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20 Cards in this Set
- Front
- Back
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Definition of a transition element |
A d-bock element that forms an ion with an incomplete d-subshell |
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What are the 2 anomalies in the electron configuration of two transition elements |
Cr - Chromium / Cu - copper Have 1 electron in their for 4s subshell |
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What 3 elements are in d-block but are not transition elements? Why? |
Sc 3+ - no d-subshell Zn 2+ - full d-subshell Ag+ - full 4d subshell All form only one ion |
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Coloured compound formed of Fe(OH)2 |
Green precipitate |
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Coloured compound formed of Fe(OH)3 |
Rusty brown |
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Coloured compound formed of Cu(OH)2 |
Blue precipitate |
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Coloured compound formed of MnO4- |
Purple ppt |
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Coloured compound formed of Mn2+ |
Pale pink |
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Coloured compound formed of Mn(OH)2 |
Brown ppt |
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Coloured compound formed of Cr2O7(2-) |
Orange |
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Coloured compound formed of Cr3+ |
Green/violet |
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Coloured compound formed of Cr2+ |
Blue ppt |
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Coloured compound formed of Cr(OH)3 |
Grey green |
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3 properties of transition elements |
1. Form elements of variable oxidation states e.g. Fe2+/Fe3+ & Cu+/ Cu2+ 2. For coloured compounds e.g. Mn2+ (pink) / Cr 2+ (blue) 3. Good catalysts e.g. Fe (Haber process) & Ni (halogenation) & MnO2 decomposition of H2O2 (pag 9) |
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What are the reagents used in a qualitative test of an unknown transition element ion? And why? |
Ammonia and NaOH Only small amount added - too much added causes ligand substitution which occurs in Cr + Cu only Ammonia can be used because it partially dissociates in aqueous conditions: NH3 + water > (reversible sign) > ammonium ion +OH- It is the OH- we are using |
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Qualitative test for Cu |
Cu2+ (aq) + 2OH- (aq) > Cu(OH)2 (s) blue solution (Cu2+) to Blue ppt (Cu(OH)2) Forms copper(II)hydroxide Must include state symbols |
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Qualitative test for Fe2+ |
Fe2+ (aq) + 2OH- (aq) > Fe(OH)2 (s) Very pale green solution (Fe2+) to green ppt (Fe(OH)2) Forms iron(II)hydroxide
Then further oxidation of Fe(OH)2 : Fe(OH)2 (s) + [O] > Fe(OH)3 (l) Green ppt (Fe(OH)2) to rusty brown ppt (Fe(OH)3) Iron(III)hydroxide |
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Qualitative test for Fe3+ |
Fe3+(aq) + 3OH-(aq) > Fe(OH)3 (s) Pale orange/yellow solution (Fe3+) to Rusty Brown ppt (Fe(OH)3) Iron(III)hydroxide |
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Qualitative test for Mn2+ |
Mn2+ (aq) + 2OH- (aq) > Mn(OH)2 (s) Pale pink solution (Mn2+) to pale brown ppt (Mn(OH)2) Managanese(II)hydroxide |
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Qualitative test for Cr3+ |
Cr3+ (aq) + 3OH- (aq) > Cr(OH)3 (s) Green/ violet solution (Cr3+) to grey-green ppt (Cr(OH)3) Chromium(III)Hydroxide |
