Open Question
Arrange the following substances in order of increasing H3O+ concentration for a 0.10 M solution of each. (a) Zn(NO3)2 (b) Na2O (c) NaOCl (d) NaClO4 (e) HClO4
Ch.16 - Aqueous Equilibria: Acids & Bases
Chapter 16, Problem 143
Which would you expect to be the stronger Lewis acid in each of the following pairs? Explain. (a) BF3 or BH3
Verified step by step guidance1
Identify the definition of a Lewis acid: A Lewis acid is a substance that can accept a pair of electrons.
Consider the electronic structure of each molecule: BF3 and BH3.
Analyze the electronegativity of the atoms involved: Boron (B) is less electronegative than Fluorine (F), and Hydrogen (H) is less electronegative than Boron (B).
Evaluate the electron deficiency: BF3 has a more significant electron deficiency due to the highly electronegative fluorine atoms pulling electron density away from boron, making it more likely to accept electrons.
Conclude which is the stronger Lewis acid: BF3 is expected to be the stronger Lewis acid compared to BH3 because it is more electron-deficient and can more readily accept an electron pair.
Verified Solution
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Lewis Acids and Bases
Lewis acids are defined as electron pair acceptors, while Lewis bases are electron pair donors. This concept expands the traditional Brønsted-Lowry definitions of acids and bases, allowing for a broader range of chemical interactions. Understanding this distinction is crucial for identifying which species in a reaction can act as an acid or a base.
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05:04
Lewis Acids and Bases
Electron Deficiency
Electron deficiency refers to the lack of a complete octet in an atom, making it more reactive and capable of accepting electron pairs. In the context of Lewis acids, species like BF3 are electron-deficient due to the presence of an empty p-orbital, which enhances their ability to act as Lewis acids compared to those with a complete octet, like BH3.
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03:56Electron Geometry
Molecular Geometry and Hybridization
The molecular geometry and hybridization of a compound influence its reactivity and acid-base behavior. BF3 has a trigonal planar geometry with sp2 hybridization, which allows for effective orbital overlap when accepting electron pairs. In contrast, BH3, with its similar geometry, is less electron-deficient, making BF3 the stronger Lewis acid in this comparison.
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03:06Hybridization and Electron Geometry
Related Practice
Open Question
For each of the Lewis acid–base reactions in Problem 16.139, draw electron-dot structures for the reactants and products, and use the curved arrow notation to represent the donation of a lone pair of electrons from the Lewis base to the Lewis acid.
Textbook Question
Classify each of the following as a Lewis acid or a Lewis
base.
(e) OH-
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Textbook Question
Calculate the pH and the concentrations of all species present
(H3O+ , F-, HF, Cl-, and OH-) in a solution that contains
0.10 M HF 1Ka = 3.5 * 10-42 and 0.10 M HCl.
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views
Textbook Question
When NO2 is bubbled into water, it is completely converted
to HNO3 and HNO2:
2 NO21g2 + H2O1l2S HNO31aq2 + HNO21aq2
Calculate the pH and the concentrations of all species present
(H3O+ , OH-, HNO2, NO2
-, and NO3
-) in a solution
prepared by dissolving 0.0500 mol of NO2 in 1.00 L of
water. Ka for HNO2 is 4.5 * 10-4.
973
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Open Question
Normal rain has a pH of 5.6 due to dissolved atmospheric carbon dioxide at a current level of 400 ppm. Various models predict that burning fossil fuels will increase the atmospheric CO2 concentration to between 500 and 1000 ppm by the year 2100. (a) Calculate the pH of rain in a scenario where the CO2 concentration is 750 ppm. CO2 reacts with water to produce carbonic acid according to the equation: CO2(aq) + H2O(l) ⇌ H2CO3(aq). Assume all the dissolved CO2 is converted to H2CO3. Acid dissociation constants for H2CO3 are Ka1 = 4.3 * 10^-7; Ka2 = 5.6 * 10^-11. (Worked Example 16.11 is a model for this calculation.) (b) Will rising CO2 levels affect the acidity of rainfall?