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Volume p184 • What is volume: It is the measurement of the amount of space an object can occupy. It may be solild, liquid or gas. Units of Volume • Millilitre (mL) • Litre (L) 1 mL = 1 cm • Cubic centimetres (cm3) • Cubic millimitre (mm3) • Cubic meter (m3) 3 Taking a reading on a graduated cylinder • To know the value of each graduation: - Find two major graduations. - Substract them from eachother. - Divide by the number of spaces. Example: -Two major graduations 25 et 30 -So 30 – 25 = 5 -There are 5 spaces so: 5/5=1 - Each graduation is worth 1. A) Volume of a liquid • The instruments are: - Graduated cylinders, beakers, erlenmeyer flask, etc. • The meniscus: When the liquid is not perfectly flat, it will curve a little. You have to read under the meniscus. Meniscus Meniscus 53 mL To measure 10 mL, you must pour 10 mL of water in the graduated cylinder and read under the menuscus. 18 mL 400 mL You can try! B) Regular solid • Use a ruler to measure the sides. • For a rectangular prism or cube, use the following formula: V= Length x Width x height - Cylinder: V=πXr2Xh. π = 3.14 r = radius h = height • Example 1: 2 cm X 3 cm X 5 cm = 30 cm3 • Example 2: 3,14 x 1,52 x 8 = 56,52 cm3 You can try! = 8 cm 3 cm 5 cm r = 1.5 cm 2 cm C) Irregular solid • Example: a nail, a penny, an eraser, a paperclip etc. • You will need a graduated cylinder or an overflow can. Water displacement method • Fill the graduated cylinder with water and write down the volume. (example 20 mL) • Place the solid into the cylinder and read the new volume. • Subtract the first reading from the second reading. The difference is the object’s volume. You can try! Volume = 40 mL - 30 mL = 10 mL Overflow can -Place a beaker under the overflow can - Fill up the overflow can until the water is overflowing. -Place the object in the can. - Collect the water that overflows and measure its volume. Volume lab activity Object Small metal cylinder Large metal cylinder Rectangular prism Marble Rubber stopper Volume measured with a ruler Volume measured by water displacement