The following anions can be separated by precipitation as silver salts: Cl- , Br- , I- , CrO4 2-. If Ag is added to a solution containing the four anions, each at a concentration of 0.10 M, in what order would they precipitate?Compound:
a. AgCl ksp: 1.8x10^-10
b. Ag_2_CrO_4_ksp: 1.1 x 10 ^-12
c. AgBrksp: 5.4 x10 ^ -13
d. AgIksp: 8.5 x 10 ^ -17

AgI, AgBr, AgCl and Ag₂CrO₄

Explanation:

Ksp (product solubility constant) is defined as the equilibrium constant of the general reaction:

XₐYₙ(s) → aXⁿ⁺(aq) + nYᵃ⁻(aq)

Where X is cation and Y is anion.

Ksp = [aXⁿ⁺]ᵃ [nYᵃ⁻]ⁿ

The presence of XₐYₙ(s) produce ax moles of aXⁿ⁺ and nx moles of Yᵃ⁻. Where X is the solubility of the compound.

Replacing in Ksp:

Ksp = [ax]ᵃ [nx]ⁿ

Solving for x, Solubility (S) is defined as:

For AgCl, Ag₂CrO₄, AgBr and AgI solubilities are:

= 1.34x10⁻⁵M

= 6.50x10⁻⁵M

= 7.35x10⁻⁷M

= 9.22x10⁻⁹M

The lower solubility is the first compound in precipitate, thus, order of precipitation is:

AgI, AgBr, AgCl and Ag₂CrO₄

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.