Chemical Evidence
📋 What it is
Chemical tests reveal invisible evidence — like whether a stain is blood or which substance is present.
🗣️ Coach says
Some evidence you can’t see with your eyes. Chemical tests make it visible: a reagent that turns colour in the presence of blood, or a test that identifies a powder. The chemistry gives a yes/no the eye can’t.
🧠 Memory hook
A chemical test makes invisible evidence visible — colour change = a clue.
😂 Giggle
Why did the chromatography paper feel colorful?
Because it was always running with different dyes!
😲 Whoa!
Forensic chemists can detect a substance in amounts far too small to see — sometimes a few billionths of a gram — using tools that split a sample into its exact chemical “fingerprint”.
✅ Quick check: Why use a chemical test when a stain “looks like” blood?
Say your answer out loud first — then reveal.
Because looks can deceive (rust, ketchup look similar); a chemical test confirms what it actually is.
Chemistry gives a definite identification the eye can’t.
🧪 Try it! (2 minutes)
Test a mystery: does a drop of lemon juice fizz on baking soda? A reaction reveals what’s present.