Colorful Concentrations

Today in class we started off by turning in our Density of Pennies Lab. We then went over the concept of percent error and how to calculate it. The formula to find the percent error is theoretical value subtracted from the actual value, then divide that by the theorectical value and then that answer is multipled by one hundred. Mr. Lieberman said this is important to know and that we will be using it continually throughout the year.



After that, Mr. Lieberman showed us a demonstration using salt water, two different types of beads, and isopropyl alcohol in a plastic bottle. When Mr. Lieberman shook the bottle, the two liquids combined and the beads were everywhere, but then the white beads floated to the top and the blue beads sunk to the bottom. As the water and alcohol began to seperate, the white beads slowly moved down and the blue beads floated up and the two met in the middle. The point of the demonstration was to show how density effected where the four substances stayed in the bottle and what happened when they were mixed together.



For the last half hour of class we started the Beverage Density Lab. Mr Lieberman showed us how to use the pipet -not with your mouth :). Then we began the lab by placing the beaker on the balance and "rezeroing" the balance. Next, everyone poured each of the different concentrations- 0%, 5%, 10%, 15%, and 20%- into idividual beakers and took them back to the lab tables. Yes, the mixtures were very pretty colors but not to be mistaken for Gatorade : ) We then used the pipet to measure out 5 mL, not 10 mL, of each concentration and put it in the big beaker to measure the mass. Our group's data showed that the mass of the concentrations increased as the amount of sugar in each mixture increased. We then used the mass we measured and the volume of 5 mL to calculate the density. Tomorrow we will continue the lab and do part B. The finished lab will be due Wednesday and Mr. Lieberman explained that we will need to do another graph for question number one of the post-lab questions.

The next scribe is Mollie M.