EXPERIMENT No: 2

OBJECTIVE: To determine specific gravity of a liquid using Hydrometer Method

APPARATUS: Hydrometer, glass cylinders, liquid

THEORY:

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.

PROCEDURE:

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.

OBSERVATIONS

S.No	OIL	Name of liquid WATER STEM READINGS	OREN
1	0.870	0.996	1.225
2	0.872	0.996	1.226
3	0.870	0.996	1.225
Av.S.G	0.871	0.996	1.225

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:

Hint:

( 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

EXPERIMENT NO: 1lab water

OBJECTIVE: To determine specific gravity of a liquid, using measuring Beaker: Eureka can density bottle method.

APPARATUS: Measuring Beaker, Eureka Can, Density Bottle, Balance, Water liquid,Solid object, vernier ect.

THEORY:

Specific gravity, also called Relative Density, of a substance may be defined as the ratio of its mass density to the mass density to the water taken at atmospheric pressure at 4 degree Celsius. Since it is a ratio, specific gravity has no unit.

Mass density is defines as the mass of material per unit volume. So to determine density of a liquid it is necessary to determine the mass of a know volume of liquid. Measurement of volume must be done with due care.

PROCEDURE:

(a) Using measuring Beaker Method

1. Weigh the empty measuring beaker using a suitable balance and record the mass.

2. Fill the beaker with water and read the volume as accurately as possible. Record the volume.

3. Weigh the beaker plus water and record the mass. The mass of water can be calculated by subtracting mass of empty.

4. Determine mass density as

P = mass in gram or mass in Kg

Volume in ml volume in m³

5. Calculate average mass density

6. Repeat above steps using given using given liquid in place of water

7. Calculate specific gravity as

SG = _p_

p_w

(b) Using Eureka Can method:

The Eureka Can is a container with a fixed spout. If filled until overflow from the spout, the final lever when the liquid has stopped flowing will always be the same provided the can is lever and the liquid is not contaminated. If the can is initially full and a solid object is placed in it, a volume of liquid will be displaced equal to the volume of the object. This us a basic method of obtaining a know volume of liquid.

1. Take a solid object (cylinder or cube) which may fit in the Eureka Can.

2. Accurately measure dimensions of the object, calculate its volume and record the volume.

3. Place the Eureka Can at the edge on the working surface and fill it with water until it overflows.

4. Weigh an empty beaker, record its mass and place this under the spout.

5. Carefully lower the objects into the can until fully immersed and collect the displaced water in the beaker.

6. Weigh the beaker plus collected water and record the mass. The mass of the water can be calculated by subtracting mass of empty beaker.

7. Calculate mass density.

8. Repeat the above procedure using given liquid in place of water.

9. Calculate specific gravity of the liquid.

(c) Using Density Bottle Method:

1. Dry the bottle and stopper.

2. Weigh the bottle with stopper and record the weight.

3. Fill the bottle with water and replace the stopper.

4. Carefully dry the outside of the bottle with a cloth or tissue paper and remove any excess the water from the stopper such the liquid in the hole is level with the top of the stopper.

5. Volume of water is 100 cm³ (ml) when the water is level with the top of the stopper.

6. Weigh the bottle with stopper and water. Record the mass. The mass of water may be calculated by subtracting mass of empty bottle with stopper.

7. Calculate mass density.

8. Repeat the above method using the given liquid in place of water.

9. Calculate specific gravity of the liquid.

OBSERVATIONS AND RESULTS:

(a) Using Measuring Beaker Method:

For Water.

S.No	Wt. of empty beaker (gm)	Wt. of beaker + water (gm)	Mass of water (3-2)(gm)	Vol. of Water (cm3)	Mass density of water (4/5) g/cm3
(1)	2	3	4	5	6
1	100.5	147.0	46.5	50	0.930
2	100.5	195.9	95.4	100	0.954
3	100.5	246.8	146.3	150	0.975

Average p_water = 0.95311 gm/ cm³.

For liquid.

S.No	Wt. of empty beaker (gm)	Wt. of beaker + liquid (gm)	Mass of liquid (3-2)(gm)	Vol. of liquid (cm3)	Mass density of liquid (4/5) g/cm3
(1)	2	3	4	5	6
1	100.5	159.0	58.5	50	1.170
2	100.5	216.8	116.3	100	1.163
3	100.5	278.6	178.1	150	1.187

Average p_liquid = 1.187344 gm/ cm³.

Specific gravity of liquid = P_liquid = 1.2457

P p_water

(b) Using Eureka Can Method

Volume of Solid Object V =32.04cm³

For water:

S.No	Wt. of empty beaker (gm)	Wt. of beaker + water (gm)	Mass of water (3-2)(gm)	Mass density of water (4/5) g/cm3
(1)	2	3	4	5
1	25.1	53.8	28.7	0.896
2	25.2	54.8	29.6	0.924
3	25.1	52.8	27.7	0.865

Average p_water = 0.895 gm/ cm³.

For Liquid:

S.No	Wt. of empty beaker (gm)	Wt. of beaker + liquid (gm)	Mass of liquid (3-2)(gm)	Mass density of liquid (4/5) g/cm3
(1)	2	3	4	5
1	18.4	54.3	35.9	1.120
2	18.4	53.1	34.7	1.083
3	18.4	45.3	26.9	0.594

Average p_liquid = 0.932333gm/cc.

Specific gravity of liquid = P_liquid = 1.042

P_water

(c) Using Density Bottle Method

For water:

Volume of water = 100 cm³

S.No	Wt. of empty beaker (gm)	Wt. of beaker + water (gm)	Mass of water (3-2)(gm)	Mass density of water (4/5) g/cm3
(1)	2	3	4	5
1	50.6	151.8	101.2	1.012
2	50.6	151.8	101.2	1.012
3	50.6	151.7	101.1	1.011

Average P_water = 1.012gm/cc

For Liquid:

S.No	Wt. of empty beaker (gm)	Wt. of beaker + liquid (gm)	Mass of liquid (3-2)(gm)	Mass density of liquid (4/5) g/cm3
(1)	2	3	4	5
1	50.6	173.1	122.5	1.225
2	50.6	173.2	122.6	1.226
3	50.6	173.1	122.5	1.225

Average p_liquid = 1.225gm/cc

Specific gravity of liquid = P_liquid = 1.210

P _pwater

DISCUSSION OF RESULTS:

Hint:

( i ) What may the reason for different methods giving different result? Mistake in measuring and reading

(2) Which types of Eureka Can give you accurate result, a narrow, deep can or wide shallow can?

Wide shallow can give the accurate results.

CONCLUSION AND RECOMMEDATION: