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In a second atomic absorption experiment, a student prepared a blank solution and measured itsabsorbance, in absorbance units (AU), three times. The measured values were 0.0044 AU, 0.0079 AUand 0.0062 AU.

Required:
a. Calculate the mean of the blank.
b. Calculate the precision of the blank.
c. Calculate the accuracy of the measurement if the true value of the blank is 0.0030 AU.

1 Answer

5 votes

Answer:

  • 0.0062AU
  • 0.00082.
  • 106.7% error

Step-by-step explanation:

a.) Average or mean value of readings,
x_(o) = (0.0044 + 0.0079 + 0.0062) / 3

=
(0.0185)/(3) = 0.0062 AU

b.) The accuracy of the readings is determined by taking determining the standard deviation (SD) of the readings:

SD = ∑
\sqrt{x- x_(o)}/n


(0.0062 - 0.0044)^(2) = 0.0000032


(0.0062 - 0.0079)^(2) = 0.00000289


(0.0062 - 0.0062)^(2) = 0

SD =
(√(0.0000032 + 0.00000289 + 0) )/(3) = 0.00082.

c.) The % accuracy is the distance between the average value and true value

=
(0.0062-0.0030)/(0.0030) *100 = 106.7% error.

User Anulal S
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