Test Index

WAEC Chemistry 2016 Paper

© africaexams.com

Question : 40

Total: 50

Consider the following half-cell reactions.

\to

Al³⁺_(aq) + 3e^-

Cu²⁺_(aq) + 2e^-

\to

The overall equation for the reaction is

Al_(s) + Cu²⁺_(aq) $\to$ Al³⁺_(aq) + Cu_(s)
2Al_(s) + Cu²⁺_(aq) $\to$ 2Al_(aq) + Cu_(s)
2Al_(s) + 3Cu²⁺_(aq) $\to$ 3Cu_(s) + 2Al³⁺_(aq)
3Al_(s) + 2Cu²⁺_(aq) $\to$ Cu_(s) + 3Al³⁺_(aq)

Solution:

Al_(s)

\to

Al³⁺_(aq) + 3e^- ______(i)

Cu²⁺_(aq) + 2e^-

\to

Cu_(s) ________(ii)

To balance the electrons, multiply equation (i) by 2 and equation (ii) by 3 and then add the resulting equations

2Al_(s)

\to

2Al³⁺_(aq) + 3e^-

3cu²⁺_(aq) + 6e^-

\to

3Cu_(s)

2Al_(s) + 3Cu²⁺_(aq)

\to

3Cu_(s) + 2Al³⁺_(aq)

© africaexams.com

Go to Question:

Prev Question

Next Question