(b) The rate of decrease in N2H4 partial pressure in a closed reaction vessel from the reaction N2H4(g) + H2(g) → 2 NH3(g) is 74 torr per hour. What are the rates of change of NH3 partial pressure and total pressure in the vessel?

Verified step by step guidance

Identify the stoichiometry of the reaction: N2H4(g) + H2(g) → 2 NH3(g). This tells us that 1 mole of N2H4 reacts with 1 mole of H2 to produce 2 moles of NH3.

Recognize that the rate of decrease in N2H4 partial pressure is given as 74 torr per hour. According to the stoichiometry, for every mole of N2H4 that reacts, 2 moles of NH3 are produced.

Calculate the rate of increase in NH3 partial pressure. Since 2 moles of NH3 are produced for every mole of N2H4 that reacts, the rate of increase in NH3 partial pressure is twice the rate of decrease in N2H4 partial pressure.

Determine the rate of change of total pressure in the vessel. The total pressure change is the sum of the changes in partial pressures of all gases involved. Consider the stoichiometry and the fact that H2 is consumed and NH3 is produced.

Apply the concept of partial pressures and stoichiometry to find the net change in total pressure. Since 1 mole of N2H4 and 1 mole of H2 produce 2 moles of NH3, calculate the net change in moles of gas and relate it to the change in total pressure.

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 based on the balanced equation. In this case, the stoichiometric coefficients indicate that one mole of hydrazine (N2H4) produces two moles of ammonia (NH3). Understanding these ratios is essential for determining the rates of change of the substances involved in the reaction.

Rate of Reaction

The rate of reaction refers to the speed at which reactants are converted into products. It can be expressed in terms of the change in concentration or partial pressure of a substance over time. In this scenario, knowing the rate of decrease of N2H4 allows us to calculate the corresponding increase in NH3 and the total pressure change in the vessel.

Total Pressure in a Closed System

In a closed system, the total pressure is the sum of the partial pressures of all gases present. According to Dalton's Law of Partial Pressures, changes in the partial pressures of individual gases will affect the total pressure. By calculating the change in NH3's partial pressure, we can determine how the total pressure in the vessel is affected by the reaction.

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Textbook Question

For each of the following gas-phase reactions, write the rate expression in terms of the appearance of each product and disappearance of each reactant:

(a) 2 H₂O(g) → 2 H₂(g) + O₂(g)

(b) 2 SO₂(g) + O₂(g) → 2 SO₃(g)

(d) N₂(g) + 2 H₂(g) → N₂H₄(g)

Textbook Question

(a) Consider the combustion of hydrogen, 2 H21g2 + O21g2 ¡ 2 H2O1g2. If hydrogen is burning at the rate of 0.48 mol>s, what is the rate of consumption of oxygen? What is the rate of formation of water vapor?

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Textbook Question

(b) The reaction 2 NO1g2 + Cl21g2¡2 NOCl1g2 is carried out in a closed vessel. If the partial pressure of NO is decreasing at the rate of 56 torr/min, what is the rate of change of the total pressure of the vessel?

Textbook Question

A reaction A + B → C obeys the following rate law: Rate = k[B]². (a) If [A] is doubled, how will the rate change? Will the rate constant change?

Textbook Question

A reaction A + B → C obeys the following rate law: Rate = k[B]². (b) What are the reaction orders for A and B? What is the overall reaction order?

Textbook Question

A reaction A + B → C obeys the following rate law: Rate = k[B]². (c) What are the units of the rate constant?