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CHEMICAL CHANGES FOR SOLVING CRIMES - Coggle Diagram
CHEMICAL CHANGES FOR SOLVING CRIMES
One of these methods is this Kastle-Meyer test, it is based on the following principles.
This chemical reaction causes the transformation of phenolphthalin, a colorless substance, into phenolphthalin, wich is bright pink.
Hemoglobin in the blood and hydrogen peroxide together react with a substance called phenolphthalln
The results of a scientific test which are affected by external variables must be rejected, as they are false
False positive
The Kastle-Meyer test produces a false positive when it produces the bright pink color of phenolphthalein.
False negative
The Kastle-Meyer test yields a false negative when it falls to produce the bright pink of phenolphthalein.
To detect both false positives and false negatives, control experiments must be conducted.
Positive control
This involves runnig the test on a blood sample, using the same reactants, and following the same procedure as with the test sample.
Negative Control
This involves running test with a sample that we know has no blood, using the same reactants, and following the same procedure as with the test sample.
material for mixing with blood
Cotton swabs
Distilled water
Hydrogen peroxide
Alchohol
Phenolphthalin
Test Sample