When aluminum foil is placed in liquid bromine, a chemical reaction occurs between the aluminum and the bromine. This reaction produces aluminum bromide, which is a white solid. The chemical equation for this reaction is:

2Al + 3Br2 → 2AlBr3

In this reaction, the aluminum atoms lose three electrons each to the bromine atoms, forming aluminum ions (Al3+) and bromide ions (Br-). The aluminum ions and bromide ions then combine to form aluminum bromide.

The formation of aluminum bromide is a chemical change because the original substances (aluminum and bromine) have been converted into a new substance (aluminum bromide). This new substance has different properties than the original substances. For example, aluminum bromide is a white solid, while aluminum is a silver metal and bromine is a reddish-brown liquid.