practical chemistry Flashcards
name the neutral gases
hydrogen
oxygen
water vapor
how to identify hydrogen gas
- -> burning wooden splinter extinguished with a pop sound
- -> burns with a pale blue flame
how to identify oxygen gas
- -> burning wooden splinter gets rekindled
- -> turns colourless pyrogallol solution brown
how to identify water vapor
–> anhydrous white colour copper sulphate turns blue hydrous copper sulphate
–> blue anhydrous cobalt chloride paper turns pink hydrous cobalt chloride
name the acidic gases
- -> carbon dioxide
- -> sulphur dioxide
- -> hydrogen sulphide
- -> nitrogen dioxide
- -> chlorine
- -> HCL
- -> ammonia
how to identify carbon dioxide gas
–> it is liberated when carbonate reacts with an acid
–> turns lime water milky
–> when co2 is passed in excess the milky color disappears
–> colorless and odorless gas with brisk effervescence
–> when passed through acid KMnO4 (pink) there is no change
–> when passed through acid K2Cr2O7 (orange) there is no change.
HOW TO IDENTIFY SULPHUR DIOXIDE GAS
–> liberated when sulphate/bisulphate reacts with an acid
–> turns limewater milky
–> when So2 is passed in excess the milky color disappears
–> colorless gas with suffocating smell
–> when passed through acid KMnO4 (pink) solution, turns colorless
–> when passed through acid K2Cr2O7 (orange) solution, turns clear green
how to identify hydrogen sulphide
–> liberated when sulphide reacts with an acid
–> colourless gas with rotten egg smell
–> turns acid KMnO4 (pink) solution colourless with yellow particles of sulphur
–> turns acid K2Cr2O7 (orange) solution green with yellow particles of sulphur
–> turns white lead acetate [Pb(CHCOO)2]silvery black
how to identify nitrogen dioxide gas
–> reddish-brown gas
–> liberates violet vapours from potassium iodide solution
–> potassium iodide paper turns brown
how to identify chlorine gas
–> greenish-yellow gas
–> turns blue litmus red and bleaches it
–> turns moist starch iodide paper blue black
how to identify hydrogen chloride
–> gives dense white fumes with a glass rod dipped in NH3 solution
–> gives a curdy white precipitate with AgNo3 which is soluble in NH4OH
how to identify ammonia gas
–> gives dense white fumes with a glass rod dipped in HCl
–> CuSO4 reacts with NH3 to give a pale blue ppt
–> CuSo4 reacts in excess with NH3 to give a deep inky blue solution
flame test for Na+
golden yellow flame
flame test for K+
lilac flame (a type of purple)
flame test for Ca2+
brick red flame
