- #1
Makai
- 3
- 0
Homework Statement
My son picked a science experiment for his 5th grade project. It was supposed to be on evaporation. Basically a steam powered boat with candles heating up a cigar tube with a hole for the steam to escape and push the boat. However he got ambitious and changed the experiment with his teacher to see what would work better fresh water vs. a salt water solution. My son theorized that fresh water would push the boat better than salt water after researching about boiling points and elevated boiling points due to the addition of salt water. The conditions were the same as far as time frame, amount of water, and temp of water added to the tube. However his results show that on average the salt water powered boat traveled farther than the fresh water in the same given time. His observations were that the fresh water started pushing steam out sooner than the salt water, however the salt water powered steam was more consistent than the fresh water. Can you point me in a direction that supports these results. Do they sound valid or do we have a case of experimental error. I helped him and made sure that we kept all processes the same so we weren't influencing a result. Is the added solution with a higher boiling point releasing steam at a higher pressure due to more molecular bonds being broken?
Homework Equations
The Attempt at a Solution
He is looking into vapor pressure and is trying to come to a conclusion. Vapor pressure is lowered with salt added to the water so it takes more heat to release vapor so would this create more pressure thus pushing the boat faster.
Thanks