Iodine Test — Definition, Formula, Properties & Uses | AllChemicals | AllChemicals

Q: What is the formula for Iodine Test?

The formula or notation for Iodine Test is: Starch + I₂/I₃⁻ → blue-black complex; used to detect iodine or starch

Formula / Notation	Starch + I₂/I₃⁻ → blue-black complex; used to detect iodine or starch
Also Known As	Starch-iodine test, iodine starch test, amylose-iodine complex

What is Iodine Test?

A chemical test for starch using iodine solution (iodine in potassium iodide). Starch turns dark blue-black in the presence of iodine due to starch molecules forming a complex with triiodide ions. The test is used in qualitative analysis and food science.

Formula & Notation

Starch + I₂/I₃⁻ → blue-black complex; used to detect iodine or starch

Other Names / Synonyms: Starch-iodine test, iodine starch test, amylose-iodine complex

Properties & Characteristics

The iodine test is a qualitative chemical test for the presence of starch (polysaccharide with amylose) or, conversely, to test for iodine using starch as the indicator. When iodine (I₂, or triiodide I₃⁻) contacts amylose, it becomes trapped in the helical coils of the amylose chains, forming a deep blue-black complex. The colour appears at room temperature and disappears on heating (as the helix uncoils) and reappears on cooling.

Uses & Applications

The iodine test is used in: food science (detecting starch in food samples, monitoring amylase activity during starch hydrolysis), analytical chemistry (starch indicator in iodometric titrations for detecting iodine/iodide), biochemistry (monitoring starch hydrolysis by amylase), and botany (testing leaves for photosynthetic starch production).

Safety Information

Iodine is a mild irritant and oxidising agent. Lugol's solution (KI + I₂ in water) used for iodine test is an irritant to mucous membranes. Radioactive iodine (¹³¹I) used in thyroid diagnosis and therapy requires radiation protection. Iodine vapour from opened bottles is irritating to respiratory mucous membranes.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Iodine Test

Formula Starch + I₂/I₃⁻ → blue-black complex; used to detect iodine or starch

Index All "I" terms

Synonyms Starch-iodine test, iodine starch test, amylose-iodine complex

Frequently Asked Questions

What is Iodine Test?

A chemical test for starch using iodine solution (iodine in potassium iodide). Starch turns dark blue-black in the presence of iodine due to starch molecules forming a complex with triiodide ions. The test is used in qualitative analysis and food science.

What is Iodine Test used for?

Is Iodine Test hazardous?

What is the formula for Iodine Test?

More "I" Terms

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