Question

Part A.

Use the attached flow chart of a qualitative analysis separation and identification scheme to answer the following question.

LLS LF TOI aims awa seel ter thei Ve're ents | | NH. HCI (Agʻ, Fe**, Cr"*, Al’, Ca?", Ni?", Zn?", Na", NH.', and Mg") Step 1: Observations and tests: Step 2: HCI color, Na', and NHA Step 3a: NH3, NHACI AgCl (s, white) Step 4: (NH4),C Fe(OH)3 (s, rust) Ag(NH3)2 Cr(OH), (s, gray-green) Step 5a: Evaporate Al(OH)3 (s. colorless) CaC,04 (s, white) || HNO to remove NHA Step 3b: NaOH AgCl (s, white) NaOH, H2O, Mg(OH)2 (s, white) Zn(OH).' Fe(OH)3 (s, rust) Al(OH).'.CO. Red flame Ni(OH), (s, green) K.Fe(CN) НСІ Fe Heat to remove H202 ZnK [Fe(CN).]2 K.Fe(CN). Step 3c: HCI Mg(OH)2 (s, white) NiNH + (s, gray-blue) pale violet Step 5c: HCI, Fe [Fe(CN).] All, Cr2O72 Mg Reagent, DMG (s, blue) NaOH Mg(OH)2 Ni(CH-N2O2) (s, blue lake) (s, red) Al(OH)3 CrO2, yellow Step 3d: BaCl HCI, Aluminon, NH3 Al(OH) BaCro. FIGURE 2: Cation Flow Chart (s, red lake) (s. vellow) test HCI Step 5b: NH; (s, colorless)

What ion is present in solution if the following observations were seen (enter your answer as the chemical symbol without the charge)

Addition of HCl: no precipitate

Addition of NH₃/NH₄Cl: a precipitate forms

Addition of NaOH and H₂O₂: no precipitate

Heat to remove H₂O₂ and addition of HCl: a colorless solid is formed

Addition of HCl, Aluminon and NH₃: a red lake is observed

Part B

Which ion produces a blue-green flame upon a flame test?

A) K+

B) Li+

C) Ca 2+

D) Sr 2+

E) Na +

F) Cu 2+

G) Ba 2+

Answer 1

Part A.

The ion present is aluminium ion.

Symbol of the ion without charge = Al

According to the flowchart provided, all of the observations match with the qualitative test of aluminium. The last test i.e. the formation of red lake is the confirmatory test of aluminium,

Part B:

Correct option: F) Cu²⁺

Flame color of K⁺ = lilac

Flame color of Li⁺ = red

Flame color of Ca²⁺ = brick red

Flame color of Sr²⁺ = crimson red

Flame color of Na⁺ = yellow

Flame color of Cu²⁺ = blue-green   (especially true for Cu(II) halides)

Flame color of Ba²⁺ = green