Determination of volume Using the Volume Displacement Method

1. The volume displacement method is used when measuring the volume of an object that is irregularly shaped and sinks in water.

Determine whether the volume displacement method can be used:

2. Fill a beaker halfway with water. Be sure that the beaker is large enough that the object or substance has plenty of room. If not, choose a larger container.

3. Add the object or substance to the beaker.

4. If the object floats, only the part of the object’s volume that is underwater is displaced. This will not give an accurate measurement of the object’s total volume, so the volume displacement method cannot be used.

5. If the object or substance dissolves in water, the volume displacement method cannot be used.

Using the volume displacement method to determine the volume of an object:

6. Any calibrated volumetric piece of equipment such as a 50 ml, 100 ml, 250 ml, 500 ml, or 1000 ml graduated cylinder can be used.

7. Observe the size of the object to determine which piece of volumetric equipment can be used. The object should fit into and be easily removed from the piece of equipment.

8. Pour enough water into your selected volumetric equipment, for example, a graduated cylinder, so that when the object is added it will be totally under the water. Record the volume of water in milliliters (ml).

9. Tilt the graduated cylinder and place the object in the cylinder. Tilting the graduated cylinder helps prevent water from splashing out of the cylinder. Observe and record the total volume contained in the graduated cylinder in milliliters (ml).

10. Determine the volume of the object. Subtract the volume of water recorded when the graduated cylinder was filled with water alone from the volume of water when the graduated cylinder was filled with water and the object. For example:

11. Convert the volume in units of milliliters (ml) to the volume in units of cubic centimeters (cm3). One ml of water is equal to one cm3.

1 ml = 1 cm³

Therefore, the volume of the object is:

22 ml = 22 cm³

12. Decide whether the results would be more accurate if another type of graduated cylinder were used.

a. For example, if the change in volume is only 1 ml when a 1000 ml graduated cylinder is used, a 500 ml graduated cylinder could give a more accurate volume.

b. If needed, follow steps 7 through 10 again with a different type of volumetric equipment.