Accuracy+&+Precision


 * Chemistry **
 * Name**

Accuracy and Precision in Measurement  In this experiment, the volume of the graduated cylinder to the 50 mL mark will be calculated from measurements of its internal diameter and height of the graduation. **//The mass of a measured volume of water will be calculated//** **//from its density (m = V x D)//** and then determined be weighing. The error and percentage error in each part of the experiment will be calculated on the basis of accepted values. **// Experiment error is calculated by subtracting the accepted value from the //** **//observed value (E = O - A).//** **// The percentage error is the ratio of the experimental error to the accepted //** **//value expressed as a percentage (% error = E/A x 100%).//** The sign of the experimental error and the percentage error may be either positive (experimental result too high) or negative (the experimental result is too low)

** Objective ** The purpose of this lab is to measure and calculate several physical properties; and determine experimental error and percentage error.

Apparatus ** Balance **
 * 100 mL beaker **
 * Graduated cylinder, 100 mL **
 * Ruler **
 * Thermometer **

Procedure I

1. Measure/record the inside diameter of the graduated cylinder.

2. Measure/record the inside height of the cylinder to the 50 mL mark.

3. Calculate the volume of the cylinder to the 50 mL mark. (V = ¼ L)

4. Record the accepted value of the volume (write down 50 mL)

5. Calculate the error.

6. Calculate the percentage error.

Procedure II

1. Measure/record the mass of the graduated cylinder (make sure it is dry).

2. Fill the beaker half fill with water and record its temperature.

3. Look up/record the density for water on p. 859 in the textbook

4. Fill the graduated cylinder with the water and record the volume.

5. Measure/record the mass of the graduated cylinder with the water in it.

6. Subtract recorded mass from step #1 from mass from step #5: This is the accepted mass of the water. Record this.

7. Calculate the mass of the water using the density from step #3 (**//observed//** value)

8. Calculate the error.

9. Calculate the percentage error.