error and percent error

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error= measured value-actual value

percent error= error X100%

actual value

percent error= measured value-actual valeu X100%

actual value

Joshua uses his thermometer and finds the boiling point of ethyl alcohol to be

75 o C. He looks in a reference book and finds that the actual boiling point of ethyl

alcohol is 80 o C. What is his percent error?

-75

80

5

6.5%

A student estimated a mass to be 250g, but upon carefully measuring it, found the actual mass to be 240g. What is the percent error?

-250

240

10

4.16%

2. A student measured the temperature of boiling water and got an experimental reading of 97.5oC. What is the percent error?

-100

97.5

3.5%

3. An experimental measurement was taken of 10.4 mL and the actual measurement was 9.7 mL. What is the percent error?

-10.4

9.7

0.7

6.73%

Experimental = 62.5 g and accepted value = 65.2 g. Solve for percent error.

4.32%

5. Joe measured the volume of an object 5 times and got results of 34.5 mL, 34.9mL, 34.2 mL, 33.4 mL, and 35.9mL. What is his average experimental result?

34.5

+34.9

34.2

33.4

35.9ml

34.58

The actual volume of the object was 34.1 mL. What is the percent error of his average result?

-34.58

34.1

0.48

1.38%

A student estimated a mass to be 325g, but upon carefully measuring it, found the actual mass to be 342g. What is the percent error?

-325

342

-17

-5.23

The density of water at 4oC is known to be 1.00 g/mL. What is her percent error?

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3. An object has a mass of 35.0 grams. On Anthony’s balance, it weighs 34.85 grams. What is the percent error of his balance?

-35.0

34.84

0.16

0.45%

4. The concentration determined for an unknown sample of hydrochloric acid by a student is 0.1355 M. According to the instructor’s information, the true molarity (M) of this solution is 0.1364 M. What is the percent error in this experiment?

-0.1355

0.1364

-0.0009

0.66%

5. The melting point of potassium thiocyanate determined by a student in the laboratory turned out to be 174.5 oC. The accepted value of this melting point is 173.2 oC. What is the percent error in this reading?

-174.5

173.2

1.3

0.75%

6. An object with an actual mass of exactly 0.54 g is given to 2 students. One student obtains a mass of 0.59 g for the object, while another says the mass is 0.49 g. Which of the students, if either has the greater percent error?

-0.59 -0.49

0.54 0.54

0.05 0.05

8.47% 10.20%

The second kid had the greater percent error which was 10.20%.