Reef Chemistry Question of the Day #129 Strontium

[Randy Holmes-Farley]

Reef Chemistry Question of the Day [HASHTAG]#129[/HASHTAG]

Strontium in seawater is most similar chemically to which of the following other ions in seawater?

A. Sodium
B. Lithium
C. Chloride
D. Calcium
E. Iron
F. Aluminum

Good luck!





















.

 

[sureal00]

I would go with D. calcium since in helps with calcifying

 

[JimWelsh]

I would go with D. calcium since they are both alkaline earth metals, or Group 2 in the Periodic Table.

 

[beaslbob]

c

(don't know LOL)

 

[redfishbluefish]

Who ever would have guessed my experiences in radiochemistry would help me answer Randy's questions years and years later! Someone has a patent on the use of hydroxyapatite (a calcium containing compound) to separate radioactive strontium from it's daughter isotope, rubidium. Strontium is immediately "absorbed" by the hydroxyapatite, while the rubidium is readily and easily eluted off the column.

So I'm going to guess D, calcium.

 

[beaslbob]

dern.

Now I have to be a nuclear scientist to answer these,

 

[pedro]

D. Calcium

 

[hart24601]

Calcium but only because I remember it from one of Randy's articles.

 

[Randy Holmes-Farley]

And the answer is...D. Calcium

Strontium looks very much like calcium, only larger. In fact, it looks so much like calcium that when calcium carbonate is precipitating from a solution that also contains strontium, some strontium gets into the crystals in place of calcium.

In seawater, there's a specific amount of strontium that gets into precipitating calcium carbonate, which is determined by how well it actually fits int eh the crystals, and how much strontium is present relative to calcium. In normal seawater, about 1% of the calcium ions gets substituted for by strontium.

Curiously, that ratio holds about the same whether the precipitation happens abiotically (nonbiologically, such as on heaters and pumps) or in coral skeletons. That fact suggests (but does not prove) that corals are not actually putting strontium into their aragonite skeletons, but that it just "accidentally" gets substituted for calcium.

This has more:
http://www.advancedaquarist.com/issues/nov2003/chem.htm