The student should standardize the EDTA with a known solution of copper wire, or calcium carbonate . Nickel metal takes TIME to dissolve. If in doubt check with Dr. Sherren. Use the EDTA as it is in the bottle. Weigh the required amount on the analytical balance and place in a 200 ml.
Solution is slow so shake patiently.
The solution should be standardized with either Copper wire or Calcium carbonate. If the solution is not to be used within 48 hours store in plastic container. Dissolving 70 gm of solid NH 4 Cl in 600 ml. Calculate percent nickel in sample. Include a computer print-out for the calculation.