- CALCIUM OXIDE
- ACETIC ACID (25%) - Dilute concentrated acid with distilled water, 1:4.
- POTASSIUM CHROMATE INDICATOR - Dissolve 5 g K2Cr04 in 100 mL deionized water.
- STANDARD SILVER NITRATE TITRANT, 0.03 N - Dissolve 5.0964 g AgN03 in deionized water and carefully dilute to 1 L. This solution can be checked against a standard sodium chloride solution if desired. Store silver nitrate solution in a brown bottle and keep in the dark.
- 50 mL BURET, FUNNEL, AND STAND
- 1 L VOLUMETRIC FLASK
- 250 mL ERLENMEYER FLASKS
- MAGNETIC STIRRER
- FUNNEL, FUNNEL STAND, AND FILTER PAPER
- HOT PLATE AND HOT WATER
- Accurately weigh 1 g of ground sample into a porcelain crucible.
- Add 0.25 g of calcium oxide and mix.
- Weigh out 0.25 g of calcium oxide into a separate crucible to serve as a blank. To each crucible add sufficient water to give a thin paste.
- Place sample & blk into furnace and increase temperature gradually until temperature reaches 550oC.
- Ash at this temperature for at least 90 min.
- Remove the sample & blk from the muffle furnace and cool.
- Add about 15 mL of hot water to the crucibles and break the ash into a fine powder.
- Pour the mixtures through filter paper into 250 mL Erlenmeyer flasks and rinse the crucibles with water into filter.
- Wash the residue in the filters with five 10 mL portions of hot water. Bring up the final volume to the 100 mL mark on the Erlenmeyer with dH20.
- Cool the filtrate and add dilute acetic acid dropwise until the solution is about pH 6.0 to 7.0. (Check pH with pH paper.)
- Cool and add 5 drops of the potassium chromate indicator to the sample and to the blank.
- Titrate the blank, then the sample, with standard AgN03 to a persistent light orange-red. (Be consistent in end-point recognition.)
- Calculate value and report with 2 decimals.
- Pour the waste into a carboy for pick up by the hazardous waste manager.
- %Cl = ((mL AgN03 for sample - mL AgN03 for blank) X NAgN03 X 3.545)/g sample
- %NaCl = %Cl (1.65)