menu
bartleby
search
close search
Hit Return to see all results
close solutoin list

Oxygen dissolved in water can cause corrosion in hot-water heating systems. To remove oxygen, hydrazine (N 2 H 4 ) is often added. Hydrazine reacts with dissolved O 2 to form water and N 2 . (a) Write a balanced chemical equation for the reaction of hydrazine and oxygen. Identify the oxidizing and reducing agents in this redox reaction. (b) Calculate Δ r H °, Δ r S °, and Δ r G ° for this reaction involving 1 mol of N 2 H 4 at 25 °C. (c) Because this is an exothermic reaction, energy is evolved as heat. What temperature change is expected in a heating system containing 5.5 × 10 4 L of water? (Assume no energy is lost to the surroundings.) (d) The mass of a hot-water heating system is 5.5 × 10 4 kg. What amount of O 2 (in moles) would be present in this system if it is filled with water saturated with O 2 ? (The solubility of O 2 in water at 25 °C is 0.000434 g per 100 g of water.) (e) Assume hydrazine is available as a 5.0% solution in water. What mass of this solution should be added to totally consume the dissolved O 2 [described in part (d)]? (f) Assuming the N 2 escapes as a gas, calculate the volume of N 2 (g) (measured at 273 K and 1.00 atm) that will be produced.

BuyFindarrow_forward

Chemistry & Chemical Reactivity

9th Edition
John C. Kotz + 3 others
Publisher: Cengage Learning
ISBN: 9781133949640

Solutions

Chapter
Section
BuyFindarrow_forward

Chemistry & Chemical Reactivity

9th Edition
John C. Kotz + 3 others
Publisher: Cengage Learning
ISBN: 9781133949640
Chapter 18, Problem 79SCQ
Textbook Problem
1 views

Oxygen dissolved in water can cause corrosion in hot-water heating systems. To remove oxygen, hydrazine (N2H4) is often added. Hydrazine reacts with dissolved O2 to form water and N2.

  1. (a) Write a balanced chemical equation for the reaction of hydrazine and oxygen. Identify the oxidizing and reducing agents in this redox reaction.
  2. (b) Calculate ΔrH°, ΔrS°, and ΔrG° for this reaction involving 1 mol of N2H4 at 25 °C.
  3. (c) Because this is an exothermic reaction, energy is evolved as heat. What temperature change is expected in a heating system containing 5.5 × 104 L of water? (Assume no energy is lost to the surroundings.)
  4. (d) The mass of a hot-water heating system is 5.5 × 104 kg. What amount of O2 (in moles) would be present in this system if it is filled with water saturated with O2? (The solubility of O2 in water at 25 °C is 0.000434 g per 100 g of water.)
  5. (e) Assume hydrazine is available as a 5.0% solution in water. What mass of this solution should be added to totally consume the dissolved O2 [described in part (d)]?
  6. (f) Assuming the N2 escapes as a gas, calculate the volume of N2(g) (measured at 273 K and 1.00 atm) that will be produced.

(a)

Interpretation Introduction

Interpretation:

The balanced chemical equation for the given reaction between hydrazine and oxygen also the oxidizing and reducing agents in the reaction should be identified.

Concept introduction:

Redox reaction: It occurs when oxidation and reduction takes place at the same time in a chemical reaction.

Chemical equation is the representation of a chemical reaction, in which the reactants and products of the reactions are represented left and right side of an arrow respectively by using their respective chemical formulas.

Reactant of a chemical reaction is the substrate compounds or the compounds which undergo a chemical reaction.

Product of a chemical reaction is the produced compounds or the compounds formed after a chemical reaction. 

Balanced chemical equation of a reaction is written according to law of conservation of mass.

Stoichiometry of a chemical reaction is the relation between reactants and products of the reaction and it is represented by the coefficients used for the reactants and products involved in the chemical equation.

