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(i) Identify the gas ev, S evoly i, ved on the basis of colour, odour or chemical reaction of the gas as given in following table:, Observation, , , , , , Inference, CO, (carbonate) indicated, , ° hae ike is) With evolution of colourless, odourless gas which, ° rele 8as having smell of rotten ©ggs is produced which tums lead acetate | $?- (sulphide) indicated,, f eae Bas with pungent smell is evolved which turns ferrous sulphate | NO,~ (nitrite) indicated., , ene gas having smell of burning sulphur which turns acidified dichromate | SO,?- (sulphite) indicated., ¢ No gas is evolved., , , , °, , , , CO,*, S*, NO,-, SO, may be absent., , , , , , Test for dil. H,SO, group, , , , , , , , , , , , , , , , , , No., Ss. Se Experiment Observation Inference, Cg Pinch Of @ given salt, add ail 8,50, Colourless, odourless gas is evolved CO,” indicated ., 2s ace with brisk effervescence. (carbonate), Sa’t 1n the same test tube and pass the _| Lime water turns milky but becomes colourless} _CO,?- confirmed., gas through freshly prepared lime water. in excess of CO,. :, , , , , , , , CAL-REACTIONS INVOLVED, , CO,” + HSO,—> so + CO, + H,0, Ca(OH), + CO, ——> CaCO, + H,0, , Lime water (White ppt.), , CaCO, + CO, + HO ——> Ca(HCO,), (soluble), Calcium bicarbonate, , Lime water turns milky when CO, gas is passed but milkyness disappears when excess of CO, is passed., Result. The given salt contains CO?, Test for S? (sulphide ions), , , , , , S.No. Experiment Observation Inference, 1. | To a pinch of given salt, add 2-3 ml of dil. H,SO,. | A gas having smell of rotten eggs is evolved. S* indicated., 2. | Bring a piece of filter paper dipped in lead acetate | Lead acetate paper turns black. S* confirmed,, , solution near the mouth of the test tube., 3. | To the sodium carbonate extract of the salt add A violet colouration. S* confirmed., , , , , , , , , , , , sodium hydroxide and sodium nitroprusside., , SCHEMICALREACTIONS, s> + HSO,-——->H,S + SO,, (Smell of, rotten eggs), Pb(COOCH,), + H,S ——>PbS + 2CH,COOH, , , , Lead acetate Black ppt., Na,S + Na,[Fe(CN);NO] ——> Na,{Fe(CN);NOS], Sodium Sodium Violet colouration, sulphide nitroprusside, , Result. The given salt contains S* ions., Test for NO,” (Nitrite ions), , Experiment Observation ee [ Inference, , , , , , , , S.No., , is, , 2. | Place a paper dipp =, the test tube. 3, 3. = cy ae add dil. H,SO, and freshly Brownish black colouration. NO, confirmed., , prepared ferrous sulphate solution., , , , , , . jest i ‘i Pungent smelling brown gas evolved. NO, indicated., hh of salt, add 2-3 ml of dil. H,SO,., eee ed in starch and KI solution on Starch iodide paper turns bluish black. NO, confirmed.