✔ 最佳答案
Method 1: Use two half equations
1.
Write the two half equations for the oxidation and reduction:
Al → Al3+ + 3e- ...... (1)
2H+ + 2e- → H2 ...... (2)
2.
Combine the two half equations by (1)x2 + (2)x3 in order to eliminate the electrons on the both sides. The overall balanced equation is thus:
2Al + 6H+ → 2Al3+ + 3H2
Method 2: Balance the charge on the both sides
1.
Since H+ has one positive change, and Al3+ has three positive charge. Therefore, put "3" as coefficient of H+ and "1" as the coefficient of Al3+ in order to make the total numbers of charges equal on the both sides.
Al + 3H+ → 1Al3+ + H2
2.
Put "1" as the coefficient of Al to make the numbers of Al equal on the both sides. Put (3/2) as the coefficient of H2 in order to make the numbers of H equal on the both sides.
1Al + 3H+ → 1Al3+ + (3/2)H2
3.
Multiply all coefficients on the both sides in order to make them simplest whole numbers. The overall balanced equation is thus:
2Al + 6H+ → 2Al3+ + 3H2
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