3. What evidence is there for a chemical reaction when the two solutions are
mixed?
When the solution of KSCN is added to the solution Fe(NO3)3
a reaction occurs. We conclude a reaction has occurred because the solution,
which were initially a pale yellow and colorless, turned a reddish-brown color
upon mixing. No precipitate is evident. Only a solution with the new color.
The product of the reaction is soluble, but also is colored. We've seen solutions
that are colored like this before. For example; solution containing Cu2+
are bluish green, solutions containing Ni2+ are green. Both of these
examples the ion that imparts color to the solution is a transition metal.
In the reaction we are looking at the reactants are;
Fe3+(aq) + SCN-(aq)
--->
Before mixing the Fe3+(aq) solution is a yellowish in
color. After adding the SCN-(aq) the solution changes
color to the reddish-brown. The product turns out to be best described as a
'complex ion' which in this case means a substance with one Fe3+
ion and one SCN-ion. The formula of the product is FeSCN2+(aq).