INTRODUCTORY CHEMISTRY
(CHEM1411_216_1310)
SECTION 216
NADA AL-QAHTANI
201001915
MS. TABASSUM ASHFAQ
REPORT #2
Separation of solid state mixture components
Separation of solid state mixture components
Objectives:
1- To learn how to separate a heterogeneous mixture
2- To determine the percentage of each component in the total mixture
Introduction
A mixture is a physical combination of two or more pure substances where each
substance keeps its own chemical identity. For example, each substance in a slatwater mixture has the same chemical properties as it would have when pure, the water
is present as H2O molecules and the salt is present as sodium ions (NA+) and chloride
ions (Cl-)
Materials:
1- Clean, dry evaporating dish.
2- Electronic balance.
3- Laboratory instructor.
4- Wire gauze.
Mass of ammonium chloride in known mixture (decomposition of NH4Cl)
Place the evaporating dish (with sample) on a wire gauze as shown in figure 1. Have
the laboratory instructor approve your apparatus before heating. Make sure the
ventilation is proper. Heat the dish slowly, but gradually increase the heat to moderate
level until the white fumes of ammonium chloride stop vaporizing (approx. 15
minutes). Occasionally stir the mixture to speed up the process. Next, use the tongs to
remove the evaporating dish. Keep the evaporating dish on the ceramic sheet. Cool
the dish to room temperature, weigh, and record the mass on the Report Sheet.
Mass of silicon dioxide in the known mixture (extraction of NaCl)
a. Add about 20 ml of distilled water to the solid in the evaporating dish and stir
gently for 5 minutes. Carefully decant the solution into a beaker. Add about 10
ml more of distilled water to the solid, stir again for about 1 minute, and
decant into the beaker. Once more repeat the 10 ml wash procedure and decant
into the beaker. The process effectively extracts the NaCl form the SiO2.
Discard the decanted solution in the beaker, and return to the evaporating dish
any sand that may have been decant accidently.
b. Return the evaporating dish (with the wet sand) to the wire gauze. Heat slowly
to avoid spurting, evaporate the water, and stir with a glass rod to break up
lumps of the solid. Continue to heat slowly to avoid spurting of sand until the
sample looks dry, and then heat strongly for about ten minutes so that the
bottom of the dish is red. Allow the dish to cool to room temperature, weigh,
and record the mass.
Pick up a sample of unknown mixture of ammonium chloride, sodium chloride, and
silicon dioxide from your instructor. Record the unknown number on the Report
Sheet. Repeat the experimental procedure for the unknown mixture.
At the end of the laboratory period, wash the apparatus. Dispose off any sand in the
waste basket.
Obtained Data:
1- Mass of evaporating dish 53.4836g
2- Mass of evaporating dish & sample 54.8392g
3- Mass of evaporating dish & sample after heating 54.7992g
4- Mass of evaporating dish & sample after washing and drying 54.4641g
Calculation and Results:
1- Mass of original mixture 54.8392 - 53.4836 = 1.35569g
2- Mass of ammonium chloride in sample 54.8392 – 54.992 = 0.04g
3- Percent ammonium chloride in sample (0.04 x 100) ÷ (1.35569) = 2.9%
4- Mass of NaCl in sample 54.7991 – 54.4641 = 0.3351g
5- Percent NaCl sample (0.3354 x 100) ÷ (1.35569) = 24.7%
6- Mass of silicon dioxide in sample 54.4641 – 53.4836 = 0.9805g
7- Percent silicon dioxide in sample (0.9805 x 100) ÷ (1.35569) = 72.3%
Conclusion
The experiment was completed to a high degree of success. Familiarity with the
methods of separating substances from one another using decantation, extraction, and
sublimation techniques was gained, and the material was recovered to a reasonable
degree of accuracy.