A 350 mL saturated solution of magnesium hydroxide, Mg(OH)2 is prepared at 25 degrees Celsius. The solubility product constant, Ksp, for Mg(OH)2 is 1.8 x 10^-11 at 25 degrees Celsius.
1) Find the molar solubility of Mg(OH)2 at 25 degrees Celsius?

2) What is the concentration (mol/L) of hydroxide ion, OH-, in the saturated solution at 25 degrees Celsius?

For 1: The solubility of magnesium hydroxide at 25°C is

For 2: The concentration of hydroxide ion in the saturated solution at 25°C is

Explanation:

The equation for the ionization of the magnesium hydroxide is given as:

                                    s            2s

Expression for the solubility product of will be:

We are given:

Putting values in above equation, we get:

Hence, the solubility of magnesium hydroxide at 25°C is

Concentration of hydroxide ion in the solution = 2s =

Hence, the concentration of hydroxide ion in the saturated solution at 25°C is

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2