Why must the litmus paper must be moistened with water before using it to test for ammonia?
2007-08-22 01:43:52 · 3 answers · asked by icydollie xD 1 in Science & Mathematics ➔ Chemistry
Ammonia, NH3, is a gas. It dissolves in the water to make NH4OH a base. Household ammonia is the dissolved gas.
2007-08-22 01:56:46 · answer #1 · answered by science teacher 7 · 0⤊ 0⤋
Because Ammonia as such in solid state does not give litmus test... It's hydroxide, tho, gives litmus test... Ammonium Hydroxide is produced by the reaction of ammonia with water... NH3 + H2O -------> NH4OH
This NH4OH dissociates to form NH4+ and OH-...
NH4OH <-------> NH4+ + OH-
This OH- is actually the 'base' part of ammonium hydroxide... (not counting the lone pair of electrons on N)... Thus, only moistened ammonia can give litmus test...
2007-08-22 08:56:52 · answer #2 · answered by Ann 3 · 0⤊ 0⤋
Because NH3 is a gas, and it would just pass over dry litmus paper without reacting. The water in moist litmus paper would react to form OH-, and that would turn pink litmus blue.
NH3 + H2O ===> NH4+ + OH-
2007-08-22 08:58:23 · answer #3 · answered by steve_geo1 7 · 0⤊ 0⤋