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Chemistry IGCSE > Identification > Flashcards

Flashcards in Identification Deck (16):
0

Test for ammonia:

• use a drop of concentrated HCl; dense white fumes should be produced
• use damp red litmus paper; it should turn blue

1

Test for carbon dioxide:

Bubble the gas through limewater (calcium hydroxide - CaOH). Carbon dioxide turns limewater a milky color.

2

Test for hydrogen:

Use a lighted splinter. The gas should burn with a 'pop' sound.

3

Test for oxygen:

Use a glowing splinter. The gas should rekindle the glowing splinter.

4

Test for sulphur dioxide (SO2):

Bubble the gas through acidified potassium dichromate (K2Cr2O7). The orange solution should turn green.

5

Test for carbonate:

Add dil. HCl and pass the liberated gas through limewater. It should turn milky and form effervescence (lots of bubbles).

6

Test for chloride/bromide/iodide:

Add dil. HNO3 + aq. silver nitrate (AgNO3) OR dil. lead nitrate (Pb(NO3)2)

Chloride should form white ppt. insoluble in acid, bromide should form cream ppt., and iodide should form yellow ppt., with same characteristic.

7

Test for sulphate:

Add dil. HCl + barium chloride OR barium nitrate.

It should form white ppt. insoluble in acid.

8

Test for nitrate:

Add aluminium powder and excess aq. NaOH. Heat and mix it, then test the gas with:
i) red litmus: turns blue
ii) conc. HCl: forms dense white fumes

9

Test for ammonium:

Adding aq. NaOH: no ppt. If the mixture is warmed, a pungent-smelling gas that turns litmus paper blue will be produced.

Adding aq. NH3: no ppt.

10

Test for calcium:

Adding aq. NaOH: forms white ppt (insoluble in excess).

Adding aq. NH3: no ppt.

11

Test for aluminium:

Add aq. NaOH: forms white ppt. soluble in excess NaOH to form a colourless solution.

Add aq. NH3: forms white ppt. insoluble in excess NH3.

12

Test for zinc:

Adding aq. NaOH: white ppt. forms, soluble in excess NaOH.

Adding aq. NH3: white ppt. forms, soluble in excess NH3 to form a colourless solution.

13

Test for cupric (Cu2+):

Adding aq. NaOH: forms blue ppt., insoluble in excess.

Adding aq. NH3: forms blue ppt., soluble in excess NH3 to form a dark blue solution.

14

Test for ferrous (Fe2+):

Adding aq. NaOH: forms green ppt., insoluble in excess.

Adding aq. NH3: forms green ppt., insoluble in excess.

15

Test for ferric (Fe3+):

Adding aq. NaOH: forms brown ppt., insoluble in excess.

Adding aq. NH3: forms brown ppt., insoluble in excess.