Calcium formate - a recipe...

[Danchik]

Yes on the 4x question.

Yes, you can add it based on weight if you have an idea how much moisture is in each product (which can be hard to know.

The mass ratio of formic acid (2 x molecular weight) to calcium hydroxide (1 x molecular weight) is 2 x 46 to 1 x 74 = 92:74 = 1:0.80

Thank you!

If the certification for formic acid states that the concentration is 85%, should I take this into account when calculating...?

 

[Randy Holmes-Farley Verified Community Expert]

Thank you!

If the certification for formic acid states that the concentration is 85%, should I take this into account when calculating...?

Yes. Probably most of the remainder is water.

 

[Danchik]

Yes. Probably most of the remainder is water.

Thank you for your communication and clarification:)
Have a nice day!

 

[Miami Reef]

Randy, you’re a genius. What would we do without you?

 

[Randy Holmes-Farley Verified Community Expert]

Randy, you’re a genius. What would we do without you?

lol, thanks. :)

 

[Danchik]

Hi, @Randy Holmes-Farley :)

I mixed up a small solution and some kind of yellow precipitate appeared at the bottom... what could it be?

Does it need to be settled and filtered off?

Answer:

Formic acid - 2.8g brought to 50g of water

Calcium hydroxide - 2.2 g

 

[Randy Holmes-Farley Verified Community Expert]

Probably some trace elements such as iron. I’d just leave them behind.

 

[Danchik]

Probably some trace elements such as iron. I’d just leave them behind.

Got it. Thank you!

I also ran into a problem... I mixed a new solution with a 4x concentration in 50g of water. But for some reason, the calcium hydroxide did not dissolve all of it(

Recipe:
Formic acid - 11g added to 50g of water
Calcium hydroxide - 8.8g

Although the proportion is correct.. if at 1 concentration there is no calcium hydroxide precipitate (sand) This was seen in a previous experiment, previous post :)

Why is the concentration not working...? You said earlier that it was enough to multiply by x4, the reagents.
Is there something else I didn't take into account...:thinking-face:

 

[Randy Holmes-Farley Verified Community Expert]

Got it. Thank you!

I also ran into a problem... I mixed a new solution with a 4x concentration in 50g of water. But for some reason, the calcium hydroxide did not dissolve all of it(

Recipe:
Formic acid - 11g added to 50g of water
Calcium hydroxide - 8.8g

Although the proportion is correct.. if at 1 concentration there is no calcium hydroxide precipitate (sand) This was seen in a previous experiment, previous post :)

Why is the concentration not working...? You said earlier that it was enough to multiply by x4, the reagents.
Is there something else I didn't take into account...:thinking-face:

That might be over the solubility limit of calcium formate, which is about 17g/ 100 g water.

 

[Danchik]

That might be over the solubility limit of calcium formate, which is about 17g/ 100 g water.

I thought that this water solubility refers to the finished dry product

What do we get...
Formic acid is highly soluble in water, the only question is calcium hydroxide, which will dissolve as long as the formic acid is sufficient.

That's why I planned to make a concentrated solution to make it less frequently

 

[Randy Holmes-Farley Verified Community Expert]

I thought that this water solubility refers to the finished dry product

What do we get...
Formic acid is highly soluble in water, the only question is calcium hydroxide, which will dissolve as long as the formic acid is sufficient.

That's why I planned to make a concentrated solution to make it less frequently

If you have both calcium and formate ions in solution, they are governed by the same solubility limit as solid calcium formate and will combine into calcium formate solids if too much is present.