The hot water system can corrode because of the presence of dissolved oxygen in water. This dissolved oxygen leads to corrosion. However, this oxygen can be removed from water with the use of hydrazine. The formula for hydrazine is N2H4. It reacts with oxygen to produce water and N2.

Explanation of Solution

The formula for hydrazine is N2H4. It reacts with oxygen to produce water and N2.

The balanced chemical equation for the reaction of hydrazine and oxygen is,

    N2H4(l)+O

(b)

Interpretation Introduction

Interpretation:

The value of ΔrH°, ΔrS° and ΔrGo for the given reaction of 1molofN2H4at25oc should be identified.

Concept introduction:

The Gibbs free energy or the free energy change is a thermodynamic quantity represented by ΔGo. It is related to entropy and entropy by the following expression,

    ΔGo= ΔHo- TΔSo

The sign of ΔGo should be positive for a product-favored reaction. Thus, spontaneous reactions are referred to those that have negative free energy formation.

The sign of ΔSo should be positive for an entropy-favoured reaction and the sign of ΔH should be negative for an enthalpy favoured-reaction.

ΔrHo is negative for an exothermic reaction and positive for endothermic reactions. The entropy change is positive whenever number of moles of gases is increasing in any reaction.

(c)

Interpretation Introduction

Interpretation:

The change in temperature expected in heating system that has 5.5×104L of water should be identified.

Concept introduction:

The Gibbs free energy or the free energy change is a thermodynamic quantity represented by ΔGo. It is related to entropy and entropy by the following expression,

    ΔGo= ΔHo- TΔSo

The sign of ΔGo should be positive for a product-favored reaction. Thus, spontaneous reactions are referred to those that have negative free energy formation.

The sign of ΔSo should be positive for an entropy-favoured reaction and the sign of ΔHo should be negative for an enthalpy favoured-reaction.

ΔrHo is negative for an exothermic reaction and positive for endothermic reactions. The entropy change is positive whenever number of moles of gases is increasing in any reaction.

(d)

Interpretation Introduction

Interpretation:

The amount of O2 present in hot water heating system of 5.5×104kg should be identified.

Concept introduction:

Moles: One mole is equivalent to the mass of the substance consists same number of units equal to the atoms present in 12g of 12C.

From given mass of substance moles could be calculated by using the following formula,

  Molesofsubstance GivenmassofsubstanceMolecularmass

(e)

Interpretation Introduction

Interpretation:

The mass of solution that has 5% dissolved hydrazine in water required to totally consume the dissolved amount of O2.

Concept introduction:

Moles: One mole is equivalent to the mass of the substance consists same number of units equal to the atoms present in 12g of 12C.

From given mass of substance moles could be calculated by using the following formula,

  Molesofsubstance GivenmassofsubstanceMolecularmass

Mass: It is the quantitative measure of a substance. The amount of matter present in substance is expressed as mass. The S.I. unit of mass is kg.

(f)

Interpretation Introduction

Interpretation:

The volume of N2 produced under given conditions should be calculated.

Concept introduction:

Moles: One mole is equivalent to the mass of the substance consists same number of units equal to the atoms present in 12g of 12C.

From given mass of substance moles could be calculated by using the following formula,

  Molesofsubstance GivenmassofsubstanceMolecularmass

Mass: It is the quantitative measure of a substance. The amount of matter present in substance is expressed as mass. The S.I. unit of mass is kg.

Still sussing out bartleby?

Check out a sample textbook solution.

See a sample solution

The Solution to Your Study Problems

Bartleby provides explanations to thousands of textbook problems written by our experts, many with advanced degrees!

