Testing For Cations Flashcards

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1
Q

How to test for Na+

A

Add 2 drops dilute of NaOH
no precipitate

Add more NaOH solution
Heat and test gas produced with RED litmus.
Litmus stays red

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2
Q

How to test for NH4+

A

Add 2 drops dilute of NaOH
No precipitate

Add more NaOH solution
Heat and test gas produced with red litmus.
Litmus goes blue

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3
Q

How to test for Fe 2+

A

Add 2 drops of dilute NaOH.

Green precipitate forms

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4
Q

How do you test for Fe 3+

A

Add 2 drops of dilute NaOH solution.

Rust brown precipitate

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5
Q

How to test for Cu 2+

A

Add 2 drops of dilute NaOH
Blue precipitate

Add new sample.
Add 2 drops of excess NH3 solution
Blue precipitate then deep blue solution

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6
Q

How to test for Ag +

A

Add 2 drops of dilute NaOH solution

Brown precipitate

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7
Q

How to test for Mg 2+

A

Add 2 drops of dilute NaOH solution
White precipitate

Add excess NaOH
Precipitate remains

New sample
Add dilute sulphuric acid solution
Colourless solution

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8
Q

How to test for Ba 2+

A

Add 2 drops of dilute NaOH
White precipitate

Add excess NaOH
Precipitate remains

New sample
Add dilute sulphuric solution
White precipitate

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9
Q

How to test for Zn 2+

A

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)

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10
Q

How to test for Al 3+

A

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

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11
Q

How to test for Pb 2+

A

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

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12
Q

How to test for Cr 3+

A

Add NaOH
Green precipitate , soluble in excess

Add NH3
Grey Green Precipitate, insoluble in excess

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13
Q

How to test for Ca 2+

A

Add aqueous sodium hydroxide
White precipitate, insoluble in excess

No ppt when add NH3

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