Testing For Cations Flashcards
How to test for Na+
Add 2 drops dilute of NaOH
no precipitate
Add more NaOH solution
Heat and test gas produced with RED litmus.
Litmus stays red
How to test for NH4+
Add 2 drops dilute of NaOH
No precipitate
Add more NaOH solution
Heat and test gas produced with red litmus.
Litmus goes blue
How to test for Fe 2+
Add 2 drops of dilute NaOH.
Green precipitate forms
How do you test for Fe 3+
Add 2 drops of dilute NaOH solution.
Rust brown precipitate
How to test for Cu 2+
Add 2 drops of dilute NaOH
Blue precipitate
Add new sample.
Add 2 drops of excess NH3 solution
Blue precipitate then deep blue solution
How to test for Ag +
Add 2 drops of dilute NaOH solution
Brown precipitate
How to test for Mg 2+
Add 2 drops of dilute NaOH solution
White precipitate
Add excess NaOH
Precipitate remains
New sample
Add dilute sulphuric acid solution
Colourless solution
How to test for Ba 2+
Add 2 drops of dilute NaOH
White precipitate
Add excess NaOH
Precipitate remains
New sample
Add dilute sulphuric solution
White precipitate
How to test for Zn 2+
Add 2 drops of dilute NaOH solution
White precipitate
Add excess NaOH
Precipitate dissolves
Add 2 drops of excess NH3 solution
White precipitate forms and dissolves.
(After addition of excess NaOH)
How to test for Al 3+
Add 2 drops of dilute NaOH solution
White precipitate
Add excess NaOH
Precipitate dissolves
Add 2 drops of excess NH3 solution
White precipitate forms
New sample
Add dilute sulphuric acid
Colourless solution
How to test for Pb 2+
Add 2 drops of dilute NaOH solution
White precipitate
Add excess NaOH
Precipitate dissolves
Add 2 drops of excess NH3 solution
White precipitate forms
New sample
Add dilute sulphuric acid
White precipitate
How to test for Cr 3+
Add NaOH
Green precipitate , soluble in excess
Add NH3
Grey Green Precipitate, insoluble in excess
How to test for Ca 2+
Add aqueous sodium hydroxide
White precipitate, insoluble in excess
No ppt when add NH3
