15. What is Hess's Law? How is it used? Why is it important in chemistry? Explain your ideas and provideat least one relevant example to support your answer.

Hess’s law states that the overalls energy change in the chemical reaction is equal to the sum of…

Answered: 15. What is Hess's Law? How IS It used?…

Chemistry In Focus

7th Edition

ISBN:9781337399692

Author:Tro, Nivaldo J.

Publisher:Tro, Nivaldo J.

Chapter9: Energy For Today

Section: Chapter Questions

Problem 15E

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Similar questions

What quantity of heat energy must have en applied to a block of aluminum weighing 42.7 g if the temperature of the block of aluminum increased by 15.2 °C? (See Table 10.1.)
The first step in the preparation of lead from its ore (galena, PbS) consists of roasting the ore. PbS(s)+32O2(g)SO2(g)+PbO(s) Calculate the standard enthalpy change for this reaction, using enthalpies of formation (see Appendix C).
The following reactions can be used to prepare samples of metals. Determine the enthalpy change under standard state conditions for each. (a) 2Ag2O(s)4Ag(s)+O2(g) (b) SnO(s)+CO(g)Sn(s)+CO2(g) (c) Cr2O3(s)+3H2(g)2Cr(s)+3H2O(l) (d) 2Al(s)+Fe2O3(s)Al2O(s)+2Fe(s)
9.84 Some claim it would be more logical to use heats of atomization, the energy required to convert any molecule to its separated atoms, rather than heats of formation for doing calculations with Hess's law. If you had a table of heats of atomization and calculated the combustion energy of a fuel, would you get the same answer as you would get using heats of formation? Explain your answer.
You discover that you cannot carry out a particular reaction for which you would like the enthalpy change. Does this mean that you will be unable to obtain this enthalpy change? Explain.
9.45 What happens to the temperature of a material as it undergoes an endothermic phase change? If heat is added, how can the temperature behave in this manner?
Is the following reaction the appropriate one to use in determining the enthalpy of formation of methane, CH4(g)? Why or why not? C(g)+4H(g)CH4(g)
Strontium metal is responsible for the red color in fireworks. Fireworks manufacturers use strontium carbonate, which can be produced by combining strontium metal, graphite (C), and oxygen gas. The formation of one mole of SrCO3 releases 1.220103 kJ of energy. (a) Write a balanced thermochemical equation for the reaction. (b) What is H when 10.00 L of oxygen at 25C and 1.00 atm are used by the reaction?
When a gas expands, what is the sign of w? Why? When a gas contracts, what is the sign of w? Why? What are the signs of q and w for the process of boiling water?
9.41 Under what conditions does the enthalpy change equal the heat of a process?
9.19 If the algebraic sign of E is negative, in which direction has energy flowed?
9.95 How much heat is required to convert 250 g of water from liquid at 23°C: into steam at 107°C? (The necessary heat capacities and enthalpy changes can be found in the chapter or online.)

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15. What is Hess's Law? How IS It used? Why is It Importaht in chemistry? Explalh your Ideas and provide at least one relevant example to support your answer.