Get Started

Chapter 18 Solutions

Chemistry & Chemical Reactivity
Show all chapter solutions
add
Ch. 18.4 - Without looking up their standard entropies in...Ch. 18.4 - Without doing any calculations, predict the sign...Ch. 18.4 - Calculate rS for the following reaction at 25 C....Ch. 18.5 - Based on rH and rS, predict the spontaneity of the...Ch. 18.5 - Calculate rS for the following reaction at 25 C...Ch. 18.5 - Calculate S(universe) for the following reaction...Ch. 18.5 - 3. If rH° = +467.9 kJ/mol-rxn and rS° = +560.7 J/K...Ch. 18.6 - For a reaction to be spontaneous, rG will be...Ch. 18.6 - A reaction for which rG 0 is (a) product-favored...Ch. 18.7 - Using values of fH and S to find rH and rS,...Ch. 18.7 - Calculate the standard free energy change for the...Ch. 18.7 - Oxygen was first prepared by Joseph Priestley...Ch. 18.7 - Determine the value of rG for the reaction C(s) +...Ch. 18.7 - Determine the value of the equilibrium constant,...Ch. 18.7 - Nitrogen and oxygen can react to form nitrogen...Ch. 18.7 - 1. Given that H° = −2219 kJ/mol-rxn and that rS° =...Ch. 18.7 - 2. Using values of rG°, determine the value of rG°...Ch. 18.7 - 3. The value of Kp for the following reaction at...Ch. 18.7 - Consider the hydrolysis reactions of creatine...Ch. 18.7 - Assume the reaction A(aq) + B(aq) C(aq) +...Ch. 18.A - The decomposition of diamond to graphite...Ch. 18.A - It has been demonstrated that buckminsterfullerene...Ch. 18 - Which substance has the higher entropy? (a) dry...Ch. 18 - Which substance has the higher entropy? (a) a...Ch. 18 - Use S values to calculate the standard entropy...Ch. 18 - Use S values to calculate the standard entropy...Ch. 18 - Calculate the standard entropy change for the...Ch. 18 - Calculate the standard entropy change for the...Ch. 18 - Calculate the standard entropy change for the...Ch. 18 - Calculate the standard entropy change for the...Ch. 18 - Is the reaction Si(s) + 2 Cl2(g) SiCl4(g)...Ch. 18 - Is the reaction Si(s) + 2 H2(g) SiH4(g)...Ch. 18 - Calculate S(universe) for the decomposition of 1...Ch. 18 - Calculate S(universe) for the formation of 1 mol...Ch. 18 - Classify each of the reactions according to one of...Ch. 18 - Classify each of the reactions according to one of...Ch. 18 - Using values of fH and S, calculate rG for each of...Ch. 18 - Using values of fH and S, calculate rG for each of...Ch. 18 - Using values of fH and S, calculate the standard...Ch. 18 - Using values of fH and S, calculate the standard...Ch. 18 - Using values of fG, calculate rG for each of the...Ch. 18 - Using values of fG, calculate rG for each of the...Ch. 18 - For the reaction BaCO3(s) BaO(s) + CO2(g), rG =...Ch. 18 - For the reaction TiCl2(s) + Cl2(g) TiCl4(), rG =...Ch. 18 - Determine whether the reactions listed below are...Ch. 18 - Determine whether the reactions listed below are...Ch. 18 - Heating some metal carbonates, among them...Ch. 18 - Calculate rH and rS for the reaction of tin(IV)...Ch. 18 - The standard free energy change, rG, for the...Ch. 18 - The standard free energy change, rG, for the...Ch. 18 - Calculate rG at 25 C for the formation of 1.00 mol...Ch. 18 - Calculate rG at 25 C for the formation of 1.00 mol...Ch. 18 - For the synthesis of ammonia from its elements at...Ch. 18 - For the decomposition of solid calcium carbonate...Ch. 18 - Compare the compounds in each set below and decide...Ch. 18 - Using standard entropy values, calculate rS for...Ch. 18 - About 5 billion kilograms of benzene, C6H6, are...Ch. 18 - Hydrogenation, the addition of hydrogen to an...Ch. 18 - Is the combustion of ethane, C2H6, product-favored...Ch. 18 - Write a balanced equation that