# metal salt solutions g/l means hydrate or anhydrous

I want to redo an experiment. They've used

Nickel chloride: 40 g/L


Nickel chloride can be bought in two forms: anhydrous ($\ce{NiCl2}$) and hydrate ($\ce{NiCl2.6H2O}$). The paper doesn't say which one they've used. Which one did they mean in the paper? In one liter of water should I dissolve 40 grams of $\ce{NiCl2}$ or 40 grams of $\ce{NiCl2.6H2O}$? Is there a convention?

## 1 Answer

Unless the experimental part of the paper provides additional details, such as equivalents or moles or the colour of the nickel chloride used ($\ce{NiCl2*6H2O}$ is green, while the anhydrous chloride is yellowish) you're up to guessing.

However, if the experiment you're trying to repeat is conducted in aqueous solution, it is safe to assume that you can use the hexahydrate.

Btw, gloves and proper waste management are a good idea here.

• I would rather interpret it as a concentration, which would imply that there are $40~g~\ce{NiCl2}$ in $1~L$ solvens. It then does not make a difference what kind of salt you use, but its effect on the concentration might be huge... – Martin - マーチン Apr 24 '14 at 8:30
• Thanks a lot. This is the link to the paper www2.bren.ucsb.edu/~dturney/port/papers/Modern%20Electroplating/… I want to make the second alloy on page 313, 'Iron-nickel Magnetic[37]'. I'd really appreciate it if you can take a look and confirm whether I should assume hexahydrate or anhydrous. Thanks. – r d Apr 24 '14 at 8:34
• @ramda I can only guess, but from comparison with the other entries in the table (such as the one above), I'd say that the hexahydrate is safe. The prices for anhydrous nickel chloride are astronomical anyway, so I'd rather dry it myself by heating the hexahydrate in thionyl chloride, if necessary. But in this case, I'd use the hydrates of all three components in the mixture. – Klaus-Dieter Warzecha Apr 24 '14 at 8:53