Question

CHE 120 Activity 2. Measurement Evaluations: Accuracy & Precision Associated Resources: Accuracy & Precision Handout Exercice #1: Two students weigh a powdered metal, 1: Wo students weigh a powdered metal and report the results of their multiple trials below. The exact (true/accepted) value for this mass is 8.72 9. Student #1: 8.72 g: 8.74 g: 8.70 g Student #2:8.50 g: 8.48 g: 8.519 a) Calculate the average mass from each set of data Average Set 1: _ Average Set 2: b) Without doing any calculation, which set of data is the most accurate c) Calculate the % error for each set of data using the respective average as experimentar vode Clearly show your work % error Set 1 = % error Set 2 = d) Does your calculated % error confirm your answer in b)? Explain e) Without doing any calculation, which set of data is the most precise?

Answer 1

Ta) Average mass 8.72g+ 8.74 g+ 8.709 8.72g ser2 8.488 + 8.51 8.50g 8.498 be ceuse the esccect va lue fob we lonsides seti, Me value 5 Set I olete is accurate mass is given 8.429. when 8-72, 8, 74 . (4hese va lue mass are in pes te ct oreles. cie Cein conclude Mhe average will be middle value. e8.ld are O.02 inoreese) in Such eese we c) percentuge e xperimentalvaulne-yuevalue x100%. Truevalhe set I =y 8. 72g- 8.72g x10 0%, = 8-727 -O 23 x100% = -2-64%. 8.72 8.49 8-8.72gx100%. 8.72g set 2=> =Q.64%. avoid Mhe -ve s1gn.ie %. error

d) Yes, the percentage error confiom Me ansever in 6.The per- - centage eroor lells how big/small your error. Smaller val ue of peolestage eroor means that 1s elose to eal value. laoger value of percenrage error indi caute theat is Far set 1, percen tage eroo errorl on this escpe- set 2, the percentage error s small error (sligut from real ralue. In alway žero· thet rmeans there is no yiment. but in 2.64/, thet meanJ devi a Hon from Foue value). C) set I dara is most: there is a CIse. pre