Question

For each chemical reaction listed in the table below, decide whether the highlighted atom is being oxidized or reduced or neither oxidezed nor reduced.
a. 4HF(g) + SiO2(s) -> SiF4(g) + 2H20(g) Higlithed: Si
b. C(s) + 02(g) -> CO2(g) Higlithed: C
c. Na2CO3(s) + H3PO4(aq) -> Na2HPO4(aq) + CO2(g) +H2O(l) Higlithed: C
d. CuSO4(aq) + Zn(s) -> ZnSO4(aq) + Cu(s) Higlithed: Cu

Answer 1

a. The oxidation state of Si in SiO₂ is +4 and the oxidation state of Si in SiF₄ is +4. So, it is neither reduced nor oxidized.

b. The oxidation state of C in C (s) is 0 and the oxidation state of C in CO₂ is +4. As the oxidation state increases, it is being oxidized.

c. The oxidation state of C in Na₂CO₃ is +4 and the oxidation state of C in CO₂ is +4. So, it is neither oxidized nor reduced.

d. The oxidation state of Cu in CuSO₄ is +2 and it is 0 in Cu (s). So, it is reduced.