Reading Scales Section 1.3

Our Metric Rulers are Marked off in Centimeters 10 centimeters are in one decimeter.

Give Your Ruler Measurements to Two Decimal Places The Hundredths Place is the Uncertain Digit Example : 2.05 cm

2.80 cm When the end of the measured object is exactly on a millimeter mark, place a zero in the hundredths place.

2.39 cm In measuring the above object, the end is just to the left of the fourth millimeter mark (to the right of 2 cm).

Read a meniscus in the standard ways: Read the bottom of a down-curved meniscus. Read the top of an up-curved meniscus.

The smallest marks on a 50 mL Graduated Cylinder are whole milliliters. The estimated uncertain digit is in the tenths place mL Read the bottom of a water meniscus.

The smallest marks on a 10 mL Graduated Cylinder are tenths of milliliters. The estimated uncertain digit is in the hundredths place. Example: 5.24 cm 3 Example: 5.24 cm 3

Exception: If the surface of the material in the graduated cylinder is not smooth such as with sand or bubbles on a liquid surface, round to the last certain digit.

When you have a mixture of precision such as 15.4 mL and 30 mL, use the lesser precision in all calculations that involve your measurements. Example: 30 mL – 15 mL = 15 mL (not 14.6) = 15 mL (not 14.6)

Scales on beakers are not good enough for precise measurements. Their scales are used for estimating volumes.