A water sample is suspected to be contaminated by iron (III) ions. How could you determine if the sample is really contaminated?
I would add a little KCNS to it. A blood red color forms if iron(III) is present (due to the formation of the complex ion, FeCNS^+2.)
To determine if a water sample is contaminated with iron (III) ions, you can perform a simple test called a colorimetric test. Here's how you can do it:
1. First, collect a small volume of the water sample in a clean and transparent container.
2. Add a few drops of a chemical indicator called thiocyanate ion (SCN-) to the water sample. Thiocyanate ion forms a reddish-brown complex with iron (III) ions, which helps us to detect its presence.
3. Observe the color change in the water sample. If the water sample turns reddish-brown, it indicates the presence of iron (III) ions and confirms contamination. If there is no color change, it suggests that the water sample is not contaminated with iron (III) ions.
It's important to note that this test provides a qualitative result, confirming the presence or absence of iron (III) ions. If you require a quantitative measurement of the contamination level, you would need to use more advanced analytical techniques, such as atomic absorption spectroscopy or inductively coupled plasma spectroscopy.