OBJECTIVE: To determine specific gravity of a liquid using Hydrometer Method
APPARATUS: Hydrometer, glass cylinders, liquid
Specific gravity or relative density is the density of the fluid to the density of water.
Specific gravity can be determined directly from the density of a liquid as measured divided by density water. A convenient alternative method is to use a specially calibrated instrument called Hydrometer. Hydrometer is hallows glass float designed to float upright in liquids of various densities. The depth to which it sinks in the liquid is a measure of the density of the liquid. A scale is provided on its stem which is calibrated to read specific gravity. The sensitivity of the Hydrometer depends on the diameter of the stem. A very sensitive hydrometer has a large bulb and a thin stem.
1. Place the tall glass cylinders on the flat working surface.
2. Fill with a liquid and allow air to the top.
3. Carefully insert the Hydrometer and allow it to settle in the center of the cylinder. Take care not to let it touch the sides otherwise surface tension effects may cause errors.
4. Read the scale, after the hydrometer has settled, at the bottom of the free water surface i.e. at the bottom of the meniscus.
5. Record the reading and gently take out the Hydrometer.
6. Repeat the procedure ( step 3 to 5 ) three times
7. Follow above procedure for other given liquid also
8. Compare specific gravities of given liquids.
Name of liquid
DISCUSSION OF RESULTS:
Syrup has the highest S.G than oil and water. Its S.G is 1.225.Oil has the lowest S.G than water and syrup. Its S.G is 0.871
CONCLUSION AND RECOMMEDATION:
( i ) Would be the specific gravity of mercury be same on the moon where gravity is sixth that on the earth?
Specific mercury at earth is 13.5, but at the moon is one sixth that on the earth mean:
Specific gravity at the moon= 1/6 (13.5) =2.25
So, specific gravity of mercury is not be same on the moon.
(ii) Why Hydrometer sinks more in the lighter liquids than the heavier ones?The heavier liquids has more density than the lighter liquids.
(iii) Why it is easy to swim in sea water than swimming polls?
It is because the density of sea water is high than swimming polls. The density of sea water is 1025 kg/m3