Reef Chemistry Question of the Day 293: Let's Count Ions!

[Randy Holmes-Farley]

Reef Chemistry Question of the Day 293

The number of ions in a reef tank is truly mind boggling.

In 100 gallons of seawater, there are about 255,000,000,000,000,000,000,000,000 individual ions.

Let's count them one by one!

Someone had to do it, right? How else would we know?

OK, we'll assign that to a newbie and try a different exercise.

Counting by numbers of ions, not by weight of ions, which are there more of in seawater?

A. Calcium ions
B. Ions that contribute to alkalinity
C. All trace elements added together
D. Potassium Ions

PS, this is an open book test, unless you are truly a chem wizard!

Good luck!

Previous Reef Chemistry Question of the Day:

Reef Chemistry Question of the Day 292: Fireworks

Reef Chemistry Question of the Day 292 In honor of the Fourth of July (Independence Day, sorry, Great Britain), let's have some fireworks fun. Which of these favorite reefing chemicals provides the orange color in many fireworks? A. Calcium B. Magnesium C. Phosphate D. Nitrate Good luck and...

www.reef2reef.com

 

[Dburr1014]

A.

Yes, I'm going to need luck.

 

[Miami Reef]

A.

Yes, I'm going to need luck.

I agree with @Dburr1014

A.

 

[taricha]

Gonna have to think about this one... not sure my guess yet.

 

[Reefahholic]

Chloride, Sodium, or Calcium??

What’s the answer?

 

[Dan_P]

Reef Chemistry Question of the Day 293

The number of ions in a reef tank is truly mind boggling.

In 100 gallons of seawater, there are about 255,000,000,000,000,000,000,000,000 individual ions.

Let's count them one by one!

Someone had to do it, right? How else would we know?

OK, we'll assign that to a newbie and try a different exercise.

Counting by numbers of ions, not by weight of ions, which are there more of in seawater?

A. Calcium ions
B. Ions that contribute to alkalinity
C. All trace elements added together
D. Potassium Ions

PS, this is an open book test, unless you are truly a chem wizard!

Good luck!

Previous Reef Chemistry Question of the Day:

Reef Chemistry Question of the Day 292: Fireworks

Reef Chemistry Question of the Day 292 In honor of the Fourth of July (Independence Day, sorry, Great Britain), let's have some fireworks fun. Which of these favorite reefing chemicals provides the orange color in many fireworks? A. Calcium B. Magnesium C. Phosphate D. Nitrate Good luck and...

www.reef2reef.com

Since Ca and K are so close in atomic weight and concentration, I wonder if I eliminate them or use them as evidence for the need to think more carefully about this question. I am thinking that inorganic carbon, HCO3, is about 1/5 the concentration of Ca or K, so, ions contributing to alkalinity is out.This leaves me scratching my head.

 

[Reefer Matt]

I believe the order is
A, D, B, C in order of greatest to least from my online research.

 

[Salty_Northerner]

Reef Chemistry Question of the Day 293

The number of ions in a reef tank is truly mind boggling.

In 100 gallons of seawater, there are about 255,000,000,000,000,000,000,000,000 individual ions.

Let's count them one by one!

Someone had to do it, right? How else would we know?

OK, we'll assign that to a newbie and try a different exercise.

Counting by numbers of ions, not by weight of ions, which are there more of in seawater?

A. Calcium ions
B. Ions that contribute to alkalinity
C. All trace elements added together
D. Potassium Ions

PS, this is an open book test, unless you are truly a chem wizard!

Good luck!

Previous Reef Chemistry Question of the Day:

Reef Chemistry Question of the Day 292: Fireworks

Reef Chemistry Question of the Day 292 In honor of the Fourth of July (Independence Day, sorry, Great Britain), let's have some fireworks fun. Which of these favorite reefing chemicals provides the orange color in many fireworks? A. Calcium B. Magnesium C. Phosphate D. Nitrate Good luck and...

www.reef2reef.com

How many zeros is that omg, and I thought.. am I old enough to read about them all ! Lol

 

[Christoph]

Its a tight race between potassium and calcium. Potassium is ~ 10 mmol/l while calcium is ~10,5 mmol/l in typical seawater. Trace elements in the µg/l range are not a real contributor. Alkalinity contributing ions (carbonate, bicarbonate, borate) should also be greatly outnumbered.

So my answer is A, Calcium

Backgrond info: 1 mol equals 6,022 x 10^23 particles. One could spend an eternity counting

 

[Randy Holmes-Farley]

Its a tight race between potassium and calcium.

