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A coffee-cup calorimeter of the type shown in Figure 5.17 contains 150.0 g of water at 25.1°C. A 121.0-g block of copper metal is heated to 100.4°C by putting it in a beaker of boiling water. The specific heat of Cu(s) is 0.385 J/g•K. The Cu is added to the calorimeter, and after a time the contents of the cup reach a constant temperature of 30.1°C. (a) Determine the amount of heat, in J, lost by the copper block.

 

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A house is designed to have passive solar energy features. Brickwork incorporated into the interior of the house acts as a heat absorber. Each brick weighs approximately 1.8 kg. The specific heat of the brick is 0.85 J/g-K. How many bricks must be incorporated into the interior of the house to provide the same total heat capacity as 1.7 x 103 gal of water?

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Limestone stalactites and stalagmites are formed in caves by the following reaction:

Ca2+ (aq) + 2 HCO3– (aq) → CaCO(s) + CO2 (g) + H2O (l)

If 1 mol of CaCO3 forms at 298 K under 1 atm pressure, the reaction performs 2.47 kJ of P-V work, pushing back the atmosphere as the gaseous CO2 forms. At the same time, 38.95 kJ of heat is absorbed from the environment. What are the values of ΔH and of ΔE for this reaction?

 

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Suppose an Olympic diver who weighs 52.0 kg executes a straight dive from a 10-m platform. At the apex of the dive, the diver is 10.8 m above the surface of the water. (c) Does the diver do work on entering the water? Explain.

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Suppose an Olympic diver who weighs 52.0 kg executes a straight dive from a 10-m platform. At the apex of the dive, the diver is 10.8 m above the surface of the water. (b) Assuming that all the potential energy of the diver is converted into kinetic energy at the surface of the water, at what speed in m/s will the diver enter the water?

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Suppose an Olympic diver who weighs 52.0 kg executes a straight dive from a 10-m platform.At the apex of the dive, the diver is 10.8 m above the surface of the water. (a) What is the potential energy of the diver at the apex of the dive, relative to the surface of the water?

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At 20°C (approximately room temperature) the average velocity of N 2 molecules in air is 1050 mph. (b) What is the kinetic energy (in J) of an N2 molecule moving at this speed?

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At 20°C (approximately room temperature) the average velocity of N 2 molecules in air is 1050 mph. (a) What is the average speed in m/s?

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Methanol (CH3OH) is used as a fuel in race cars. (d) Calculate the mass of CO2 produced per kJ of heat emitted. 

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Methanol (CH3OH) is used as a fuel in race cars. (c) Calculate the heat produced by combustion per liter of methanol. Methanol has a density of 0.791 g/mL.

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Methanol (CH3OH) is used as a fuel in race cars. (b) Calculate the standard enthalpy change for the reaction, assuming H2O(g) as a product.

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Methanol (CH3OH) is used as a fuel in race cars. (a) Write a balanced equation for the combustion of liquid methanol in air.

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Naphthalene (C10H8) is a solid aromatic compound often sold as mothballs. The complete combustion of this substance to yield CO2(g) and H2O(/) at 25°C yields 5154 kJ/mol. (b) Calculate the standard enthalpy of formation of naphthalene.

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Naphthalene (C10H8) is a solid aromatic compound often sold as mothballs. The complete combustion of this substance to yield CO2(g) and H2O(/) at 25°C yields 5154 kJ/mol. (a) Write balanced equations for the formation of naphthalene from the elements and for its combustion.

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Gasoline is composed primarily of hydrocarbons, including many with eight carbon atoms, called octanes. One of the cleanest-burning octanes is a compound called 2,3,4-trimethylpentane, which has the following structural formula. 

The complete combustion of one mole of this compound to CO 2(g) and H2O(g) leads to ΔH° = -5064.9 kJ/mol. (c) By using the information in this problem and data in Table 5.3, calculate ΔHf° for 2,3,4-trimethylpentane.

 

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Gasoline is composed primarily of hydrocarbons, including many with eight carbon atoms, called octanes. One of the cleanest-burning octanes is a compound called 2,3,4-trimethylpentane, which has the following structural formula. 

The complete combustion of one mole of this compound to CO 2(g) and H2O(g) leads to ΔH° = -5064.9 kJ/mol. (b) Write a balanced equation for the formation of C8H18(l) from its elements.

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Gasoline is composed primarily of hydrocarbons, including many with eight carbon atoms, called octanes. One of the cleanest-burning octanes is a compound called 2,3,4-trimethylpentane, which has the following structural formula. 

The complete combustion of one mole of this compound to CO 2(g) and H2O(g) leads to ΔH° = -5064.9 kJ/mol. (a) Write a balanced equation for the combustion of 1 mol of C8H18(l).

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Complete combustion of 1 mol of acetone (C 3H6O) liberates 1790 kJ:
C3H6O (l) + 4 O (g) → 3 CO(g) + 3 H2O (l)     ΔH° = -1790 kJ

Using this information together with data from Appendix C, calculate the enthalpy of formation of acetone.

 

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Using values from Appendix C, calculate the value of ΔH° for each of the following reactions:

(d) Fe2O3(s) + 6 HCI(g) → 2 FeCI3(s) + 3 H2O(g)

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Using values from Appendix C, calculate the value of ΔH° for each of the following reactions:

(c) CH4(g) + 4 Cl2(g) → CCl4(l) + 4 HCI(g)

 

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Using values from Appendix C, calculate the value of ΔH° for each of the following reactions:

(b) 2 Na(OH)(s) + SO3(g) → Na2SO4(s) + H2O(g)

 

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Using values from Appendix C, calculate the value of ΔH° for each of the following reactions:

(a) 4 HBr(g) + O2(g) → 2 H2O(/) + 2 Br2(/)

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Write balanced equations that describe the formation of the following compounds from elements in their standard states, and use Appendix C to obtain the values of their standard enthalpies of formation: (d) CH3COOH(/).

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Write balanced equations that describe the formation of the following compounds from elements in their stan·
dard states, and use Appendix C to obtain the values of their standard enthalpies of formation: (c) Fe2O(s)

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Write balanced equations that describe the formation of the following compounds from elements in their standard states, and use Appendix C to obtain the values of their standard enthalpies of formation: (b) AgNO3(s)

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