Answer:
Al (s) + 3Fe3+ (aq) ---> Al3+ (aq) + 3Fe2+(aq)
Step-by-step explanation:
atoms become positive (or less negative) ions when they lose electrons. They become negative (or less positive) ions when they gain electrons, since each electron (e-) has a charge of -1.
So, since Al changes to Al3+ which is positive, it loses electrons. And when Fe3+ changes to Fe2+, it becomes less positive, so it gained electrons.
Now, write the half (balanced) equations:
Al ---> Al3+ + 3e-
Fe3+ + e- ----> Fe2+
To combine both equations, we have to eliminate electrons. To do so, make sure both half equations have the same no. of electrons. We can multiply the equation of Fe by 3 so that it has 3 electrons.
3Fe3+ + 3e- ----> 3Fe2+
Finally, we can combine both equations (remember to eliminate the electrons).
Al (s) + 3Fe3+ (aq) ---> Al3+ (aq) + 3Fe2+(aq)
Check to see if both sides of the equation have equal charges. Ions always have an aqueous state.