Chapter 17: Problem 134
A \(50.0-\mathrm{mL}\) sample of \(0.0150 \mathrm{M} \mathrm{Ag}_{2} \mathrm{SO}_{4}\) is added to \(25.0 \mathrm{~mL}\) of \(0.0100 \mathrm{M} \mathrm{PbCl}_{2}\). What is the net ionic equation for the reaction that occurs? What are the concentrations of ions in the mixture at equilibrium?
Short Answer
Expert verified
The net ionic equations are: \(\text{Pb}^{2+} + \text{SO}_4^{2-} \rightarrow \text{PbSO}_4(s)\) and \(2 \text{Ag}^+ + 2 \text{Cl}^- \rightarrow 2 \text{AgCl}(s)\). All ionic concentrations become zero at equilibrium due to complete reactions.
Step by step solution
01
Identify the Possible Reaction
When mixing solutions of Ag鈧係O鈧 and PbCl鈧, we need to identify if any double displacement reactions occur. The possible exchange reactions are:
1. Ag鈧係O鈧 + PbCl鈧 鈫 PbSO鈧 + 2 AgCl
We need to determine which, if any, of these products are insoluble.
02
Determine the Solubility of Potential Products
Using a solubility chart:
- PbSO鈧 is known to be poorly soluble in water.
- AgCl is also known to be poorly soluble in water.
Therefore, both products could precipitate out of solution.
03
Write the Ionic Equation
The total ionic equation for the potential formation of precipitates is:\[2 \text{Ag}^+ + \text{SO}_4^{2-} + \text{Pb}^{2+} + 2\text{Cl}^- \rightarrow \text{PbSO}_4(s) + 2\text{AgCl}(s)\]
04
Write the Net Ionic Equation
The net ionic equation removes spectator ions (those that do not participate in the reaction). Here, all ions are involved in forming a solid, so:\[\text{Pb}^{2+} + \text{SO}_4^{2-} \rightarrow \text{PbSO}_4(s) \text{ and } 2 \text{Ag}^+ + 2 \text{Cl}^- \rightarrow 2 \text{AgCl}(s)\]This expresses the precipitation reactions.
05
Calculate Initial Concentrations
Calculate initial concentrations before mixing:- For Ag鈧係O鈧 in 75.0 mL :: \([\text{Ag}^+] = 0.0150 \times \frac{50}{75} = 0.0100 \text{M}\)- For SO鈧劼测伝 in 75.0 mL :: \([\text{SO}_4^{2-}] = 0.0075 \text{M}\)- For Pb虏鈦 in 75.0 mL :: \([\text{Pb}^{2+}] = 0.0100 \times \frac{25}{75} = 0.00333 \text{M}\)- For Cl鈦 in 75.0 mL :: \([\text{Cl}^-] = 0.00667 \text{M}\)
06
Determine Limiting Reactant
Use stoichiometry to find the limiting reactant.
- Balancing act for Pb虏鈦 with SO鈧劼测伝 gives 0.00333 M Pb虏鈦 utilized.
- For Cl鈦 with Ag鈦, 0.00667 M must balance against twice that of Ag鈦. It requires every 0.0 M Cl鈦 consumed per mole. Given that all ion concentrations precipitate, all 0.0100 M Ag鈦 will precipitate making it excess.
This indicates Ag鈦 and SO鈧劼测伝 are completely consumed.
07
Calculate Ions at Equilibrium
Since the limitations have indicated precisely how much of each reactant is consumed, the remaining concentrations in the mixture are:\[[\text{Ag}^+] = 0.000 M , [\text{SO}_4^{2-}] = 0.000 M ,[\text{Pb}^{2+}] = 0.000 M [\text{Cl}^-] = 0.000 M \] The reactions' theoretical complete precipitation makes any simulation not feasibility resulting in an equilibrium mixture of all zeros.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Solubility Rules
Understanding solubility rules is crucial for predicting if a reaction will occur when mixing different solutions. Solubility rules help us determine whether compounds are soluble or insoluble in water. This is essential in identifying precipitates formed in a reaction.
Here are some basic rules:
Here are some basic rules:
- Compounds containing alkali metal ions (like K鈦, Na鈦) and ammonium ion (NH鈧勨伜) are generally soluble.
- Nitrates (NO鈧冣伝) and acetates (CH鈧僀OO鈦) are usually soluble.
- Sulfates (SO鈧劼测伝) are soluble, except when combined with lead (Pb虏鈦), barium (Ba虏鈦), and strontium (Sr虏鈦).
- Chlorides (Cl鈦), bromides (Br鈦), and iodides (I鈦) are soluble except when bound to silver (Ag鈦), lead (Pb虏鈦), and mercury (Hg鈧偮测伜).
Precipitation Reactions
Precipitation reactions occur when two soluble salts combine in solution to form one or more insoluble products, known as precipitates. This is a typical double displacement reaction where the cations and anions exchange partners.
For our case study involving \( ext{Ag}_2 ext{SO}_4\) and \( ext{PbCl}_2\), a double replacement reaction suggests:
For our case study involving \( ext{Ag}_2 ext{SO}_4\) and \( ext{PbCl}_2\), a double replacement reaction suggests:
- Ag鈦 from silver sulfate combines with Cl鈦 from lead chloride.
- Pb虏鈦 from lead chloride combines with SO鈧劼测伝 from silver sulfate.
- \[2 ext{Ag}^+ + 2 ext{Cl}^- ightarrow 2 ext{AgCl}(s)\]
- \[ ext{Pb}^{2+} + ext{SO}_4^{2-} ightarrow ext{PbSO}_4(s)\]
Chemical Stoichiometry
Chemical stoichiometry involves the calculation of reactants and products in chemical reactions. It provides a quantitative means to predict the amounts of reactants consumed and products formed.
Using initial concentrations and balanced equations in stoichiometry helps identify limiting reactants鈥攖hose entirely consumed in the reaction, thus restricting the amount of product formed.
Using initial concentrations and balanced equations in stoichiometry helps identify limiting reactants鈥攖hose entirely consumed in the reaction, thus restricting the amount of product formed.
- In our scenario, we determine initial concentrations for each ion.
- Perform stoichiometric calculations to find the limiting reactant, which affects the completion of the reaction.
- By calculating the stoichiometry, we identify that all ions in the mixture are completely precipitated, resulting in zero concentration at equilibrium.