Question

Chemistry 12 Question!


Low solubility means to have a solution that has a solubility of less than 0.1 M. Is that true?

Answer 1

However, something is confusing in this sentence.

Equal volumes of 0.2 M compound A and 0.2 M compound B are mixed. ppt is formed which means low solubility, but why it is 0.2 M? The M should be less than 0.1 M in order to be qualified for low solubility.

Please explain. Thank you.

Answer 2

@matt101

Answer 3

low solubility has a particular value?
i never heard about that value then
lets google

Answer 4

@baru @ganeshie8

Answer 5

ok

Answer 6

The term soluble means > 0.1 mol/L at 25 degree celcius

Answer 7

Insoluble means less.

Answer 8

let me tag ppl
@AravindG

Answer 9

@sweetburger :)

Answer 10

I haven't heard about low solubility being <1. There ain't any IUPAC standard for low solubility as far as I know. There is relative solubility though. It helps to compare solubilities.

Answer 11

Ok, I guess they are teaching me something to prepare me for those information in the future. Thank you guys

Answer 12

@rvc can I ask you a question?

Answer 13

about double arrows and regular arrows?

Answer 14

in reactions

Answer 15

double arrows meaning?

Answer 16

for example?

Answer 17

I know it s indicating equillibrium

Answer 18

but when to use it I do not know because there is a bunch of information given, and I am told to write an equation

Answer 19

I do not know if I have to use double arrow for indicating equilibrium solution or one arrow indicating dissociation. Do you know ?

Answer 20

atm i m sure @baru will help u :)

Answer 21

ok

Answer 22

im bit distrubed n busy

Answer 23

ok thank you for your time :)

Answer 24

XD no I won't... Don't know a thing in chem

Answer 25

lol really?

Answer 26

Ok this question is confusing as hell, I am gonna ask from my teacher.

Answer 27

:)

Answer 28

It depends on the reactants you have and the experimental conditions.
See

N2+3H2<-->2NH3 is a famous equilibrium equation.

We use double arrows here because the product has the tendency to go in backward reaction. Usually unless it a common known equilibrium, the question usually tells us about the condition. So if we can decide to put double arrows or not.

Answer 29

I know I'm super late (been a busy month for me) but I'll try to clear things up if you still aren't sure.

0.1 M seems to be an arbitrary cutoff by which something is considered to have low solubility. For instance, if you have one substance with a solubility of 0.101 M and another with a solubility of 0.099 M, the difference in solubility is trivial, but by your definition only one is considered to have "low solubility". I'd say that using 0.1 M as a cutoff is only useful when you have substances with very different solubilities (e.g. orders of magnitude different).

As far as your question is concerned, you need to realize that the 0.2 M refers only to the STARTING concentrations of each substance when SEPARATED. Let's pretend these substances are each ions (an anion and a cation) which, on their own, dissolve in water. However, when you mix the two together, you create an equilibrium situation between the dissociated ions and the precipitate they form. If that PRECIPITATE has a low solubility (i.e. less than 0.1 M), most of the ions will come together to form the precipitate, and very few will remain dissociated as they were in their original, separate solutions. When we talk about solubility, we're talking about the concentration of the DISSOCIATED ions, not the precipitate (which isn't dissolved, meaning it doesn't make sense to talk about its "concentration" anyways), which in this case will be extremely low (and likely less than 0.1 M).

I hope that made sense and answered your question!