3.2. Measuring volume The volume of a body is a measurement of the space it occupies. For objects that have a regular shape, such as a cube, sphere, prism or cylinder, the volume can be calculated by using formulas, measuring some lengths and making calculations. For liquids or objects with an irregular shape, we use measuring instruments such as a graduated cylinder, a burette or a pipette. 32 What volume of liquid do these graduated cylinders contain? The measurements are all in mL. a) b) c) 33 In your notebook, do a magnified drawing to show that the level of liquid in each graduated cylinder is: a) 5.2 mL b) 27 mL c) 180 mL A C T I V I T I E S 1 Eye level Lower part of the meniscus When we pour a liquid into a narrow tube, it sticks to the sides, causing the outer part to form a cur ve called a meniscus. Graduated cylinders are designed to indicate the measurement at the bottom of the meniscus. To avoid errors when taking measurements, the graduated cylinder must be horizontal and our eyes must be level with the height of the measurement, that is, the bottom of the meniscus. Some f lasks, Erlenmeyer f lasks and beakers only give approximate measurements. Flask Erlenmeyer flask Beaker 25 mL graduated cylinder. It allows 0.5 mL to be measured. 50 mL graduated cylinder. It allows 1 mL to be measured. 250 mL graduated cylinder. It allows 5 mL to be measured. Burette Pipette Instruments for measuring volume precisely. Their graduation depends on their size and the manufacturer. 21
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