[Lab Report Operation Unit] Experiment 1(b) Measuring specific gravity of a liquid by using hydrometer method

Title: Experiment 1B Measuring specific gravity of a liquid by using hydrometer method.

Objective:s To determine specific gravity of a liquid using hydrometer method.

Apparatus: Hydrometer, glass cylinders and liquid.

Theory: Specific gravity or relative is the ratio of 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 directly 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.

Procedure i. ii. iii.

iv. v. vi. vii. viii.

A tall glass cylinder was placed on a flat working surface. A liquid was filled in it and air was allowed to rise to the top. The hydrometer was carefully inserted and was allowed to settle in the centre of the cylinder. The hydrometer must not be touch with the sides of cylinder to prevent errors. The scale of the hydrometer has been read after it had settled as the bottom of the free water surface. The reading was recorded and the hydrometer was gently taken out. Step 3 to 5 was repeated three times. The above procedure was followed with using other liquid. The specific gravities of given liquids were compared.

Observation S.No

Name of liquid (Stem reading) Water

Oil

Syrup

1

1.000

0.91

1.005

2

1.000

0.91

1.005

3 Av.S G

1.000

0.91

1.005

1.000

0.91

1.005

Discussion There are four method to measure the specific gravity of a liquid such as by using measuring beaker, eureka can, density bottle and hydrometer method. Based on the result, each method shows different result. The most accurate method to get the specific gravity of liquid is by using hydrometer, followed by eureka can, then measuring by using beaker and lastly by using density bottle. There might be an error during conducting the experiment. The result may varies because of an improper handling of apparatus during the experiment. The objectives are reached, specific gravity can be calculated by using any of these method but the most accurate method is by using hydrometer.

Question a. Reasons for different methods giving different result are because of the accuracy of the different apparatus that were use in the experiment. b. A narrow deep type of eureka can gives us an accurate results. c. The specific gravity of mercury is not the same on the moon compared on the earth. d. The hydrometer sinks more in the lighter liquid than the heavier ones because lighter liquid is less dense than heavier liquids. e. It is easy to swim in sea water than swimming pools because the sea water is less dense than the water in the swimming pools.

Conclusion Different methods of determining the specific gravity gives out the different accuracy of the results.