# Question a46a8

Feb 25, 2017

Yes it will.

#### Explanation:

List the 1/2 equations in order least positive to most positive:

 " " "E"^@("V")

stackrel(color(white)(xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx))(color(blue)(larr)

" "sf(Al^(3+)+3erightleftharpoonsAl" "-1.66)

" "sf(Cu^(2+)+2erightleftharpoonsCu" "+0.34)

stackrel(color(white)(xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx))(color(red)(rarr)

Note we use the $r i g h t \le f t h a r p \infty n s$ symbol to show that the 1/2 cells can go in either direction depending on what they are coupled with.

The 1/2 cell with the most +ve ${\text{E}}^{\circ}$ is the one which will take in the electrons.

From this we can see that the 2nd 1/2 cell will be driven left to right and the 1st 1/2 cell right to left in accordance with the arrows.

So the 2 half - reactions are:

$\textsf{A l \rightarrow A {l}^{3 +} + 3 e \text{ } \textcolor{red}{\left(1\right)}}$

$\textsf{C {u}^{2 +} + 2 e \rightarrow C u \text{ } \textcolor{red}{\left(2\right)}}$

To get the electrons to balance you can see that we need to multiply equation $\textcolor{red}{\left(1\right)}$ by 2 and equation sf(color(red)((2))# by 3 then add both sides together:

This gives

$\textsf{2 A l + 3 C {u}^{2 +} + \cancel{6 e} \rightarrow 2 A {l}^{3 +} + \cancel{6 e} + 3 C u}$

So you can see that aluminium should displace copper(II) ions from a solution of its salt.