Aim: Determine the % by mass composition of a sand-salt mixture.
Background: Gravimetric analysis is a method which is based on the isolation of the desired sample in pure forms or in some combined form from a sample, and weighing the isolated constituent. Then from the weights of the sample or precipitate, a percentage can be calculated out of the constituent. Solubility is the amount of a substance which is called the solute, dissolves in a volume of liquid substance called the solvent. Sodium chloride can be dissolved in water therefore we can say it is soluble and sand is made up of tiny rock particles or silica which do not dissolve in water therefore insoluble. From the NaCl solubility curve it can be said a slight increase in temperature can assist in dissolving the salt but not by any significant amount.
Significance: Gravimetric analysis accurately measures things we as a society, community and us need to know. It can determine the % composition of things in samples, helps us figure out what it is composed (by the various separation techniques) and teaches us the beauty of science. Determining the % mass composition of a sand-salt mixture can tell us how much salt is in our beaches and this is important in some ways. Equipment | Quantity | Safety Glasses | X1 | Beaker (250mL) | X1 | Stirring Rod | X1 | Filter Funnel | X1 | Filter Paper | X1 | Conical Flask | X1 | Electronic Balance | X1 | Sand-Salt Sample | Given Amount | Evaporating Basin | X1 | Bunsen Burner | X1 | Gauze Mat | X1 | Tripod | X1 | Thermometer | X1 | Distilled Water | Given Amount |
1. Record mass of sand-salt sample, beaker, evaporating basin and filter paper on electronic balance. 2. Add distilled water to sample. Mix thoroughly with stirring rod until salt dissolves. 3. Filter out salty water from sand to a conical flask. 4. Evaporate salty water on an evaporating basin. 5. Naturally