WCL (Wet Chemistry Lab) sample Options

[Juramike]

We'll soon know what kinds of crops we can grow on Mars! Bonus, the fruits will be already freeze-dried!

Handy list of preferred pH's of common garden plants.

-Mike

[nprev]

Hmm. What does this tell us (if anything at all) about the existence of superoxides at the site? Straining my memory of ancient high-school chemistry here, I would expect such compounds to be aggressive electron donors & therefore acidic.

(Okay, now tell me I got that backwards. Plus, I know it's a subsurface sample, but you'd expect this stuff to get circulated down at least a couple of cm due to wind action over time.)

[Juramike]

Hmm. What does this tell us (if anything at all) about the existence of superoxides at the site? Straining my memory of ancient high-school chemistry here, I would expect such compounds to be aggressive electron donors & therefore acidic.

Yup. The pKa of hydroperoxy anion (HOO-) is 4.88 (acidic like vinegar). So at any pH above 5, the predominant form will be the superoxide anion (O2--)

At pH 9, the ratio of superoxide anion to hydroperoxy anion will be about 10,000 : 1.

(Source: Wikipedia/superoxide + others to confirm)

-Mike