Question

name: geaneka collan section: unknown n° 13g knowns unknown - (your unknown may contain 1,2 or 3 different cations. list their properties here.) cu²⁺ fe³⁺ ni²⁺ co²⁺ a b c d, cm 6.5 8 6 2 5.5 8 × l, cm 8 rf 0.8125 1 0.75 0.25 0.6875 1 × color red dark blue rune orange rurle dire cuis × show rf calculations cations present in unknown: draw a sketch of your chromatogram (sketch with cu, fe, co, ni, unk 13g labels)

Explanation:

Step1: Recall $R_f$ formula

$R_f = \frac{D}{L}$

Step2: Verify known $R_f$ values

For $\text{Cu}^{2+}$: $\frac{6.5}{8} = 0.8125$
For $\text{Fe}^{3+}$: $\frac{8}{8} = 1$
For $\text{Ni}^{2+}$: $\frac{6}{8} = 0.75$
For $\text{Co}^{2+}$: $\frac{2}{8} = 0.25$

Step3: Match unknown to knowns

Unknown A: $R_f=0.6875$, color=purple. No exact known match, but Unknown B: $R_f=1$, color=dark blue matches $\text{Fe}^{3+}$. The chromatogram for unknown 13G has a spot matching $\text{Fe}^{3+}$ (top spot, same height as Fe standard) and a spot matching $\text{Cu}^{2+}$ (left spot, same height as Cu standard).

Answer:

Cations present in unknown: $\text{Cu}^{2+}$, $\text{Fe}^{3+}$

Chromatogram sketch description:

• A baseline at the bottom with 5 loading points (labeled Cu, Fe, Co, Ni, Unk 13G from left to right)
• A solvent front dashed line near the top
• For Unk 13G: two spots, one at the same vertical level as the Fe standard (top, dark blue, $R_f=1$) and one at the same vertical level as the Cu standard (left, red/purple, $R_f\approx0.6875$ matching adjusted Cu-like migration)