Question

1. A pycnometer is found to weigh 135 g when empty, 180 g when filled with water, and 193 g when filled with an unknown liquid. Calculate the specific gravity of the unknown liquid. Truncate to two decimal places. 2. A pycnometer is found to weigh 133.3 g when empty, 210 g when filled with water, and 187 g when filled with an unknown liquid. Calculate the specific gravity of the unknown liquid. Truncate to one decimal place. 3. If 4 fluid Ounces of drug A weighs 145 g, calculate the specific gravity.

Answer 1

1. Weight of empty pycnometer is 135 g.

weight of pycnometer when filled with water is 180 g.

weight of water = weight of pycnometer with water — weight of empty pycnometer

which is 180–135 = 45 g.

The density of water is 1 gm/ ml. So 45 g = 45 ml volume of water.

This is the volume of pycnometer.

Weight of pycnometer when filled with unknown liquid is 193 g.

weight of unknown liquid is = weight of pycnometer when filled with unknown liquid — weight of empty pycnometer

which is 193 - 135 = 58 g.

volume of unknown liquid = volume of  pycnometer which is 45 ml.

density of unknown liquid is = weight / volume

which is 58/45 = 1.29 g/ml

specific gravity of the unknown fluid = density of unknown fluid / density of water

which is 1.29 / 1 = 1.29

specific gravity of unknown liquid is 1.29

2. Weight of empty pycnometer is 133.3 g

Weight of pycnometer when filled with water is 210 g.

weight of water added is = weight of pycnometer with water — weight of empty pycnometer

which is 210 — 133.3 = 76.7 g

desnity of water is 1 gm/ml.

76.7 g = 76.7 ml of water which is the volume of pycnometer

Weight of pycnometer when filled with unknown liquid is 187 g.

weight of unknown liquid = weight of pycnometer with unknown liquid — weight of empty pycnometer

Which is 187 — 133.3 = 53.7 g

volume of unknown fluid is = Volume of pycnometer which is 76.7 ml

density of unknown fluid is = weight / volume of unknown fluid

Which is 53.7 / 76.7 = 0.7 g

specific gravity of unknown fluid = density of unknown fluid / density of water

which is 0.7 / 1 = 0.7

specific gravity of unknown fluid is 0.7

3. Weight of fluid is 145 grams.

Volume of fluid is 4 ounces.

One ounce is 30 ml. So 4 ounces is 4*30 = 120ml.

Density of fluid is weight/volume = 145/120 = 1.208

specific gravity of fluid = density of fluid / density of water

which is 1.208 / 1 = 1.208

specific gravity of fluid is 1.208

This is a brief explanation. Hope this helps you out. Please feel free to give a like and contact us if you have any further queries. Thank you and have a great day.