LABORATORY EQUIPMENT METRIC RULER

Many laboratory activities require measurements. Science uses the S.I. (Metric System) of measurements.

Types of measurements: Linear (length or distance) Mass (weight) Volume Temperature

All measuring instruments have calibrations All measuring instruments have calibrations. These are the markings or divisions on the measuring tool.

Linear measurements are made using a Meter Stick or Metric Ruler.

The basic unit for linear measurement is the meter (m. ) The basic unit for linear measurement is the meter (m.). Other commonly used units are the centimeter (cm.) and millimeter (mm.). One advantage of the metric system is that everything is based on the number, 10, or some multiple of 10. 10 mm. = 1 cm. (and 1 mm. = 0.1 cm.) 100 cm. = 1 m. (and 1 cm. = 0.01 m.) Also, 1000 m. = 1 kilogram (kg.).

cm. marks mm. marks A metric ruler

Metric Details Millimeters and Centimeters 10 millimeters = 1 Centimeter 10 Centimeters = 1 Decimeter 1 2 2 centimeters Lets find this point!

Metric Details Millimeters and Centimeters 10 millimeters = 1 Centimeter 10 Centimeters = 1 Decimeter 1 10 Centimeters or 1 Decimeter Lets find this point!

When making measurements, scientists use a concept and a practice known as significant figures (Sig. Figs.)

Significant figures include an estimated digit that is always one place beyond the calibrations on any measuring instrument.

Estimating the last digit in a measurement You might estimate the end of the cylinder to be half-way between the lines or 0.05 cm. This digit must be included in the measurement.

Estimating the last digit in a measurement This measurement should be read as 4.95 cm. This measurement has 3 significant figures.

Reading a metric ruler correctly: This point can be read as 1.65 cm. or 16.5 mm.

Reading a metric ruler correctly: This point can be read as 6.70 cm. or 67.0 mm.

Mass measurements are made using a balance. There are several kinds of balances: Triple beam balance Dial-a-gram balance Electronic/ digital balance Analytical balance

The triple beam balance:

Mass, in the metric system, is measured in grams (g. ), centigrams (cg Mass, in the metric system, is measured in grams (g.), centigrams (cg.) or milligrams (mg.). 10 mg. = 1 cg. (and 1 mg. = 0.1 cg.) 100 cg. = 1 g. (and 1 cg. = 0.01 g.) Also, 1000 g. = 1 kilogram (kg.)

As with all measuring instruments, Sig. Fig As with all measuring instruments, Sig. Fig. Rules must be followed when reading a balance. How would you read this measurement?

How would you read this measurement? This should be read as 105.00 grams (g.)