depicts the...Ch. 18 - When vapors from hydrochloric acid and aqueous...Ch. 18 - Calculate S(system), S(surroundings), and...Ch. 18 - Methanol is now widely used as a fuel in race...Ch. 18 - The enthalpy of vaporization of liquid diethyl...Ch. 18 - Calculate the entropy change, rS, for the...Ch. 18 - Using thermodynamic data, estimate the normal...Ch. 18 - The following reaction is reactant-favored at...Ch. 18 - When calcium carbonate is heated strongly, CO2 gas...Ch. 18 - Sodium reacts violently with water according to...Ch. 18 - Yeast can produce ethanol by the fermentation of...Ch. 18 - Elemental boron, in the form of thin fibers, can...Ch. 18 - Estimate the vapor pressure of ethanol at 37 C...Ch. 18 - The equilibrium constant, Kp, for N2O4(g) 2...Ch. 18 - Estimate the boiling point of water in Denver,...Ch. 18 - The equilibrium constant for the butane ...Ch. 18 - A crucial reaction for the production of synthetic...Ch. 18 - Calculate rG for the decomposition of sulfur...Ch. 18 - Methanol can be made by partial oxidation of...Ch. 18 - A cave in Mexico was recently discovered to have...Ch. 18 - Wet limestone is used to scrub SO2 gas from the...Ch. 18 - Sulfur undergoes a phase transition between 80 and...Ch. 18 - Calculate the entropy change for dissolving HCl...Ch. 18 - Some metal oxides can be decomposed to the metal...Ch. 18 - Copper(II) oxide, CuO, can be reduced to copper...Ch. 18 - Calculate fG for HI(g) at 350 C, given the...Ch. 18 - Calculate the equilibrium constant for the...Ch. 18 - Titanium(IV) oxide is converted to titanium...Ch. 18 - Cisplatin [cis-diamminedichloroplatinum(II)] is a...Ch. 18 - Mercury vapor is dangerous because breathing it...Ch. 18 - Explain why each of the following statements is...Ch. 18 - Decide whether each of the following statements is...Ch. 18 - Under what conditions is the entropy of a pure...Ch. 18 - In Chapter 13, you learned that entropy, as well...Ch. 18 - Consider the formation of NO(g) from its elements....Ch. 18 - Write a chemical equation for the oxidation of...Ch. 18 - The normal melting point of benzene, C6H6, is 5.5...Ch. 18 - Calculate the standard molar entropy change, rS,...Ch. 18 - For each of the following processes, predict the...Ch. 18 - Heater Meals are food packages that contain their...Ch. 18 - Use values of fG for solid and gaseous iodine at...Ch. 18 - Oxygen dissolved in water can cause corrosion in...Ch. 18 - The formation of diamond from graphite is a...Ch. 18 - Iodine, I2, dissolves readily in carbon...Ch. 18 - Write an equation for the reaction of Fe2O3(s) and...Ch. 18 - Write an equation for the decomposition of 1.0 mol...Ch. 18 - Consider the reaction of NO and Cl2 to produce...Ch. 18 - Two processes that can be used to generate...Ch. 18 - Hydrogen and methane are two possible replacements...Ch. 18 - The Haber-Bosch process for the production of...Ch. 18 - Muscle cells need energy to contract. One...

Additional Science Textbook Solutions

Find more solutions based on key concepts
Show solutions add
Fried fish from fast-food restaurants and frozen fried fish products are often low in omega-3 and high in solid...

Nutrition: Concepts and Controversies - Standalone book (MindTap Course List)

What evidence shows that white dwarfs must be very small?

Horizons: Exploring the Universe (MindTap Course List)

Describe the secondary structure of DNA as proposed by Watson and Crick.

Chemistry for Today: General, Organic, and Biochemistry

The spring constant of an automotive suspension spring increases with increasing load due to a spring coil that...

Physics for Scientists and Engineers, Technology Update (No access codes included)