Without referring to tables, predict which of the following has the higher enthalpy in each case: (c) 1 mol H_{2} (g) and 0.5 mol O_{2} (g) at 25°C or 1 mol H_{2}O (g) at 25°C

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Without referring to tables, predict which of the following has the higher enthalpy in each case: (b) 2 mol of hydrogen atoms or 1 mol of H_{2}

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Without referring to tables, predict which of the following has the higher enthalpy in each case: (a) 1 mol CO_{2 }(s) or 1 mol CO_{2} (g) at the same temperature

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(a) What is meant by the term state function?

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For the following processes, calculate the change in internal energy of the system and determine whether the process is endothermic or exothermic: (c) A chemical reaction releases 6.47 kJ of heat and does no work on the surroundings.

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For the following processes, calculate the change in internal energy of the system and determine whether the process is endothermic or exothermic: (b) A 50-g sample of water is cooled from 30°C to 15°C, thereby losing approximately 3140 J of heat.

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For the following processes, calculate the change in internal energy of the system and determine whether the process is endothermic or exothermic: (a) A balloon is heated by adding 850 J of heat. It expands, doing 382 J of work on the atmosphere.

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(a) State the first law of thermodynamics.

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(b) An adult person radiates heat to the surroundings at about the same rate as a 100-watt electric incandescent lightbulb. What is the total amount of energy in kcal radiated to the surroundings by an adult in 24 h?

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A watt is a measure of power (the rate of energy change) equal to 1 J/s. (a) Calculate the number of joules in a kilowatthour.

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What is the kinetic energy in joules of an 850-lb motorcycle moving at 66 mph? (c) Where does the kinetic energy of the motorcycle go when the rider brakes to a stop?

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What is the kinetic energy in joules of an 850-lb motorcycle moving at 66 mph? (b) By what factor will the kinetic energy change if the speed of the motorcycle is decreased to 33 mph?

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(a) What is the kinetic energy in joules of an 850-lb motorcycle moving at 66 mph?

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Calculate the kinetic energy in joules of a 45-g golf ball moving at 61 m/s. (c) What happens to this energy when the ball lands in a sand trap?

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Calculate the kinetic energy in joules of a 45-g golf ball moving at 61 m/s. (b) Convert this energy to calories.

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(a) Calculate the kinetic energy in joules of a 45-g golf ball moving at 61 m/s.

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Suppose you toss a tennis ball upward. (c) If the same amount of energy were imparted to a ball the same size as a tennis ball but of twice the mass, how high would the ball go in comparison to the tennis ball? Explain your answers.

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Suppose you toss a tennis ball upward. (b) What happens to the potential energy of the ball as it moves higher? Explain your answers.

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Suppose you toss a tennis ball upward. (a) Does the kinetic energy of the ball increase or decrease as it moves higher? Explain your answers.

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Does ΔH_{rxn} for the reaction represented by the following equation equal the standard enthalpy of formation for CH_{3}OH(I)? Why or why not?

C(graphite) + 4 H(g) + O(g) → CH_{3}OH(l)

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Which will release more heat as it cools from 50°C to 25°C, 1 kg of water or 1 kg of aluminum? How do you know?

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Imagine a container placed in a tub of water, as depicted in the accompanying diagram. (a) If the contents of the container are the system and heat is able to flow through the container walls, what qualitative changes will occur in the temperatures of the system and in its surroundings? What is the sign of q associated with each change? From the system’s perspective, is the process exothermic or endothermic?

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In the accompanying cylinder diagram a chemical process occurs at constant temperature and pressure. (a) Is the sign of w indicated by this change positive or negative?

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Imagine that you are climbing a mountain. (a) Is the distance you travel to the top a state function? Why or why not?

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The contents of the closed box in each of the following illustrations represent a system, and the arrows show the changes to the system during some process. The lengths of the arrows represent the relative magnitudes of q and w. (a) Which of these processes is endothermic?

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