Aim for FiveChemistry

Short free-response question

Precipitating lead(II) iodide

  • Unit 4
  • 4 points
  • About 9 minutes

You can use a calculator on this question, just like on exam day.

A shorter multipart question that sticks to one or two topics. Each part usually asks for one calculation, claim or explanation. On the exam: 4 questions (Questions 4–7), part of the 1-hour-45-minute free-response section; calculator allowed.

The question

A student mixes 50.0 mL of 0.200 M Pb(NO₃)₂(aq) with 50.0 mL of 0.300 M KI(aq). A yellow precipitate of PbI₂(s) forms. All potassium salts and all nitrate salts are soluble. Assume the volumes are additive.

Suggested time: 9 minutes

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Part (a)

1 point

Write the balanced net ionic equation for the reaction that occurs.

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Part (b)

1 point

Identify the limiting reactant. Justify your answer with a calculation.

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Part (c)

1 point

Calculate the maximum mass of PbI₂(s) that can form.

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Part (d)

1 point

Calculate the concentration of Pb²⁺(aq) remaining in the solution after the precipitation is complete.

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