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Ch.19 - Chemical Thermodynamics
Chapter 19, Problem 71

(a) Use data in Appendix C to estimate the boiling point of benzene, C6H6. (b) Use a reference source, such as the CRC Handbook of Chemistry and Physics, to find the experimental boiling point of benzene.

Verified step by step guidance
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Step 1: Identify the relevant thermodynamic data for benzene from Appendix C, such as the standard enthalpy of vaporization (\( \Delta H_{vap}^\circ \)) and the standard entropy of vaporization (\( \Delta S_{vap}^\circ \)).
Step 2: Use the Clausius-Clapeyron equation to relate the enthalpy and entropy of vaporization to the boiling point. The equation is \( \Delta G = \Delta H_{vap}^\circ - T \Delta S_{vap}^\circ \), where \( \Delta G = 0 \) at the boiling point.
Step 3: Rearrange the equation to solve for the boiling point temperature \( T \): \( T = \frac{\Delta H_{vap}^\circ}{\Delta S_{vap}^\circ} \).
Step 4: Substitute the values of \( \Delta H_{vap}^\circ \) and \( \Delta S_{vap}^\circ \) from Appendix C into the equation to calculate the estimated boiling point of benzene.
Step 5: Compare the estimated boiling point with the experimental value found in a reference source, such as the CRC Handbook of Chemistry and Physics, to evaluate the accuracy of the estimation.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Boiling Point

The boiling point of a substance is the temperature at which its vapor pressure equals the external pressure surrounding the liquid. At this point, the liquid transitions to a gas. For pure substances, the boiling point is a characteristic property that can be influenced by factors such as atmospheric pressure and the presence of impurities.
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Data Interpretation

Data interpretation involves analyzing and extracting meaningful information from provided data sets, such as those found in appendices or reference materials. In the context of estimating boiling points, it requires understanding how to apply empirical data, such as molecular weight or structure, to predict physical properties of compounds.
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Reference Sources

Reference sources, like the CRC Handbook of Chemistry and Physics, compile reliable and experimentally determined data for various chemical substances. These sources are essential for verifying theoretical estimates and provide standardized values for properties such as boiling points, which are crucial for accurate scientific communication and research.
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Related Practice
Textbook Question

Consider the following reaction between oxides of nitrogen: NO2(g) + N2O(g) → 3 NO(g) (b) Calculate ΔG at 800 K, assuming that ΔH° and ΔS° do not change with temperature. Under standard conditions is the reaction spontaneous at 800 K?

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Textbook Question

Consider the following reaction between oxides of nitrogen: NO2(g) + N2O(g) → 3 NO(g) (c) Calculate ΔG at 1000 K. Is the reaction spontaneous under standard conditions at this temperature?

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Textbook Question

Methanol (CH3OH) can be made by the controlled oxidation of methane: CH4(g) + 12 O2(g) → CH3OH(g) (b) Will ΔG for the reaction increase, decrease, or stay unchanged with increasing temperature?

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Textbook Question

(a) Using data in Appendix C, estimate the temperature at which the free-energy change for the transformation from I2(s) to I2(g) is zero. (b) Use a reference source, such as Web Elements (www.webelements.com), to find the experimental melting and boiling points of I2. (c) Which of the values in part (b) is closer to the value you obtained in part (a)?

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Open Question
Acetylene gas, C2H2(g), is used in welding. (b) How much heat is produced in burning 1 mol of C2H2 under standard conditions if both reactants and products are brought to 298 K?
Textbook Question

The fuel in high-efficiency natural-gas vehicles consists primarily of methane (CH4). (a) How much heat is produced in burning 1 mol of CH4(g) under standard conditions if reactants and products are brought to 298 K and H2O(l) is formed?

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