Layered Solutions: A Lab on Density

Observations/ Data: -The red solution was a little murky with some of the salt not settled. -Yellow and green seemed to dissolve well and allowed light to pass through. -When the colors were added into the last test tube, they all blended together, making a dark liquid as seen in the first picture. -We started adding more slowly, and allowed the liquid to run down the side, making it layer, as seen with the red and yellow on the bottom tube. -We were unable to layer all 3 colors as we ran out of time to add the green.

Questions 1-3 on the board: 1- The independent variable for this lab was the amount of salt added. This was the IV because the amount of salt added to each mixture was changed. The red tube had 4 grams of salt, the yellow had 3 grams and the green had 2 grams. 2- The dependent variable is the resulting/ measured variable from the lab. By changing the amount of salt, we were able to see solutions (mixtures) that layered because they had different densities. 3- Constants are variables that remain the same for every part of a lab experiment. Variables from this lab include, adding 15 mL of water to each of the 3 test tubes, adding 2 squirts of each colored liquid to the 4 th test tube, adding 1 drop of food coloring to each test tube, using the same sized test tubes, using the same type of pipette for each test, and using the same scale for each measurement.

Conclusion Statement: The mixtures ended up in layers because they had different densities. The red solution had 4g of salt in 15mL of water and was most dense, which is why it sank to the bottom. The yellow had 3g of salt in 15mL of water, while the least dense, green, had 2g of salt in 15 mL of water, which is why it layered on the top. If added carefully, the solutions layered, rather than mix together, which is what happened the first try. Density is an amount of mass inside a given amount of volume.

CLAIM: (a general statement about the main idea of the lab) The mixtures ended up in layers because they had different densities. EVIDENCE: (specific, measured or observed information from the lab) The red solution had 4g of salt in 15mL of water and was most dense, which is why it sank to the bottom. The yellow had 3g of salt in 15mL of water, while the least dense, green, had 2g of salt in 15 mL of water, which is why it layered on the top. If added carefully, the solutions layered, rather than mix together, which is what happened the first try. REASONING: (Explains the idea behind your evidence) Density is an amount of mass inside a given amount of volume.