Ammonia and hydrogen chloride react to form solid ammonium chloride: NH₃(g) + HCl(g) → NH₄Cl(s)
Two 2.00-L flasks at 25 °C are connected by a valve, as shown in the drawing. One flask contains 5.00 g of NH₃(g), and the other contains 5.00 g of HCl(g). When the valve is opened, the gases react until one is completely consumed. (b) What will be the final pressure of the system after the reaction is complete? (Neglect the volume of the ammonium chloride formed.)

Verified step by step guidance

Step 1: Calculate the number of moles of NH3 and HCl using the formula n = m/M, where m is the mass and M is the molar mass.

Step 2: Determine the limiting reactant by comparing the mole ratio of NH3 to HCl from the balanced chemical equation.

Step 3: Calculate the moles of the limiting reactant that will react completely and the moles of the excess reactant that will remain.

Step 4: Use the ideal gas law, PV = nRT, to calculate the pressure of the remaining gas in the combined volume of the two flasks.

Step 5: Sum the partial pressures of any remaining gases to find the final pressure of the system.

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Key Concepts

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

Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions. It involves using balanced chemical equations to determine the proportions of substances consumed and produced. In this case, the stoichiometry of the reaction between ammonia (NH3) and hydrogen chloride (HCl) indicates that they react in a 1:1 ratio to form ammonium chloride (NH4Cl). Understanding stoichiometry is essential for predicting how much of each reactant will be consumed and how much product will be formed.

Ideal Gas Law

The Ideal Gas Law relates the pressure, volume, temperature, and number of moles of a gas through the equation PV = nRT. This law is crucial for calculating the final pressure of the gas mixture after the reaction. In this scenario, after the reaction between NH3 and HCl, the remaining gas will be at a specific volume and temperature, allowing us to use the Ideal Gas Law to find the final pressure of the system.

Limiting Reactant

The limiting reactant is the substance that is completely consumed first in a chemical reaction, thus determining the amount of product formed. In this case, either NH3 or HCl could be the limiting reactant depending on their initial amounts. Identifying the limiting reactant is essential for calculating the final pressure, as it dictates how much of the other reactant remains unreacted and influences the total number of moles of gas present after the reaction.

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Textbook Question

A 4.00-g sample of a mixture of CaO and BaO is placed in a 1.00-L vessel containing CO₂ gas at a pressure of 97.33 kPa and a temperature of 25 °C. The CO₂ reacts with the CaO and BaO, forming CaCO₃ and BaCO₃. When the reaction is complete, the pressure of the remaining CO₂ is 20.0 kPa. (a) Calculate the number of moles of CO₂ that have reacted. (b) Calculate the mass percentage of CaO in the mixture.

Textbook Question

Ammonia and hydrogen chloride react to form solid ammonium chloride: NH31g2 + HCl1g2¡NH4Cl1s2 Two 2.00-L flasks at 25 °C are connected by a valve, as shown in the drawing. One flask contains 5.00 g of NH31g2, and the other contains 5.00 g of HCl(g). When the valve is opened, the gases react until one is completely consumed. (a) Which gas will remain in the system after the reaction is complete?