Question

Consider the following reagents: zinc, copper, mercury (density \(13.6 \mathrm{~g} / \mathrm{mL}\) ), silver nitrate solution, nitric acid solution. (a) Given a \(500-\mathrm{mL}\). Erlenmeyer flask and a balloon, can you combine two or more of the foregoing reagents to initiate a chemical reaction that will inflate the balloon? Write a balanced chemical equation to represent this process. What is the identity of the substance that inflates the balloon? (b) What is the theoretical yield of the substance that fills the balloon? (c) Can you combine two or more of the foregoing reagents to initiate a chemical reaction that will produce metallic silver? Write a balanced chemical equation to represent this process. What ions are left behind in solution? (d) What is the theoretical yield of silver?

Short answer

(a) Yes, we can combine zinc with nitric acid to initiate a chemical reaction that will inflate the balloon. The balanced chemical equation is: \( Zn + 2 HNO_3 \rightarrow Zn(NO_3)_2 + H_2 \). The substance inflating the balloon is hydrogen gas (H₂). (b) We cannot calculate the theoretical yield of H₂ as the specific quantities for each reagent are not provided. (c) Yes, we can combine copper with silver nitrate to initiate a chemical reaction that will produce metallic silver. The balanced chemical equation is: \( Cu + 2 AgNO_3 \rightarrow Cu(NO_3)_2 + 2 Ag \). The ions left behind in the solution are Copper(II) ions \( (Cu^{2+}) \) and Nitrate ions \( (NO_3^{-}) \). (d) We cannot calculate the theoretical yield of Ag as the specific quantities for each reagent are not provided.

Step-by-step solution

Identify the possible reactions

Two primary types of reactions can occur here: single displacement and double displacement. Zinc, copper, and mercury are metals, and they can initiate single displacement reactions with the silver nitrate solution by displacing silver and forming respective nitrates. Nitric acid can react with these metals to form nitrates and produce hydrogen gas. For example, Zinc reacting with nitric acid will form zinc nitrate and hydrogen gas, which will inflate the balloon.

Write a balanced chemical equation

Here's the balanced chemical equation for the reaction of zinc with nitric acid: \( Zn + 2 HNO_3 \rightarrow Zn(NO_3)_2 + H_2 \)

Identify the substance that inflates the balloon

The substance inflating the balloon is hydrogen gas (H₂). (b)

Calculate the theoretical yield of H₂

To calculate the theoretical yield of H₂, we need to know the moles of the limiting reactant. Since the exercise does not provide specific quantities for each reagent, we are unable to calculate the theoretical yield of H₂. (c)

Identify possible reactions to produce metallic silver

To produce metallic silver, we can consider two of the given reagents, such as zinc or copper, for single displacement reactions with silver nitrate.

Write a balanced chemical equation

Here's a balanced chemical equation for the reaction of Copper with Silver Nitrate: \( Cu + 2 AgNO_3 \rightarrow Cu(NO_3)_2 + 2 Ag \)

Identify the ions left behind in solution

The ions left behind in the solution are Copper(II) ions \( (Cu^{2+}) \) and Nitrate ions \( (NO_3^{-}) \). (d)

Calculate the theoretical yield of silver

As mentioned earlier, to calculate the theoretical yield of Ag, we need to know the moles of the limiting reactant. Since the exercise does not provide specific quantities for each reagent, we are unable to calculate the theoretical yield of Ag.

Key concepts

Single Displacement Reactions

In chemistry, single displacement reactions involve one element replacing another element in a compound. This type of reaction typically occurs between a metal and a compound. For example, zinc (Zn) can react with silver nitrate (AgNO₃). Zinc displaces the silver to form zinc nitrate (Zn(NO₃)₂) and silver (Ag) is freed. Such reactions can be represented by the general formula \( A + BC \rightarrow AC + B \).

• Zinc displacing silver in silver nitrate
• Copper displacing silver in silver nitrate

To predict whether a single displacement reaction will occur, refer to the activity series which ranks elements based on their reactivity. An element higher on the series can displace one lower on the list from a compound.

Balanced Chemical Equation

A balanced chemical equation accurately represents a chemical reaction, showing the conservation of mass. This means the number of atoms for each element involved in the reaction remains equal before and after the process. One of the balanced chemical equations provided in the original solution is \( Zn + 2 HNO_3 \rightarrow Zn(NO_3)_2 + H_2 \).

To balance any chemical equation:

• List and count the number of each type of atom on both sides of the equation.
• Adjust the coefficients (the numbers before compounds) to balance the elements.
• Check your work to ensure all atoms are balanced and the total charge matches on both sides if applicable.

Balancing helps us understand the stoichiometry—the relative quantities of reactants and products.

Theoretical Yield

Theoretical yield is the maximum amount of product that can be produced in a chemical reaction, based on the amounts of the limiting reactant. Calculating it involves stoichiometry and balanced chemical equations. Suppose we want to find out the theoretical yield of hydrogen gas in the reaction \( Zn + 2 HNO_3 \rightarrow Zn(NO_3)_2 + H_2 \).

• First, determine the amounts of each reactant available.
• Theoretical yield calculations require using the balanced equation to convert moles of the limiting reactant to moles of the desired product.

Since the step by step solution did not include specific quantities, we could not determine an exact theoretical yield, but with actual amounts, this calculation produces a precise prediction.

Limiting Reactant

In a chemical reaction, the limiting reactant is the reactant that gets used up first and thus limits the amount of product that can be formed. Identifying the limiting reactant is crucial to calculating the theoretical yield.

Steps to identify the limiting reactant include:

• Convert all given information into moles.
• Use the balanced chemical equation to determine the mole ratio needed for the reaction.
• Compare the mole ratio of available reactants to determine which is in short supply.

The limiting reactant determines the extent of the reaction and hence the amount of product formed. For example, if zinc is the limiting reactant in the reaction with nitric acid, it will establish the maximum amount of hydrogen gas produced.