In: Chemistry
The element technetium (atomic number 43) is radioactive and one of its isotopes, 99Tc, is used in medicine for diagnostic imaging. The isotope is usually obtained in the form of the pertechnetate anion, TcO4-, but its use sometimes requires the technetium to be in a lower oxidation state. Reduction can be carried out using Sn2+ in an acidic solution. The skeleton equation is TcO4- + Sn2+ → Tc4+ + Sn4+ (acidic solution) Balance the equation by the ion–electron method.
First, define the “ACIDIC” solution/conditions as H+ presence and
Basic solution implies OH- once it is balanced.
Also; note that ALL species must be balanced, as well as charges
Typical steps:
1) split half redox cells
2) balance atoms other than O,H
3) balance O by adding H2O
4) balance H by adding H+
5) balance charge by adding e-
6) balance e- by multiplying by the Greatest common divisor
7) Add both equations
8) simplify repeating elements, H+, H2O, and e- typically
9) add OH- if we need basic media, otherwise this is done.
10) Simplify again
TcO4- + Sn2+ → Tc4+ + Sn4+
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TcO4- = Tc+4
Sn+2 = Sn+4
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TcO4- = Tc+4 + 4H2O
Sn+2 = Sn+4
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8H+ + TcO4- = Tc+4 + 4H2O
Sn+2 = Sn+4
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3e- + 8H+ + TcO4- = Tc+4 + 4H2O
Sn+2 = Sn+4 + 2e-
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6e- + 16H+ + 2TcO4- = 2Tc+4 + 8H2O
3Sn+2 = 3Sn+4 + 6e-
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3Sn+2 + 6e- + 16H+ + 2TcO4- = 2Tc+4 + 8H2O + 3Sn+4 + 6e-
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3Sn+2 + 16H+ + 2TcO4- = 2Tc+4 + 8H2O + 3Sn+4
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3Sn+2(aq) + 16H+(aq) + 2TcO4-(aq) = 2Tc+4(aq) + 8H2O(l) + 3Sn+4(aq)