The Use of Analytical Balance in Determining the Water Content of a Given Hydrated Salt
Objective 1. Use the analytical balance to weigh a given hydrated salt as accurate as possible in order to determine the weight of water in the salt
Introduction
Balances are important laboratory equipment as they are used to determine the mass of materials. Today, most balances used in the laboratory are analytical balances which can give readings up to four decimal places or higher. High accuracy is needed in certain experimental work such as material analysis or those involving small change in material mass. Unknown masses of materials are normally estimated with the use of twodecimal place balances, before they are determined accurately with the analytical balances. As the analytical balance is very expensive and sensitive, adequate training has to be acquired by users so that they can use it correctly.
Apparatus and Materials 1. Sand 2. CuSO4 · xH2O salt 3. Evaporating dish 4. Analytical balance 5. Small testtubes 6. Drying flask 7. Thermometer 8. Electrical heater
Experimental Procedure
Results and calculations
Mass of Test tube : 15.8945g
Mass of Test tube + CuSO4 ∙ xH2O salt : 17.6698g
Mass of Test tube + CuSO4 ∙ xH2O salt after heat for 30 min : 17.1844g
Mass of Test tube + CuSO4 ∙ xH2O salt after reheated for 10 min : 17.1537g
Mass of CuSO4 ∙ xH2O salt : 1.7753g Mass of CuSO4 :1.2592g
Discussion
Many salts readily dissolve in water to form solutions. When water is allowed to evaporate from the solutions, crystals appear. Often, the crystals that appear to be dry actually hold a good deal of water within the crystalline structure. If the crystals are heated, however, this water is driven off.
Introduction
Balances are important laboratory equipment as they are used to determine the mass of materials. Today, most balances used in the laboratory are analytical balances which can give readings up to four decimal places or higher. High accuracy is needed in certain experimental work such as material analysis or those involving small change in material mass. Unknown masses of materials are normally estimated with the use of twodecimal place balances, before they are determined accurately with the analytical balances. As the analytical balance is very expensive and sensitive, adequate training has to be acquired by users so that they can use it correctly.
Apparatus and Materials 1. Sand 2. CuSO4 · xH2O salt 3. Evaporating dish 4. Analytical balance 5. Small testtubes 6. Drying flask 7. Thermometer 8. Electrical heater
Experimental Procedure
Results and calculations
Mass of Test tube : 15.8945g
Mass of Test tube + CuSO4 ∙ xH2O salt : 17.6698g
Mass of Test tube + CuSO4 ∙ xH2O salt after heat for 30 min : 17.1844g
Mass of Test tube + CuSO4 ∙ xH2O salt after reheated for 10 min : 17.1537g
Mass of CuSO4 ∙ xH2O salt : 1.7753g Mass of CuSO4 :1.2592g
Discussion
Many salts readily dissolve in water to form solutions. When water is allowed to evaporate from the solutions, crystals appear. Often, the crystals that appear to be dry actually hold a good deal of water within the crystalline structure. If the crystals are heated, however, this water is driven off.
References: * Bettelheim, Brown, Campbell, and Farrell (2007).Introduction to General, Organic, and Biochemistry. (8th ed.) Pearson Questions: