Question

Will a double replacement reaction occur if a potassium hydroxide solution is mixed with a lead(II) nitrate solution? Briefly explain.

Answer 1

Explanation:

A chemical reaction equation that contains same number of atoms on both reactant and product side is known as a balanced chemical reaction equation.

And, when positive and negative ions of the two reactant species exchange their position then this type of reaction is known as double replacement reaction.

For example, $KOH + Pb(NO_{3})_{2} \rightarrow KNO_{3} + Pb(OH)_{2}$

Here, number of reactant molecules are as follows.

K = 1

OH = 1

Pb = 1

$NO_{3}$ = 2

Number of product molecules are as follows.

K = 1

OH = 2

Pb = 1

$NO_{3}$ = 1

Hence, to balance this equation multiply KOH by 2 on reactant side and multiply $KNO_{3}$ by 2 on product side.

Therefore, the balanced chemical reaction equation is as follows.

      $2KOH + Pb(NO_{3})_{2} \rightarrow 2KNO_{3} + Pb(OH)_{2}$

Since, both positive and negative ions on the reactant side get exchanged. Hence, it is a double replacement reaction.

Answer 2

No - a precipitation will occur though. Potassium nitrate is soluble in water, so the potassium and nitrate ions will remain spectator ions and stay in solution. Lead (II) hydroxide is not soluble, and will precipitate out of solution to form a solid product.