We’re being asked to predict what would form first at the cathode and at the cathode when NaCl, MgBr2, and LiI undergo electrolysis.
Recall that the cathode is where reduction occurs while the anode is where oxidation occurs.
Since NaCl, MgBr2, and LiI are ionic compounds, the will form ions when molten.
Sodium is from Group 1A, it has a charge of +1. The chloride ion, Cl–, has a charge of –1:
NaCl → Na+ + Cl–
Magnesium is from Group 2A, it has a charge of +2. The bromide ion, Br–, has a charge of –1:
A mixture of molten salts, NaCl, MgBr2 and LiI undergoes electrolysis. Which species would you predict would form first at the cathode and at the cathode?
1) Li formed at the anode, F2 formed at the cathode.
2) Li formed at the cathode, F2 formed at the anode.
3) Mg formed at cathode, I2 formed at the anode.
4) Mg formed at anode, I2 formed at the cathode.
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