Question

Solid aluminum is placed in a beaker with a blue solution of copper(II) nitrate. The resulting reaction causes the blue solution to turn colorless. The solid aluminum is consumed while a spongy, dark brown solid forms. Based on the observations listed above, which of the following inference(s) would be valid?
A. A synthesis reaction occurred.
B. A single replacement reaction occurred.
C. A double replacement reaction occurred.
D. A redox reaction occurred.

Answer 1

Answer:

Option D. A redox reaction occurred.

Explanation:

From the question given above it evident that a redox reaction has occurred because there is a colour change when aluminum was introduced into the beaker containing blue solution of copper(II) nitrate.

The equation for the reaction is given below below:

2Al + 3Cu(NO3)2 —> 2Al(NO3)3 + 3Cu

The oxidation number of Al changes from 0 to +2 indicating oxidation and the oxidation number of Cu changes from +2 to 0 indicating reduction.

As the oxidation - reduction reaction occurs, a colour change is observed.