Activity 3


rusting

About rust



Rust

is a product formed from a reaction between

iron atoms

and

Oxygen molecules

Chemical makeup


 Fe2O3


 

Rusting in action

 

before

after


WOW!

Our experiment

Question:

How does 
the shape of the iron object 
affect 
the rate of rust formation?

Hypothesis

The smaller the large side to small side ratio of the iron block, the more square it will be;

therefore, there will be more iron atoms relatively insulated by the outside iron atoms, 

thus the block will rust less in a set amount of time (1000 ticks).

Here's a drawing to explain our hypothesis. As you can see, there is a very square block and a thin, long block. They are made from the same amount of iron atoms, but the square block has 1 atom insulated by the others.
The long block has all of its atoms open to the system.

Procedure



Variables

Constant: Temperature, number of molecules

Varied: Iron-block geometry
/\
Independent
Dependent
\/
Rust molecules/Iron atoms left in block

Procedure


  1. Open NetLogo 5.0.5, if it not there then download it.
  2. Navigate to Files => Model Library =>Find the rust model inside Connected Chemistry=>Open
  3. Select 9x9 block under iron-block-geometry.
  4. Press 'setup' and then 'go'.
  5. Wait 1000 ticks (shown on the top side of the model view), and then record how many iron atoms have left the block and how many are still in  it.
  6. 'Setup' and 'go' one more time.
  7. Wait 1000 ticks again, recording the same data.
  8. Repeat steps 3-7 as many times as desired, changing the block geometry in step 3 to the needed shape.

Data


Table



Graph


After the experiment,

our claim changed from our hypothesis.
Our claim was:
The smaller the large side to small side ratio of the iron block, the more the block will rust in a set amount of time (1000 ticks).

Our claim was different than our hypothesis because the data supported this claim more.

Conclusion

Our hypothesis stated that if a person set up an experiment to see how the shape of an object affects the amount of rust formed, then the object with the smaller the ratio of the two sides, the less iron will rust in 1000 ticks, because it will be more square like and therefore have a larger percent of iron encased, which will be guarded from the oxygen, not allowing it to rust.
This hypothesis was supported and not supported the trials.
Comparing the 6x6 square iron box to rectangular box that were also tested, seeing that the average amount of iron that turned to rust was about 17%, while some rectangles averaged at between 3 and 5% rusted. The hypothesis is also opposed, when comparing the 9x9 iron box with the 19x3 and 19x5 iron boxes, seeing that their average percent rust produced were 3.5% and 4.2%, respectively.In this case, the hypothesis was supported, since the 9x9 iron box had a higher average percentage of rust than the 19x3 or 19x5 boxes.

Why?




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