Concept explainers
A hydrogen atom in the organic base pyridine, C5H5N, can be substituted by various atoms or groups to give XC5H4N, where X is an atom such as Cl or a group such as CH3. The following table gives Ka values for the conjugate acids of a variety of substituted pyridines.
- (a) Suppose each conjugate acid is dissolved in sufficient water to give a 0.050 M solution. Which solution would have the highest pH? The lowest pH?
- (b) Which of the substituted pyridines is the strongest Brønsted base? Which is the weakest Brønsted base?
(a)
Interpretation:
The conjugate acid which have the highest
Concept Introduction:
The
Higher the value of
Answer to Problem 112IL
The solution containing
Explanation of Solution
An equilibrium constant
For Any acid HA,
The relative strength of an acid and base in water can be also expressed quantitatively with an equilibrium constant as follows:
An equilibrium constant
Given:
The
Initial Concentration of each solution is
Set up an ICE table for the reaction of
Substitute the values in equation (2) to calculate
Substitute the value of
The value of
Substitute the value of hydronium ion concentration in equation (1) to calculate the value of
Therefore, the value of
Similarly, Substitute the value of
The value of
Substitute the concentration of hydronium ion in equation (1) to calculate the value of
Therefore, the value of
Substitute the value of
The value of
Substitute the concentration of hydronium ion in equation (1) to calculate the value of
Therefore, the value of
Substitute the value of
The value of
Substitute the concentration of hydronium ion in equation (1) to calculate the value of
Therefore, the value of
The solution containing
(b)
Interpretation:
Strongest
Concept Introduction:
A conjugate acid-base pair contains two compounds that differ only by a hydrogen ion and a charge of
The stronger the acid, the weaker its conjugate base and vice-verca. That is, the larger the values of
Answer to Problem 112IL
The strongest bronsted base is
Explanation of Solution
The dissociation of
A small value of
The dissociation of
A large value of
The strongest bronsted base is
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Chapter 16 Solutions
Chemistry & Chemical Reactivity, Hybrid Edition (with OWLv2 24-Months Printed Access Card)
- Pure liquid ammonia ionizes in a manner similar to that of water. (a) Write the equilibrium for the autoionization of liquid ammonia. (b) Identify the conjugate acid form and the base form of the solvent. (c) Is NaNH2 an acid or a base in this solvent? (d) Is ammonium bromide an acid or a base in this solvent?arrow_forwardHydrazine, N2H4 (having the structure H2NNH2), and its derivatives have been used as rocket fuels. Draw the Lewis electron-dot formula for the hydrazine molecule. Describe the geometries expected about the nitrogen atoms in this molecule. Why would you expect hydrazine to be basic? Which substance, NH3 or N2H4, would you expect to be more basic? Why? Write the chemical equation in which hydrazine reacts with hydrochloric acids to form the salt N2H5Cl. Consider the positive ion of this salt. How does its basic character compare with that of NH3 and N2H4? Explain.arrow_forwardFor oxyacids, how does acid strength depend on a. the strength of the bond to the acidic hydrogen atom? b. the electronegativity of the element bonded to the oxygen atom that bears the acidic hydrogen? c. the number of oxygen atoms? How does the strength of a conjugate base depend on these factors? What type of solution forms when a nonmetal oxide dissolves in water? Give an example of such an oxide. What type of solution forms when a metal oxide dissolves in water? Give an example of such an oxide.arrow_forward
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