Solutions and Precipitates [closed]








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If a solution of $\pu{20mL}$ of $\pu{ 0.050M}~\ce{K+ }$is added to $\pu{80mL}$ of 
$\pu{0.50M}\ce{ClO4-}$ will a precipitate form and what is the value of $Q\_\mathrm{sp}$? For $\ce{KClO4}, K\_\mathrm{sp}= 1.07 \times{10^{-2}}$


\*I know that we have to show what we tried originally, which is great and I think the best way to learn. I am honestly looking at this problem and have no idea what any of it means. I'm self-teaching chemistry from a textbook, and the sample problems were nothing like this! I looked online for videos but I don't know what I am looking for, and I am unsure of the difference between $Q\_\mathrm{sp}$ and $K\_{\mathrm sp}$?? Does anyone have some kind of video, or sample problem, or explanations and definitions that could help me solve this on my own? I don't know what I am doing in this problem! Any help is appreciated!




If we take it generally, e.g. for a reaction $$\ce{A + C <=> C + D}$$ 


then $K$ in $$K = \frac{\ce{[C][D]}}{\ce{[A][B]}}$$ means the reaction equilibrium constant and $\ce{[X]}$ is a convention for the molar concentration of $\ce{X}$ in mol/L, in this case the equilibrium concentration.


OTOH. very similar quantity $Q$ in $Q = \frac{\ce{[C][D]}}{\ce{[A][B]}}$ is called the [reaction quotient](https://en.wikipedia.org/wiki/Reaction_quotient) with plugged in the actual concentrations of the involved compounds. 


If $Q \lt K$, the reaction is ongoing forward, toward the products on the right reaction side.


If $Q \gt K$, the reaction is ongoing backward, toward the reagents on the left reaction side.


If $Q = K$, the reaction is in equilibrium, with the net reaction rate being zero. It means, on the molecular level, there reaction is ongoing in both directions at the equal rate.


Now, $K\_\mathrm{sp}$ is a specific equilibrium constant, called a [solubility product](https://en.wikipedia.org/wiki/Solubility_equilibrium) and $Q\_\mathrm{sp}$ is a reaction quotient of eventual precipitation/dissolution process.


For the reaction $$\ce{AB(s) <=>[\ce{H2O}]A+(aq) + B-(aq)}$$, 


$$K\_\mathrm{sp}=\ce{[A+][B-]}$$ is for the equilibrium between solution and precipitate.


$$Q\_\mathrm{sp}=\ce{[A+][B-]}$$ is for the current concetration of ions.


If $Q\_\mathrm{sp} \lt K\_\mathrm{sp}$, all precipitate is dissolved and the solution is not saturated yet.


If $Q\_\mathrm{sp} = K\_\mathrm{sp}$, the solution is saturated and the dynamic equilibrium is ongoing between the solution and precipitate.


If $Q\_\mathrm{sp} \gt K\_\mathrm{sp}$, the precipitate is being formed, or the solution is oversaturated, what is ametastable state, that is easily disturbed.


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