2010 Organic Chemistry Café
Distinguishing Test Group 1
Distinguishing Tests (Solutions) HCI Prelim 2007/P3/2c(i) 1) Reagents and conditions: AgNO3 (alc), heat
Cream precipitate of AgBr formed.
No precipitate formed
KMnO4 cannot be used as both will react to form white ppt and purple KMnO4 will decolourise. JJC Prelim 2007/P2/5b 2) Reagents and conditions: Method 1: Hot acidified KMnO4 Method 2: AgNO3(alc), heat
Method 1: Purple KMnO4 decolourises.
Method 1: Purple KMnO4 decolourises. Effervescence seen. Gas evolved gives a white precipitate with limewater.
Method 2 : Cream precipitate formed
Method 2 : No precipitate formed
3) Reagents and conditions: aq Na2CO3
No effervescence seen.
Effervescence seen. Gas evolved gives a white precipitate with limewater.
AJC Prelim 2007/P3/5b 4) Reagents and conditions: Method 1: Hot acidified KMnO4. Method 2: Hot acidified K2Cr2O7.
Method 1: Purple KMnO4 decolourised. Method 2: Orange K2Cr2O7 turned green.
Method 1: Purple KMnO4 remained. Method 2: Orange K2Cr2O7 remained.
Compiled by: Amanda Ang, Rebecca Ng and Lim Fangyin
2010 Organic Chemistry Café
Distinguishing Test Group 1
5) Reagents and conditions: Method 1: dilute HCl, heat followed by Neutral FeCl3 (aq) Method 2: dilute HCl, heat followed by acidified KMnO4,heat under reflux
Method 1: Alcohol product from hydrolysis shows purple coloration with FeCl3.
Method 1: Alcohol product from hydrolysis shows no purple coloration.
Method 2: Purple KMnO4 will not decolourise.
Method 2: Purple KMnO4 will decolourise.
NJC Prelim 2007/P2/2c(i) 6) Reagents and conditions: Method 1: Na2CO3 (aq) Method 2: 1. Dilute NaOH, heat 2. Alkaline, aq I2, warm Method 3: 1. Dilute NaOH, heat 2. Hot, acidified KMnO4
Method 1: Effervescence produced. Gas evolved gives a white ppt with limewater
Method 1: No effervescence produced.
Method 1: No yellow precipitate formed.
Method 1: Yellow precipitate of CHI3 formed from alcohol product of hydrolysis.
Method 3: Alcohol product from hydrolysis does not decolourise purple KMnO4.
Method 3: Purple KMnO4 decolourised by alcohol product from hydrolysis.
ACJC Prelim 2007/P3/1d 7) Reagents and conditions: Method 1: dilute HCl, heat, followed by Hot acidified K2Cr2O7 Method 2: dilute HCl, heat, followed by Hot acidified KMnO4
Method 1: Orange K2Cr2O7 turns green
Method 1: Orange K2Cr2O7 remains
Method 2: Purple KMnO4 decolourise
Method 2: Purple KMnO4 remains
Compiled by: Amanda Ang, Rebecca Ng and Lim Fangyin
2010 Organic Chemistry Café 8) Reagents and conditions:
Distinguishing Test Group 1
Method 1: Neutral FeCl3 (aq) Method 2: Br2 (aq) Method 3: KMnO4, H2SO4, heat Method 4: Alkaline aq I2, warm Method 5: Tollen’s reagent, heat
Method 1: Purple coloration observed. Method 2: Reddish brown aqueous Br2 will decolourise Method 3: Purple KMnO4 remains Method 4: Yellow ppt formed Method 5: Silver mirror not seen
Method 1: No purple coloration. Method 2: Reddish brown Br2 remains. Method 3: Purple KmnO4 decolourised Method 4: Yellow ppt not formed Method 5: Silver mirror seen
MJC Prelim 2007/P3/2b(ii) 9) Reagents and conditions: Method 1: Tollens’ Reagent, warm Method 2: KMnO4, H2SO4, heat Method 3: Alkaline aq I2, warm
Method 1: No silver mirror formed. Method 2: Purple KMnO4 remains Method 3: Yellow ppt formed
Method 1: Silver mirror formed. Method 2: Purple KMnO4 decolourised Method 3: No yellow ppt formed.
Compiled by: Amanda Ang, Rebecca Ng and Lim Fangyin
2010 Organic Chemistry Café
Distinguishing Test Group 1
MJC Prelim 2007/P3/3d(iii) 10) Reagents and conditions: Br2 (aq)
Reddish-brown Br2 remains.
Reddish-brown Br2 decolourises. White fumes of HBr seen.
11) Reagents and conditions: Method 1: Na2CO3 (aq) Method 2: NaOH (aq), heat Method 3: Neutral FeCl3
Method 1: Effervescence seen. Gas evolved gives a white precipitate with limewater.
Method 1: No effervescence seen.
Method 2: No effervescence seen
Method 2: Gas evolved is pungent. Colourless NH3 gas turns red litmus blue.
Method 3: No purple coloration seen
Method 3: Purple coloration observed
12) Reagents and conditions: Method 1: Br2 (aq) Method 2: Hot acidified KMnO4
Method 1: Reddish-brown Br2 decolourises.
Method 1: Reddish-brown Br2 remains.
Method 2: Purple KMnO4 decolourises. Effervescence seen. Gas evolved give a white ppt with lime water
Method 2: Purple KMnO4 decolourises. No effervescence seen.
Compiled by: Amanda Ang, Rebecca Ng and Lim Fangyin
