Redox reactions? (HELP!?)?

Which of the following are redox reactions? And tell why?

[ i have a test tomorrow and i do not get this! ]

a) Al2O3 ----> 4Al + 3O2

b) SiCl4 + 2Mg ----> Si + 2MgCl

c) H2SO4 + 2NaOH ----> Na2SO4 + 2H20

d) AgNo3 + NaCl ----> AgCl + NaNO3

THanks so much!

1 Answer

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  • 9 years ago
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    b

    SiCl4 + 2Mg --> Si + 2MgCl2

    Si in SiCl4 = 4+ and becomes 0 as the neutral element, reduced by Mg, gained 4 electrons

    Mg starts at 0 and becomes 2+ in MgCl2, oxidized by Si, loses 2e- / Mg atom

    Al2O3 --> deomposition, no oxidation state changes

    H2SO4 + 2NaOH --> acid base, no oxidation changes

    AgNO3 + NaCl --> double replacement, no oxidation changes

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