Answer Happy

Problem Set in Precipitation, Acid-Base and Complexometric
Titration
7. After removing the membranes from an eggshell, the shell is dried and its mass recorded as 5.613g. The eggshell is transferred to a 250-ml beaker and dissolved in 25 mL of 6M HCI. After filtering, the solution containing the dissolved eggshell is diluted to 250 mL in a volumetric flask. A 10.00-ml aliquot is placed in a 125-ml Erlenmeyer flask and buffered to a pH of 10. Titrating with 0.04988 M EDTA requires 44.11 mL to reach the endpoint. Determine the amount of calcium in the eggshell as % CaCO3. 8. The alkalinity of natural waters is usually controlled by OH-,C03, and HCO3, which maybe present singularly or in combination. Titrating a 100.0-ml samle to a pH of 8.3 requires 18.67 mL of 0.2812 M solution of HCl. A second 100.0-ml aliquot requires 48.12 mL of the same titrant to reach a pH of 4.5. Identify the sources of alkalinity and their concentrations in parts per million.