April 27, 2011


Somehow, at the same time, my a friend and I both decided to be bewildered about how fresh water floats on salt water and stays separated. So, being good scientists, we decided to test it in lab my room. IMMEDIATELY.

We started by heating up water and saturating it with salt and then bringing it back down to room tempurature. I can now tell you that saturated salt water solution tastes horrible. I think that's why you aren't supposed to eat things in lab. We put blue food coloring in the salt water as an indicator. And, finally, we poured clear fresh water carefully on top. My friend had this clever way of pouring it through a paper towel as to minimize disturbances. And then we let it sit. For like a week. Basically, until I got sick of it sitting on my desk.

Here's how it started, at 2:30 am.

We were amazed that it was still separated at 2:33 am. Don't ask us why.

At 2:40 am we decided to start a new one, this time with a mixed zone. The yellow is fresh water, the blue is salt water, and the green is the two premixed together.

And at 2:50 we decided our science wasn't valid because we didn't have a control. So, we carefully poured yellow fresh water over red fresh water, resulting in none other than...
And at 3:40 am, the colors were still well separated.

When I woke up the next day at 12:30 pm, they were STILL SEPARATED. Except the orange, because we didn't reach any entropically unlikely states. :(.

And at 5pm, they were still separated.

At this point, we were pretty convinced that fresh water does in fact float on salt water. It got really boring from this point on - nothing changed. After a week, everything looked exactly the same as when we started.

But, it didn't taste the same. Before we poured it off, I decided to use a straw and taste the layers. The fresh water was salty. It was really gross. But the dye was still separated. So, we learned that salt diffuses faster than dye, but have no clue how fast that happens because I was unwilling/didn't think to taste it every now and then.

Yay for food grade science.