The melting point of Paradichlorobenzene is 53.0C .In a laboratory activity two students try to verify this value .The first student records 51.5C,53.5C ,55.0C,52.3C and 54.2C. The second student records 52.3C,53.2C,54.0C AND 53.5C. A. Calculate the average value for the two students. B. Calculate the Percent error for each student. C. Which student is most precise ?Most accurate? Explain.

a. 53.3°C.

b.  Percent error for both students is 53.3°C

c. Both students are equal in accuracy.

2nd student is most precise

Explanation:

The percent error is defined as:

|M - T| / T * 100

Where M is measurement,

and T is theoretical value

a. To obtain the average of both measurements we need to sum the measurements and divide these in the number of measurements:

51.5°C+53.5°C+55.0°C+52.3°C+54.2°C+52.3°C+53.2°C+54.0°C+53.5°C / 9

= 53.3°C

b. Percent error for 1st student:

51.5°C+53.5°C+55.0°C+52.3°C+54.2°C / 5 = 53.3°C

|53.3°C - 53.0°C| / 53°C * 100

0.57%

Percent error for 2nd student:

52.3°C+53.2°C+54.0°C+53.5°C / 4 = 53.3°C

|53.3°C - 53.0°C| / 53°C * 100

0.57%

c. Now, precision is how close are the measurements to each other and the accuracy how close are the measurements to the theoretical value:

The accuracy is obtained with percent error, the lower percent error the most accurate measurement. That means:

both students are equal in accuracy.

And precision is obtained with relative standard desviation.

Desviation standard / Average * 100

(We can solve the standard desviation in a scientific calculator):

1st student:

2.65%

2nd student:

1.34%

The lower RSD the most precise measurements.

a