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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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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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Given the data
N2 (g) + O2 (g) → 2 NO (g)            ΔH = +180.7 kJ
2 NO (g) + O2 (g) → 2 NO2 (g)      ΔH = -113.1 kJ
2 N2O (g) → 2 N2 (g) + O2 (g)       ΔH = -163.2 kJ

use Hess’s law to calculate ΔH for the reaction
N2O (g) + NO2 (g) → 3 NO (g)

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From the enthalpies of reaction
H2 (g) + F2 (g) → 2 HF (g)          ΔH = -537 kJ
C (s) + 2 F2 (g) → CF4 (g)          ΔH = -680 kJ
2 C (s) + 2 H2 (g) → C2H4 (g)     ΔH = +52.3 kJ

calculate ΔH for the reaction of ethylene with F 2:
C2H4 (g) + 6 F2 (g) → 2 CF4 (g) + 4 HF (g)

 

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Calculate the enthalpy change for the reaction
P4O6 (s) + 2 O2 (g) → P4O10 (s)
given the following enthalpies of reaction:
P4 (s) + 3 O2 (g) → P4O6 (s)          ΔH = -1640.1 kJ
P4 (s) + 5 O2 (g) → P4O10 (s)        ΔH = -2940.1 kJ

 

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A 2.200-g sample of quinone (C6H4O2) is burned in a bomb calorimeter whose total heat capacity is 7.854 kJ/°C. The temperature of the calorimeter increases from 23.44°C to 30.57°C. What is the heat of combustion per gram of quinone? Per mole of quinone?

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Two solid objects, A and B, are placed in boiling water and allowed to come to the temperature of the water. Each is then lifted out and placed in separate beakers containing 1000 g water at 10.0°C. Object A increases the water temperature by 3.50°C; B increases the water temperature by 2.60°C. (a) Which object has the larger heat capacity?

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Consider the decomposition of liquid benzene, C6H6 (l), to gaseous acetylene, C2H2 (g):
C6H6 (l) → 3 C2H2 (g)         ΔH = +630 kJ 

(d) If C6H6 (g) were consumed instead of C6H6 (l), would you expect the magnitude of ΔH to increase, decrease, or stay the same? Explain.

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Consider the decomposition of liquid benzene, C6H6 (l), to gaseous acetylene, C2H2 (g):
C6H6 (l) → 3 C2H2 (g)         ΔH = +630 kJ 

(c) Which is more likely to be thermodynamically favored, the forward reaction or the reverse reaction?

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Consider the decomposition of liquid benzene, C6H6 (l), to gaseous acetylene, C2H2 (g):
C6H6 (l) → 3 C2H2 (g)         ΔH = +630 kJ

(b) What is ΔH for the formation of 1 mol of acetylene?

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Consider the decomposition of liquid benzene, C6H6 (l), to gaseous acetylene, C2H2 (g):
C6H6 (l) → 3 C2H2 (g)         ΔH = +630 kJ
(a) What is the enthalpy change for the reverse reaction?

 

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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

(d) If the reaction were written to produce H2O (g) instead of H2O (l), would you expect the magnitude of ΔH to increase, decrease, or stay the same? 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

(c) Which is more likely to be thermodynamically favored, the forward reaction or the reverse reaction? Explain.

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