Double bonds

• To test for a double bond (or unsaturation), bromine (or bromine water) is added to an alkene and it turns from orange/brown to colourless.
• To test for a double bond (or unsaturation), add cold, dilute, acidified potassium manganate (VII) to an alkene and a colour change of purple to colourless is seen.
• Alkanes are not as reactive as alkenes as they do not have a double bond in their structure and therefore do not have an area of high electron density.