Use the table \'Standard Reduction Potentials\' located in the \'Tables\', to pr

Question

Use the table 'Standard Reduction Potentials' located in the 'Tables', to predict if a reaction will occur when Mg metal is put into a 1M aqueous Al3+ solution.

If a reaction will occur, write a balanced net ionic equation for the reaction. If no reaction will occur, leave all boxes blank.

Use a table of Standard Reduction Potentials to predict if a reaction will occur between Cr metal and Cl2(g), when the two are brought in contact via standard half-cells in a voltaic cell.

If a reaction will occur, write a balanced net ionic equation for the reaction, assuming that the product ions are in aqueous solution. If no reaction will occur, leave all boxes blank.

Explanation / Answer

1)

from data table:

Eo(Mg2+/Mg(s)) = -2.372

Eo(Al3+/Al(s)) = -1.662

The chemical reaction taking place is

2 Al3+(aq) + 3 Mg(s) --> 2 Al(s) + 3 Mg2+(aq)

Eocell = Eocathode - Eoanode

= (-1.662) - (-2.372)

= 0.71 V

For spontaneous reaction, Eocell must be positive

here:

Eo cell is positive

So, This reaction is spontaneous

Answer:

2 Al3+(aq) + 3 Mg(s) --> 2 Al(s) + 3 Mg2+(aq)

2)

from data table:

Eo(Cr3+/Cr(s)) = -0.74

Eo(Cl2(g)/2Cl-) = 1.36

The chemical reaction taking place is

3 Cl2(g) + 2 Cr(s) --> 6 Cl-(aq) + 2 Cr3+(aq)

Eocell = Eocathode - Eoanode

= (1.36) - (-0.74)

= 2.1 V

For spontaneous reaction, Eocell must be positive

here:

Eo cell is positive

So, This reaction is spontaneous

Answer:

3 Cl2(g) + 2 Cr(s) --> 6 Cl-(aq) + 2 Cr3+(aq)

Both the reactions are spontaneous

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