just use the ratio of molar masses - FeCl2 . 4H2O is 198.83 g/mol and FeCl2 is 126.75 g/mol - this means that 1g of FeCl2 . 4H2O is equivalent to 0.6375g of FeCl2.

You could also probably make the tetrahydrate by dissolving the anhydrous chloride in water and then letting it evaporate (without heat) to leave the hydrated product.

Open the following link that may work for you

http://aonomus.wordpress.com/2010/03/06/ferrous-chloride-synthesis-procedure/

Respected, the answer given by Ryan is correct. I also suggest that you follow the following link for the answer I got for my question.

https://www.researchgate.net/post/How_to_prepare_1000_ppm_of_Cadmium?ev=tp_feed_post_xview

Dear Ryan

I can not understand the answer that you have written for me completely. You mentioned that just use the ratio of molar masses - FeCl2 . 4H2O is 198.83 g/mol and FeCl2 is 126.75 g/mol - this means that 1g of FeCl2 . 4H2O is equivalent to 0.6375g of FeCl2.

How you calculate it? I would be so much appreciative of you to explain it more to me. For example 0.42 gr of FeCl2.4H2O is equal to how much gr of FeCl2?

Or 0.4 gr of FeCl2.4H2O is equal to how much gr of FeCl2?

Did you use bellow equivalent to find out the answer?

gr of FeCl2.4H2O . Molar mass of FeCl2.4H2O = gr of FeCl2. Molar mass of FeCl2

gr of FeCl2 = (gr of FeCl2.4H2O .Molar mass of FeCl2.4H2O) / Molar mass of FeCl2

gr of FeCl2 = (1 . 126.75) / 198.83 = 0. 637479....

Best regards

Rozita Nasiri

I agree with Rayan Winburn

Also, I agree with Rayan Winburn .

On purifying ferrous chloride sol. in aq. dil. HCl from ferric iron impurities; cf. my post at: https://www.researchgate.net/post/How_can_i_dissolve_the_FeCl2_salt_in_the_aqueous_solution_while_the_ultimate_pH_be_about_31