Why did the nail rust in the distilled but not salted water?

Question

Ok, here is another answer that I need rather quickly, scientific I should add. My 4th grader has a science project due tomorrow. We have tested 3 samples and found that a nail placed in plain distilled water rusted, but the nail placed in salted distilled water did not. The trouble is, we can not find scientific data to support the findings. Please help!!! Oh, we understand why the nail rusted in the plain water, but we don't understand the science behind the salt watered nail seeming untouched.

Answer 1

For rusting to occur, two things must be present, water and oxygen, if any one of the two are lacking then rusting might not occur or may occur at a very slow rate.....now in distilled water, the water is pure and contains as much oxygen as possible, hence the nail placed in this water would rust......in salt water, the salt would displace most or all of the oxygen present and so the nail placed in this water would not be affected by both oxygen and water, but by water only...so this would not rust.

Answer 2

You should see your nail being disolved by the salt water and the color of the water changing unless--- you have several items held dangling in the water by wire and tied together creating a battery. The iron can end up being protected by something else being sacrificed. The same principle as providing a copper chunk of metal on the boat bottom which sacrifices itself to prevent the bronze propellers from corroding. With all metal items grounded (tied) together, the most electropositive metal or alloy will be corroded.

Answer 3

because there's more oxygen in the distilled water. if you place a nail in a test tube, boil the water for a while and place paraffin wax in, it wont rust easily as most of the oxygen has been boiled off and sealed from the air

Answer 4

I WOULD SAY THAT THE SALT IN THE WATER PRESERVED THE NAIL. i FIND THIS A SURPRISE MYSELF. SALT PRESERVES FOOD AND KEEPS IT FROM SPOILING BUT I NEVER THOUGHT IT WOULD WORK FOR A NAIL! this SHOULD BE NEWS WORTHY.