348 DIY Science: Illustrated Guide to Home Chemistry Experiments
oALIpToN ACTIvITIES
If you have time and the required materials, consider
performing this optional activity:- Have a friend or lab partner make up an unknown
cation sample solution for you. Test that solution to
determine which cations are present.
FIGURE 19-4:
A blue precipitate upon
addition of potassium
ferricyanide confirms the
presence of ferrous ionsRQEWEvI UESTIOnS
q 1 : Examine the matrix that you filled in for Table 19-5. Which, if any, of the cations cannot be unambiguously identified using only
the five primary reagents?
q: 2 If any of the cations cannot be unambiguously identified using only the five primary reagents, can they be identified using one or
more of the secondary reagents? If so, which secondary reagents are useful for identifying which cations?
q: 3 If you have a sample that is known to contain only iron(II) and/or iron(III) and/or copper(II) cations, what is the minimum
number and identity of the reagents needed to identify unambiguously the cations present in the unknown? What characteristic
reactions would serve to discriminate these three cations?