PurposeThe purpose of this experiment was to separate this mixture into components, determine the mass and percentage of each component. In addition to test the accuracy of an alternative method of subtraction to find the mass of the sodium chloride directly.Start with a mixture of sand (SiO2), sodium chloride (NaCl), and ammonium chloride (NH4Cl), and use these separation processes: sublimation filtration evaporation First "sublimate" the ammonium chloride (NH4Cl); heat the mixture until the ammonium chloride (NH4Cl) passes into the gaseous phase.The remaining solid will be a mixture of the remaining two compounds, sodium chloride (NaCl) and sand (SiO2); these compounds do not undergo sublimation. Next, add water. Sodium chloride (NaCl) (and any small amount of ammonium chloride that may have been retained) dissolves in water, sand (SiO2) does not.
"filter" the entire mixture; this allows the water, in which the sodium chloride (NaCl) is dissolved, to pass through, but not the sand. Sodium chloride (NaCl) is now separated from the sand (SiO2).Experimental MethodEquipment: two clean 50 mL beakers, evaporating dish, thermometer, Bunsen burner, and scale Chemicals: water and Powered mixture of (SiO2), (NaCl), and (NH4Cl)Part 1: Sublimation of Ammonium Chloride (NH4Cl) Using a scale, weight and record the mass of the empty evaporating dish. Add 10 g of the Powder Mixture to the evaporating dish. Weigh and record the total mass (evaporating dish plus powder mixture).
Then remove the evaporating dish from the scale. Take a thermometer and attached it onto the evaporating dish. The thermometer will turn on and display room temperature, 21.5 °. Take a Bunsen burner and place it on the workbench.
Place the evaporating dish on the Bunsen burner, a white vapor will rise from the dish. Continue heating for another minute after the vapors is seen to complete sublimation of the compound. Ammonium chloride sublimes at 338 °C. Turn off the burner and move the evaporating dish from the Bunsen burner to the workbench to cool. Place the evaporating dish on the balance and record the mass of the evaporating dish plus remaining solid powder.Part 2: Filtration of sand (SiO2)Place two clean 50 mL beakers on the workbench.
Weigh one empty beaker on the balance and record its mass. Pour the contents of the evaporating dish into the beaker just weighed and record the new weight. Add 30 mL of to the solid mixture. Record the new weight. The solid substance at the bottom is the sand (SiO2).
Remove the solution from the balance. Move the empty beaker remaining onto the balance and record the mass. Take the first beaker and place it on the empty beaker to separate the solid from the liquid. Place the beaker with the solid sand on the balance and record the total mass.Part 3:Calculation of the Sodium Chloride (NaCl) Content and Evaporation An alternative method to find the mass of the sodium chloride directly. The solution can be heated to boil off the water leaving the salt behind.
Place the beaker of sodium chloride solution on the Bunsen burner. Set the flame to low and bring the solution to a boil. When all of the water has boiled off, turn off the burner and place the beaker on the workbench to cool. Place the beaker, now containing solid sodium chloride (NaCl), on the balance. Record this mass.