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Consider the combustion of liquid methanol, CH 3OH (l):

CH3OH (l) + 3/2 O2 (g) → CO2 (g) + 2 H2O (l)     ΔH = -726.5 kJ

(b) Balance the forward reaction with whole-number coefficients. What is ΔH for the reaction represented by this equation? Explain.

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Consider the combustion of liquid methanol, CH 3OH (l):

CH3OH (l) + 3/2 O2 (g) → CO2 (g) + 2 H2O (l)     ΔH = -726.5 kJ

(a) What is the enthalpy change for the reverse reaction? Explain.

 

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At one time, a common means of forming small quantities of oxygen gas in the laboratory was to heat KClO3:
2 KClO3 (s) → 2 KCl (s) + 3 O2 (g)   ΔH = -89.4 kJ

The decomposition of KClO3 proceeds spontaneously when it is heated. Do you think that the reverse reaction, the formation of KClO3 from KCl and O2, is likely to be feasible under ordinary conditions? Explain your answer.

 

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Without referring to tables, predict which of the following has the higher enthalpy in each case: (d) 1 mol N2 (g) at 100°C or 1 mol N2 (g) at 300°C.

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Without referring to tables, predict which of the following has the higher enthalpy in each case: (c) 1 mol H2 (g) and 0.5 mol O2 (g) at 25°C or 1 mol H2O (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 H2

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Without referring to tables, predict which of the following has the higher enthalpy in each case: (a) 1 mol CO(s) or 1 mol CO2 (g) at the same temperature

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

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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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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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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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Consider the accompanying energy diagram. (a) Does this diagram represent an increase or decrease in the internal energy of the system?

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(b) How many milliliters of 0.125 M H 2SO4 are needed to neutralize 0.200 g of NaOH?

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(a) How many milliliters of 0.120 M HCl are needed to completely neutralize 50.0 mL of 0.101 M Ba(OH)2 solution?

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What mass of NaOH is needed to precipitate the Cd  2+ ions from 35.0 mL of 0.500 M Cd(NO3)2 solution?

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What mass of KCl is needed to precipitate the silver ions from 15.0 mL of 0.200 M AgNO3 solution?

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Glycerol, C3H8O3, is a substance used extensively in the manufacture of cosmetics, foodstuffs, antifreeze, and plastics. Glycerol is a water-soluble liquid with a density of 1.2656 g/L at 15°C. Calculate the molarity of a solution of glycerol made by dissolving 50.000 mL glycerol at 15°C in enough water to make 250.00 mL of solution.

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Pure acetic acid, known as glacial acetic acid, is a liquid with a density of 1.049 g/mL at 25°C. Calculate the molarity of a solution of acetic acid made by dissolving 20.00 mL of glacial acetic acid at 25°C in enough water to make 250.0 mL of solution.

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