For those who watch Ted Lasso, it's like Roy Kent's comment on whether he dislikes Jamie more than he likes Keeley.

https://imgix.ranker.com/user_node_img/50138/1002752327/original/1002752327-photo-u84408358?auto=format&q=60&fit=crop&fm=pjpg&dpr=2&w=650

 

[Miami Reef]

@Randy Holmes-Farley

 

[LadAShark]

Here is a cheat sheet based on mass, now convert it to ions https://www.lenntech.com/composition-seawater.htm

 

[InactionJackson]

Calcium

 

[Randy Holmes-Farley]

And the answer is...

Counting by numbers of ions, not by weight of ions, which are there more of in seawater?

A. Calcium ions
B. Ions that contribute to alkalinity
C. All trace elements added together
D. Potassium Ions


Calcium is very close to potassium, but it just edges it out by about 1 percent. One thing about major ions such as calcium and potassium: they do not randomly vary up and down by location the way trace elements do (except by salinity changes), so calcium is always higher than potassium, unless you are near a river input or something else perturbing the seawater.

Total ions adding up to give alkalinity (bicarbonate, carbonate, borate, phosphate, silicate, hydroxide) together are about 5x lower than calcium and potassium.

All trace elements are much lower, even if all are added together.

 

[Miami Reef]

Phosphate gives alkalinity? I never knew that.

 

[Reefer Matt]

Yay. I got one right, and the correct order. Go internet!

 

[Randy Holmes-Farley]

Phosphate gives alkalinity? I never knew that.

Chemistry and the Aquarium: What is Alkalinity?

Randy provides an overview of alkalinity as to why it's important, how it's measured, and how can it be tested.

reefs.com

Chemical Nature of Alkalinity
Based on the definition of total alkalinity given above, it is clear that anything that absorbs protons when the pH is dropped from normal levels to about 4-5 will be counted toward alkalinity. In seawater there are a variety of things that contribute, and in reef tanks the list is even longer. Equation 3 is the defining equation for total alkalinity in normal seawater.


TA (total alkalinity) = [HCO3–] + 2[CO3—] + [B(OH)4–] + [OH–] + [Si(OH)3O–] + [MgOH+] + [HPO4—] + 2[PO4—] – [H+]

The reason for the 2 in front of the carbonate and phosphate concentrations is that they take up two protons as the pH is dropped down to pH 4. All of the other ions just take up a single proton (except protons themselves which must be subtracted).

The main chemical species that contribute to alkalinity in seawater (and the reason it is useful to reefkeepers) are bicarbonate and carbonate (equations 1 and 2). The table below (from “Chemical Oceanography” by Frank Millero; 1996) shows the contribution to alkalinity from the major contributors in seawater at pH 8. If you start at higher pH, the relative contribution of bicarbonate will go down relative the others.

 

[LadAShark]

And the answer is...

Counting by numbers of ions, not by weight of ions, which are there more of in seawater?

A. Calcium ions
B. Ions that contribute to alkalinity
C. All trace elements added together
D. Potassium Ions


Calcium is very close to potassium, but it just edges it out by about 1 percent. One thing about major ions such as calcium and potassium: they do not randomly vary up and down by location the way trace elements do (except by salinity changes), so calcium is always higher than potassium, unless you are near a river input or something else perturbing the seawater.

Total ions adding up to give alkalinity (bicarbonate, carbonate, borate, phosphate, silicate, hydroxide) together are about 5x lower than calcium and potassium.

All trace elements are much lower, even if all are added together.

Interestingly, different seas have differing concentrations of sodium and chloride, with some having more chloride than sodium and vice versa, though the concentrations remain somewhat similar.

I'm noticing a wide variation in calcium concentration in the red sea in the literature, also. Not sure what to make of that.

 

[Randy Holmes-Farley]

Interestingly, different seas have differing concentrations of sodium and chloride, with some having more chloride than sodium and vice versa, though the concentrations remain somewhat similar.

I'm noticing a wide variation in calcium concentration in the red sea in the literature, also. Not sure what to make of that.

The main world oceans are all about the same, but mostly enclosed spaces like the Red Sea, can differ.

That said, where did you read that info? In this article there is far more chloride than sodium, like normal ocean water:

https://www.researchgate.net/figure/Red-Sea-water-specifications_tbl2_275251989

 

[Miami Reef]

So dosing phosphate can raise the total alkalinity (just like silica), but won’t effect the amount of bicarbonate an’s carbonate?