have caused the experiment to fail to prove that mass can't be created nor destroyed. For one thing, how accurately did you measure the steel wool. If you took 3 cc of it steel wool, how tightly was that "wrapped" when it was measured. Stell wool, as you know, is quite flexible and there probably were air holes in it. That is, you may have measured a lot of space when measuring the steel wool. How accurately did you measure the 20 mL copper(II) solution. On a triple beam balance or better than that. You don't say how far the experiment was off (that is you don't say how much mass appeared to be created). Did you check for heat in the vessel? Could that have been heat that caused the durofilm to expand. I hope this helps you get started.

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    posted by DrBob222

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