Asolution of potassium chromate reacts with a solution of lead(ii) nitrate to produce a yellow precipitate of lead(ii) chromate and a solution of potassium nitrate.

(a) write the balanced chemical equation.

(b) starting with 0.100 mol potassium chromate, determine the mass of lead chromate that can be formed.

a. K₂CrO₄ + Pb(NO₃)₂ > PbCrO₄ + 2 KNO₃

b. Mass of PbCrO₄= 32.3 g

Explanation:

Part a

Data Given:

Reactants:

potassium chromate reacts with a solution of lead(II) nitrate

Product

lead(II) chromate and a solution of potassium nitrate

balanced chemical equation= ?

Solution:

Balance Chemical Equation:

A balanced chemical equation is that in which the number of the reactant atoms equal to the number of the product atom.

Formulas of the Reactants

potassium chromate= K₂CrO₄

lead(II) nitrate = Pb(NO₃)₂

Formulas of products

lead(II) chromate = PbCrO₄

potassium nitrate KNO₃

potassium chromate reacts with a solution of lead(II) nitrate to produce a yellow precipitate of lead(II) chromate and a solution of potassium nitrate.

Complete reaction is as under

                       K₂CrO₄ + Pb(NO₃)₂ > PbCrO₄ + KNO₃

Check the chemical equation and count the number of atoms at the reactant side and product side.

If the number of atoms of the reactants equal to the number of atoms of products then the reaction is balanced but if not equal, then reaction is not balanced

Balancing is an trial and error process to get a balance reaction.

Balanced Equation:

        K₂CrO₄ + Pb(NO₃)₂ > PbCrO₄ + 2 KNO₃

Now count the number of atoms of reactant and product

Number of atoms of Reactant:

K = 2

Cr = 1

O = 10

Pb = 1

N = 2

Number of atoms of Product:

K = 2

Cr = 1

O = 10

Pb = 1

N = 2

Now this reaction is balanced as the atoms of the reactant atoms equal to the number of the product atoms.

So, the Coefficient of KNO₃ is 2 in balanced equation

Part b

Given Data

Amount of potassium chromate = 0.1 mol

Mass of  lead chromate = ?

Solution:

First we look at the balanced chemical reaction for more details

Balanced Equation:

        K₂CrO₄ + Pb(NO₃)₂ > PbCrO₄ + 2 KNO₃

           1 mol                                          1 mol

As,

It is cleared from the reaction, that 1 mole of potassium chromate produce 1 mole of lead chromate

So,

It 0.1 mole of potassium chromate will must produce 0.1 mole of lead chromate.

                1 mole of   K₂CrO₄ ≅ 1 mole of PbCrO₄

                0.1 mole of   K₂CrO₄ ≅ 0.1 mole of PbCrO₄

To Calculate mass we have to convert moles of PbCrO₄ to mass

Formula used

             Mass = no.of moles x molar mass

Molar mass of PbCrO₄ = 323 g/mol

Put values in above formula

                Mass = 0.1 mole x 323 g/mol

                Mass = 32.3 g

Mass of PbCrO₄= 32.3 g

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the answer is c.the valence of the atoms combine .