Molar solubility

Molar solubility

Molar solubility is the number of moles of a substance (the solute) that can be dissolved per liter of solution before the solution becomes saturated. It can be calculated from a substance's Solubility Product constant (Ksp) and Stoichiometry. The units are mol/L, sometimes written as M.

Calculation

Given excess of a simple salt AxBy in an aqueous solution of no common ions (A or B already present in the solution), the amount of it which enters solution can be calculated as follows:

The Chemical equation for this salt would be:
{\text{A}_x \text{B}_y}_{(s)} \Longleftrightarrow x \text{A}_{(aq)}  +  y \text{B}_{(aq)}\,
where A, B are ions and x, y are coefficients...

1. The relationship of the changes in amount (of which mole is a unit), represented as N(∆), between the species is given by Stoichiometry as follows:
-\frac{N_{ AxBy(\Delta)}}{1} = \frac{N_{A(\Delta)}}{x} = \frac{N_{B(\Delta)}}{y}\,
which, when rearranged for ∆A and ∆B yields:
N_{A(\Delta)} = -xN_{AxBy(\Delta)}\,
N_{B(\Delta)} = -yN_{AxBy(\Delta)}\,


2. The Deltas(∆), Initials(i) and Finals(f) relate very simply since, in this case, Molar solubility is defined assuming no common ions are already present in the solution.
N_{(i)} + N_{(\Delta)} = N_{(f)}\, The Difference law

N_{A(i)} = 0\,
N_{B(i)} = 0\,

Which condense to the identities
N_{A(f)} = N_{A(\Delta)}\,
N_{B(f)} = N_{B(\Delta)}\,


3. In these variables (with V for volume), the Molar solubility would be written as:
S_0 = -\frac{N_{ AxBy(\Delta)}}{V}\,

4. The Solubility Product expression is defined as:
K_{sp} = [A]^x[B]^y\,



These four sets of equations are enough to solve for S0 algebraically:

K_{sp} = {\left(\frac{N_{A(f)}}{V}\right)}^x {\left(\frac{N_{B(f)}}{V}\right)}^y\,

K_{sp} = {\left(\frac{N_{A(\Delta)}}{V}\right)}^x {\left(\frac{N_{B(\Delta)}}{V}\right)}^y\,

K_{sp} = \frac{{(N_{A(\Delta)})}^x {(N_{B(\Delta)})}^y}{V^{(x+y)}}\,

K_{sp} = \frac{{(-xN_{AxBy(\Delta)})}^x {(-yN_{AxBy(\Delta)})}^y}{V^{(x+y)}}\,

K_{sp} = \frac{{(-1)}^x {(x)}^x {(N_{AxBy(\Delta)})}^x {(-1)}^y {(y)}^y {(N_{AxBy(\Delta)})}^y}{V^{(x+y)}}\,

K_{sp} = x^x y^y \frac{{(-1)}^x {(-1)}^y {(N_{AxBy(\Delta)})}^x {(N_{AxBy(\Delta)})}^y}{V^{(x+y)}}\,

K_{sp} = x^x y^y \frac{{(-1)}^{(x+y)}{(N_{AxBy(\Delta)})}^{(x+y)}}{V^{(x+y)}}\,

\frac{K_{sp}}{x^x y^y} = {\left(-\frac{N_{AxBy(\Delta)}}{V}\right)}^{(x+y)}\,

\frac{K_{sp}}{x^x y^y} = {\left(S_0\right)}^{(x+y)}\,

Hence;

S_0 = \sqrt[(x+y)]{\frac{K_{sp}}{x^x y^y}}\,


Wikimedia Foundation. 2010.

Игры ⚽ Поможем решить контрольную работу

Look at other dictionaries:

  • Solubility equilibrium — is any type chemical equilibrium between solid and dissolved states of a compound at saturation. Solubility equilibria involve application of chemical principles and constants to predict solubility of substances under specific conditions (because …   Wikipedia

  • Solubility — Soluble redirects here. For the algebraic object called a soluble group , see Solvable group. Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent to form a… …   Wikipedia

  • Molar concentration — In chemistry, the molar concentration, ci is defined as the amount of a constituent ni divided by the volume of the mixture V [1]: It is also called molarity, amount of substance concentration, amount concentration, substance concentration, or… …   Wikipedia

  • Hildebrand solubility parameter — The Hildebrand solubility parameter (δ) provides a numerical estimate of the degree of interaction between materials, and can be a good indication of solubility, particularly for non polar materials such as many polymers. Materials with similar… …   Wikipedia

  • Hexachlorobutadiene — Chembox new ImageFile = Hexachloro.png ImageSize = 200px IUPACName = Hexachloro 1,3 butadiene OtherNames = Perchlorobutadiene, perchloro 1,3 butadiene Section1 = Chembox Identifiers CASNo = 87 68 3 PubChem = 6901 SMILES… …   Wikipedia

  • Molality — In chemistry, the molality, b (or m), of a solvent/solute combination is defined as the amount of solute, nsolute, divided by the mass of the solvent, msolvent (not the mass of the solution)[1]: If a mixture contains more than one solute or… …   Wikipedia

  • Calcium carbonate — Calcium carbonate …   Wikipedia

  • Mass concentration (chemistry) — In chemistry, the mass concentration ρi (or γi) is defined as the mass of a constituent mi divided by the volume of the mixture V:[1] Contents …   Wikipedia

  • Concentration — For other uses, see Concentration (disambiguation). In chemistry, concentration is defined as the abundance of a constituent divided by the total volume of a mixture. Four types can be distinguished: mass concentration, molar concentration,… …   Wikipedia

  • Mass fraction (chemistry) — In chemistry, the mass fraction wi is the fraction of one substance with mass mi to the mass of the total mixture mtot, defined as [1]: The sum of all the mass fractions is equal to 1: It is one way of expressing t …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”