Review-of-related-literature.docx

Review of Related Literature

Tests for Alkanes and Alkenes Related Topics: More Lessons for IGCSE Chemistry Math Worksheets

A series of free IGCSE Chemistry Activities and Experiments (Cambridge IGCSE Chemistry). This activity compares the reaction with bromine water of several liquid alkanes and alkenes. The test for unsaturation is demonstrated. The activity can be extended to include testing the samples with a 1% potassium manganate(vii) solution. Small samples of the liquids are also ignited and the appearance of the flames compared. Testing alkanes and alkenes using bromine water How to distinguish between and alkene and alkane using bromine water. Alkenes are unsaturated and decolourise an orange solution of bromine water. Alkanes are saturated and do not react with bromine water, so the orange colour persists. In the following experiment, the first test tube contained cyclohexene and the second test tube containes cyclohexane. Addition of bromine (bromine water) and potassium manganate (VII) KMnO 4 to cyclohexene The cyclohexene decolourises the bromine water and changes the potassium manganate from purple to brown. There will be no colour change if cyclohexane is used instead of cyclohexene.

Color of precipitate formed on reaction of acetylene with Tollen's Reagent Ask Question

I am asked to find the color of the precipitate formed by the passage of acetylene gas into an aqueous solution of ammoniacal silver nitrate. I thought ammoniacal silver nitrate was Tollen's reagent, but acetylene is neither a ketone nor an aldehyde so I don't know how to figure out the color of the precipitate. organic-chemistry hydrocarbons organic-reduction

shareimprove this question edited Jul 3 '18 at 8:53

Gaurang Tandon 5,29062663 asked Jul 10 '15 at 19:36

user17319 29112

add a comment

1 Answer 5

You are correct that ammoniacal silver nitrate is Tollen's reagent. Tollen's reagent is most notable for its reaction with aldehydes to produce a silver mirror, but it also reacts with several other types of compounds, notably alpha-hydroxy ketones and terminal alkynes. With terminal alkynes, the alkyne reacts as a acid to form a silver acetylide which precipitates. In the case of acetylene, both hydrogens can react: HC≡CH+2AgNO3+2NH4OH⟶AgC≡CAg+2NH4NO3+2H2OHC≡CH+2AgNOX3+2NHX4OH ⟶AgC≡CAg+2NHX4NOX3+2HX2O The colour of the precipitate is variously described as yellow, gray-white, or white. The actual colour you observe is probably strongly dependent on the purity of the sample and the size of the precipitated particles. shareimprove this answer answered Jul 10 '15 at 20:39

bon 12.5k94279



6 Please, note!!!! Silver acetilenide formed is a sensitive, even if relatively weak explosive !!! Do NOT produce any significant quantities of it and do not dry it, as drying increases its sensitivity dramatically! – permeakra Jul 12 '15 at 8:21