Separation Lab
Purpose
Use physical properties and physical changes to separate a mixture of ammonium chloride, NH4Cl;
sodium chloride, NaCl (salt); and silicon dioxide, SiO2 (sand).
Procedure
With the weighing paper provided by the scale, measure out 4.3 g of sand on the scale by the hood, 3.7
g of salt on the scale between labs 3&4, 0.1g of ammonium chloride, NH4Cl on the scale between labs
1&2.
Obtain a crucible and wash thoroughly. Dry using a Bunsen burner for 2 minutes. Allow to
completely cool at least 5 minutes. When no heat can be felt from the crucible, determine the mass.
Add the mixture of ammonium chloride, sand and salt. Re-mass. Calculate the mass of the sample.
Set up a ring stand with a ring and clay triangle to hold the crucible. Heat the crucible with a Bunsen
burner until the ammonium chloride sublimes as a white vapor. Do not waft the fumes! Ammonium
chloride fumes are irritating and can cause your throat to become sore/scratchy. Continue heating for 3
minutes after the white vapor stops. Using a clean metal spatula or a glass rod, stir the mixture. If the
end appears white continue heating. Pick up the Bunsen burner and heat the sides of the crucible to be
sure all of the ammonium chloride, NH4Cl has sublimed. Allow the crucible to thoroughly cool! If
you can feel any heat with your hand, it is too hot for the scales! Have patience! Determine the mass
of the crucible and residue (sand and salt). Determine the mass of ammonium chloride that sublimed
(crucible with sample – crucible with residue).
Add ~ 10 mL of water to the crucible – do not over fill! Stir the mixture to be sure all of the salt
dissolves. Get a filter paper and sign it in pencil. Determine the mass. Clean a 100 mL beaker and
sign the white spot. Determine the mass. Set up a filtration system with a funnel held by a ring with
the filter paper to catch all of the sand and the cleaned beaker underneath to catch the salt water. Pour
the mixture into the filter paper and allow the salt water to filter through. If all the mixture does not
come out of the crucible, hold on an angle and squirt water into the crucible – this should help to clean
it out. Do not allow the water level to go above the filter paper line – the sand could go behind the
filter paper instead of being caught. Rinse the sand a couple of times with water to be sure all the salt
dissolves and goes through the filter paper instead of being stuck in the paper. Place the filter paper
and sand on a watch glass in the oven to dry.
Place the beaker of salt water on the ring with wire gauze and heat to evaporate the water. When most
of the water is gone, gently heat because the salt will start to splatter out causing you to lose some of
your results. The beaker may be placed in the oven for final drying. A watch glass over the beaker
will help you not to lose product – but you’re going to have to find the mass of the salt on the watch
glass.
The next day when the sand and salt are dry as well as cool. Determine the mass. Calculate the mass
of the sand and then the salt. Determine the percent of sand in the whole sample and the percent of salt
in the whole sample. Add the ammonium chloride, sand and salt masses to determine the total mass
recovered. Then calculate the percent recovered.
Chemistry Lab
Separation Lab Data Record
Names__________________________________________ Hour_______
Directions: Fill in the following blanks with your observations and results. Remember your units and
keep 3 digits in all numbers.
Mass of sand (4.3g)
_____
Mass of salt (3.7g)
_____
Mass of ammonium chloride (0.1g)
_____
Mass of evaporating dish and unknown
_______
Mass of evaporating dish
_______
Mass of unknown
_______
Mass of evaporating dish and residue after sublimation
_______
Mass of NH4Cl (ammonium chloride)
_______
Percent of NH4Cl
_______
Mass of watch glass, filter paper and SiO2
_______
Mass of watch glass and filter paper
_______
Mass of SiO2 (silicon dioxide)
_______
Percent of SiO2
_______
Mass of beaker and NaCl
_______
Mass of beaker
_______
Mass of NaCl
_______
Percent of NaCl (sodium chloride)
_______
Mass of separated components
_______
Percent recovery of all components
_______
% error __________
% error __________
% error __________