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level: Level 1

Questions and Answers List

level questions: Level 1

Question	Answer
A fuel is burned in a cylinder equipped with a piston. The initial volume of the cylinder is 0.250 L, and the final volume is 0.980 L. If the piston expands against a constant pressure of 1.35 atm, how much work (in J) is done? 11 L@atm = 101.3 J2	-99.8 J
Gases A(g) and B(g) are confined in a cylinder-and-piston arrangement like that in Figure 5.4 and react to form a solid product C(s): A1g2 + B1g2 ¡ C1s2. As the reaction occurs, the system loses 1150 J of heat to the surroundings. The piston moves downward as the gases react to form a solid. As the volume of the gas decreases under the constant pressure of the atmosphere, the surroundings do 480 J of work on the system. What is the change in the internal energy of the system?	-670 J
Indicate the sign of the enthalpy change, ∆H, in the following processes carried out under atmospheric pressure and indicate whether each process is endothermic or exothermic: (a) An ice cube melts; (b) 1 g of butane 1C4H102 is combusted in sufficient oxygen to give complete combustion to CO2 and H2O.	∆H is negative
Indicate the sign of the enthalpy change, ∆H, in the following processes carried out under atmospheric pressure and indicate whether each process is endothermic or exothermic: (a) An ice cube melts; (b) 1 g of butane 1C4H102 is combusted in sufficient oxygen to give complete combustion to CO2 and H2O.	In (a) the water that makes up the ice cube is the system. The ice cube absorbs heat from the surroundings as it melts, so ∆H is positive and the process is endothermic. In (b) the system is the 1 g of butane and the oxygen required to combust it. The combustion of butane in oxygen gives off heat, so ∆H is negative and the process is exothermic.
How much heat is released when 4.50 g of methane gas is burned in a constant-pressure system? (Use the information given in Equation 5.17.)	-250 kJ