[BTEW13]

I'm new to this forum but had a question about an exam I took recently in my undergraduate chemistry class. The exam contained a list of compounds and I was required to label whether each was soluble, insoluble, or slightly soluble. My professor marked that I got two wrong and I still think I was right.

One was Lithium Hydroxide (LiOH) and the other was Sodium Chromate (Na2CrO4). I marked that each was soluble and my professor claims that each is only slightly soluble. According to the chart in my text book that states the solubility rules for ionic compounds in water, these two should both be soluble.

Does anyone here have any input as to whether or not I'm right and if not, why?

btw, I did use the search function before I made a new topic.

Thanks in advance

[Borek]

Solubility of sodium chromate: around 25% w/w (more precisely, 47 g of Na₂CrO₄·10H₂O per 100 g of water). Well soluble if you ask me.

Solubility of lithium hydroxide: definitely lower, around 11% w/w (12.8 g of LiOH per 100 g of water). Still, that's 5 mol/liter, well soluble if you ask me (although it has much lower solubility than other alkali metals hydroxides).

Unless you were told what it is supposed to mean in the context of the course "slightly soluble" is a useless term, as it is not well defined and ambiguous. For me both substances are well soluble, even if LiOH definitely differs from its analogues.

[Babcock_Hall]

I recently made a stock solution of lithium hydroxide at 2 M.  Old LiOH (s) picks up carbon dioxide from the atmosphere, and Li₂CO₃ is not very soluble.

[Hunter2]

The soloubilty of LiOH is the lowest in the row of the alcali elements.  LiOH < NaOH < KOH> RbOH< CsOH.

Sodiumdichromate: I would say good solubilty in comparison of potassium dichromate.

[Krakenshark]

i'm afraid your wrong. if something is soluble that means it will completely dissolves in water. slightly soluble means it will only dissolves a bit in water. when a question ask if something is soluble or not, they want to know if 100 g of the substance will completely dissolve in water.

[chenbeier]

Soloubility of LiOH is 12,8 g / 100g H₂O

Calculate yourself how  much water you need for 100 g LiOH.

[mjc123]

i'm afraid your wrong. if something is soluble that means it will completely dissolves in water. slightly soluble means it will only dissolves a bit in water. when a question ask if something is soluble or not, they want to know if 100 g of the substance will completely dissolve in water.

That's not a meaningful definition. 100g of anything will dissolve in water, if you have enough water.