The following three solutions are mixed: 100.0 mL of 0.100 M Na2SO4, 50.0 mL of 0.300 M ZnCl2, and 100.0 mL of 0.200 M Ba(CN)2. (a) What ionic compounds will precipitate out of solution?

Verified step by step guidance

Step 1: Identify the ions present in the solutions. The ions are Na+, SO4^2-, Zn^2+, Cl-, Ba^2+, and CN-.

Step 2: Use the solubility rules to predict which combinations of these ions will form insoluble compounds. The solubility rules state that most sulfate salts are soluble, except those of barium, lead, and calcium. Therefore, BaSO4 will precipitate. Most chloride salts are soluble, so no precipitate will form with Cl-. Most salts with the cyanide ion are soluble, so no precipitate will form with CN-.

Step 3: Write the chemical equation for the precipitation reaction. The equation is Ba^2+ + SO4^2- -> BaSO4(s).

Step 4: Check the stoichiometry of the reaction. In this case, the reaction is a 1:1 reaction, so no further steps are needed.

Step 5: If necessary, calculate the amount of precipitate formed using the stoichiometry of the reaction and the initial concentrations of the ions. However, this problem only asks for the identity of the precipitate, not the amount.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Solubility Rules

Solubility rules are guidelines that help predict whether an ionic compound will dissolve in water. They state that certain ions, such as alkali metal ions and ammonium, generally form soluble compounds, while others, like silver, lead, and mercury, often form insoluble salts. Understanding these rules is essential for determining which ionic compounds may precipitate when solutions are mixed.

Precipitation Reactions

A precipitation reaction occurs when two soluble ionic compounds react in solution to form an insoluble compound, known as a precipitate. This process can be represented by a balanced chemical equation, where the products include the precipitate and any remaining soluble ions. Identifying the potential precipitates requires knowledge of the ions present in the mixed solutions.

Ionic Compounds and Their Formulas

Ionic compounds are formed from the electrostatic attraction between positively charged cations and negatively charged anions. The formula of an ionic compound reflects the ratio of these ions, which is determined by their charges. For example, in Na2SO4, sodium (Na+) and sulfate (SO4^2-) combine in a 2:1 ratio. Recognizing the formulas of the compounds involved is crucial for predicting the possible precipitates.

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Textbook Question

How could you use a precipitation reaction to separate each of the following pairs of cations? Write the formula for each reactant you would add, and write a balanced net ionic equation for each reaction. (a)

Textbook Question

How could you use a precipitation reaction to separate each of the following pairs of anions? Write the formula for each reactant you would add, and write a balanced net ionic equation for each reaction.(a)

Textbook Question

The following three solutions are mixed: 100.0 mL of 0.100 M Na2SO4, 50.0 mL of 0.300 M ZnCl2, and 100.0 mL of 0.200 M Ba(CN)2. (b) What is the molarity of each ion remaining in the solution assuming complete precipitation of all insoluble compounds?

Textbook Question

A 250.0 g sample of a white solid is known to be a mixture of KNO3, BaCl2, and NaCl. When 100.0 g of this mixture is dis-solved in water and allowed to react with excess H2SO4, 67.3 g of a white precipitate is collected. When the remaining 150.0 g of the mixture is dissolved in water and allowed to react with excess AgNO3, 197.6 g of a second precipitate is collected. (a) What are the formulas of the two precipitates?

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Textbook Question

(b) What is the mass of each substance in the original 250 g mixture?