skip graphical navigation
PBS KidsZOOM Home Back to Activity
Science Rocks!


Water Density

next

your results

Sent in by:
Mrs. Darden's Science Class in Thomson, GA

Did you know that you can make water more dense?
Materials

Materials Needed


  • clear straws
  • clay
  • salt
  • blue, red and yellow food coloring
  • 3 plastic cups filled with water
  • eye droppers

Instructions

Instructions


  1. Add a few drops of blue food coloring to one of the cups filled with water. Add red to the other cup and yellow to the third cup.
  2. Then, add different amounts of salt to each cup. Add lots of salt to one color, a medium amount of salt to the other, and no salt to the last cup.
  3. Using clay, make a base for the straw. Stick the straw into clay to keep it standing straight.
  4. Now, using the eye dropper, put drops of the different colored water into the straw. What happens?
  5. The different colors float on top of each other in the straw. That's because the more salt there is in the water, the denser the water is and the lower it will be in the straw. Density is one thing that makes things float. So, the color that floats at the top of the straw has the least amount of salt in it and is the least dense.


This is kind of complicated, so here's the science scoop again. The color with the most salt in it is the most dense, so it stays at the bottom. The color with a medium amount of salt in it is medium dense, and the color with no salt in it is the least dense.Keep experimenting with density. Think of a question that you'd like answered. Like, "What would happen if I added different amounts of sugar to the water instead of salt?" Make a prediction, test it out, and then share any discoveries you make at the ZOOMsci feedback section.

Some of your Results

Isaac, age 12 of Auckland wrote:
I added lots of salt to blue and medium to yellow and none to red. The colours floated on top of each other in this order. Red, Yellow and blue.

Laith, age 12 of Auckland wrote:
all the colours mixed up and the one with the most salt was lowest

Isaac, age 12 of Auckland wrote:
The colours floated on top of each other in the straw.

Tate, age 12 of Auckland wrote:
I found it cool how the colours didn't mix but stayed separate from each other. First I put the red which had the most salt in and that went down to the bottom then I put in the yellow which had a small amount of salt and that stayed above the red. Then I put in the green which stayed at the top of the straw and none of the mixed with each other.

Hayoung, age 13 of Auckland wrote:
When I did it, it has floated. I think this experiment is so interested and excited!

Antoine, age 12 of Auckland wrote:
When I did it, it worked, but the colours got mixed a bit.

Hannah, age 12 of Auckland, NZ wrote:
when I did it I had green yellow and red for my colours I put lots of salt inin the green so the green went to the bottom and put some in the yellow and like nothing in the red so the yellow went to the middle and the red stayed at the top so it looked like a triffic light

Elizabeth, age 12 of Auckland, NZ wrote:
The more salt I added the more denser it got and it was like a trafic light

Rebecca, age 16 of Auckland, NZ wrote:
I had the colours green, yellow and red and they were traffic colours and the more salt I added the more denser it got.

Lillian, age 12 of Auckland, NZ wrote:
The water with the least amount of salt in it floated on the top and the water there was also had a lot of salt was at the bottom of it.

Connor, age 12 of Auckland wrote:
the water layed

Lillian of Auckland, NZ wrote:
The colour with the most salt stayed at the bottem of the straw, the colour with a little bit of salt was in the middle and the colour with no salt was on the top.

Christine, age 12 of Auckland, NZ wrote:
The more salt I added the denser it got but I did the experiment with red, green and yellow and it turned out like a traffic light

Matt, age 12 of New Zealand wrote:
The colour that had the most salt was more dense in comparison to the colour with no salt. The colour with a lot of salt would go to the bottom and the one colour with the less amount of salt would go to the top

Yeonsu, age 12 of Auckland, NZ wrote:
It was really cool the colours layered each other when I did it. I did the colours green, yellow and blue. The colours did mix a little bit but it was a really good experiment!!!

Magdalena, age 12 of Auckland, NZ wrote:
I saw the different colours float on top of each other in the straw. That's because the more salt there is in the water, the denser the water is and the lower it will be in the straw.

Molly, age 12 of Auckland, NZ wrote:
It went just like it was suppose to and it showed me the affect of the different densities in the cups of water.

Greg, age 12 of Auckland, NZ wrote:
in the 1 with lots of salt: I put the water in at the top of the straw and it stayed at the top in the 1 with medium: it went slightly further down the the other 1 in the 1 with no salt: it went straight down

James, age 12 of Auckland, NZ wrote:
When I did the experiment the water seperateding looked really cool!! like a drink I one had exept this would not taste nice because of the salt, I put lots in the blue water and medium in the red and none in the plain water

Emma, age 12 of Auckland, NZ wrote:
I used the colours Green red and blue. Green had the most amount of salt in it, then red and blue had none. I put the green in first and it sunk to were the bendy bit is. Then I put the red in and it sat between the bendy bit and the top of the straw. Next I put the blue in and it stayed at the top. Obviously the green did have the most salt in it because it stayed at the bottom.

Sonny, age 12 of North Shore, NZ wrote:
The colour on top was the Green (Lime Raro) and the one in the middle was the Yellow one (Yellow Food Colouring) and the one at the bottom was the normal water. I think this happened was because the one with the most salt was the heaviest and the most dense so it will sink to the bottom.

Tommy, age 12 of Auckland, NZ wrote:
it was pretty cool, the ones with more salt were more dense

Taryn, age 12 of Auckland, NZ wrote:
The blue sank to the bottom because it had the most salt. The yellow was in the middle because it had some salt, and the red had no salt and went to the salt.

Bella, age 12 of Auckland, NZ wrote:
this project is really cool the three different colors did get dense on each other. The one with the most salt was at the bottom, the one with medium was in the middle and the one with no salt was well it was at the top it was really fun!

Rose, age 14 of Auckland, NZ wrote:
It worked wow

Samantha, age 11 of Auckland, NZ wrote:
The three different colors stayed on top of each other. There was a green layer of water, a blue layer of water and a pink layer of water.

Centaine, age 12 of W. Auckland, NZ wrote:
the water with the least amount of salt floated at the top and the water with a lot of salt were at the bottom.

Morgan, age 12 of Auckland, NZ wrote:
Well I used the colours red, purple and green and it did exactly what it said would happen. The colours didn't mix into each other. This must be a way to make a traffic light drink

Cecilia, age 12 of Auckland, NZ wrote:
the coloer with the most salt sank to the bottemthe coloer with no salt was at the top of the straw.

Olivia, age 12 of Auckland, NZ wrote:
It was pretty cool, the red which had the most salt in it I put in first and it sat at the bottom of the straw. Then I added the black which had a small amount of salt in it, I thought they were going to mix toether. But they didn't the black just sat on top of the red! then I added the blue which had no salt and it just sat on top of the black! (I used red, black and blue food colouring instead of red, green and yellow).


not yet implemented