LAB: SEPARATION OF A MIXTURE Name______Hr_____

DISCUSSION: Mixtures can be separated by a variety of physical means including: screening, floatation, paper chromatography, dissolving and filtering. Also, the composition of mixtures of two substances can vary. In this lab you will separate a mixture of sulfur (S) and salt (NaCl) and determine the % composition of each.

MATERIALS: weighing boat rubber stopper filter paper crucible tongs test tube evaporating dish ring stand and ring hot plate NaCl-S mixture funnel wash bottle balance scoopula

SAFETY: 1) Wear safety glasses 2) Tie back long hair 3)

4) 5) PROCEDURE: 1. Determine the mass of a weighing boat and record it in the table below. 2. Put a scoop of the NaCl-S mixture on the weighing boat and record mass in the table below. 3. Add deionized H2O (using wash bottle) to a test tube until it is about 1/4 full. Carefully add the NaCl-S mixture to the water and stopper the test tube. Shake the test tube vigorously for 2-3 min. 4. Find the mass of a piece of filter paper and record it in the table below. 5. Find the mass of an evaporating dish and record it in the table below. 6. Prepare a funnel and the weighed filter paper for filtration as demonstrated by your teacher. Support the funnel in a ring stand. Place the evaporating dish below the funnel. 7. Pour the contents of the test tube into the filter paper so that it drains into the evaporating dish. 8. Using small amounts of water, rinse the test tube, shake, and pour into the funnel. 9. After the water has drained through the paper, carefully pull out the filter paper, unfold it, and set it on a warm hot plate to dry. (Hot plate setting = 2-3) **Use caution! Sulfur can ignite and burn.** 10. Put the evaporating dish on the hot plate and evaporate the salt solution “filtrate” to dryness. Heat gently to avoid splattering until dry. (Hot plate setting = 8-10) 11. Use crucible tongs to remove the evaporating dish from hot plate. Set on lab bench and allow the dish to cool. Then find the mass and record it below. 12. Find the mass of the yellow solid plus the filter paper after it is dry and record below. 13. Clean and dry your lab station: □ Throw out filter paper with sulfur □ Rinse extra sulfur from test tube into waste beaker □ Rinse evaporating dish and dry with towel □ Wash hands

DATA: Mass of weighing boat and mixture Mass of weighing boat alone Mass of mixture Mass of filter paper and yellow solid Mass of filter paper alone Mass of yellow solid (sulfur) Mass of evaporating dish and dried solid Mass of evaporating dish alone Mass of dried solid alone (sodium chloride)

CALCULATIONS: % by mass = mass of component x 100 Calculate the % by mass of each component (S or NaCl) mass of mixture in your mixture. Use lab data! Show work below.

% sodium chloride: ______% sulfur: ______

Compare your results with the actual percentages: ______% NaCl ______% S

ANALYSIS:

1. Error analysis: We will assume you were able to use the balance correctly. Please be more specific than “human error”. Analyze each of the following situations: a) If the calculated %s were lower than the actual %s, what errors might have happened during the procedure?

b) If the calculated %s were higher than the actual %s, what errors might have happened during the procedure?

2. Using your matter flowchart/concept map, how would you classify the following? (Explain each choice)

the initial salt/sulfur mixture: the salt water:

3. Draw a particle view of the salt water evaporation you performed in step 10 of the procedure. Label "before" and "after" evaporation. Use specific shapes to represent NaCl and H2O molecules in each view.