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22 solutions

Internal Energy

Q. The piston-cyliuder assembly below represents a physical change occurring at constant pressure. (a) Is wsys +, —, or 0? positive negative zero [b] [d]Hsys +, —, or 0? positive negative zero (c) Can you determine Whether [d]Esurr is +,-, or 0? positive negative zero cannot determine

Solved • Jun 28, 2019

Internal Energy

Q. When a gas is compressed in a cylinder fitted with a piston, the work done is 510 J. At the same time, 264 J of heat is released to the surrounding. (a) Is this process endothermic or exothermic? (b) Calculate the change in the internal energy of the system and state whether the internal energy has increased or decreased. The internal energy has __.

Solved • Jul 18, 2019

Internal Energy

Q. When a gas is heated, it absorbs 178 joules of heat from the surroundings. At the same time, the gas expands, doing pressure-volume work (P*V work ) on the surroundings that is equal to 333 joules. (a) Determine whether the amounts of heat (q) and work (w) exchanged should have positive or negative signs. heat (q) positive or negative work (w) positive or negative (b) Calculate the change in internal energy (ΔE) of the gas. (c) Determine whether one or more of the following is a state function:. internal energy (E) of a system, change in internal energy (ΔE) of a system, heat (q) absorbed or released by a system, work (w) done on or by a system. (Select all that apply.)

Solved • Jul 18, 2019

Internal Energy

Q. In a system, 4 mol of water is condensed. (a) If 156 kJ of heat is lost by the system to the surroundings, and the amount of work performed on the system is 12200 J, what is the change in the internal energy of the system? (b) Which of the following are state functions: heat transferred (q), work performed (w), internal energy (E)? (Select all that apply.)

Solved • Jul 18, 2019

Internal Energy

Q. The production of hydrogen chloride gas (HCl) at 1.0 atm and 25°C is represented by the following thermochemical equation. H2(g) + Cl2(g) -> 2 HCl(g); ΔH = -184.6 kJ Suppose exactly 5 mol H2(g) reacts with exactly 5 mol Cl2(g) to form HCl(g) under the same conditions of temperature and pressure. (a) Calculate the amount of pressure-volume work that is done. (b) Calculate the change in internal energy (ΔE) of the system, assuming the reaction proceeds to completion.

Solved • Jul 18, 2019

Internal Energy

Q. Work (w) is performed by gas expansion at constant pressure (P) according to the equation w = -PΔV where ΔV is the change in volume (V2 - V1) of the system. Use this relationship to solve the problem below. The combustion of 0.25 moles of octane gas (C8H18) to CO2 gas and H2O gas (vapor) against a constant, external pressure of 2.0 atm increases the total volume of gas from 114.5 L to 151.3 L. How much work is performed by this expansion? (Include the sign of the value on your answer.)

Solved • Jul 18, 2019

Internal Energy

Q. Hydrogen gas (H2) is generated by the following reaction. Ca(s) + 2 HCl(aq) -> CaCl2(aq) + H2(g); ΔH = -542.7 kJ/mol When this reaction takes place in a cylinder (fitted with a piston) containing 1.000 mol Ca(s), 542.7 kJ heat is lost to the surroundings. Because a gas in generated, work is done by the system against a constant pressure of 1.170 atm. If the internal energy decreases by 545.60 kJ, what is the change in the volume of the system in liters?

Solved • Jul 18, 2019