Qualitative Anlaysis Lab

Name the six cations

silver (Ag+), iron(Fe3+), chromium(Cr3+), calcium( Ca2+), zinc (Zn2+) and nickel (Ni2+)

Purpose of Qualitative Analysis Lab

To test for six cations present in an unknown sample using separation techniques

What color confirms silver/silver chlroide (Ag+ /AgCl)

white

What color confirms Iron III ( Fe3+) ?

Blue

What color confirms chromate (Cr3+) ?

Yellow

What color flame confirms Calcium (Ca2+) ?

Bright Red

What color confirms Zinc II ( Zn2+)?

gray blue

What color confirms Ni²⁺ with DMG? ?

Pinkish Red

What color is Fe(OH)₃ precipitate?

rusty brown

How is Ag⁺ identified in qualitative analysis?

Add HCl = AgCl forms, dissolve in NH₃ , add HNO₃ = white AgCl reforms + confirmed

How is Fe³⁺ identified?

Add NH₃ = brown Iron III Hydroxide Fe(OH)₃ , add potassium hexacyanoferrate = blue

How is Cr³⁺ identified?

Add NaOH + H₂O₂

How is Ca²⁺ identified?

Dissolve precipitate in HCl and perform flame test with nichrome wire to find orange-red / brick-red flame

How is Ni²⁺ identified?

Dissolve precipitate in 15 M NH₃, add DMG (dimethylglyoxime) = pinkish red

How is Zn²⁺ identified?

Add HCl then potassium hexacyanoferrate = gray-blue precipitate

How do precipitates form?

An exception to the solubility aka insoluble compounds