Density

Tuesday and Wednesday were block schedule days. 1st and 3rd periods met on Tues and 2nd period met on Weds. We did a penny density lab investigation. Pennies made before 1982 were 95% copper and 5% zinc. After 1982 they began making them with 97.5% zinc and 2.5% copper as a way to save money. The newer pennies are less dense than the older pennies. We used the water displacement method to measure their volume and electronic balances to measure their mass. With this data we were able to calculate their densities. We compared our results and discussed precision versus accuracy and how many significant figures we would use. Thursday we started class with a short chemistry vocabulary review quiz, then started coloring in our periodic tables to show the different families of elements (Alkali metals, Alkaline Earth Metals, Halogens, etc.) Friday we had a shortened class schedule because of the snow and spent our time reviewing how to solve density problems. Density Practice.