[LHM]

The molarity of a Cu₂₊ is to be determined from its absorbance. The absorbance is 0.10 units at a 0.050 M. What will be the percent uncertainty in the concentration of a 0.050 M solution if the uncertainty in the absorbance reading is +/- 0.01 absorbance units?

I originally just did 0.01/0.10 * 100 = 10%, which is the right answer. However, it then occurred to me that since there's a +/- in front of the 0.01, then shouldn't it technically be (0.01-(-0.01))/0.10 * 100 = 20%? How come my first answer was right, and my second one is wrong?

[chronictonic]

The actual answer is +/- 10%. you do it in two calculations instead of one, but they will give you eith negative 10% or positive so you only really have to do one. you had the right idea to start with, brew