According to the following reaction, what mass of PbCl2 can form from 235 mL of 0.110 M KCl solution? Assume that there is excess Pb(NO3)2. 2 KCl(aq) + Pb(NO3)2(aq) → PbCl2(s) + 2 KNO3(aq)

Respuesta :

Answer:

3.59 g of PbCl₂ can form from 235 mL of 0.110 M KCl solution.

Explanation:

2 KCl(aq) + Pb(NO₃)₂(aq) → PbCl₂(s) + 2 KNO₃(aq)

The Molarity (M) or Molar Concentration is the number of moles of solute (substance that is in minor proportion in a solution) that are dissolved in a certain volume.

The Molarity of a solution is determined by the following formula:

[tex]Molarity M=\frac{number of moles of solute}{Volume}[/tex]  

Molarity is expressed in units [tex]\frac{moles}{liter}[/tex]

Then, knowing that 235 mL is 0.235 L (1 L=1000 mL or 1 mL=0.001 L) and taking into account the molarity of KCl, you can apply a rule of three as follows: if in 1 L of KCl solution there are 0.110 moles of the substance, in 0.235 L of solution how many moles of KCl are there?

[tex]moles of KCl=\frac{0.235 L*0.110moles}{1L}[/tex]

moles of KCl=0.02585

Another rule of three is applied as follows: by stoichiometry of the reaction you can see that 2 moles of KCl form 1 mole of PbCl₂. So if 0.02585 moles of KCl react, how many moles of PbCl₂ are formed?

[tex]molesofPbCl_{2} =\frac{0.02585molesofKCl*1molofPbCl_{2} }{2molesofKCl}[/tex]

moles of PbCl₂=0.012925

In the periodic table of elements you can see the following atomic masses:

  • Pb: 207 g/mol
  • Cl: 35.45 g/mol

Then the molar mass of PbCl₂ is:

PbCl₂= 207 g/mol + 2*35.45 g/mol= 277.9 g/mol

Then a last rule of three applies: if in 1 mole of PbCl₂ there are 277.9 g of the compound, in 0.012925 moles of PbCl₂ how much mass is there?

[tex]mass=\frac{0.012925moles*277.9g}{1 mole}[/tex]

mass=3.59 g

3.59 g of PbCl₂ can form from 235 mL of 0.110 M KCl solution.

The mass of PbCl₂ obtained from the reaction between 235 mL of 0.110 M KCl solution and excess Pb(NO₃)₂ is 3.59 g

We'll begin by calculating the number of mole of KCl in the solution.

Volume of KCl solution = 235 mL = 235 / 1000 = 0.235 L

Molarity of KCl = 0.110 M

Mole of KCl =.?

Mole = Molarity × Volume

Mole of KCl = 0.110 × 0.235

Mole of KCl = 0.02585 mole

Next, we shall determine the number of mole of PbCl₂ produced from the reaction.

2KCl(aq) + Pb(NO₃)₂(aq) → PbCl₂(s) + 2KNO₃(aq)

From the balanced equation above,

2 moles of KCl reacted to produce 1 mole of PbCl₂.

Therefore,

0.02585 mole of KCl will react to produce = [tex]\frac{0.02585}{2} \\\\[/tex] = 0.012925 mole of PbCl₂.

Finally, we shall determine the mass of 0.0129 mole of PbCl₂. This can be obtained as follow:

Molar mass of PbCl₂ = 207 + (35.5×2) = 278 g/mol

Mole of PbCl₂ = 0.012925 mole

Mass of PbCl₂ =?

Mass = mole × molar mass

Mass of PbCl₂ = 0.012925 × 278

Mass of PbCl₂ = 3.59 g

Therefore, the mass of PbCl₂ obtained from the reaction is 3.59 g

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