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Purpose:
Just as isotopes are atoms that are identical chemically (same
number of protons) but slightly different in mass (different number
of neutrons), these mystery containers will have the same number
of coins (10) but a different combination of coin types (masses).
Even though you will not see the makeup of the coins you will
be able to predict it exactly with a gram scale and some Algebra.
Setup:
- Gram scale
- Film container
- 10 dimes and 10 nickels
Procedure:
- Find the mass of the empty film container
- Find the total mass of the 10 nickels and divide by 10 (N)
- Find the total mass of the 10 dimes and divide by 10 (D)
- Have someone place a random combination of each (but totaling
ten) inside a film container e.g. 9 dimes + 1 nickel
or 8 dimes + 2 nickels...
- Measure the mass of the full film container
- Subtract off the mass of the empty film container to get the
Total mass of the coins
- Use this data and some simple Algebra (see Analysis) to determine
the makeup of Nickles (x) and Dimes (10-x)
- Open the container to verify
- Repeat with 2 more combinations
Data:
| 10 Nickels ___._g |
÷10 N=___._(g)
|
| 10 Dimes ___._g |
÷10 D=___._(g)
|
| film container |
___._g |
| Coins + Container |
Coins (T) |
Prediction (x) and (10-x) |
Actual |
| ___._g |
___._g |
(x)___ nickles
(10-x)___dimes |
(x)___ nickles
(10-x)___dimes |
| ___._g |
___._g |
(x)___ nickles
(10-x)___dimes |
(x)___ nickles
(10-x)___dimes |
| ___._g |
___._g |
(x)___ nickles
(10-x)___dimes |
(x)___ nickles
(10-x)___dimes |
Analysis:
xN + (10-x)D = T
xN + 10D - xD = T
x(N-D) = T - 10D
x = (T - 10D) ÷ (N-D)
Conclusion:
Finally, update your website with the details of this lab experience
including a short descriptive summary, all data, calculations
and error conclusions! The instructor will grade this lab
web entry according to this rubric.
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