Be able to describe the observations of OTO (from Chlorine test kit) with tap water and water passed through a Brita filter. Explain.
When tap water was reacted, the solution turned yellow due to the high chlorine ion concentration. The Brita water turned a lighter shade of yellow due to the Cl⁻ ions being removed. The Cl⁻ was removed because it stuck to the activated carbons which have tiny pores so there is a high surface area to react.
(a) Be able to estimate the standard deviation for a set of data using the "2/3's rule" described in this experiment. (b) Also, know how to calculate a standard deviation by hand for a given set of data.
(a) 1. put the number in increasing order.
2. Find the average of the numbers.
3. 2/3 * # of data points
4. + or - two points on either side of the average.
5. Report answer
(b) [(∑(x-x1)^2)/(N-1)]^.5