Several portions of a solution, each having a bulk of 100 c.c.,
were exposed for varying lengths of time, and the arsenic in each
determined.
_____________________________________________________________________
| | | |
| | Acid Solutions. | Neutralised Solutions. |
| Time Exposed. | "Iodine" Arsenic Found. |"Iodine" Arsenic Found. |
| | Required. | Required |
|_______________|___________________________|_________________________|
| | | |
| -- | 18.2 c.c. = 0.0136 gram | 18.1 c.c. = 0.0136 gram |
| 1 hour | 18.2 " = 0.0136 " | 18.2 " = 0.0136 " |
| 2 hours | 17.7 " = 0.0133 " | 18.0 " = 0.0135 " |
| 4 " | 17.5 " = 0.0131 " | 18.4 " = 0.0138 " |
| 5 " | 17.0 " = 0.0127 " | 18.3 " = 0.0137 " |
|_______________|___________________________|_________________________|
~The Titration.~--Make a _standard solution of iodine_ by weighing up in
a beaker 16.933 grams of iodine and 30 grams of potassium iodide in
crystals; add a few c.c. of water, and, when dissolved, dilute to 1
litre: 100 c.
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