Consider the reaction between 0.156 L of 0.105 M magnesium nitrate and 0.166 L of 0.106 M potassium hydroxide.

a. What mass of precipitate will form?

b. What is the Concentration of nitrate ions left in solution after the reaction is complete?

(a)

Interpretation:

The mass of the precipitate formed after reaction between given solution of magnesium nitrate and potassium hydroxide is to be calculated.

Concept Introduction:

The molarity of a solution is the molar concentration of the solution, it measures the number of moles of solute dissolved in one liter of the solution. The formula for molarity is given as,

M=nV

Where,

• n represents the number of moles of the solute.
• V represents the volume of the solution.

The limiting reagent of a reaction is that reactant of the reaction that controls the amount of product formed. The amount of a limiting reagent is lower than its required amount to complete the reaction.

The volume of 0.105 M magnesium nitrate solution is 0.156 L.

The volume of 0.106 M potassium hydroxide solution is 0.166 L.

The molarity of a solution is given as,

M=nV

Where,

• n represents the number of moles of the solute.
• V represents the volume of the solution.

Rearrange the above equation for the value of n.

n=MV    (1)

Substitute the value of molarity and volume of magnesium nitrate solution in equation (1).

n=0.105 M1 mol⋅L−11 M0.156 L=0.0164 mol

The number of moles of magnesium nitrate present in the reaction mixture is 0.0164 mol.

Substitute the value of molarity and volume of potassium hydroxide solution in equation (1).

n=0.106 M1 mol⋅L−11 M0.166 L=0.0176 mol

The number of moles of potassium hydroxide present in the reaction mixture is 0.0176 mol.

The balance chemical reaction between the magnesium nitrate and potassium hydroxide is represented as,

MgNO32aq+2KOHaq→MgOH2s+2KNO3aq

One moles of MgNO32 reacts with two moles of KOH to produce one mole of MgOH2 and two moles of KNO3 Therefore, the relation between the number of moles of MgNO32 and KOH reacts is given as,

nMgNO32=nKOH2

Where,

• nKOH represents the number of moles of KOH.
• nMgNO32 represents the number of moles of MgNO32.

Substitute the value of number of moles of KOH in the above equation.

nMgNO32=0

(b)

Interpretation:

The concentration of nitrate ions left in solution after completion of the reaction between given solution of magnesium nitrate and potassium hydroxide is to be calculated.

Concept Introduction:

The molarity of a solution is defined as the number of mole of solute dissolved in one liter of the solution. The formula for molarity is given as,

M=nV

Where,

• n represents the number of moles of the solute.
• V represents the volume of the solution.