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| | | |
INDICATOR | N/10 | N/10 |COLOR IN ACID|COLOR IN ALKA-
| H_{2}SO_{4}| NaOH |SOLUTION |LINE SOLUTION
_______________|____________|__________|_____________|______________
| cc. | cc. | cc. |
Methyl orange | 10 | 9.90 | Red | Yellow
Lacmoid | 10 | 10.00 | Red | Blue
Litmus | 10 | 10.00 | Red | Blue
Rosalic acid | 10 | 10.07 | Yellow | Pink
Phenolphthalein| 10 | 10.10 | Colorless | Pink
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It should also be stated that there are occasionally secondary
changes, other than those outlined above, which depend upon the
temperature and concentration of the solutions in which the indicators
are used. These changes may influence the sensitiveness of an
indicator. It is important, therefore, to take pains to use
approximately the same volume of solution when standardizing that is
likely to be employed in analysis; and when it is necessary, as is
often the case, to titrate the solution at boiling temperature, the
standardization should take place under the same conditions. It is
also obvious that since some acid or alkali is required to react with
the indicator itself, the amount of indicator used should be uniform
and not excessive. Usually a few drops of solution will suffice.

The foregoing statements with respect to the behavior of indicators
present the subject in its simplest terms. Many substances other than
those named may be employed, and they have been carefully studied to