Precision of Measurements

Goals: 1. Know what measurement tool is used to take different measurements. 2. Understand that the precision of a measurement is determined by the instrument used.

Volume Measurements Volume is the amount of space an object occupies. To determine volume of a regularly shaped object, we use a metric ruler (length x width x height). To determine the volume of an irregularly shaped object, we use the displacement method.

Reading a Graduated Cylinder

Reading a Graduated Cylinder Always measure from the bottom of the meniscus You must record 1 digit more than the interval of the instrument MENISCUS

Determining the Interval Example: Look at the sample graduated cylinder. The interval is the value of each of the lines. In this case, the interval is “1”. Our measurement needs to go to one digit past the “ones” place. Therefore, in this example, our Measurement would need to go to the tenths place.

Example: Graduated Cylinder The interval is 1 mL Our measurement needs to be to the tenths place So a proper measurement might be 73.0 mL

Length Measurements Interval is 0.1 cm So our measurement needs to go out to the hundredths place!

Determining the Intervals Take a look at the measurement tools at your station. Determine the interval of the following: 10 mL graduated cylinder: _______ Thermometer: _________ Triple beam balance: _________

Have Ms. V check your intervals BEFORE you proceed with taking measurements!